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Marine Biological Laboratory Library 

Woods Hole, Mass. 

Presented by 

The ThoDdst Press 
Jime 26, 1962 




f CO 


Studies in the Philosophy of Science /^^^^t^r^^^ 

'^» '^ 

presented to Z^;; Jijs« A3IY) 

^ •^' 




in collaboration with 



Preface by Michael Browne, O. P., S. T. M. 



Originally published as a 



Volume XXIV, Nos. 2, 3, & 4 

April, July, October 




Introduction by James A. Weisheipl, O. P. 

Copyright, 1961 

Dominican Fathers, Province of St. Joseph 

Cum permissu sujperiorura 

Library of Congress Catalog Card Number: 61-15888 


Printed in U. S. A. 




Letter of the Master General, Michael Browne, O.P., 

S.T.M, Ph.D V 

Introduction: The Dignity of Science xvii 

By James A. Weisheipl, O.P., D.Phil. (Oxon.) 


Demonstration and Self-Evidence 3 

By Edward D. Simmons, Ph.D. (Marquette Univ.) 

The Significance of the Universal ut nunc 27 

By John A. Oesterle, Ph.D. (Univ. of Notre Dame) 

William Harvey, M.D.: Modern or Ancient Scientist? 39 

By Herbert Ratner, M.D. (Loyola Univ., Chicago) 



Medicine and Philosophy in the Eleventh and Twelfth Cen- 
turies: The Problem of Elements 75 
By Richard P. McKeon, Ph.D. (Univ. of Chicago) 

The Origins of the Problem of the Unity of Form . 121 

By Daniel A. Callus, O.P., S.T.M., D.Phil. (Oxford 
Univ., England) 





The Celestial Movers in Medieval Physics 150 

By James A. Weisiieipl, O.P., Ph.D., D.Phil. (River For- 
est, 111.) 

Gravitational Motion according to Theodoric of Freiberg 191 

By William A. Wallace, O.P., Ph.D., S.T.D. (Dover, 

' Mining All Within ': Clarke 's Notes to Rohault's Traite de 

Physique 217 

By Michael A. Hoskin, Ph.D. (Cambridge Univ., Eng- 


Darwin's Dilemma 231 

By Charles DeKoninck, Ph.D. (Universite Laval, 

4)Y5I2: The Meaning of Nature in the Aristotelian Philos- 
ophy of Nature 247 

By Sheilah O'Flynn Brennan, Ph.D. (St. Mary's Col- 
lege, Notre Dame) 

Order in the Philosophy of Nature 266 

By Melvin Glutz, C.P., Ph.D. (Passionist Monastery, 

Motionless Motion 283 

By Roman A. Kocourek, Ph.D. (College of St. Thomas, 
St. Paul) 

Time, The Measure of Movement 295 

By Sister M. Jocelyn, O.P., Ph.D. (Rosary College, River 




Evolution and Entropy 305 

Bj^ Vincent E. Smith, Ph.D. (St. John's Univ., Jamaica, 


From the Fact of Evolution to the Philosophy of Evolutionism 327 
By Raymond J. Nogar, O.P., Ph.D. (River Forest, 111.) 

The Rhythmic Universe 366 

By Sister Margaret Ann McDowell, O.P., M.S., Ph.D. 
(St. Mary of the Springs, Columbus) 

Mind, Brain, and Biochemistrys 383 

By Albert S. Moraczew^ski, O.P., Ph.D. (Texas Medical 
Center, Houston) 

Conscience and Superego 408 

By Michael Stock, O.P., Ph.D. (Dover, Mass.) 



Contemporary Challenge to the Traditional Ideal of Science . 447 
By Ambrose McNicholl, O.P., Ph.D. (Angelicum, Rome) 

A Social Science Founded on a Unified Natural Science . . 469 
By Benedict M. Ashley, O.P., Ph.D. (River Forest, 111.) 

The Role of Science in Liberal Education 486 

By Sister M. Olivia Barrett, R.S.M., Ph.D. (St. Xavier 
College, Chicago) 

American Catholics and Science 503 

By Patrick H. Yancey, S.J., Ph.D. (Spring Hill College, 

Notes on Our Contributors 521 

The Writings of William Humbert Kane, O.P. ... 524 




Roma, (8-48) 

Convento S. Sabina (Aventino) 




It was with great pleasure that we learned of this special 
occasion to honor the Very Reverend William Humbert Kane, 
O. P., founder of The Albertus Magnus Lyceum at River Forest, 
Illinois. We were particularly pleased to hear that this homage 
on the part of brethren and Sisters of our Order as well as 
religious of various other Orders and a host of eminent laymen 
transcended nationalities and provincial boundaries. It is only 
by cooperative effort among learned men that the sublime ideal 
of St. Albert the Great can be realized in a troubled world. 

No one can view recent developments in atomic physics 
without grave concern not only for the future of humanity, 
but also for the very scientists who have merited the respect 
of their peers and the admiration of the masses and withal have 
come to feel a certain uneasiness of their own consciences. 

Scientists have become accustomed to the adulation of the 
general public. This adulation, growing with every new dis- 
covery, led them to spurn the traditional channels of wisdom, 
and to close their eyes ever more to the legitimate claims of 
supernatural religion, moral principles, perennial philosophy, 
and other elements of culture which contribute to a truly 
human life. In the nineteenth century certain specialists in a 
particular branch of physics, chemistry, biology or psychology 



were willing to be considered the oracles of all human wisdom. 
The narrow confines of a specialized branch of natural science, 
as we know, provided no vantage point. Consequently, what- 
ever could not be comprehended by the specialized principles 
was misinterpreted, ridiculed or rejected. However, recent 
developments within many branches of science have shaken 
these imprudent positions. From the turn of the century to 
the present day an ever increasing number of scientists have 
found themselves asking questions which formerly were looked 
upon by them as purely " philosophical." 

Pope Leo XIII saw clearly that all social errors, and conse- 
quently a large part of social evils, are ultimately traceable to 
false philosophical principles. These are as erroneous today as 
they were in the nineteenth century. Throughout his encyclicals 
he used the principles of St. Thomas Aquinas, that " prince and 
master " of all Scholastic doctors, to analyze prevailing thought 
and to outline the rehabilitation of Christian society. In his 
immortal encyclical Aeterni Patris he observed: " If anyone 
will but turn his attention to the sad condition of our times, 
and contemplate thoughtfully the state of things which exists 
publicly and privately, he will surely perceive that the fertile 
cause of the evils which actually surround us, or of which we 
fear the coming, consists in this, that the wicked maxims on 
divine and human things which have recently sprung from the 
schools of the philosophers have invaded all classes of society, 
and are approved by a very great number." ^ Consequently, 
he urged all Bishops, teachers and students " to restore the 
illustrious system of St. Thomas Aquinas to its former glory " 
that the coming generations may nourish themselves " abun- 
dantly from those purest streams of wisdom that flow from the 
Angelic Doctor, as from an inexhaustible and precious foun- 
tain." " That same pontiff in the year 1880, by his Apostolic 
Letter Cum hoc sit,^ made and declared Thomas Aquinas, 
" who ever shone as the sun in his doctrine and virtue," the 
heavenly patron of all Catholic schools, commending him 

^ AAS, XII (1879) , 98. ' Ibid., p. 112. =* AAS, XIII (1880) , 56-59. 


especially as the guardian, leader and master of philosophical 
and theological studies.* The call of Pope Pius XI, Ite ad 
Thomam, rings as clear today as it did in 1923 when he 
addressed Studiorum Ducem to the whole Catholic Church/ 
In more recent times, a deep need was felt by many for a 
heavenly patron in the natural sciences. In the solemn Decree 
Ad Deum of December 16, 1941, the late Pope Pius XII wrote: 
" It is no wonder, then, that the universities and the more 
important Catholic colleges, not only in Italy, but in Germany, 
France, Hungary, Belgium, Holland, as well as in Spain, 
America and the Philippine Islands, besides numbers of pro- 
fessors of physics and other natural sciences, at the present time 
look upon Albert the Great as a beacon shining in a world 
engulfed in gloom. To make sure of the help of Almighty God in 
their exacting researches into the world of nature, they eagerly 
desire to have for their guide and heavenly intercessor him who, 
even in his own day, when many, puffed up with a hollow 
science of words, were turning their eyes away from the things 
of the spirit, has taught us by his example how we should rather 
mount from the things of earth to the things above." ^ Speaking 
of the important role played by Our own predecessor. Father 
Martin S. Gillet, the late Holy Father continues: " It is, there- 
fore, with sentiments of deepest pleasure that we accede to the 
wish expressed by the Catholic Academicians at their recent 
convention in Trier, by universities and by other international 
gatherings of scientists, and brought to Our notice by the 
Master General of the Order of Friars Preachers, who, on behalf 
of himself and of the Order over which he presides, adds a 
fervent plea that We may deign to constitute Saint Albert the 
Great the heavenly Patron of students of the natural sciences." ^ 
The Decree Ad Deum, constituting Albert the heavenly Patron 
of those who cultivate the natural sciences, was issued on the 

* Cf. Letter of Pius XII to Martin Stanislaus Gillet, March 7, 1942. AAS, XXXIV 
(1942), 89. 
^ AAS, XV (1923), 323. 
"AAS, XXXIV (1942), 90. 
' Ibid. 


tenth anniversary of the Decree In thesauris sapientiae by 
which Pope Pius XI enjoined upon the universal Church the 
veneration of Saint Albert the Great, Bishop and Confessor, 
with the additional title of Doctor.^ 

We have watched with paternal concern the growth of The 
Albertus Magnus Lyceum at the Pontifical Faculty of Phi- 
losophy in River Forest, Illinois. Since its small beginnings in 
the Autumn of 1950 under the inspiration of Father Kane and 
the support of the Very Reverend Edward L. Hughes, at that 
time Provincial of the Province of St. Albert the Great, it has 
grown in wisdom and prestige. This growth has taken place to 
a great extent under the care of the Very Reverend Edmund J. 
Marr, Provincial of the Province of St. Albert the Great. We 
have been particularly pleased to observe the devotion of its 
members to the solid principles of St. Thomas and St. Albert, 
and at the same time the concern of its members with vital 
problems of modem science. Problems such as the relation of 
Thomistic philosophy to modern science, the foundations and 
nature of modern science, the true constitution of matter, the 
biological problem of evolution as distinct from evolutionism, 
the validity of depth psychology, the influence of physiological 
and biochemical factors on mental diseases and many other 
problems, cannot be solved without the mutual cooperation of 
well trained minds. The Albertus Magnus Lyceum has grad- 
ually enlisted the cooperation of Our sons in other Provinces, 
the cooperation of Our Sisters of various communities, and most 
important, perhaps, it has enlisted the cooperation of eminent 

We are aware that the inspiration for the Lyceum was due 
in large measure to the vision and zeal of its founder, Father 
Humbert Kane. Despite many difficulties and obstacles, he 
saw the need of cooperation within a specially recognized 
institute, and he did not falter. It is indeed a happy coinci- 
dence that the tenth anniversary of The Albertus Magnus 

«AAS, XXIV (1932), 5-17. 


Lyceum should coincide with the sixtieth anniversary of the 
birth of its founder. 

We take this opportunity to impart our paternal blessing to 
Father Humbert Kane, on the occasion of his sixtieth birthday, 
and to The Albertus Magnus Lyceum, founded by him ten 
years ago. We ask the blessing of St. Thomas Aquinas and 
of St. Albert the Great for all his associates concerned with 
problems of philosophy and science. 

Given at Rome, from the Convent of Santa Sabina, on the 
Feast of St. Margaret of Hungary, V. O. P., January 19, 1961. 


Fr. Michael Browne, 0. P. 
Master General 


The Dignity of Science 

WHEN the first atomic bomb struck the populous 
seaport capital of Hiroshima on August 6, 1945, the 
entire civilized world was profoundly shocked at 
the horror unleashed by science. Ordinary citizens and inter- 
national leaders recoiled at the awful potential of the atomic 
bomb. Science no longer meant the production of useful gad- 
gets, discovery of effective drugs, or development of quicker 
and better means of communication. It meant something much 
more, something that affects human consciences and destiny. 
The moral issues involved in the Hiroshima bombing and in 
nuclear warfare in general have been widely discussed, some- 
times with considerable vehemence. But even apart from the 
moral issues, it is clear to many today that scientific progress 
has reached a precarious ledge in its lofty climb. Careful 
maneuvering along the ledge can indeed lead to still further 
heights. It is the sight of some new height still to be conquered 
that urges the scientist, as well as the mountain climber, for- 
ward with confident step. But a single misstep at such heights 
could bring on a landslide or a plunge to final doom. The 
alternatives are clear, and have been clear since Hiroshima: 
the possibility of further progress or the annihilation of civili- 
zation. Henceforth mankind has to work out its salvation in 
the shadow of the mushroom cloud. 

The successful launching of Sputnik I in October of 1957 
threw government departments, military officers, scientists, 
educators and journalists into panic. Incredible as it seemed, 
the Soviet Union had overtaken the United States in missile 
thrust and guidance systems. American prestige dropped, par- 
ticularly in uncommitted countries; investigations were begun 
into the so-called " missile lag," and educators hastened to build 



up the science program in schools of all sizes. Despite the fact 
that Soviet students of science are thoroughly indoctrinated 
with the philosophy of Dialectical Materialism, some American 
educators urged diminishing, and eliminating if possible, courses 
in the humanities in a frantic effort to produce more trained 
scientists. The panic instilled by Sputnik I almost obliterated 
the vision and hope of wiser educators: the molding of a human 
being, whether he be a theoretician or a technician. Before 
Sputnik I many educators realized the inherent danger to 
society and to the individual of excessive specialization, which 
neglects history, literature, culture, sound philosophy, religion 
and even ordinary grammar. These educators tried to give 
potential scientists an appreciation of the real dignity of science 
through the history of science, the philosophy of science, or a 
study of the Great Books of mankind. Because of Sputnik I 
this movement has suffered a temporary set-back. Perhaps 
after the fear and panic have subsided, there may still be the 
possibility of educating human beings intelligently devoted to 
science, rather than technicians unaware of the dignity of their 

Long before the atom bomb came to the attention of the 
ordinary man, an important revolution had been taking place 
within science itself, a theoretical revolution which, in fact, 
made the atom bomb possible. The story of this transition from 
the mechanical age of physics to the age of relativity and 
quantum mechanics has been written many times in this gener- 
ation. The path which leads from Clerk Maxwell's hypothesis 
identifying magnetic and luminiferous media to the theories of 
relativity and quantum was constructed by many experimental 
and theoretical physicists. It is a path which leaves far behind 
the assurances of Newtonian solids in a void, the fallacy, as 
Whitehead called it, of " misplaced concreteness." The tran- 
sition from classical mechanics to the two principal theories 
of modem physics, relativity and quantum, had an unsettling 
effect on philosophers of physical theory. Before the end of the 
nineteenth century Carl Neumann, Ernst Mach and Karl Pear- 


son had already perceived some of the weaknesses of Newton- 
ian axioms and some of the ambiguities in Newtonian concepts. 
But they were not wilHng to reject the basic theory of New- 
tonian science. Even after Planck's paper of 1900 and Einstein's 
theory of 1905, theoreticians of science, such as Henri Poincare 
and Pierre Duhem, were unwilling to reject Newtonian prin- 
ciples as erroneous. Instead they conceived all scientific theories 
as conventional constructs and approximations of the truth. A 
scientific theory may be induced from experimental data; its 
predictions may be verified in every detail. But, for Poincare 
and Duhem, the theory was only one way out of many for 
interpreting the data; it was an hypothetical approximation. 
The same data could be interpreted with equal verification by 
other hypotheses. The irreconcilability of relativity theory and 
quantum mechanics, as well as the wave and particle theories 
of light, gave much weight to this interpretation of scientific 

Later authors, it is true, have considered Poincare's interpre- 
tation of science and hypothesis to be somewhat naive and over- 
simplified, and they have rejected certain details of his conven- 
tionalism {commodisme) . Nevertheless, the fundamental ele- 
ments of his view have been incorporated into the generally 
accepted theory of science today. His insistence on the hypo- 
thetical character of scientific theory has, in fact, been extended 
by modem theoreticians beyond the limits intended by Poin- 
care himself. He was willing to grant certainty at least to the 
first principles of scientific investigation and to other types of 
knowledge. Obviously, he did not reduce his own philosophical 
speculations to the status of mere convention and hypothesis. 
In the currently accepted view of scientific knowledge, ex- 
pounded in philosophies of science, there are three fundamental 
points which ought to give us pause. (1) It insists that no 
scientific knowledge can be taken as absolutely certain, that 
is, without an intrinsic doubt concerning its alterability. The 
hypothetical character of all scientific knowledge, it is said, 
requires that we accept current scientific knowledge on a tenta- 


tive basis only. (2) It insists that all true knowledge must be 
' scientific,' and therefore hypothetical. This means that even 
the first principles of scientific investigation must be regarded 
as hypothetical and tentative. (3) It restricts ' scientific knowl- 
edge ' to investigations modeled on, and employing the scien- 
tific method of modern physics. This means that the various 
branches of speculative and practical philosophy, theology, 
history and so forth are not at all scientific, while biology, 
psychology, anthropology and sociology deserve the name of 
' science ' only insofar as they employ the unique ' scientific 
method ' of physics. 

Here is not the place to controvert these fundamental points. 
However, a brief comparison of modem scientific theory with 
the scientific optimism of Aristotle and the ancients is most 
revealing. Modern theoreticians apparently have abandoned 
hope in the power of man's speculative reason; they seem to be 
content with universal uncertainty and a solitary path to knowl- 
edge. Whatever may be said of Aristotle's science, he was, at 
least, much more confident in the powers of human reason and 
more appreciative of the dignity of scientific knowledge. (1) 
The tentative status of hypotheses and theories proposed by 
modem theoreticians falls far short of Aristotle's ideal of scien- 
tific knowledge. Science, for Aristotle, is the attainment of true 
and certain causes within reality. Such causes are, of course, 
discovered only after careful research and analysis. Whatever 
hypotheses, theories or suspicions one may have during the 
investigation, they are not to be confused with genuine science. 
Such hypotheses are indispensable and inevitable, but they are 
only means to the ultimate goal of scientific explanation. (2) 
Aristotle's lofty, and perhaps unattainable, ideal of scientific 
knowledge did not blind him into thinking that all true knowl- 
edge must be of this type. Defending the dignity of science 
against the skeptics of the Academy on the one hand, and pro- 
testing the universality of science on the other, Aristotle saw 
that not all knowledge can be ' scientific,' that is, demonstrable, 
for then there would be no beginning. He insisted that the 


starting point of scientific investigation must be prior and more 
certain than the torturous path leading to a true solution. This 
starting point is the light of absolutely first principles, known 
with certainty before all scientific demonstration. The complex 
process of investigating nature was recognized as extremely 
difficult, but Aristotle did not think it hopeless. There is the 
security of an immoveable starting point. (3) For Aristotle the 
investigation of nature occupied a preeminent place in the 
pursuit of knowledge; he himself devoted most of his life to it. 
But he did not claim this as the only pursuit of mankind. Even 
in the study of the world and man Aristotle recognized various 
approaches, each of which is legitimately called ' science.' In 
other words, ' science ' is an analogical term, and its dignity 
requires that it be recognized in its diversity and complemen- 
tarity. The pluralist approach to reality respects the principles, 
method and limitations of each legitimate endeavor. No one 
branch can be erected into a monolithic idol without destroying 
the integrity of truth and the dignity of science. 

The warfare between scientists and religion cannot be sub- 
dued for long. This is not because of any intrinsic incompati- 
bility between science and true religion, but because of the third 
point mentioned above. If the scientist refuses to acknowledge 
any theories other than those proposed by his own method, con- 
flicts are bound to break out periodically. Today the conflict 
is most evident in the conception some neo-biologists have of 
evolution on the one hand, and the testimony of sound phi- 
losophy and revelation on the other. This was evident in the 
Darwin Centennial held at the University of Chicago in 1959. 
Some biologists claimed the triumph of science over revelation, 
since evolutionary theory now proves that man is no more than 
a form of evolved matter, and religion a superstition. Even 
apart from the embarrassing fact that the methodology of pre- 
history is far removed from that of modern physics, we might 
pause to marvel at this strange note of triumph. Man is no 
more than the beast, the weed, the puff of air! Rejoice! Man 
is not very much after all! Dialectical Materialism has been 


saying this for over a century. Will there be no voice to defend 
the nobility of man and the dignity of science? 


We have every right to expect Catholic philosophers and 
scientists to enter the arena in defence of human dignity, be- 
cause they know from revelation and the perennial philosophy 
that man's soul is spiritual, made to the image and likeness of 
God. We also expect Catholic philosophers and scientists to 
make positive contributions to science and its theoretical foun- 
dations. In other words, we expect Catholic philosophers and 
scientists to appreciate the true dignity of scientific knowledge 
and research — not because they might be more gifted, but 
because they have the advantage of the true faith and the 
resources of a philosaphia perennis. This does not mean that 
Catholics are in a position to judge scientific details a priori, 
or without careful study. Scientific research and analysis are 
laborious occupations for everyone, Catholic and non-Catholic; 
and progress in scientific knowledge is a result of cooperative 
effort, utilizing every means at one's disposal. Nevertheless, 
Catholics start out with the assurance that the truths revealed 
by God are absolutely certain and that no truth discoverable by 
science can contradict them. These revealed truths include 
both supernatural realities beyond the scope of reason and 
certain natural realities within the competence of reason and 
science, such as the existence of God and the immortality of 
the human soul. Further, the Catholic starts with the assurance 
that all truth is from God and can lead back to Him if the 
whole pattern of reality is considered. Finally, the Catholic 
has at his disposal a font of ancient wisdom which Leo XIII 
called the philosophia perennis. This perennial philosophy, of 
course, is not a matter of divine revelation; nor does it pretend 
to contain all the answers. But it does propose true answers 
to some of the more basic questions of science and human life, 
answers which can be evaluated by natural reason, and which 
can be accepted as a starting point for further serious investiga- 


tion. Even the method whereby fruitful investigation can be 
continued today is to be found in the perennial philosophy of 
the ancients. Only an unreasonable or prejudiced thinker would 
dismiss this wisdom of the ancients without fair study. An 
ancient truth does not cease to be true just because it is ancient. 
Nor does the perennial philosophy cease to be philosophy just 
because someone else thought of it first. 

When Leo XIII called for the restoration of the philosophia 
perennis in Catholic schools, he explicitly desired this to be the 
light by which modern problems of natural science, social 
ethics and metaphysics are to be worked out. " Even physics, 
the study which is now held in such high esteem, and which by 
its many wonderful discoveries has secured to itself everywhere 
special admiration, will not only receive no detriment but a 
powerful help from the restoration of the ancient philosophy." 
Leo XIII pointed out that the consideration of facts and the 
observation of nature are alone not sufficient for the fruitful 
appreciation and advancement of natural science. One needs 
discussion of more fundamental questions of science, reflection 
on the data obtained, synthesis of various aspects, analysis of 
scientific theory itself and epistemological evaluation in the 
light of human knowledge as a whole. " To these investigations 
it is wonderful what light and powerful aid is afforded by 
scholastic philosophy, if it be wisely handled." The examples 
of St. Thomas Aquinas and Blessed Albertus Magnus were pro- 
posed to modern investigators of nature by Pope Leo. Over 
half a century later Pope Pius XII gave modern scientists St. 
Albert the Great for their heavenly patron, " in order that stu- 
dents of the natural sciences, bearing in mind that he had been 
given them as their guide, might follow in his footsteps and not 
cling too tightly to the investigation of the fragile things of this 
life, nor forget that their souls are meant for immortality, but 
use created things as rungs in a ladder that will elevate them 
to understand heavenly things and take supreme delight in 

Leo XIII had ordered the restoration of scholastic philoso- 


phy, particularly that of St. Thomas Aquinas, in all centers 
of Catholic learning — seminaries, colleges, institutes and uni- 
versities — that Catholic intellectuals might contribute to the 
solution of modern problems. The carrying out of this directive 
was a difficult task. There are some observers today who claim, 
with considerable justification, that the Leonine directive has 
never been earned out fully even to this day. However, there 
were special difficulties in the 1880's. Scholastic philosophy was 
a philosophy, and ' philosophy ' since the time of Leibniz and 
Wolff meant metaphysics and ethics. Metaphysics, for Wolff 
and his innumerable disciples, was divided into general ontology 
and special ontology, embracing cosmology, psychology and 
theodicy. Consequently some Catholics fancied that Thomistic 
philosophy had to be truncated to fit the Procrustean bed of 
Wolffian metaphysics. Furthermore, the acquisition of scien- 
tific knowledge is a difficult task, requiring special training and 
devotion. Professional philosophers in seminaries and universi- 
ties could hardly be expected to acquire detailed knowledge of 
highly developed sciences. Consequently it seemed more ex- 
pedient to let science alone and concentrate on a metaphysical 
type of cosmology and rational psychology. 

The first university to attempt to fulfill the wishes of Leo 
XIII was the Catholic University of Lou vain. In a papal brief 
of December 25, 1880, the bishops of Belgium were directed to 
establish a chair of Thomistic philosophy. By July, 1882, 
arrangements had been made with the University, and Canon 
Desire Mercier, professor of philosophy at the Seminary of 
Malines, was appointed to the chair. To prepare himself for 
this new and unique post. Dr. Mercier (with beard and with- 
out clerical garb) undertook formal training in psychology 
under the famous Charcot in Paris. At Louvain he followed the 
formal courses and laboratory work in physiology, neurology, 
chemistry, mathematics and linguistics. He was convinced that 
no domain of modem science can be considered foreign to 
Thomistic philosophy. In 1888 Msgr. Mercier founded, with 
the enthusiastic approval of the pontiff, the Institut Superleur 


de PhUosophie, or Ecole saint Thomas d'Aquin. Outlining the 
program of the Institut, Msgr, Mereier said, " The science of 
today is above all a science of the most exact individual re- 
search. . . . Let us train, in greater numbers, men who will 
devote themselves to science for itself, without any aim that is 
professional or directly apologetic, men who will work at first 
hand in fashioning the materials for the edifice of science." The 
new Institut was to be a center of study and research where 
work would be done on " science in the making." Msgr. Mereier 
accepted the tripartite division of speculative knowledge ex- 
plained by St. Thomas: natural philosophy, mathematics and 
metaphysics. Natural philosophy and experimental science 
constituted a unified discipline of mind, quite distinct from 
metaphysics. But, as Mereier expressed it, Thomistic natural 
philosophy seeks ' ultimate ' causes (projiter quid) , while ex- 
perimental science seeks ' proximate ' causes (quia) . Mercier's 
distinction, which was accepted by his distinguished associates, 
Michotte and Nys, is still found in many modem manuals of 
scholastic philosophy. 

The influence of Mereier was very great, both at Louvain and 
elsewhere. The example of Louvain was soon followed by the 
Catholic institutes and universities of Munich, Milan, Paris, 
Cologne, Miinster, Fribourg, Nijmegen, the " Gregorian," the 
" Angelicum " and the Catholic University of America. 

After the death of Cardinal Mereier in 1926, a number of 
Louvain professors under the inspiration of Femand Renoirte 
have come to see a sharp distinction between the non-causal 
explanations of modern science and the causal explanations of 
Thomistic philosophy. For them St. Thomas' natural philoso- 
phy seems to be of the metaphysical order and different from 
the technique of modern science. In effect, this was a return 
to the Wolffian conception of philosophy, although today it is 
presented as the authentic teaching of St. Thomas. Alumni of 
Louvain have made this view widely known in the Netherlands 
and in the United States. According to this view the philosophy 
of nature is a metaphysical study, differing essentially from the 


experimental sciences, because it reaches " a level of thought in 
which no sense-perceptible element is retained and therefore no 
verification by the senses is possible." In " support " of this 
view, proponents invariably quote, out of context, a passage 
from St. Thomas' In Boethium De trinitate, q. 5, a. 1 ad 6. 
However, apart from the impossibility of justifying this view in 
the writings of St. Thomas, St. Albert or any of the schoolmen, 
it seems to be unsatisfactory for many reasons. It is based on 
what seems to be a misconception of metaphysics; it apparently 
ignores the genesis of analogical concepts; and it widens the 
chasm between philosophy and science, returning to the in- 
soluble situation of Wolffian Idealism. It denies the dignity of 
natural science by giving it too little intellectual content, and 
it denies the dignity of natural philosophy by rarefying it be- 
yond sense contact. There is no doubt that the physical uni- 
verse can be studied ' metaphysically,' but only at the expense 
of those very details of interest to the natural philosopher. The 
universe which interests the natural philosopher is full-blooded, 
and quite un-metaphysical. 

A more realistic approach to the relation of philosophy to 
science was made by Jacques Maritain in his monumental 
Distinguer pour JJnir: ou Les Degres dii Savoir (1932) and in 
his detailed La Philosophie de la Nature of 1935. This dis- 
tinguished Thomist learned contemporary philosophy from 
Henri Bergson and biology from Hans Driesch before finding 
his home in Thomism. First, Maritain accepts the traditional 
division of speculative philosophy into natural philosophy, 
mathematics and metaphysics. Second, he realizes that the 
experimental sciences have developed greatly since the time of 
Aristotle and St. Thomas Aquinas. Third, he examines modem 
' science ' and sees that it is not a homogeneous whole; in fact, 
it includes two specifically different types of knowledge. One 
type is formally mathematical, even though empirical. This 
type Maritain calls eTnpiriometrique, because it is concerned 
solely with the measurable aspect of empirical observation. 
This concern is characteristic of all parts of modern physics 


and a great part of modern chemistry. However, for Maritain, 
this type of knowledge was familiar to Aristotle and St. Thomas 
as scientiae mediae between pure mathematics and natural phi- 
losophy. The second type of knowledge found in modem science 
is essentially empirical, descriptive of phenomena, ' perinoetic ' 
and somewhat hypothetical in character. This type Maritain 
calls empirioschematique, because it is concerned solely with 
ordering empirical observation by means of non-mathematical 
constructs. This concern is characteristic of such experimental 
sciences as biology, botany, anthropology, physiology, neu- 
rology and psychology. Finally, Maritain comes to reconciling 
his analysis of modern science with the traditional division of 
speculative knowledge. The empiriometric sciences present no 
difficulty, since they are scientiae mediae between mathematics 
and the first degree of abstraction. The empirioschematic sci- 
ences, however, present a problem. They do not attain the 
essential natures of material things; they are rather descriptive, 
hypothetical and superficial (perinoetic) . Aristotle's natural 
philosophy, on the other hand, intuitively attains the essential, 
ontological natures of changeable being; it is ' dianoetic,' pro- 
found and certain. Therefore Maritain suggests that Aristo- 
telian natural philosophy and modem empirioschematic science 
belong to two dift'erent levels of intelligibility within the tradi- 
tional first degree of abstraction, the former resolving its 
definitions to ' being,' the latter to sense and ' mobility.' The 
view of Jacques Maritain, therefore, is similar to that of Car- 
dinal Mercier, except . that Maritain alone accounts for the 
unique position of physics in modern science. 

There is no denying the acumen of M. Maritain's analysis 
and the astuteness of his solution. There is only one difficulty: 
if the empirioschematic sciences are as superficial and hypo- 
thetical as Maritain believes, then they are not sciences at all, 
but only dialectical preparations for science. Scientific knowl- 
edge, as understood by Aristotle and St. Thomas, consists in 
true demonstration, that is, a causal explanation of essential 
properties. But this is impossible without dianoetic knowledge 


of essential natures. In other words, without knowledge of the 
essential nature of the subject and the property, there can be 
no demonstration; there can be no scientific knowledge properly 
so called. The anomaly of M. Maritain's position is that he 
reconciles modern empirioschematic science with Thomistic 
philosophy of nature by depreciating modern science. Un- 
doubtedly there are many areas of modern ' science ' which are 
superficially descriptive, tentative and dialectical in content. 
If, on the other hand, there are areas of modern science which 
truly attain essential natures and through them demonstrate 
characteristic attributes, as often seems to be the case in the 
biological sciences, then the situation is very different from that 
presented by M. Maritain. 

A better solution was recognized by Fr. Aniceto Fernandez- 
Alonso, O. P. In 1936 he published a remarkable paper entitled 
" Scientiae et Philosophia secundum S. Albertum Magnum." 
Examining the scholastic scene of the 1930's, Fr. Fernandez 
saw that all scholastics wished to recognize a real distinction 
between modem science and Aristotelian philosophy. This dis- 
tinction was variously described as one of content (accidental 
relations vs. substantial essences, phenomena vs. noumena, 
sensible vs. intelligible) or one of method (inductive vs. de- 
ductive, proximate causes vs. ultimate causes, quia demonstra- 
tions vs. propter quid demonstrations) . Fr. Fernandez then 
went on to show that none of these can differentiate the specu- 
lative sciences, for every science, whether it be called empirical 
or philosophical, must deal with substance and accidents, must 
be intelligible and sensible; further, every science must be in- 
ductive and deductive, must demonstrate through immediate 
(propter quid) and remote (quia) causes. Fr. Fernandez's 
own view can be summarized briefly in three propositions, each 
of which he proves at great length. (1) All modern science and 
all natural philosophy are specifically distinct from metaphysics. 
(2) All sciences formally illuminated by mathematical prin- 
ciples are specifically distinct from sciences of nature, although 
materially they all study the same physical universe. (3) Aris- 


totelian natural philosophy and the so-called empirical, or 
experimental sciences constitute one specific discipline, both 
materially and formally: they are two parts of one and the 
same science concerning ens mobile, and each part has need of 
the other. These propositions are all justifiable according to 
the principles of Albertus Magnus. Fr. Fernandez concludes his 
study by saying, " The division of human knowledge into philo- 
sophic and scientific as into two species necessarily and always 
distinct by the very nature of the objects and the formal inde- 
pendence of one from the other is an assertion which can be 
made in Platonic, Cartesian, Hegehan and Bergsonian philoso- 
phy, but cannot be made in Aristotelian or Albertine philoso- 
phy, nor according to the truth of the matter." 

Today the view of Fr. Fernandez is defended by the Very 
Reverend William Humbert Kane, O.P., and the Albertus 
Magnus Lyceum. On reading the paper in 1936, Fr. Kane 
immediately recognized the merits of this view, and his own 
quest for a solution fell into place. Through his stimulating 
classes! and informal discussions he developed a group of dis- 
ciples and friends who were equally convinced of the impor- 
tance of a unified view of Thomistic natural philosophy and 
modern investigations. By 1950 sufficient unified interest was 
shown in the study of natural philosophy and modern prob- 
lems to warrant suggesting a special institute directed by 
Fr. Kane for serious work in this area. The idea of such an 
institute was, indeed, unique in the Dominican Order; on the 
other hand, nowhere in the Order were there so many men con- 
vinced of the importance of Thomistic natural philosophy for 
the solution of modern problems. The idea of an institute de- 
voted to special research was also unique among Dominicans 
in the United States; on the other hand, the time was ripe for 
such a venture in this country. Consequently the idea was 
formally presented to the Provincial of the Dominican Province 
of St. Albert the Great, the Very Reverend Edward L. Hughes, 
O. P., by the Regent of Studies and President of the Pontifical 
Faculty of Philosophy at River Forest, Illinois, the Very Rev- 


erend Sebastian E. Carlson. By special decree of the Provincial, 
the Albertus Magnus Lyceum was established at River Forest 
in 1951, its official date of inception being celebrated on Novem- 
ber 15, the feast of St. Albert. 

On this tenth anniversary of its establishment the Lyceum 
takes great pleasure in presenting this volume of studies to its 
founder and former director on his sixtieth birthday. The 
volume reflects the wide interest of its members and friends. 
From small beginnings the Lyceum has grown to include 
Dominicans of other Provinces and many non-Dominicans. It 
has developed a serious interest in scientific methodology, the 
history and philosophy of science, various technical problems of 
physics, biology, evolution and psychology; and it has had a 
decided influence on the teaching of natural science in the 
schools. Of course, much remains to be done in these vast areas 
of natural science and more specialists are needed even now. 
Here one can apply the phrase of St. Thomas: Fiat aliqualiter 
per plura, quod non potest fieri per unum. 

The Lyceum's view of natural philosophy and the modem 
sciences has been presented in innumerable writings, lectures, 
symposia and discussions. Nevertheless, its view has been 
frequently misunderstood and misrepresented by those who, 
presumably, disagree with its position. Presumably they have 
read at least some of the writings which they attack. But it is 
unreasonable to expect fruitful discussion and disagreement 
without mutual understanding. By far the most commonly 
misunderstood point is the Lyceum's (and Maritain's) dis- 
tinction of modern sciences. Neither Maritain nor the Lyceum 
considers * modern science ' to be a single, homogeneous body 
of knowledge. They make a careful distinction between those 
sciences which are formerly mathematical and those which are 
not. Formally mathematical sciences {empiriometrique, scien- 
tiae mediae, mathematical-physical sciences) are acknowledged 
to be really distinct from the philosophy and science of nature. 
Although extrinsic, the mathematical-physical sciences are of 
utmost importance to the naturalist in the examination of prob- 


lems and in the quest for proper solutions, demonstrative or 
tentative. Conversely, the natural sciences are of importance 
to the mathematical physicist in giving him the extrinsic foun- 
dation for his own science. Further, the Lyceum considers the 
non-mathematical parts of modem science to belong to a single 
science concerning ens mobile ut mobile. In practice, courses in 
natural philosophy rarely get beyond general considerations, 
and courses in experimental science rarely get beyond particular 
considerations and experiments. However, the Lyceum con- 
siders that in both the general and particular parts of this 
unique discipline there are to be found diverse types of cer- 
tainty: demonstrative, most probable, tentative, hypothetical, 
factual and even historical. Finally, the Lyceum maintains that 
the single science of nature is autonomous in its own field, and 
in the order of learning prior to and independent of metaphysics. 
There are many advantages to this view. First, it recognizes 
the dignity of a scientific study of the natural world which 
includes man, animals, plants and inanimate realities. Second, 
it recognizes the importance of this science for moral, meta- 
physical and theological concepts. Third, it offers a real possi- 
bility of cooperation between the professional philosopher and 
the experimental scientist. Fourth, it is consistent with the 
teaching of St. Thomas and St. Albert, for whom natural science 
is incomplete unless after studying the general theory found in 
the Physics, one proceeds to more and more particular species 
and varieties of living and non-living natures. Fifth, it is con- 
sistent with the actual practice of modern scientists, who begin 
with very particular varieties and gradually ascend to a more 
embracing unity, usually in old age. Here the statement of 
Heraclitus would be applicable: " The way up and the way 
down is one and the same." 


It is not very often that an institution can celebrate its own 
anniversary and that of its founder at the same time. Hence 
it is a privilege for the Lyceum to celebrate its tenth anni- 
versary by presenting these special studies to Fr. William 


Humbert Kane on his sixtieth birthday, July 12, 1961. His 
inspiring devotion to study, to teaching and to the Dominican 
way of life deserve some recognition from his brethren and 
friends besides the normal courtesies of academic and religious 
life. This Festschrift is presented to him with warm affection, 
deep respect and eternal gratitude. It is a token, indeed a very 
small token, of our great esteem. Those who esteem Fr. Kane's 
life-long work recognize his influence on the intellectual life 
in the United States, both within and without the Dominican 
Order. Those who have not had the privilege of knowing him 
will find in this volume the fruits of much of his labor. 

William (Dean) Kane was born in La Grange, a suburb of 
Chicago, on July 12, 1901. After completing Lyons Township 
High School and attending Aquinas College in Columbus, he 
entered the Order of Preachers in Somerset, Ohio, in 1920, and 
took the religious name of Humbert. After the normal course 
of studies he was ordained to the priesthood in Washington on 
June 9, 1927. But while he was studying theology at the Do- 
minican House of Studies in Washington, he studied pre- 
medicine at the Catholic University of America (1923-26) and 
medicine at Georgetown University School of Medicine (1926- 
28) in preparation for the Chinese missions. Successfully com- 
pleting his Lectorate dissertation, " The Criterion of Philo- 
sophical Truth," in 1928, he was sent to the Collegio Angelico 
in Rome for two years graduate study in philosophy. His ex- 
amination and dissertation on " Finality in Nature " obtained 
for him the Doctorate of Philosophy summa cum laude in June 
of 1930. His life thereafter was completely devoted to teach- 
ing, and it is for this that he is best known. In thirty years of 
teaching — biology, logic, natural philosophy, metaphysics and 
theology — he has given much serious thought to the text of St. 
Thomas and to modem problems. From 1933 until 1940 Fr. 
Kane was Lector Primarius in the House of Philosophy at River 
Forest, and from 1940 until 1948 he was Pro-Regent of Studies 
for the newly created Province of St. Albert the Great. On 
December 17, 1944, the River Forest studium was established 


as a Pontifical Faculty of Philosophy, and Fr. Kane became its 
first President. On that day, too, he received the ring and 
biretta of a Master in Sacred Theology, a degree which he had 
rightfully earned through his teaching. Returning to Rome as 
Professor of Natural Philosophy in 1948, he created such an 
impression on the students that he was thought to be more 
European than American in his devotion to study. In 1951 
when the Albertus Magnus Lyceum was established, he re- 
turned to the United States to be its director. The bulk of his 
writings date from this return to River Forest. Now at sixty, 
the Very Rev. William Humbert Kane feels that his work is 
just beginning, but he has the assurance that his ideals have 
taken root in the minds and hearts of his disciples. We extend 
to him our gratitude, prayers and best wishes AD MULTOS 

For the preparation of this volume special gratitude is due 
not only to the eminent contributors, who enthusiastically en- 
dorsed the project from the start, but also to those members of 
the Albertus MagTius Lyceum who are not represented here. 
Particular acknowledgement must be made to the President, 
the Very Rev. Sebastian E. Carlson, and to the Secretary of 
the Lyceum, the Rev. William B. Mahoney, whose tireless 
efforts supported the whole project. The Lyceum gratefully 
acknowledges the encouragement and contribution of the 
Master General of the Order of Preachers, the Most Rev. 
Michael Browne, and his Socius for the North American 
Provinces, the Very Rev. John A. Driscoll. Our sincere grati- 
tude is offered to the Very Reverend John E. Marr, O. P., 
Provincial of the Province of St. Albert, who has given his en- 
couragement and support to this volume. Since the effort has 
reached beyond provincial boundaries, we extend this same 
gratitude to the Very Reverend W. D. Marrin, O. P., Provincial 
of the Province of St. Joseph. Above all, we are grateful to 
The Thomist Press and the editorial staff of The Thomist who 
have joined with the Albertus Magnus Lyceum in honoring our 
Father William Humbert Kane, O. P., S. T. M. 

James A. Weisheipl, O. P. 
D.Phil. (Oxon.) 

Part One 



I. Scientific Methodology 

IT can be forcefully argiied that there is no place in phi- 
losophy for an " epistemological critique " of knowledge, 
as though the integrity of the intellect stood in doubt till 
it was somehow philosophically " cleared." ^ Surely, for reason 
to attempt to establish the trustworthiness of reason is for it 
to try to pull itself up by its own epistemological boot 
straps. The history of thought gives ample evidence that criti- 
cal attempts to justify the philosophical effort are in vain. No 
m.atter how honest the epistemological critique in intention, 
it results characteristically in an unnatural imposition of 
artificial limits placed upon our capacities to know. Witness 
the divergent streams of extreme rationalism and extreme 
empiricism which find their source in the critique of Descartes.^ 
Significantly, St. Thomas did not find it necessary to initiate his 
philosophical effort with a critique of knowledge. A Thomist 
speaks meaningfully of epistemology best in reference to a 
metaphysical inquiry into the character of intentional being. 
He takes epistemology as an attempt to understand what it is 
to know, not an attempt to defend the radical integrity of our 

^ Cf., Gilson, fitienne, Realisme Thomiste et Critique de la Connaissance (Paris: 
J. Vrin, 1947) ; Realisme Methodique (Paris: P. Teque, 1935) . 

^ Gilson 's frequently quoted remark on Berkeley and the Cartesian critique bears 
repetition here: " Everyone is free to decide whether he shall begin to philosophize 
as a pure mind; if he should elect to do so the difHculty will not be how to get 
into the mind, but how to get out of it. Four great men have tried it and failed. 
Berkeley's own achievement was to realize at last, that it was a useless and foolish 
thing even to try it. In this sense at least, it is true to say that Berkeley brought 
Descartes' ' noble experiment ' to a close, and for that reason his work should always 
remain as a landmark in the history of philosophy." The Unity of Philosophical 
Experience (New York: Chas. Scribner's Sons, 1937) , pp. 196-197. 


capacities for knowledge. That we can know is evident. It is 
both futile and unnecessary to attempt to prove this.* 

Although St. Thomas did not hamper his capacities for 
knowledge by imposing a 'priori restrictions upon them, he saw 
that, in a sense, they imposed restrictions upon him. There is 
no question, from the very start, as to the radical integrity 
of sense and intellect. Despite the fact that we are sometimes 
in error, it is evident that we can, and adequately, know what 
is. But our capacities for knowing are in no sense unlimited. 
Honest reflection upon the epistemological facts reveals that 
the human intellect is that lesser type of intellect which is at 
once a reason. For us all doctrine and discipline is from pre- 
existing knowledge.* We learn by moving from what is already 
known to what follows from this. The fact is clear that, as 
far as learning is concerned, the human intellect is naturally 
discursive. Moreover, the price of discursive advance in knowl- 
edge is the construction within the intellect of logical artifices 
such as definitions and argumentations. The method of con- 
struction which is called for by the demands of discourse is in 
no sense arbitrary. As always, the final cause is the cause of 
the causality of the other causes. The end of the logical con- 
struct requires certain determinate rules according to which 
the objects known are to be ordered in knowledge in reference 
to one another. Thus, there are definite rules of procedure 
which constrain the intellect in its discursive progress.^ These 

* Cf., Smith, Gerard, S. J., "A Date in the History of Epistemology," in The 
Maritain Volume of The Thomist (New York: Sheed and Ward, 1943), pp. 246-255. 

* In I Post. Anal., lect. 1, n. 9: " Omnis autem disciplinae acceptio ex prae- 
existenti cognitione fit." (The quotations from St. Thomas will be taken from the 
Leonine for the Summa, the Decker for the De Trinitate, the Lethielleux for the 
Sentences, and from the respective Marietti editions for each of the other works 

The general rules of discursive procedure, we shall note, are one with the laws 
of logic. Logic is simultaneously an art and a science. As an art it is directive of a 
productive activity — precisely, for logic, the construction within the reason of the 
instruments of discourse, such as definition and argumentation. The character of 
any work-to-be-produced sets the standard according to which the artistic effort 
is to be effected. Thus every art has its own determinate rules of procedure. In the 
case of logic, of course, these are the rules of sound discourse. And in the case of 


can be said to constitute a method, and the reflexive investi- 
gation of them can be spoken of as methodology. It should be 
clear that this is not method in the manner of Cartesian 
method, nor is it methodology in the manner of epistemological 

There is for man but one reason. Hence, there is generally 
but one method, that is, the discursive method which measures 
up to the demands of that one reason. But there are many 
different things to be known, on radically different scientifically 
relevant levels. As a consequent, the general method of the 
reason must be proportioned to each scientifically different 
object for each formally different scientific effort. The general 
method of the reason is logic. Logic is at best analogously 
common to every scientific inquiry. By itself it is inadequate 
to any particular scientific subject matter. Logic must be con- 
tracted, and in analogously different ways, to the needs of 
every scientifically different subject. This contraction of logic 
is realized in the particular scientific methods proper to each 
formally different scientific subject.^ Note that while logic by 
itself is inadequate to any given scientific inquiry because of 
the special demands of the proper subject of that inquiry, there 
can, because of the demands of the reason itself, be no particular 

logic, because discourse is aimed ultimately at a fully defended scientific knowledge 
of things, the rules of the art must themselves be evident in themselves or demon- 
stratively defended. Since only the most fundamental rules of logic are evident in 
themselves the majority of them must be demonstrated. Thus, in order for logic 
to be the art that it is, it must be at once the demonstrative science of the rules 
of discourse. As a matter of fact, the rules of discourse are the canons which 
express the demands of the second intentions which accrue to objects as known and 
m virtue of which these objects are to be ordered in discourse. Thus logic is simul- 
taneously the art of sound discourse and the demonstrative science of second 
intentions or rules of discourse. For a more complete exposition and defense of this 
position, cf., Simmons, Edward, " The Nature and Limits of Logic," The Thomist, 
XXIV (January, 1961), pp. 47-71. 

®In In Boeth. de Trin., q. 6, a. 1, St. Thomas distinguishes between the demon- 
strative method characteristic of natural science (rationabiliter) , the method of 
mathematics (disciplinabiliter) ,. and the method of metaphysics {intellectualiter) . 
These represent different contractions of the general logic of demonstration in favor 
of formal differences in diverse scientific subjects. 


scientific method which is not generally logical. Clearly, the 
investigation into general logical method is methodology in one 
sense, while the investigation into the precise method of any 
given scientific inquiry is methodology in another (related) 
sense. We can refer to the former as general methodology and 
the latter as particular or special methodology.^ 

In this paper we shall concern ourselves with the role of the 
self-evident proposition in the theory of demonstration. This 
is a study in general methodology. The point made will be 
of a common character, and the methodological principles 
uncovered will be only generally relevant for scientific inquiry. 
In every case an appropriate contraction of the doctrine pre- 
sented will be necessary before it is proximately adequate to 
any given scientific effort. Before proceeding, however, there 
remains one more distinction to be made, the better to locate 
the discussion of this paper. General methodology is identical 
with logical theory, and, as such, admits of the distinction 
between formal and material logic. This is a distinction which is 
both legitimate and significant, but it is a distinction which 
is frequently misunderstood. Although it is a distinction which 
should be made within the limits of general logical theory, it is 
not infrequently understood in such a way that formal logic is 
identified with general methodology while material logic is asso- 
ciated intrinsically with particular scientific methodology. This 
mistaken view makes logic less than adequate to the demands 
of reason even in abstraction from the particular demands 
of any given scientific subject. And, while it may not positively 
vitiate the investigation into particular scientific method, it 
places an unreasonable burden upon it. Just as there are 
general rules of logical procedure to be followed if discourse is 
to be consistent or valid, so there are general rules of procedure 
to be followed if discourse is to be of some determinate scientific 
force. Categorical syllogism is defined in terms of validity. 
The rules which must be followed to make the syllogism pre- 
cisely a syllogism (e. g., the middle term must be fully 

^ Cf., In II Met., lect. 5, n. 335; In II De Anima, lect. 3, n. 245. 


distributed at least once) are canons of valid or consistent 
discourse. Demonstration, on the other hand, while pre- 
supposing validity, is defined in terms of scientific force. And 
there are general rules, able to be determined apart from any- 
particular scientific subject, which must be followed if a syllo- 
gism is to be demonstration (e. g., the premises must be 
necessarily true) , and even more determinate general rules 
which must be followed if the demonstration is to be of a 
certain type (e. g., explanatory demonstration must have a 
middle term which is related to the scientific subject as its 
real definition) . These rules, while quite clearly remaining of 
a general logical character (i. e., open to contraction in the 
face of special scientific subject matter, but not yet con- 
tracted ) are canons of properly scientific, and not simply con- 
sistent, discourse. Rules such as these are proper to material 
logic, while the rules of merely consistent discourse are rules 
of formal logic. There are reasons which explain why formal 
logic is sometimes confused with the whole of logic and why 
material logic is sometimes confused with particular scientific 
methodology.* But these reasons only help to excuse the man 

* The formal subject of the science of logic is the second intention. Second inten- 
tions are logical forms or relations of the reason which accrue to objects (first 
intentions) precisely as known. Some second intentions accrue to an object 
properly in virtue of its mode of signifying (e. g., predicate, middle term, and 
syllogism) . Others accrue directly in virtue of the intelligible content of the object 
(e. g., species, immediate, and demonstration) . The former are second intentions in 
formal logic, and they set the demands for valid discourse. The latter are second 
intentions in Tnaterial logic, and these set the demands for scientific discourse. 
Although St. Thomas explicitly distinguishes between formal and material logic 
only on the level of the logic of the third operaton (cf., In I Post. Anal., prooem., 
nn. 5-6) , the distinction makes sense also on the levels of the first and second 
operations, as the examples above illustrate. [Cf., Simon, Yves, " Foreword," The 
Material Logic oj John of St. Thomas, translated by Yves Simon, John Glanville, 
and G. Donald Hollenhorst (Chicago: Chicago University Press, 1955), pp. ix-xxiii.] 
The subject matter for logical theory is always the second intention, and never 
directly the first intention to which the second intention accrues. Thus, there is a 
sense in which logic is only formal (investigating logical forms) and never material 
(discussing the mtelligible content of first intentions, which is the matter of dis- 
course) . And even apart from this, it is clear that second intentions in material 
logic are more proximately connected with the intelligible content of first intentions 


who is confused. They do not defend the confusion as a noetic 
fact. The theory of demonstration in general remains, as much 
as the theory simply of syllogism, the concern properly of the 
logician. It must be assumed and contracted to the needs of 
the special subject matter for any given scientific inquiry. 
Thus the concern of this paper is within the limits of logic, 
but it belongs to that branch of logic which is material logic 
rather than formal logic. This brings us significantly closer to 
the area of particular methodology than a paper in formal 
logic would, but we remain in logic without trespassing beyond. 

II. Self-evident Proposition — The Basic Truths 
OF Demonstration 

Early in the Posterior Analytics, after determining the nature 
of scientific knowledge (in brief, certa cognitio per causas ^) , 

than are those in formal logic. The connection is so intimate that Simon and his 
fellow translators suggest that the Jwhitus of material logic is reduced in actual use 
to the science which employs it (ibid., note 39, pp. 594-595) . Whether this is the 
case or not, it remains true that the formal subject of material logic as well as the 
formal subject of formal logic is no more nor less than a logical form or second 
intention. This means, of course, that material logic is integrally a part of logic 
proper and is not, as a science, to be confused with any (and every) particular 
sicence of the real. (Cf., Simmons, E., op. cit.) 

' The Posterior Analytics, Book I, Ch. 2, 71b9-12: " We suppose ourselves to 
possess unqualified scientific knowledge of a thing . , . when we think we know 
the cause on which the fact depends, as the cause of that fact and of no other, and, 
further, that the fact could not be other than it is." [Translation from The Basic 
Works of Aristotle, edited by Richard McKeon (New York: Random House, 1941), 
p. Ill] There should be no need to insist that, in the face of current usage, this 
gives a highly restricted (and exceedingly strict) meaning to " science." As we 
begin to speak of this kind of science as demonstrated knowledge there is, of course, 
a proportionately strict understanding of the meaning of " demonstration." Still, 
the terms " science " and " demonstration " admit of analogous impositions, even 
as used by us in this paper. For example, demonstrations differ analogously from 
one genus of speculative science to another — so that mathematical demonstration 
is only proportionally like metaphysical demonstration (cf. In Boeth. de Trin., q. 6, 
a. 1; In I Post. Anal., lect. 41), and even within a given science — so that a propter 
quid demonstration in one science is only proportionally like a quia demonstration 
in that same science (cf ., ibid., lect. 23) . Having introduced this strict meaning of 
science in the second chapter of The Posterior Analytics, Aristotle has set the stage 
to demand of the scientific syllogism that its premises be necessarily true and 


Aristotle defines demonstration in terms of its final cause as a 
syllogism productive of science. Then, using this definition of 
demonstration itself as a principle of demonstration, he pro- 
ceeds to demonstrate the definition of demonstration in terms 
of its matter. He argues that if a syllogism is to produce the 
kind of conclusion which is properly scientific it must proceed 
from premises which are true, primary, immediate, better 
known than, prior to, and cause of the conclusion. This is to 
say that it must proceed from necessarily true, absolutely first 
propositions, which look to no prior proposition for their evi- 
dence but are calculated to supply evidence for other proposi- 
tions. We speak of these propositions as self-evident. Scientific 
knowledge is proven in a demonstration whose premises mani- 
fest the truth of the scientific conclusion. As principles of the 
conclusion these premises are properly premises. In any given 
case, however, they may also be conclusions from other 
premises. But it is impossible, of course, that every premise 
be itself a conclusion from a prior premise. We must arrive 
ultimately at premises which are only premises, at propositions 
which are not shown to be evident by way of prior propositions 
but whose evidence is found within themselves. These absolute 
premises are ultimately the complex principles ^° of scientific 
knowledge, themselves not properly scientific, but rather pre- 
scientific. They are self-evident propositions, the propositions 
spoken of in the Posterior Analytics as " the immediate basic 
truths of syllogism " or, more determinately, of demonstration. 

immediately so (Ch. 3) . It is important to note that, for the most part, the sub- 
sequent discussion of the requirements for demonstration is centered upon the 
strictest type of propter quid demonstration and is only proportionally relevant to 
other types. 

^° The absolute premises of demonstration are significant principles of demonstra- 
tive discourse. So too is the middle term of the demonstration (which is not 
identical with any premise, though it is built into each) . The former are complex 
principles of demonstration. The latter is an incomplex principle. We are concerned 
primarily with the complex principles of demonstration in this paper, although, as 
we shall note, the definition itself plays a significant role in the discussion of these 
complex principles. As a matter of fact Aristotle lists the definition as a type of 
demonstrative principle in the very context of the discussion of immediate premises 
(cf., St. Thomas' explanation for this, op. cit., lect. 5, n. 9) . 


St. Thomas speaks of these " basic truths " as per se nota 
propositions. Although this is an apt expression, there is some 
danger of confusion here. First of all, St. Thomas may some- 
times use the term per se nota of a proposition which is not 
evident in the way in which the basic truths of demonstration 
are self-evident." Secondly, St. Thomas frequently speaks of 
the modes of perseity (the modi dicendi per se) ,^" and, despite 
the terminological suggestion to the contrary, it is not true that 
whenever we have a proposition which involves a mode of 
perseity we have a per se nota or self-evident proposition. 
These points will have to be clarified before we are through. 

For the premises of demonstration to be at all they must 
be true, for the esse of a proposition is an esse verum. For 
them to be principles of manifestation for the scientific con- 
clusion they must be necessarily true, for necessity is of the 
essence of science. And for them to be basic truths, that is 
absolute premises, the premises of demonstration must be, at 
least reductively, imviediate propositions. Here is precisely 
where the scientific proposition differs from its pre-scientific 
principle. The scientific proposition is necessarily true, and it 
is a conclusion. The scientific principle is necessarily true, but 
it can be (ultimately) in no sense a conclusion. The conclusion 
of a syllogism is characteristically mediate, for the connection 
between its extremes is manifested in a syllogism by way of a 
term commonly identified with both extremes, thus functioning 
as a middle. The basic truths of syllogism or the absolute 
premises must themselves be evident without a middle. The 
predicate must belong immediately to the subject lest we admit 
the infinite regress which would make deduction totally ineffec- 
tive. Two things, at least, should be pointed out here. First of 
all, there is a significant and not unrelated use of the term 
" immediate " which is not intended at this point. For example, 
having three angles equal to two right angles is necessarily 

^^ In II Pkys., lect. 1, n. 8: " Naturam autem esse, est per se notum, in quantum 
naturalia sunt manifesta sensui." 

" Cf., In I Post. Anal., lect. 10; In II De Anima, lect. 14, n. 401; In V Met., lect. 
19, nn. 1054-1057. 


true of both triangle and isosceles triangle. But it is true of 
isosceles triangle only insofar as isosceles triangle is triangle. 
Thus we might well say that this property belongs immediately 
to triangle and mediately (through triangle) to isosceles triangle. 
However, the proposition Every triangle has three angles equal 
to two right angles can be demonstrated as the conclusion of a 
syllogism employing the essential definition of triangle as its 
middle term. Insofar as it is able to be proven through a middle, 
it is clearly not immediate in the sense in which self-evident 
propositions are immediate. " Immediate " here means, rather, 
commensurately universal or convertible {primo or possessed 
of the intention spoken of as did ut universale) . As a matter 
of fact, not every proposition which is commensurately uni- 
versal is self-evident and not every self-evident proposition is 
commensurately universal.^^ Secondly, even though we under- 
stand the self-evident proposition to be immediate in such wise 
as to lack a demonstrative middle, it is not the case that every 
proposition which is immediate in this sense is self-evident. 
A self-evident proposition is a proposition with a subject and 
a predicate in necessary matter, and with a subject and predi- 
cate so proximately connected with one another that the 
necessary truth of the proposition can escape no one who 
understands this subject and predicate. Hence, propositions are 
said to be self-evident precisely insofar as they can be seen 
necessarily to be true once their terms are known. ^* These 

'^^For St. Thomas' position on the did ut universale, cf., In I Post. Anal., lect. 11. 
We shall see that the prime instance of the self-evident proposition has a predicate 
which is of the definition of the subject. If the predicate is the whole of the 
definition of the subject it is, of course, convertible with the subject, and we have 
a commensurately universal proposition. Every man is capable of speech is com- 
mensurately universal without being self-evident, and Every man is animal is self- 
evident without being commensurately universal. 

^* Only this type of proposition is so necessarily true, while being at the same 
time immediate, that it can ground the necessity of a scientific conclusion. In IV 
Met., lect. 5, n. 595: "Ad huius autem evidentiam sciendum, quod propositiones 
per se notae sunt, quae statim notis terminis cognoscuntur. . . ." De Mala, q. 3, 
a. 3, c: " Unde intellectus ex necessitate assentit principiis primis naturaliter 
notis. . . . Unde in intellectu contingit quod ea quae necessariam cohaerentiam 
habent cum primis principiis naturaliter cognitis, ex necessitate moveant intellectum, 


propositions are not totally non-empirical, for, as we shall note, 
they are known by way of an immediate induction from sensible 
data. Yet they do not depend directly upon empirical data 
for verification. Assent to them is founded upon an intelligi- 
bility built into them such that it is impossible to think the 
opposite. Thus, if one understands the meanings of the terms 
in the proposition The whole is greater than any of its parts 
one immediately assents to this proposition quite apart from 
the existence of this or that sensibly existing whole or part. 
The motive for assent is, in a sense, built into the proposition 
itself. The self-evident proposition is immediate because it 
looks to no prior proposition for its evidence, but there are 
propositions which are evident in this way without being self 
evident. These are the factually evident propositions which 
are true, because they report accurately on the way things 
happen in fact to be, whether they could be otherwise or not. 
Examples of propositions like this are This pencil is yellow, 
The weather is pleasant today, and / feel great. These proposi- 
tions are immediate since they do not depend on prior proposi- 
tions to manifest their truth. The evidence for them is found 
immediately in the factual situation. Insofar as a factually 
evident proposition is formally characterized by its commit- 
ment to what happens to be the case, the factually evident 
proposition cannot intend the necessity needed for an absolute 
premise of demonstration. Thus, though each is immediate, 
the factually evident proposition differs radically from the self- 
evident proposition.^^ In the Commentary on the Physics St. 

sicut conclusiones demonstratae, quando apparent; quae si negentur, oportet negari 
prima principia, ex quibus ex necessitate consequuntur." Cf., among other texts 
of this type, In I Post. Anal, lect. 5; lect. 19; De Ver., q. 11, a. 1; Stimma, I, q. 17, 
a. 3 ad 2; q. 82, a. 2; q. 85, a. 6; De Malo, q. 16, a. 7 ad 18; Quodl., VIII, a. 4. 

^^ What I refer to as the " factually evident " proposition is usually spoken of 
simply as " evident," but since the self-evident is (at least) evident it seems better 
to use a more determinate expression. There is nothing highly sophisticated intended 
by my use of " factually," despite the fact that the word " fact " does frequently 
take on a very specialized meaning in philosophical discussion. Note that none of 
my examples involves necessary matter in any sense. This helps to make the notion 
of the factually evident quite clear. Nonetheless it seems to me that This whole 


Thomas says that it is 'per se notuvi that nature exists because 
natural things are manifest to the sense /"^ Natural things exist 
is an immediate proposition. But it is not self-evident — for, 
since natural things are existentially contingent and need not 
be, we cannot assent to the proposition Natural things exist 
simply because we understand the meaning of its terms. It is 
immediately evident only on the basis of the empirical fact 
unmistakably given in our sensory-intellectual grasp of the exis- 
tence of sensible existents immediately present to the external 
sense. This is clearly a factually evident proposition. It is of 
significant relevance for the philosophy of nature, but it is not 
relevant in the way in which a self-evident proposition is 
relevant,^^ despite the fact that St. Thomas describes it as per 
se nota. One more clarification at this point. The immediacy 
of the self-evident proposition makes it indemonstrable. But 
not all indemonstrable propositions are immediate (consider 
conclusions of dialectical or probable argumentation) . Nor 
even, of course, are all immediate and indemonstrable proposi- 

is greater than its parts can be taken as a proposition which intends simply a 
report on a concrete situation. As such this is factually evident, and it is not the 
same as the proposition Every whole is such that it must be greater than any of 
its parts. This second proposition is, of course, self-evident, and it is certainly 
known by anyone who can express the former proposition (because the terms which 
must be known in order that the former be expressed immediately make evident the 
latter) . Although the most perfect instance of propter quid demonstration involves 
two premises each of which is self-evident, there is no reason why less strict 
demonstration cannot include one factually evident premise. The necessity needed 
in the antecedent of a demonstration would be lacking if every premise were 
factually evident, but it can be supplied by one self-evident proposition coupled 
with a factually evident premise. As a matter of fact, demonstration makes sense 
only in reference to scientific subjects known to exist. "Where both premises are 
self-evident it is a requirement that the existence of the scientific subject be known 
prior to demonstration and presumed within demonstration. The existence of the 
scientific subject can be expressed within a demonstration when one of its premises 
is factually evident, 

^* Cf., supra, note 11. 

^^ There would be no reason for a philosophy of nature if natural things did not 
exist; but since they need not exist, the proposition which reports on the fact of 
their existence cannot be used as a necessary premise manifesting the scientific 
necessity of any conclusion. 


tions self-evident (consider the examples given above for the 
factually evident proposition) . Certainly true propositions in 
contingent matter are indemonstrable because of a deficiency 
in matter. Self-evident propositions are always in necessary 
matter, and their indemonstrability springs from their excel- 
lence rather than from some deficiency in matter. Demonstra- 
tion makes evident something which is not already evident. 
To be demonstrable entails a privation. Because they are 
evident in themselves, self-evident propositions do not have 
this privation.^^ 

Self-evident propositions are necessarily true and immediate. 
This makes them at once primary: they have no propositions 
prior to them (upon which they depend for evidence) , and 
they are presupposed to the mediate propositions which look to 
them for evidence. Insofar as they supply evidence for these 
mediate propositions they cause them to be conclusions. And 
they can be related to the conclusion as cause to effect only 
insofar as they are prior to and better known than the conclu- 
sion. The " basic truths of syllogism " are basic insofar as they 
admit of no prior propositions necessary to make them evident. 
They are truths of the syllogism insofar as they are principles 
from which conclusions can be generated. 

III. The Types of Self-evident Proposition 

We have noted that a self-evident proposition is one which 
is known to be necessarily true once its terms are understood. 
The most perfect instance of this is found in the proposition 
in which the predicate is of the definition of the subject.^^ Once 

^* Though scientific or demonstrated knowledge is spoken of as perfect knowledge 
(cf., In I Post. Anal., led. 4, n. 5) , it is clear that it is inferior to the pre-scientific 
absolute premises of demonstration. 

^* Summa, I, q. 17, a. 3 ad 2: " Nam principia per se nota sunt ilia quae statim 
intellectis terminis cognoscuntur ex eo quod praedicatum ponitur in definitione 
subiecti." As Cajetan points out in his Commentary on the Posterior Analytics 
(Book I, Ch. 19) , St. Thomas does not intend in texts such as this one strictly 
to define the self-evident proposition but to manifest the principal case. An 
example of a self-evident proposition which does not have its predicate within the 
definition of its subject is Every rational animal is capable of speech. 


the subject is understood in its definition the identity of subject 
and predicate is grasped, and the intellect is moved to commit 
itself irrevocably to the truth of the proposition. If a proposi- 
tion has a predicate within the definition of its subject, but 
this subject defies definition by any man, then this proposition 
can be described as self-evident in itself, but not self-evident 
to us. If, on the other hand, its subject can be defined by us, 
it is self-evident both in itself and to us. If the subject is able 
to be defined only by those who are habituated to operate 
within a given scientific field, the proposition is said to be self- 
evident only to the learned. But if is is a common concept 
understood by every one, it is, of course, self-evident to all. 
Thus, it is rather easy to see, at least apropos of the prime 
type of self-evident proposition, the rationale of the traditional 
division of the "per se nota proposition into the 'per se nota in 
se and the per se nota quoad nos, and the subdivision of the 
latter into the per se nota quoad sapientes and the per se nota 
quoad omnes.-° 

St. Thomas appeals to the fact that the proposition God is 
is not self-evident quoad nos even though it is self-evident in 
itself."^ Were we to know the essence of God we could not — 
nor would we need to — demonstrate His existence, for His 
essence is His existence. Yet, since we do not know His essence 
we are able from His effects, which are known to us, to 
prove His existence. Aristotle and St. Thomas supply several 
examples of per se nota propositions which are known to all 
because their terms are common conceptions easily and surely 
grasped by all men. These examples include: The sanfie thing 
cannot he and not he; The same proposition does not admit 
simultaneously of affirmation and denial; The whole is greater 
than any of its parts; Things equal to one and the same thing 
are equal to one another; Equals taken away from equals leave 

^° This traditional division of the self-evident proposition is explained by St. 
Thomas in several texts, including: De Ver., q. 10, a. 12; In IV Met., lect. 5, n. 595; 
In I Post. Anal., lect. 5, nn. 6-7; In Boeth. de Hebd., lect. 1. Cf., also Cajetan, 
op. cit., Ch. 3. 

*^ Summa, I, q. 2, a. 1; De Ver., q. 10, a. 12. 


equals.'^ These propositions are called dignitates or axioms 
because they are the absolutely ultimate and common prin- 
ciples which guarantee the integrity of all discourse and into 
which all discourse is resolved. Discourse would be impossible 
for anyone ignorant of these axioms. Propositions per se nota 
quoad sapientes are related to the axioms as the proper is 
related to the common. They can be known only by the 
learned because the terms involved are more deteiTuinate than 
the common notions which alone are able to be understood by 
the academically unskilled. St. Thomas illustrates this by 
suggesting the proposition All right angles are equal. This is a 
proposition which is immediately evident only to one who 
knows that equality enters into the definition of right angle; 
and this is a definition, of course, which escapes the knowledge 
of many. Another example which is traditionally offered is the 
proposition Incorporeal substances are not situated in place. 
We can add to these any proposition in which the essential 
definition or some part of it is predicated of a specific subject, 
such as Every man is a rational animal. A proposition of this 
type is known as a positio or thesis."^ The axioms are necessary 
if we are to demonstrate in any scientific area, but the theses 
proper to a given area are necessary only for demonstrations 
properly within this area. Axioms may or may not be used 
explicitly as premises in demonstration, but theses are principles 
of demonstration only if they appear explicity as premises. 
Axioms can be distinguished generally into those which are 
ontological in character (e. g., the principle of identity) and 
those which are logical in character (e. g., the principle of 
contradiction) . Those which are ontological in character are 

^^/ra 1 Post. Anal., lect. 5, n. 7; In IV Met., lect. 5, n. 595. 

"^ St. Thomas considers the division of the immediate principles of demonstration 
especially in lessons 5, 18, and 19 in the first book of his Commentary on the 
Posterior Analytics. We have already noted the inclusion of definition as a principle 
(although incomplex) of demonstration. St. Thomas also speaks of a proposition 
taken as though it were immediate in one science, but proved in another (lect. 5, 
n. 7) . This proposition is called a suppositio or hypothesis. We are not concerned 
properly with this proposition in this paper. 


presupposed to any demonstration, even when they are not 
explicitly expressed as premises, precisely because the knowl- 
edge of proper concepts which is required for theses presupposes 
and in a sense depends upon a prior grasp of common con- 
cepts.^* Those which are logical in character function neces- 
sarily as methodological principles which guarantee the integrity 
of discourse without being built into it as doctrinal principles. 
For example, the principle of contradiction is an absolutely 
common methodological principle without which there could be 
no discourse at all. No proposition can function properly as a 
principle of demonstration except that it be firmly accepted 
that the affirmation of its opposite is excluded in the face of its 
own affirmation.^^ Of course axioms of an ontological character 
(when illumined by the light of metaphysical abstraction) can 
be used as premises in metaphysical discourse, just as axioms 
of a logical character must be built into proofs in logical theory 
as explicit premises. The reason for this is that metaphysics 
and logic are common sciences, so that the principles common 
to the other sciences are proper to them. As a matter of fact, 
these common propositions can even be used as explicit pre- 
mises in the particular sciences, though here they become 
principles of dialectical rather than demonstrative discourse .^^ 

** Consider the relation of being to all other concepts. De Ver., q. 1, a. 1, resp.: 
" Elud autem quod primo intellectus concipit quasi notissimum, et in quo omnes 
conceptiones resolvit, est ens; " In III Met., lect. 5. Cf. Cajetan, Comm. In De 
Ente et Essentia, q. 1. 

"^ In IV Met., lect. 6, n. 603: " Si igitur quis opinetur simul duo contradictoria 
esse vera, opinando simul idem esse et non esse, habebit simul contrarias opiniones: 
et ita contraria simul inerunt eidem, quod est impossibile. Non igitur contingit 
aliquem circa haec interius mentiri et quod opinetur simul idem esse et non esse. 
Et propter hoc omnes demonstrationes reducunt suas propositiones in hanc proposi- 
tionem, sicut in ultimam opinionem omnibus communem: ipsa enim est naturaliter 
principium et dignitas omnium dignitatum." Cf., also In I Post. Anal., lect. 6, n. 7. 

^' Though the direct use of logic is methodological, supplying either the rules of 
demonstrative or dialectical discourse, logic can, along with metaphysics, because 
of the correlatively common character of the formal subjects of each, supply 
premises for argumentation in the particular sciences. Since demonstration requires 
premises appropriate to the conclusion, the argumentation in some particular science 
with a premise from metaphysics or logic will be dialectical at best. 


IV. The Genesis of the Self-evident Proposition 

As St. Thomas teaches, the self-evident absolute premises 
from which scientific conclusions are generated are natural to 
the human intellect.-^ However, this does not mean, on the 
one hand, that they are possessed from the very start as fully 
formed conceptions dependent in no sense upon experience or, 
on the other, that they are no more than mental constructs 
fabricated by the intellect totally out of its own " stuff." In 
the final lesson of his Commentary on the Posterior Analytics 
St. Thomas finds fault with those who suggest that we already 
possess the principles but do not know this from the beginning. 
This is absurd since the principles of demonstration must be 
better known than the conclusions they generate, and it is 
impossible to know demonstratively and not be aware of this. 
St. Thomas also disputes with those who say that self-evident 
propositions arise in us from nothing. Experience indicates and 
reason demands that they come from something. But they 
cannot come from prior intellectual knowledge, for then they 
would not be immediate. They are generated from previous 
sense knowledge by way of an immediate induction."^ However, 
to say this is not to imply that they are easily achieved. ^^ This 
is simply not the case for the large majority of self-evident 

"'' Summa, I, q. 117, a. 1: " Inest enim unicuique horaini quoddam principium 
scientiae, scilicet lumen intellectus agentis, per quod cognoscuntur statim a principio 
naturaliter quaedam universalia principia omnium scientiarum." 

"® I say immediate induction to distinguish this from the mediate induction of a 
conclusion whose evidence is supplied by a sufficient enumeration of singulars. 

^' Our students seem to be easily misled into identifying the self-evident with the 
easily understood. This may be because in our classroom approach to them our 
examples of the self-evident proposition are almost exclusively axioms which are 
self-evident to all (e. g., The whole is greater than any one of its parts.) , or it may 
be because of a tendency on the part of a student to give a psychologically sub- 
jective reading to what must be understood objectively (i. e., to think " self- 
evident " means evident to myself rather than in itself) . This confusion is not 
limited to our students. For example, Joseph Brennan, in The Meaning of Phi- 
losophy (New York: Harper and Bros., 1953) , p. 94, suggests two meanings to 
" self-evident," namely, indemonstrable or completely clear to m,e. That the type- 
writer I am using is gray is both indemonstrable and completely clear to me. But 
it is in no sense self-evident. 


propositions. It takes a sufficient experience (spoken of by 
St. Thomas as an experimentum which comes about from many 
memories) ^° of the singular manifestations of a universally 
necessary truth before we are ready to penetrate beyond the 
accidentals of these singulars to the underlying necessity. This 
experimeiituvi is not always easily achieved. And the intuitive 
insight (into the necessity potentially in the expeiimentum) 
effected by the possible intellect through the light of the agent 
intellect is difficult as a matter of course. More often than not, 
it seems, propositions which are self-evident in themselves are 
not seen to be self-evident by us; and when they are, it is only 
by way of a tremendously difficult dialectical procedure. ^^ 

To grasp the truth of a self-evident proposition one must first 
grasp the meaning of the terms involved. Hence, the search for 

^"In II Post. Anal., lect. 20, n. 11; In IV Met., lect. 6, n. 599. 

^^ Thus far I have used the expression " dialectical " to refer to probable argu- 
mentation. This type of dialectical discourse is supplementary to demonstration. 
We can also speak of a pre-demonstrative dialectic — which prepares the way for 
demonstration by manifesting the absolute premises of demonstration. This is the 
way the term is used here. There is no question of a proof, in any strict sense of 
the word, for a self-evident proposition. Assent to the self-evident proposition 
depends upon and comes with an insight into the intrinsic intelligibility of the 
proposition itself. The assent is automatic with the insight, but the insight may be 
difficult to achieve. The way to insight may require long and complicated discourse 
involving division, defuiition, and even argumentation. For example, one typical 
dialectical device for manifesting the truth of a self-evident proposition is the 
reduction of its contradiction to absurdity. (Cf. In III Met., lect. 5, n. 392.) The 
important point is that once the threshhold of insight is achieved the assent is made 
in virtue of the intrinsic intelligibOity of the proposition itself. The dialectic is a 
scaffolding which can now be torn down, for it is not needed as a defense of the 
self-evident proposition once seen (no matter how instrumental it might in fact 
have been prior to msight) . Here precisely is where the immediate induction of the 
principles of demonstration differs from the mediate induction of a conclusion from 
a sufficient enumeration of singulars. The induced conclusion is assented to precisely 
in vhtue of the enumeration of singulars and cannot be known without pointing to 
them for evidence. This is not the case for the induced principle. No matter how 
many singular wholes and parts have to be observed before a man sees into the 
meaning of whole and part so that he knows the whole must be greater than its 
parts, the proposition is seen to be true independently of each and all of these 
singular wholes and parts. (In III Sent., d. 24, q. 1, a. 2, q. 1 ad 2: " Termini 
principiorum natm'aliter notorum sunt comprehensibles nostro intellectui: ideo 
cognitio quae consurgit de illis principiis, est visio. . . .") 


self-evident propositions is at least as difficult as the search 
for definitions. Cajetan suggests that it is more difficult than 
this. At the end of his Cornmentary on the Posterior Analytics 
he discusses the induction of the per se nota proposition. He 
contends that induction is necessary, not only as the source of 
the incomplex terms of the complex principles, but that it is 
necessary as well for the composition of these terms in the 
proposition. He argues that we would not know that equals 
taken from equals leave equals if we knew only the meaning 
of " equal," " to be taken from " and " to leave." For this 
reason he holds that for the genesis of this self-evident proposi- 
tion there must be induction, not only of the meanings of the 
terms, but even of their conjunction in this proposition. In some 
texts at least, as we have seen, St. Thomas indicates that the 
induction of the terms is sufficient for the intellectual grasp of 
first principles. Appeal to personal experience, after the sug- 
gestion of Cajetan, seems to indicate that sometimes the induc- 
tion of the terms alone suffices (as, for example, with the self- 
evident proposition Every man is a rational animal) , and that 
sometimes more is required (as in the example cited by 
Cajetan) . 

The self-evident proposition is not simply a report on a 
factual situation. Yet it is not a priori, and it does have an 
empirical reference. If it were not the case that some things 
happen to be such and such precisely because they cannot be 
and not be such and such, we would never grasp the self-evident 
proposition. It is only through sufficient contact with the 
things in question that an insight into the necessity which 
dictates the facts (that is, the way in which these things are) 
is achieved. ^^ It is true that we can be sure that the whole is 
greater than any of its parts even though we are not presently 
confronted by a concrete whole and its parts. The truth of 
this proposition is guaranteed by the very meanings of whole 

'"There is no intention here to suggest that all facts are necessitated. I refer 
simply to the necessity that belongs to those facts which are necessary (e. g., that 
this whole is greater than its parts) . 


and part. Still I would never know the meaning of whole and 
part if I never knew any concrete whole and its parts. And, 
what is more important, there is no intelligibility at all to 
whole or part except that there are (at least possibly) con- 
cretely existing wholes and parts. The whole is greater than 
any of its parts precisely because that's the way wholes and 
parts are. For every whole and its parts there is the fact that 
this whole happens to be greater than each of its parts — and 
behind this fact is the necessity which demands it, a necessity 
which is one with the intelligible structure of whole and part. 
The fact and the necessity which dictates it are equally real. 
Yet they differ. The fact is incommunicable, and it alone can 
be expressed in a factually evident proposition. The necessity 
behind the fact is impervious to sense. Yet it is potentially 
in what is sensed (and in what is reported on in a factually 
evident proposition) , and it is, of course, fundamentally uni- 
versal. It can be known only by an intuitive insight which is 
the result of an abstractive induction, and when known it is 
expressed in a formally universal proposition. The self-evident 
proposition comes into being only when it is inductively 
achieved from an experience of singulars — and it is meaningful 
only insofar as it bears finally upon singulars. However, the 
self-evident proposition is only materially dependent on experi- 
ence for its verification. It is directly verified in its own 
intrinsic intelligibility, which precludes the possibility even of 
conceiving the opposite. 

V. Per Se Nota and Modi Dicendi Per Se 

There is a temptation to identify per se nota or self-evident 
propositions with propositions involving a modus dicendi per 
se or a mode of perseity. However, such an identification can 
be seen to be erroneous once it is noted that the conclusion 
of a strict propter quid demonstration involves the second mode 
of perseity. As conclusion, and not premise, the proposition in 
the second mode of perseity is obviously not a self-evident 
proposition. Hence, not every per se proposition is per se nota 


or self-evident. The modes of perseity of concern to us here 
are the first, second, and fourth. A proposition involves the 
first mode of perseity when its predicate falls in the definition 
of its subject, the second when its subject falls in the definition 
of its predicate, and the fourth when the subject is related to 
the predicate as a necessary and proper cause .^^ In a strict 
"propter quid demonstration the major premise has the fourth 
mode of perseity (e. g., Evei-y rational animal is capable of 
speech) , the minor premise the first mode of perseity (e. g., 
Every man is a rational animal) , and the conclusion the second 
mode of perseity (e. g.. Every man is capable of speech) .^* 
" Per se " here indicates an essential rather than accidental 
connection between subject and predicate, and it refers exclu- 
sively to the objective structure of the propositions. Per se 
nota, on the other hand, refers rather to intelligible structure 
apropos of our knowledge of it, i. e., with or without a middle 
term, on the basis of intrinsic intelligibility or empirical data) . 
A per se nota proposition is one known immediately on the basis 
of its intrinsic intelligibility. Every proposition (including the 
conclusion) in a strict propter quid demonstration must be per 
se, but only the premises must (and can) be per se nota. 

Yet the case of the proposition in the second mode of perseity 
cannot be easily disposed of. True enough, as conclusion this 
proposition cannot be self-evident — at least not to us. But 
why isn't it self-evident to us? And is it, while not self-evident 
to us, self-evident in itself .^^ It is necessary prior to demonstra- 
tion that we know something about the subject and predicate 
of our conclusion and about the premises from which the con- 
clusion is generated — that they are and/or what they are. 
Concerning the predicate of the conclusion, namely, the proper 

^^ Cf., sufra, note 12. 

'* In I Post. Anal., lect. 13, n. 3: " Sciendum autem est quod cum in demonstra- 
tione probetur passio de subiecto per medium, quod est definitio, oportet quod prima 
propositio, cuius praedicatum est passio et subiectum est definitio, quae continet 
principia passionis, sit per se in quarto modo; secunda autem, cuius subiectum est 
ipsum subiectum et predicatum ipsa definitio in primo modo. Conclusio vero, in 
qua praedicatur passio de subiecto, est per se in secunda modo." 


passion to be proven of the scientific subject, we must know 
only its nominal definition. In fact we cannot, prior to 
demonstration, know its essential definition, for this is what is 
to be proved. To know, prior to demonstration, the essential 
definition of the proper passion in the demonstration, is to 
know its inherence in its proper subject (i. e., the scientific 
subject of this demonstration) , for the proper subject is in- 
cluded in the essential definition of the passion .^^ It would seem 
that a proposition "per se in the second mode, with a proper 
passion predicated of its subject, is self-evident in itself, since 
the subject itself is in the definition of the predicate, but not 
self-evident to us, precisely because we fail to understand the 
essential definition of the passion short of demonstration. 
Cajetan seems to agree with this position, for when he points 
out that the per se nota proposition whose predicate falls into 
the definition of its subject is only the principal type of per 
se nota proposition, he adds a second type in which a passion 
is said of its proper subject.^® If this type of proposition is self- 
evident it cannot be self-evident secundum nos, since it can 
be demonstrated, but in se tantum. Suppose this is the case, 
why should it be that this is per se nota only in se? The reason 
may be found in the type of causality exercised by the proper 
subject in reference to its proper passion. This is at least 
material causality, and in the case of the second mode of 
perseity it is precisely material causality which is actually 
involved." But matter as such is not proportioned to manifest. 
The connection between the subject and its property is mani- 
fested to us only by way of the form which is implied by the 
subject and which is the active cause of this property. The 
conclusion can be said to be virtually in the fourth mode of 
perseity because its subject implies this form. It is only in 
explicating this in the propter quid demonstration that we see 

"" Ibid., lect. 2. 

'' Catejan, In I Post. Anal, Ch. 19. 

" In I Post, Anal., lect, 10, n. 4. 


the necessary (but not, to us at least, immediate) connection 
between the subject and its property .^^ 

IV. In Conclusion 

At the very beginning of the Posterior Analytics Aristotle 
faces up to the famous dilemma of Meno. How can one ever 
be said to learn anything? Either he already knows what he 
learns — and this is not learning. Or he is ignorant of what he 
seeks to learn and thus cannot recognize it when he does come 
upon it — so that learning is impossible. ^^ The difficulty reminds 
us of the Parmenidean dilemma apropos of motion. Aristotle, 
of course, defends the possibility of motion by introducing the 

** There is, of course, no difPerence between the major premise in the strict type 
of propter quid demonstration and its conclusion unless there is a difference between 
the fourth mode of perseity and the second mode of perseity. And there is no 
difference here unless there is a difference between a real definition and the thing it 
defines. There can be, of course, no difference in re between the definition and the 
thing defined, so that the distinction between them must be a distinction of the 
reason rather than a real distinction. There is not even a foundation in the real for 
this distinction, so that it cannot be said to be a virtual logical distinction. Yet it 
must be more than the distinction exemplified between subject and predicate in the 
proposition John is John, for this is sheer tautology. If the definition and what it 
defines do not differ somehow as objects so that a proposition in the first mode of 
perseity is more than a tautology, then the prime instance of the per se nota 
proposition loses its significance and ceases to function meaningfully as an absolute 
premise at the same time that the major premise and conclusion of the strict type 
of propter quid demonstration became formally identical. This is, quite clearly, the 
death of demonstration. There is, however, a legitimate distinction to be made 
between the definition and what it defines. True, there is no advance in knowledge 
from thing to thing in defining. But there is in the definition a more perfect (clear 
and distinct) grasp of something known obscurely and confusedly prior to definition. 
This is enough to make the definition, from the point of view of the manner in 
which it is conceived, an object different from the defined; though, in itself, it 
remains identically the defined. This in turn is enough to make the per se nota 
proposition whose predicate is of the definition of the subject something more than 
tautologous. It is enough to guarantee a difference between the major and con- 
clusion in the strict propter quid demonstration, and thus to guarantee the advance 
in knowledge without which demonstration would be meaningless. Cf. Simon et al, 
op. cit., note 14, p. 618; McArthur, Ronald, "A Note on Demonstration," The New 
Scholasticism, XXXlV (1960), pp. 43-61; and especially Cajetan, In I Post. Anal., 
ch. 3. 

^» Plato, Meno, 80D-86D. 


notion of potential being (which in a sense represents a middle 
ground between being simpliciter and non-being simpliciter) . 
In a similar fashion he defends the integrity of discourse by- 
introducing the notion of the self-evident proposition. Self- 
evident propositions are the basic truths of demonstration, and 
in them scientific conclusions exist in potency. The demonstra- 
tive movement represents a true advance in knowledge from 
the potentiality of the scientific conclusion to its actuality. 
Prior to discourse the conclusion is not known simpliciter; but 
at the same time it is not unknown simpliciter. It is potentially 
known in its principles. The actual grasp of the self-evident 
proposition is the potential grasp of the scientific conclusions 
virtually contained therein. The premises of demonstration — 
taken as premises, that is, seen together to involve a middle 
term — function after the fashion of efficient causes which 
actuate the potentiality of the conclusion and make it be.^° 
The whole of the Posterior Analytics is concerned to investigate 
the logical vehicle (namely, demonstraton) which brings us 
from the self-evident principles to our scientific conclusions. 
In the first book demonstration and its types and properties 
are investigated. The second book concentrates on definition 
precisely as the medium of demonstration. Quite significantly 
the last chapter of this second book — which completes the 
Posterior Analytics — comes full round to the topic of the very 
first chapter. Meno's dilemma is absolved in terms of the uni- 
versally necessary and immediate basic principles of discourse. 
Scientific conclusions are truly conclusions insofar as they are 
different from these basic truths but are generated from them. 
They are truly scientific insofar as the basic truths of discourse 
into which they are resolved are primary and incontrovertible 
affirmations of the real. Upon the integrity of these basic truths 
or principles of demonstration depend the integrity of demon- 

*" Quodl., Vni, a. 4; " Insunt enim nobis naturaliter quaedam principia primo com- 
plexa omnibus nota, ex quibus ratio procedit ad cognoscendum in actu conclusiones 
quae in praedictis principiis potentialiter continentur. . . ." Cf., also De Ver., q. 11, 
a. 1; Surmna, I, q. 117, a. 1. 


stralion and the worth of its conclusions. Thus, in this final 
chapter, Aristotle defends the integrity of the principles them- 
selves in terms of an intuitive induction from the incontro- 
vertible data of sense experience. St. Thomas points out that 
the difference between dialectical discourse and demonstration 
is the difference between unterminated and terminated dis- 
course.'*^ The dialectician falls short of being a scientist pre- 
cisely because dialectical conclusions are not finally grounded 
in the real. The dialectical method can be referred to as a 
" rational method " precisely insofar as its conclusions remain 
within the reason. The demonstrative method is the method 
of science because it grounds its conclusions necessarily in the 
real — and it does this insofar as it resolves them into self- 
evident propositions. There is no science save that there be 
a rational progression from principles to scientific conclusions. 
Thus the scientific intellect is of necessity a ratio. But, at the 
same time, there is no science save that there be an intuition of 
basic principles — so that the scientific intellect is also an 
intellectus.^^ Demonstration may be an instrument of the 
intellect as reason, but there can be no meaningful theory of 
demonstration save that the per se nota proposition, itself 
properly the object of intellect as intellect, be significantly a 
part of that theory. 

Edward D. Simmons 

Marquette University, 

Milwaukee, Wisconsin. 

^^ In Boeth. de Trin., q. 6, a. 1 ad 1: "Alio modo dicitur processus rationalis ex 
termino, in quo sistitur procedendo. Ultimus enim terminus, ad quem rationis 
inquisitio perducere debet, est intelleclus principiorum, in quae resolvendo iudicamus; 
quod quidem quando fit, non dicitur processus vel probatio rationabilis, sed demon- 
stratio. Quandoque autem inquisitio rationis non potest usque ad ultimum terminum 
perduci, sed sistitur in ipsa inquisitione, quando per probabiles rationes proceditur, 
quae natae sunt facere opinionem vel fidem, non scientiam, et sic rationabilis pro- 
cessus dividitur contra demonstrativum." 

*^ Summa, I-II, q. 57, a. 2: " Verum autem est dupliciter considerabile; uno modo, 
sicut per se notum; alio modo, sicut per aliud notum. Quod autem est per se notum, 
se habet ut principium, et percipitur statim ab intellectu; et ideo habitus perficiens 
intellectum ad huiusmodi veri considerationem vocatur intellectus qui est habitus 
principiorum." In Boeth. de Trin., q. 6, a. 1 ad 1: "Ultimus enim terminus, ad 
quem rationis inquisitio perducere debet, est intellectus principiorum, in quae 
resolvendo iudicamus. ..." 




IN his commentary on the Posterior Analytics of Aristotle, 
St. Thomas notes that did de omni, sometimes translated 
as " true in every instance," is treated differently in the 
Posterior Analytics from the way it is in the Prior Analytics. 
In the latter work, which is concerned with the form of the syllo- 
gism and therefore with what is common to any syllogism, did 
de omni is treated only commonly, disregarding the differences 
attaching to a demonstrative or dialectical use. In this context, 
it is enough to say that did de omni is realized whenever the 
predicate is found to be in each of those things which are con- 
tained under the subject. Once, however, we begin to consider 
the syllogism on the part of matter, we must say more about 
did de omni. Hence, immediately after saying that the predi- 
cate is found in each of those things which are contained under 
the subject, St. Thomas adds: " This can happen either ut nunc, 
and in this way the dialectician sometimes uses did de omni, 
or absolutely and for all time, and in this way only the demon- 
strator uses it." ^ 

In discussing the ancient and medieval theory of universals, 
we are apt to overlook this distinction between the verified did 
de omni and the provisional one called universal ut nunc, and 
we tend to ignore the importance the latter has as a tool 
particularly for the investigation of nature. An example of the 
verified did de omni was the common property of every para- 
bolic triangle, ' to have its three angles equal to two right 
angles.' An instance of the universal ut nunc was ' white ' 
predicated as a common property of swans. The former 
property was based upon a propter quid demonstration; the 
latter was based upon, or rather derived from, an incomplete 

^ " Hoc autem contingit vel ut nunc, et sic utitur quandoque did de omni dia- 
lecticus; vel dmpliciter et secundum omne tempus, et sic solum utitur eo demon- 
strator." In I Post. Anal., lect. 9, n. 4. 



induction: no one reporting about swans had ever seen a black 

We come therefore at once to the following question. Since 
" white," as a common property, was not certain, why is it 
that we could use the universally distributive ' all ' and say 
that all swans are white? Why not use a roundabout expression 
and state: " It appears that some, if not all, swans are white." 
Or why not say, even more simply, " swan is white," as we say 
" man is white." In this more simple way of putting the matter 
we would be plainly predicating something of a universal 
(" swan ") by reason of something found in one or some 
individuals. The point then is whether this would be regarded 
as a universal ut nunc, a universal " for the time being." Pre- 
sumably not, for what we are aiming at is an enunciation like 
" man is an animal," an essential predication. But why use 
this mode of enunciation before it is warranted? 

What we are in fact faced with is two distinct modes of 
essential predication: a true one and a hypothetical one. What 
is the foundation for this distinction? Why are hypothetically 
essential predications required? Why not use unambiguous 
circumlocutions that show the essential predication to be only 
hypothetical? After all, many essential predications are in fact 
no more than hypothetical. 

To answer such questions — which in effect are one question — 
about the distinction between true and hypothetical essential 
predications, it will be opportune, first of all, to make a further 
distinction by comparing the notion of " triangle " with what 
we intend by " swan." We can define the first as to what it is, 
namely a three straight-sided figure whose exterior angle is 
equal to the two opposite interior angles. But what about 
" swan "? We define, not the swan, but the name by pointing 
to individual instances, or by describing the figure and habits 
that set swans apart from chickens, turkeys, geese, and so on. 
Now surely there must be in nature something that accounts 


for these differences. But' what is this exactly? As St. Thomas 
says: " That nature is, is fer se known, insofar as natural 
things are manifest to sense. But what the nature of any thing 
is, or what its principle of motion, is not manifest." ^ 

Meanwhile, we have the name " swan " and whoever knows 
this name, using it with the meaning agreed upon, does not 
confuse swans with chickens or geese. Still, there may exist 
somewhere, or there may have existed, some types of fowl 
between swans and geese which could make us hesitate about 
using the name to stand for what is assumed to be a definable 
nature. The opposition of contradiction between " swan " and 
" non-swan " is plain enough, but where and how it actually 
applies may be uncertain. Such is the case whenever the 
positive term referred to is imperfectly known. Lacking defini- 
tive knowledge, we have agreed to use the word in a way that 
is at least in practice meaningful. In the measure that certain 
sensible signs set swans apart from other feathered creatures, 
we are confident that our naming has some determinate basis 
in nature, that swans do in fact have a nature. Just what this 
is, however, we have to acknowledge that we do not know. 

Let us recognize, however, that even if we knew exactly 
what a swan is as we know what a plane triangle is, the term 
" swan " by itself, apart from an enunciation, would be neither 
true nor false. The same applies to the nominal definition of 
the name, whether obtained by designation or by description 
of what it stands for: " a large-bodied, web-footed water bird 
of the genus Cygnus, having a long neck and sort legs placed 
far back," etc. We can, of course, go further and state that 
there are such animals. However, the truth of this statement 
does not imply that we know exactly what a swan is. Accord- 
ingly, we are forced to acknowledge a hiatus (a) between the 
truth of the statement and the relative indetermination as to 
what a swan is; (b) between the name itself, used to stand for 

" Naturam autem esse, est per se notum, inquantum naturalia sunt manifesta 
sensui. Sed quid sit uniuscujusque rei natura, vel quod principium motus, hoc non 
est manifestum." In II Phys., lect. 1, n. 8. 


a universal that is predicable of certain individuals, and the way 
it would signify if we knew, once and for all, just what a swan 
is as we know what a plane triangle is. In other words, we can 
name things before we know precisely what the thing is that 
we name. The history of biology proves that what we had 
long considered to be a species turns out to be a genus. 

That simple naming, as distinguished from enunciation, does 
not presume that we know exactly what it is that we name is 
strikingly plain in the instance of the word " atom." It is taken 
from the Greek " indivisible," in common usage. Democritus 
imposed a further meaning upon it to signify what he believed 
to be the indivisible elements of all things, differing from 
one another by their geometrical figure. Dalton, for quite 
different reasons, was led to an analogous conception, but his 
minute spheres still retained the meaning of " indivisible." 
Rutherford finally broke down these indivisibles, and they are 
becoming unceasingly the opposite of what the name was first 
intended to mean. The word " atom " continues to make 
history, a history reflecting progress in our knowledge of the 
basal entities of the physical world. But the original meaning 
has dropped from sight, and the physicist will no longer refer 
us to nature except most indirectly. He will explain what he 
means when using this word by relating certain observations, 
such as the Brownian movement, and operations of measure- 
ment which led to interrelated measure-numbers permitting 
him to establish equations, etc., which he then goes on to 
explain in terms of hypotheses and theory that lead to further 
experiments, etc. This elaborated understanding becomes very 
atomic in one sense, if you will, but Democritus might well be 
puzzled about his word " atom." 

Of course, someone might say of Democritus that he did not 
know what he was talking about, and the same of Dalton. 
But of course they knew. What they were ignorant of was the 
real import of what they said, which could be no more than 
vague, as the history of science has proved. What we must 
recognize is that there can be uncertainty, not only as to 


whether B belongs to A, or whether B is common to A and C, 
or a commensurate property of B, but that there can also be 
uncertainty concerning what the term A exactly stands for. If 
A and B are known exactly, then their relationship can be 
known exactly too. But if they are not known exactly for 
what they are, their relationship will be proportionally vague 
and provisional. 

There is a difference, then, between a universal ut nunc as a 
simple term, viz.. A, and as a subject or a property in an 
enunciation, such as "All A is B." The following questions 
remain open: "Is A.?" ''Is B.? " "Is AB.? " The first two 
concern the bearing of the names: do these definite names refer 
to something we know definitely? The answer to the other 
question is obvious: the relation of A to B is either definitely 
known or it is provisionally posited. Yet why should we posit 
names and relations provisionally .^^ Why not wait until we 
know the named exactly and, in the case of enunciation, until 
we know the exact relation .^^ 

This brings us to the very heart of scientific method and 
to the relevance of the theory of positing a universal " for the 
time being " in the practice of science. We must, for the 
time being, posit such universals and wait to see what happens 
for having posited them. But let us not suppose that " to see 
what happens " is merely a passive attitude. The very positing 
must suggest an activity, a further induction or experimen- 
tation, with attendant hypotheses and theory which give 
further meaning to the original positing. To posit a universal 
ut nunc is to advance something that not only requires further 
testing but also suggests it. 

Now had we confined ourselves to predicating something of 
a universal nature (or of a quasi-universal nature) by reason 
of what is verified in its inferior singulars, the matter would 
be immediately closed and settled. For, if Socrates walks, we 
are quite justified in saying that " man walks," and that's the 
end of it. But if we say " man is an animal," this must be true 
of every man, not just of this man. However, this mode of 


predication, as we have suggested, need not be reserved to 
cases that are certain. Mere likeliness may suffice to posit 
propositions in that mode, such as " man came about by 
mutations that occurred in lower living beings," but they will 
be 'posited and require further proof. In other words, the 
universal ut nunc appears both in the order of simple appre- 
hension and in the order of composition and division, with all 
that this entails in the order of argumentation. 

Now there is a further aspect to this type of universality. 
It is, in a sense, pragmatic: we may have to do something 
about it. This " doing " can mean a speculative operation, as 
when we are inclined to believe that there is no last prime 
number: the statement is a challenge that sets us on to attempt 
a proof. But the doing may also be more strictly a practical 
operation, such as experimentation, or careful isolation for 
further induction. And this brings us face to face with an 
important distinction. Suppose that we have laid down a 
thermodynamic theory, which is a coordinated ensemble of 
posits, and construct on the basis of it a machine that works. 
Does this prove that the theory is true.^^ Pragmatically, it does. 
It is in this sense that as to truth, scientific theories are in 
the main pragmatic. But so far as sheer knowledge is con- 
cerned, pragmatic proof can do no more than indicate that as 
to speculative truth the theories are on the right track, that 
we are moving in the direction of the truth, not that we possess 
it. The whole point is, then, that we would not be moving on 
toward the truth if we did not take the liberty of constructing 
posits in the mode of universal terms and universal proposi- 
tions for the immediate purpose of seeing what happens when 
we do this. 

If our mind had to confine itself to terms and propositions 
that we know well and could only use these for further argu- 
ment, there is very little that we could ever come to know.^ 

This would not only preclude advances in scientific knowing, but also in vast 
areas of what we now regard as philosophy, for the " eternal truths " of philosophy 
occupy a relatively small position in relation to the whole. Indeed, it might be said 


Tentatively we must go beyond what we know, starting from 
hints, as it were, and then proceeding from what we have 
posited as if it were true. It is as if, to move on, our mind 
must come to rest, provisionally, in a myth, a verisimilitude, 
and even in strictly logical fictions. But it must do so wittingly, 
which is what it does in fact by recognizing the type of uni- 
versality we are concerned with here as being no more than 
ut nunc. 

As we get closer to things in their concretion, the universals 

that a defect of much scholastic philosophy, especially in the manual form, has 
consisted in treating so many things as falling under dici de omni absolutely and 
as though subject to rigorous demonstration. The great scholastics, however, were 
never under such illusion. St. Albert, for instance, especially with respect to the sort 
of knowledge we have in the investigation of nature, says the following: 

" It is plain, then, from what has been pointedly considered in natural things, 
that every definition or notion of natural forms is conceived with matter, which is 
subject to motion or change or to both; and it must therefore be conceived with 
time inasmuch as time is in the temporal thing. Because of this, much opinion is 
involved in this sort of knowing, so that it cannot attain to the firm, constant and 
necessary habit of science, as Ptolemy says." After contrasting the " doctrinal 
sciences (mathematics) with such knowledge, St. Albert adds: ". . . the habits 
acquired by the speculative intellect have been given the name of true science, and 
are called doctrinal and teachable; and the reason is that they are taught from 
unchanging principles, which the disciple receives from the teacher by sheer notifi- 
cation of the terms, without need of experience, as Aristotle says in Book IV, but 
by the teacher's simple demonstration the intellect of the disciple comes to rest; 
hence it is that adolescents, without experience, can so often excel in these matters — 
something which is in no way possible in the natural sciences, where experience is 
of far greater account than doctrine by demonstration." In I Metaph., Tract. I, 
cap. 1, (Borgnet, VI) pp. 1-2. 

(Constat autem ex his quae subtiliter in naturis considerata sunt, omnem difRni- 
tionem aut rationem formarum phj-^sicarum conceptam esse cum materia, quae motui 
subjacet, aut mutationi, aut utrique; et ideo concipi oportet cam cum tempore 
secundum quod tempus est in re temporali. Propter quod etiam id quod scitur de 
hujusmodi, multum miscetur opinioni, et pertingere non potest ad confirmatum 
constantem et necessarium scientiae habitum, sicut dicit Ptolemaeus. . . . habitus 
per speculativum intellectum adepti verae scientiae nomen acceperunt, et doctrinales 
et disciplinales vocantur, ideo quia ex principiis non mutantibus quae discipulus a 
magistro non accepit nisi per terminorum notitias, docentur, experientia non indi- 
gentes, ut dicit Aristoteles libro quarto, sed simplici demonstratione doctoris 
constante intellectu discipuli: propter quod etiam juvenes inexperti ut plurimum 
magis excellunt in ipsis: quod nullo modo possible fuit in physicis speculabilibus, 
in quibus experientia multo plus confert quam doctrina per demonstrationem) . 


are more and more provisional in the sense that we deliberately 
posit terms, vague and uncertain, which our mind is free to 
invest with intentions of universality, and thereupon seek to 
establish relations between those terms. Our mind has this 
power because it can bring together things which in nature 
are not 'per se connected, e. g., " man walks " or " man is 
white." In these examples we do attain a truth, however, since 
we do not mean that every man is walking or that every man is 
white. But what we learn from such examples is that what 
is accidentally one in nature can be brought together by the 
intellect to form a proposition that is per se one as a proposi- 
tion. Moreover, the mind can go further than that, and in 
fact must do so, positing terms and bringing them together 
for the purpose of getting behind the appearances upon which 
our posits are based.* 

Verisimilitude, either with respect to terms or with respect 
to composition or division, is the proper basis of universality 
ut nunc. By verisimilitude we mean that which may in fact 
have no more than a resemblance to truth, a mere appearance 
of it and recognized as being no more than that. This is enough 
for our mind to reach out beyond what we really know, beyond 
what is warranted. Actually, universality for the time being 
keeps us within the bounds of the mind, as any opinion does, 
so long as it is no more than opinion. But opinion, as dialectic 
in general, has the nature of a tool, an organon, with respect 
to truth. Constructed universals of the type v*^e are concerned 
with (as distinguished from the relation of universality we may 
tentatively invest them with) are logical organa. For dialectics 
as logica utens does not go beyond the stage of instrumentality. 

There is in all of this something of a paradox which we should 
notice. The mind goes beyond what it really knows, but in 
so doing it still remains within its own confines. How does this 
occur.'^ A situation analogous to this is the one already noted, 
of the mind's composing a proposition that is one per se about 

* Aristotle was certainly aware of this procedure. See, for example, De Caelo, III, 
chap. 7. 


something that is one only -per accidens. The per se one remains 
within the mind, yet the mind is thereby enabled to say 
something that is true, namely " man is white." However, at 
best this is only an analogy, or perhaps only an example, of 
the main point we have in mind. How does this main point 
differ from the instance of the mind's composing as per se one 
which is one only per accidens? 

Let us try to bring out the difference by considering the 
status of opinion. Here we go beyond what is warranted, either 
by a proper reason (as in the case of an opinion concerning 
something in logica docens) or by what we know truly of 
reality (e. g., why ruminants need the type of digestive system 
they have; the reason assigned could be one that would apply 
to horses, who also eat and digest gi^ass) . In thus going beyond 
reality, we do not do so in the way one real thing goes beyond 
another, as cows beyond cabbage. The " going beyond " is in 
the order of knowing. It is not as if our mind casts out a net. 
The mind does cast out nets (as, indeed, we do so well and 
frequently in logical divisions) but they remain within the 
mind and are ordered to knowledge, not to the actual handling 
of things. Of course, there is, nonetheless, a kind of reaching 
out physically toward reality and even a meddling in it when 
we perform an experiment. But why do we perform so many 
experiments? Not to improve things in any practical sense, 
at least primarily, but to improve our understanding of what 
things are so far as possible. And so we are back in the mind, 
which we have really never left. The external operation is 
performed with a view, not to altering a given order in reality, 
but to improving the knowledge in our mind. Hence the 
paradox remains, but is intelligible. We go beyond our mind 
in order for the mind to understand what it otherwise could not, 
but this " going beyond " is a dialectical extension, remaining 
an instrument for the mind's ever increasing grasp of an obscure 
physical reality. In this order, experience and experimenting 
contribute more to our knowledge than strict demonstration. 

The evolution of scientific theories, based upon wider obser- 


vations enhanced by physical instruments, suggesting new 
hypotheses that suggest further research and crucial experi- 
ments, shows that we may have to remain content with a 
knowledge that, ever progressive, remains nonetheless pro- 
visional. Now in the measure that this is true of most of our 
investigation of nature, it is clear that the domain of uni- 
versality ut nunc has far greater dimensions than that of true 
universals, and this is the point of emphasis in this paper, a 
point which seems to have been somewhat ignored in the 
scholastic tradition. There are two complementary reasons for 
the greater dimension of the universal ut nunc. First, there is 
the very nature of our mind, which is an experimental one, 
seeing that our knowledge must be derived from things them- 
selves. Second, there is the unexpected complexity of the things 
we seek to know, even of those which apparently are at close 
range, the sensible things. Even these are somehow fathomless 
in the experimental sense of the word. A simple example is 
enough to illustrate this point, our organs of external sensation. 
We agree that our skin is an organ of touch and that our eyes 
are organs of sight. This seems safe enough to say so long as 
we do not look too closely into the subject. We have initially 
recognized and understood these organs with reference to our 
sensations. But now we must delve into anatomy and physi- 
ology, and then into chemistry and physics. In this process 
we are wading toward a limit we shall never reach. Yet we 
know that the limit is somehow there though we have nothing 
more than an intimation of just what it is. And so it is that 
the whole interval between actual sensation along with the 
vaguely recognized organs, and the limit we are moving 
toward, is replete with provisionally contracted terms, with 
universals " for the time being," ever in need of reconstruction 
and implementation. 

Even a true universal such as " what a man is " does not 
settle all that man is, once for all.^ The example of sensation 

° The definition of " man " as " rational animal " has often been criticized as 
inadequate and even ridiculed as being incomplete. But this definition, though an 


and its organs shows that this true universal is quite incom- 
plete and must be implemented with a world of universals 
ut nunc. Man is a good enough example, for in one sense he 
is the being which we know best, while in another sense we 
know least of him. We know him best because of our internal 
experience; but in terms of external experience we know the 
lower forms of life far better even though these, from the former 
point of view, are by far the more obscure. Now the situation 
is such that while we may be definitely certain about some 
things we come to know from internal experience, as soon as 
we try to narrow down our knowledge of living things in terms 
of external experience, then even our simplest terms, such as 
" protoplasm " or " genes," though their related conceptions 
have some basis in experience, are in the main " logical fictions " 
in even Lord Bertrand Russell's sense of this term. 

Nevertheless, we should not wholly identify logical fictions 
with our universals ut nunc. The fictions are not intended 
to have that kind of resemblance to true universal natures. 
Logical fictions are symbolic constructions whereas the uni- 
versals ut nunc are names and bear a real verisimilitude to 

When all is said and done, however, it still remains that the 
bulk of our knowledge remains provisional and in constant 
need of implementation. That such is the status of our knowl- 
edge is not itself mere theory. It is a well established fact. The 
history of science proves that we may be quite certain of our 
uncertainties, i. e., of the provisional nature of most of our 
knowing as regards things in their ultimate concretion, and 
therefore of the fact that most of our universals are ut nunc. 
We are definitely certain that two is an even number and even 
of what a circle is (no matter how little the calculator may 
care about this) ; and that if an even number is taken from an 

essential one and a good one in precisely this sense, was never intended to be a 
complete definition. From the standpoint of completion, much remains to be said 
about what man is, and much of what we know in seeking to determine more fully 
what man is will remain provisional. 


even number, the remainder will be an even number — all this 
being a matter of strict demonstration. But we have nothing 
like this kind of certitude about dogs and cats, not to mention 
the less familiar objects of even ordinary experience. Recog- 
nizing, therefore, how provisional most of our knowledge is, 
let us, for the time being, make all possible use of universals 
ut nunc. 

John A. Oesterle 

University of Notre Dame, 
Notre Dame, Indiana. 


WILLIAM HARVEY was born in England in 1578 
and died in 1657. He received his grammar school 
education at the famous King's School in Canter- 
bury. In 1593 he entered Caius College, Cambridge, and re- 
ceived his B. A. degree in 1597. In this period, it was not 
unusual for English Protestants interested in a scientific edu- 
cation to seek it in a continental Catholic university. Harvey 
chose the Universitas Juristarum, the more influential of the 
two universities which constituted the University of Padua in 
Italy and which had been attended by Thomas Linacre and 
John Caius, and where, incidently, the Dominican priests were 
associated with University functions. 

Competency in the traditional studies of the day was char- 
acteristic of William Harvey's intellectual development. The 
degree of Doctor of Physic was awarded to Harvey in 1602 
with the unusual testimonial that " he had conducted himself 
so wonderfully well in the examination, and had shown such 
skill, memory, and learning that he had far surpassed even the 
great hopes which his examiners had formed of him. They 
decided therefore that he was skilled, expert, and most effici- 
ently qualified both in arts and medicine, and to this they put 
their hands, unanimously, willingly, with complete agreement, 
and unhesitatingly." ^ 

In 1616 he gave his first Lumleian lectures in surgery at the 
Royal College of Physicians in London. The manuscript notes 
of his first course of lectures, the Prelectiones, are preserved and 
have been reproduced in facsimile and transcript." In these 
lectures he first enunciates the circulation of the blood. 

^ D'Arcy Powers, William Harvey (London, 1897), pp. 26-27. 
' William Harvey, Prelectiones Anatomiae Universalis (London: J. & A. 
Churchill, 1886). 



He waited for 12 years, however, until 1628, before he pub- 
Hshed his great work entitled, An Anatomical Exercise on the 
Motion of the Heart and Blood in Animals. In this classic he 
foniially demonstrated the true nature of the heart and that 
the motion of the blood was circular. This work is relatively 
short and takes up 86 pages in the standard English edition of 
his collected works.^ In 1648 Harvey's demonstration was at- 
tacked in a treatise published by Dr. Jean Riolan of Paris. 
Harvey answered his critic in two lengthy letters published in 
Cambridge in 1649. 

Harvey's second famous work, Anatomical Exercises on the 
Generation of Animals, which is over five times the length of 
the first, appeared in publication in 1651 through the solicita- 
tion and under the direction of Dr. George Ent, a well-known 
physician of the period. 

In his personal life and professional career Harvey had a wide 
circle of acquaintances and friends. Though it is not certain 
whether he knew Galileo who was a fellow student at Padua, 
he knew most of the leading contemporaries of his day. This 
included Boyle, Hooke, Hobbes, Dryden, Cowley, Descartes, 
Gilbert, Wren, Bacon and others, in addition to prominent 
physicians and anatomists. 

Harvey was extremely well-read and made reference in his 
lectures and writings to the Greek philosophers and scientists of 
the fourth through the seventh centuries, B. C, to many Greek 
writers of the Christian era, to numerous Latin writers includ- 
ing many of the poets, to Albert the Great, and to numerous 
Renaissance men of the fifteenth and sixteenth centuries. In 
all, he made reference to approximately 100 authors in his 

^ The Works of William Harvey, M. D. (London: Printed for the Sydenham 
Society, 1847): Translated from the Latin by Robert Willis, M. D. It includes 
An Anatomical Exercise on the Motion of the Heart and Blood in Animals; The 
First Anatomical Exercise on the Circulation of the Blood to John Riolan; A 
Second Exercise to John Riolan, in Which Many Objections to the Circulation of 
the Blood are Refuted; Anatomical Exercises on the Generation of Animals, to 
Which are Added, Essays on Parturition, On the Membranes and Fluids of the 
Uterus, and on Conception; and miscellaneous items (Harvey's will, autopsy of 
Thomas Parr and nine short letters) . 


writings. In particular, he had a comprehensive working knowl- 
edge of Aristotle, as well as Aristotle's commentators, Avicenna 
and Averroes. According to one Harvian lecturer, Harvey refers 
to Aristotle 269 times.* References are made to Aristotle's 
logical, physical, biological and metaphysical works. It is clear 
that Harvey's superior intellectual formation through ancient 
authors — the Great Books of his day — proved no block to his 
momentous contribution to the future. 

Finally, it is pertinent to note his basic religious belief as it 
relates to his scientific work. On the title page of his Prelec- 
tiones he prefixes from his favorite poet, Virgil, the motto 
" Stat Jove principium, Musae, Jovis omnia plena." Over 
thirty years later he explicates this motto in Exercise 54 of the 
Generation of AniTnals: 

... in the same way, as in the greater world, we are told that ' All 
things are full of Jove,' so in the slender body of the pullet, and in 
every one of its actions, does the finger of God or nature no less 
obviously appear . . . We acknowledge God, the supreme and 
omnipotent creator, to be present in the production of all animals, 
and to point, as it were, with a finger to his existence in his works, 
the parents being in every case but as instruments in his hand. In 
the generation of the pullet from the egg all things are indeed con- 
trived and ordered with singular providence, divine wisdom, and 
most admirable and incomprehensible skill. And to none can these 
attributes be referred save to the Almighty, first cause of all things, 
by whatever name this has been designated, — the Divine Mind by 
Aristotle; the Soul of the Universe by Plato; the Natura Naturans 
by others; Saturn and Jove by the ancient Greeks and Romans; by 
ourselves, and as is seeming in these days, the Creator and Father 
of all that is in heaven and earth, on whom animals depend for 
their being, and at whose will and pleasure all things are and were 

In his last will and testament he states, " I doe most humbly 
render my soule to Him that gave it and to my blessed Lord 

* D. F. Fraser-Harris, " William Harvey's Knowledge of Literature Classical, 
Mediaeval, Renaissance and Contemporary." Proceedings of the Royal Society of 
Medicine, XXVII (1934), 195-99. 

* Harvey, Works, ed. cit., pp. 401-402. 


and Savior Christ Jesus and my bodie to the Earth to be buried 
at the discretion of my executor . . ," " 

Before we can determine whether Harvev was a modem 
or an ancient scientist, we must first know him as the great 
scientist he was. The twentieth century scientist, more nar- 
rowly educated for the most part, pays only lip service to 
Harvey's greatness. We can say about most contemporary sci- 
entists concerning Harvey, what Galen said about his contem- 
poraries concerning Hippocrates: they admire him, but do not 
read him; when they read him, they do not understand him; 
when they understand him, they fail to put into practice what 
he has taught.^ 

Characterizing the lip service of contemporary biologists and 
physicians is the unexpressed and hidden belief — a reflection of 
our current pride and prejudice — that what Harvey enunciated 
was so obvious, so easily discoverable, so easily observable by 
all beginning students, that the uniqueness of his discovery was 
principally his ability to liberate himself from the yoke of 
ancient traditions, thought and terminology — from dark ages, 
sterile scholasticism, authoritarianism and philosophical en- 
croachments — sufliciently to see what in itself was so patently 
observable. Even then, Harvey's liberation was incomplete 
according to many historians. 

Part of the modem difficulty stems from not reading him. 
Typical of the difficulty is the belief that Harvey's discovery 
of the circulation of the blood was a sense observation rather 
than a conclusion resulting from reason utilizing inductions 
from sense observations, as principles or propositions in a 

Part of the modem difficulty also stems from those who have 
read him, but not well. Many such readers have failed to ap- 
preciate the complexity of obtaining a new and true conclusion 
within a context in which the old conclusion was a plausible 
part of an integrated body of knowledge. The modern reader, 

' Ibid., p. Ixxxix. 

'' Galen, Si quis optimus medicus est, eundem esse philosophum,, among Isagogici 
libri, in Opera omnia, 9th ed. (Venetiis, apud Juntas: 1625), fol. 6r-v. 


by reading Harvey retrospectively as if his work were merely 
the beginning of what came afterwards, tends to miss what is 
more basic: that Harvey's discovery like most scientific dis- 
coveries results from a scientific methodology which is related 
to one's education, philosophy, habits, and experience as a 
scientist. Rather than relate Harvey's discovery to the past out 
of which it emerged, the modem reader acts as if it sprang 
de 710V0 from a pair of eyes newly able to observe through 
the Renaissance liberation from the medieval blinders that 
enveloped this age. 

The following comments are characteristic of those made by 
critics who dissociate Harvey's demonstration from the tradi- 
tion of his predecessors. Harvey " with one blow demolished 
the structure, compounded of metaphysics, far-fetched analogy, 
and mysterious ' principles ' and ' spirits,' which constitute 
the method of medieval biology." Harvey's method was char- 
acterized " by the rigid exclusion of mysterious forces and 
agencies." ^ " Harvey . . . never entirely emerged from the 
mystifying language of his contemporaries, and even regarded 
himself as a loyal Aristotelian, but he builded better than he 
knew." ^ 

The contemporary translator of the most widely read version 
of Harvey's classic on The Motions of the Heart and the Blood 
— an outstanding scientist in his own right — has this to say: 

In his more scientific passages, Harvey is remarkably terse and 
' snappy,' in the current style. In his philosophical discussions he 
becomes vague and his sentences grow beyond control ... At the 
same time, he tried to complete his demonstrations by metaphysical 
arguments based on the traditional teleology. This was the anti- 
thesis of the method by which he had achieved such brilliant 
success in the preceding chapters . . . There is a good discussion of 
the comparative and embryological aspects of the subject, and then 
a peculiar use of the traditional authority of Galen as evidence. 
One may find almost all kinds of logic in Harvey." 

* Franklin Fearing, Reflex Action (Baltimore: William & Wilkins, 1930), p. 29. 

® A. Wolf, A History of Science, Technology and Philosophy in the 16th and 
17th Centuries (London, 1935) , p. 415. 

^° Chauncey D. Leake, An English Translation with Annotations of De Motu 
Cordis (Springfield: Charles C. Thomas, 1931), Translator's Preface. 


If these comments truly delineate Harvey's contribution, we 
are faced with the following paradox: Harvey, who was edu- 
cated superbly in the traditional education of his time, who 
considered himself a loyal traditionalist in science and philoso- 
phy, and who utilized philosophical arguments based on the 
established teleology of the day, all of which are alleged to be 
antithetical to scientific advance, was also the same Harvey 
who produced a brilliant, original and revolutionary work of 
science which laid the groundwork for modern physiology and 

To explicate this paradox, it seems incumbent upon us to 
keep open the possibility that the fruit of his labors bears a 
direct relationship to the tree that bore it and the intellectual 
soil that nourished it. That Harvey was well educated, and 
respected and utilized his learning heightens this possibility. 
Furthermore, Harvey was one of the few successful investiga- 
tors in the history of science who actually thought about and 
wrote on scientific methodology, and whose thinking on this 
permits us to measure his reciprocal accomplishments. 

It is ironic, in contrast, that the modern scientist looks upon 
Harvey's contemporary, Francis Bacon, as the father of modern 
science, despite history's testimony that no scientific dis- 
covery can be attributed to the Baconian method. It is par- 
ticularly ironic since there is no indication that Bacon even 
recognized Harvey's striking contribution. A leading Bacon 
scholar writes, " The probability is that ... he regarded the 
theory as hardly worthy of serious discussion."" Contrari- 
wise, Harvey, who was Bacon's personal physician, said of him 
derogatorily that, although he enjoyed his wit and style, Bacon 
" writes philosophy like a Lord Chancellor." ^- 

The alternative of the hypothesis that Harvey's contribution 
flowed from his past is a dismal one. It forces one to conclude 
that Harvey was a schizophrenic, a duality — a sterile scholastic 
and a fertile scientist — rather than a unity; and that his " bril- 

^^ Thomas Fowler, Bacon's Novum Organum, Edited with Introduction, Notes, 
etc., 2nd ed. (Oxford, 1889) p. 28. 

^^ John Aubrey, Lives oj Eminent Men (London, 1813), vol. 2, p. 381. 


liant success " was accomplished by " almost all kinds of logic." 
We can best seek to understand the paradox of Harvey by 
seeing whether Harvey, in his turn, merely paid lip service to 
Aristotle who dominated the medieval period or actually util- 
ized him the way one scientist utilizes another. 

To show that Harvey was a genuine disciple of Aristotle, four 
illustrations of how Harvey utilizes and follows Aristotle are 
presented below. The first summarizes Harvey's essay on sci- 
entific methodology and shows Harvey's adherence to Aris- 
totle's Organon. The second illustration deals with the great 
scientific controversy in embryology as to whether animals are 
preformed or epigenetically unfold themselves in development. 
It shows Harvey decisively siding with Aristotle. The third 
reviews the actual references Harvey makes to Aristotle in 
The Motion of the Heart and Blood and shows that Aristotle 
abets rather than hinders Harvey's ultimate demonstration. 
One of these references points up the need for a modern reader 
to have a knowledge of Aristotle's works if he is to have an 
adequate understanding of Aristotle's contribution to Harvey's 
discovery and demonstration. The final analysis shows that 
Harvey's demonstration of the true motion of the heart and 
blood is a classic Aristotelian demonstration, and illustrates 
that Harvey follows in practice what he adheres to in theory, 


Harvey's essay on the scientific method is the preface to his 
work. Anatomical Exercises on the Generation of Animals, 
wliich was published 23 years after the publication of his classic, 
The Motion of the Heart and Blood, when Harvey was 73 
years old. It is a product of his later years and reflects the 
permanency of the position he held. It is not intended as a 
complete exposition of the scientific method but only as a 
preface to his work on generation. The preface " consists of 27 
paragraphs and has three headings: ' Of the Mode and Order 
of Acquiring KJnowledge '; ' Of the Former, Calling to Mind 

" Harvey, Works, ed. cit., pp. 151-167. 


Aristotle '; and ' Of the Method to be Turned to in the Knowl- 
edge of Generation.' The following is a paragraph analysis of 
this essay. 

Anatomical Exercises on the Generation of Animals 

A. Introduction 

1. Causes of writing (par. 1) 

2. Present opinions concerning generation 

a. Of Galen and physicians (par. 2) 

b. Of Aristotle and philosophers (par. 3) 

3. Concerning the falsity of these opinions (par. 4) 

4. Further exposition of final causes of writing (par. 5) 

5. Concerning the method employed 

a. That it is difiicult (par. 6) 

b. That its difficulty should not be a deterrent (par. 7) 

B. Of the Mode and Order of Acquiring Knowledge 


1. That there can be only one road to science (scientia) 

(par. 8) 

2. Explication of the road 

a. Relation of sense to universals (par. 9) 

b. As expressed by Seneca and expounded by Harvey 

(par. 10) 

3. The importance of sense for judgment (par. 11) 

4. Why it was thought fit to present this by way of intro- 

duction (par. 12) 

C. Of the Former, Calling to Mind Aristotle 

1. That knowledge (cognitio) is not innate but acquired 

(par. 13) 

2. Whence and how we come to know (par. 14) 


3. Resolution by Aristotle of the difficulty involved (par. 


4. The order of knowledge in any art or science (par. 16) 

5. Conclusions as to the relation of perfect knowledge to 

sense (par. 17) 

6. Conclusions as restated by Aristotle (par. 18) 

7. Explication of preceding passage from Aristotle (par. 19) 

8. Concluding advice to the reader concerning testimony 

of the senses (par. 20) 

D. Of the Method to be Turned to in the Knowledge {cog- 
nitio) of Generation 

1. The method proposed (par. 21) 

2. This method compared to that of Fabricius (par. 22) 

3. What will be set forth according to the method 

a. in respect to formal content (par. 23) 

b. in respect to material content (par. 24 and 25) 

4. What will be inferred from that set forth and the diffi- 

culties involved (par. 26) 

5. Conclusion (par. 27) 

Under * Of the Mode and Order of Acquiring Knowledge ' 
(Section B) Harvey rests his scientific method solidly on 

Harvey juxtaposes two key Aristotelian texts which " at first 
blush may seem contradictory." The one text emphasizes that 
there is but one road to scientific knowledge, i. e., to the rea- 
soned fact, namely, a syllogistic process by which we move 
from universals to particulars. He states that we " start from 
the thinsrs which are more knowable and clearer to us and 
proceed towards those which are clearer and more knowable 
by nature " {Physics, Bk. I, Ch. 1, 184 a 16-18) . The second 
text stresses the inductive and prior knowledge obtained from 
sense data for " that is more perspicuous to us which is based 


on induction . . . whence it is advisable from singulars to pass 
to universals " {Post. Anal., Bk. II, Ch. 13) . 

In the following section entitled " Of the same matters, 
according to Aristotle," Harvey elaborates Bk. I, Ch. 1, of the 
Posterior Analytics, which states that all doctrine and intel- 
lectual discipline, including the two forms of reasoning, the syl- 
logistic and the inductive, is acquired from antecedent knowl- 
edge, none of which is innate. He then uses a passage from 
Aristotle to explicate this antecedent knowledge, which arises in 
sense, is retained by memory, and which, when repeated, results 
in experience, from which in turn is derived the beginnings 
of art and science. He again quotes a more " elegant " passage 
of Aristotle to the same effect {Metaphysics, Bk. I, Ch. 1) . 

Harvey goes on to say that "By this Aristotle plainly tells 
us that no one can truly be entitled prudent or truly knowl- 
edgeable {scientem vere) , who does not of his own proper ex- 
perience, i.e., from repeated memory, frequent perception by 
sense, and diligent observation, know that a thing is so in fact. 
Without these, indeed, we only imagine or believe, and such 
knowledge {scientia) is rather to be accounted as belonging to 
others than to us." Harvey concludes this section with a pas- 
sage from one of Aristotle's research works: 

That the generation of bees takes place in this Avay appears both 
from reason and from those things that are seen to occur in their 
kind. Still all the incidents have not yet been sufficiently examined. 
And when the investigation shall be complete, then will sense be 
rather to be trusted than reason; reason, however, will also deserve 
credit, if the things demonstrated accord with the things that are 
perceived by sense {Gen. An., Bk. Ill, Ch. 10, 760 b 28-33) . 


A textbook in a required biological course in a leading uni- 
versity in the United States makes reference to the " pre- 
formationists " of approximately 300 years ago who thought 
that the " embryo was preformed in miniature in the micro- 
scopic spermatozoon and had but to unfold as the rosebud 
into the rose " and to the " ovicists," who " postulated a pre- 


formed embryo in the egg that needed only a slight stimulus 
to make it grow and develop." In contrast the authors cite the 
modern scientist who through " the employment of the scien- 
tific method of repeated and careful observations and deduc- 
tions has made it clear to us that the embryo is not preformed 
in its final form. . ." but that " the various parts of the new 
individual are gradually formed and undergo a tremendous 
modification from their first appearance up to their final 
state." " 

These same authors could have equally and more accurately 
written: Over 2300 years ago, Aristotle, by employing the 
scientific method of repeated careful observation as his basis 
for inference, made it clear to anybody and everybody who 
would read, that the preformationist account of embryological 
development was impossible and the epigenetic account neces- 
sary. He asked, " How, then, does it [the embryo] make the 
other parts.f^ "; he answered, " Either all the parts, as heart, 
lung, liver, eyes and all the rest, come into being together or in 
succession . . ." " That the former is not the fact is plain even 
to the sense, for some of the parts are clearly visible as already 
existing in the embryo while others are not; that it is not be- 
cause of their being too small that they are not visible is clear, 
for the lung is of greater size than the heart, and yet appears 
later than the heart in the original development " (734 a 17 ff .) . 
William Harvey, 2000 years later, who did read, came out with 
experimental confirmation and enrichment of the same view. 
He states in his Generation of Animals: 

Now it appears clearly from my research that the generation of the 
chick from the egg is the result of epigenesis (Exercise 45) . And 
first, since it is certain that the chick is produced by epigenesis, i. e. 
the addition of parts successively, we shall investigate what part 
may be observed before any of the rest are erected, and what may 
be observed in this mode of generation. What Aristotle says of 
generation ... is confirmed and made manifest by all that passes 
in the egg, viz. that all the parts are not made simultaneously, but 

^* S]jllabus, Introductory General Course in the Biological Sciences, edited by 
Merle C. Coulter. Seventh edition. (University of Chicago, 1937), p. 104. 


ordered one after the other, and that there first exists a genital 
particle, by the power of which as from a principle, all the other 
parts proceed (Exercise 51) . 

Curiously enough, however, the preformationist theory came 
into prominence again — curiously, because it did so just follow- 
ing the discovery of the microscope and the aberrations that 
passed for facts that resulted thereof. But the epigenetic theory 
has since been restored and given great richness of detail in 

It can be seen that Harvey in following Aristotle reaffirmed a 
truth that was lost during the late Renaissance, but redis- 
covered in modem times. That it was one of Harvey's prime 
objects in writing The Generation of Animals to defend and 
establish the opinion already held by Aristotle has been ex- 
pressed by Thomas H. Huxley.^ 



In The Motion of the Heart and Blood, which is more a 
demonstrative work than a descriptive one, 22 references to 
Aristotle are made. In only one instance does Harvey clearly 
disagree with Aristotle. In this instance Harvey writes, 
" Hence, since the veins are the conduits and vessels that 
transport the blood, they are of two kinds, the vasa and the 
aorta; and this not by reason of sides (as in Aristotle) , but 
office (officio) , and not, as is commonly said, by constitution, 
for in many animals, as I have said, the vein does not differ 
from the artery in the thickness of its tunic, but is distinct by 
duties (munere) and use (usu) ." ^® It should be noted that 
the disagreement is not based on Aristotle's anatomical obser- 
vations, which D'Arcy W. Thompson states to be " remarkable 

^^ Thomas H. Huxley, " Evolution in Biology," in Darwiniana Essays (New 
York, 1898), p. 193. 

^^ Harvey, Works, ed. cit., cli. 8, p. 47. The English translations of Harvey 
appearing in this article are mostly adapted from the Willis translation following 
consultation with the original Latin. Where possible key Latin terms which have 
English equivalents are substituted. The Latin text consulted is the edition of 
Bernardus Albinus (Johannes van Kercjhem, 1737) . 


for its wealth of detail [and] for its great accuracy in many 
particulars . . . ," but rather on physiological considerations, 
viz. on its ojfifice, duty and use." 

In another reference Harvey discusses an anatomical obser- 
vation which " probably led Aristotle to consider this ventricle 
double, divided transversely." ^^ Other than these, the remain- 
ing references to Aristotle are utilized to help Harvey make or 
confirm a particular point. 

Of particular interest is the reference to Aristotle where 
Harvey enunciates the possibility of " a motion, as it were, in 
a circle . . . which motion we may be allowed to call circular, 
in the same way as Aristotle says that the air and the rain 
emulate the circular motion of the superior bodies; for the 
moist earth, warmed by the sun, evaporates; the vapors drawn 
upwards are condensed, and descending in the form of rain, 
moisten the earth again; and by this arrangement are genera- 
tions of living things produced; and in like manner too are 
tempests and meteors engendered by the circular motion, and 
by the approach and recession of the sun." ^^ 

In connection with this passage, a recent translator and a 
scientist of renown, who is now President of the American 
Association for the Advancement of Science, is able to observe 
only that " Harvey seems never to have heard of [the] studies 
[of] Copernicus, J. Kepler, and G. Galilei [which] had over- 
thrown the Ptolemical theory of the circular motion of the 
stars in the heavenly spheres . . ." ~° 

But to think of this reference as a poetic metaphor to which 
scientific error can be attached rather than as a striking evo- 
cation of Aristotle's analysis of locomotion misses the precision 
for the poetry in the analogy. 

Here one has to know certain passages from Aristotle's 
works, Post. Anal, Bk. II, Ch. 12, Physics, Bk. VIII, Ch. 8 & 9, 

^^ Aristotle, History of Animals, Translated by D'Arcy W. Thompson (Oxford, 
1910). 513 a 35, fn. 3. 

"Harvey, Works, ed. cit., ch. 17, p. 79. 

'" Ibid., ch. 8, p. 46. 

^° Chauncey D. Leake, op. cit., ch. 8, p. 70, fn. 1. 


Gen. and Cor., Bk. II, Ch. 11, Meteorology, Bk. II, Ch. 4, 
among others. Aristotle divides natural locomotion into circu- 
lar and rectilinear. Only circular motion can be single and 
continuous. When Harvey concludes in Ch. 14 that " it is 
absolutely necessary to conclude that the blood in the animal 
body is impelled in a circle, and is in a state of ceaseless 
(perpetuo) motion . . ." he is talking in a strict Aristotelian 

Harvey, in the development of this conclusion, had to combat 
in his own mind the prevailing physiological concept that 
blood was produced from nutriment in a central organ, and 
was moved peripherally to be totally consumed by the body. 
That Harvey refers to Aristotle's concept of circular motion in 
his exposition, which is in the order of demonstration, suggests 
the critical role that Aristotle's concept had in the order of 



Harvey makes it clear throughout his work that his " new 
views of the motion and use of the heart and the circulation of 
the blood " "^ are the result of the application of both sense 
and reason. In his dedication to the learned physicians he 
states that " for nine years or more [he has] confirmed these 
views by ocular demonstrations [and] manifested them by 
reasons and arguments, freed from the objections of the most 
learned and skillful anatomists." In Ch. 14 entitled ' The 
Conclusion of the Demonstration of the Circulation of the 
Blood ' where he concludes that the blood is impelled to the 
whole body by the pulse of the ventricles, he states that this is 
" confirmed by reason and ocular experiment," and that one 
must " necessarily conclude " that the motion of the blood is 
circular. In the final words of the concluding chapter of his 
book, the chapter which confirms the motion and the circula- 
tion of the blood through an anatomical analysis of the heart, 

'^ Harvey, Works, ed. cit., Dedication to Learned Physicians, p. 5. 


Harvey concludes that " All these phenomenon and many 
others observed in dissecting, if rightly weighed, seem clearly 
to illumine and fully confirm the truth contended throughout 
these pages ... it would be difficult to explain in any other 
way for what cause all is constructed and arranged as we have 
seen it to be." 

Notwithstanding, the modern scientist with his dispropor- 
tionate worship of observation manages for the most part to 
ignore the role played by reason, thereby missing what is so 
magnificent in this classic work. The carefully organized nature 
of Harvey's demonstration can be detected by scrutinizing 
Harvey's table of contents, which, because it is a contraction, 
mirrors the logical structure of the masterpiece in bold outline. 
The following represents a structural analysis of the table: 

Analysis of Harvey's Table of Contents " of an Ana- 
tomical Exercise on the Motion of the 
Heart and Blood 

Part 1. Prefatory 

A. Dedicatory: extrinsic to work, 

1. To the King: to civil authority, 

2. To Learned Physicians: to peers who respect truth. 

B. Introductory: intrinsic to work, 

1 . ' Introduction ': establishes the need for the work; 
dated to the belief of scientists of that period. 

2. ' The Causes Moving the Author to Write ' (Ch. 1) : 
establishes the difficulty of the work; timeless, as the 
truths obtained from nature are permanent and belong 
to posterity. 

Part 2. Motion of the Cardiovascular System (Ch. 2-7) 

A. Motion of the Containing Parts 

1. 'Motion of the heart through dissection of living ani- 
mals.' (Ch. 2) 

^^ Words enclosed in single quotation marks are those used by Harvey as chapter 
headings. Other quotations have individual reference numbers. 


2. 'Motion of the arteries through dissection of Hving 
animals.' (Ch. 3) 

3. ' Motion of the heart and auricles through dissection 
of Hving animals.' (Ch. 4) 

4. ' Motion, action and function of the heart.' (Ch. 5) 

B. Motion of the Contained Parts from Right to Left 

1 . ' Ways by which blood passes from right ventricle to 
left.' (Ch. 6) 

2. 'That the blood pass through the lung from right 
ventricle to left.' (Ch. 7) 

Part 3. Circular Motion of the Contained Part (Ch. 8-17) 
A. The Thesis and Demonstration (Ch. 8-14) 

1. Preliminary statement of the thesis: " Of the abun- 
dance of blood passing through the heart out of the 
veins into the arteries and of the circular motion of 
the blood." (Ch. 8) 

2. The three suppositions necessary for the demon- 

a. ' The first supposition ': " the blood is incessantly 
transmitted by the pulse of the heart out of the 
vena cava into the arteries in such abundance that 
it cannot be supplied from the ingesta, and in such 
wise that the whole mass must very quickly pass 
through the heart." "^ 

(1) ' circulation of blood confirmed from it.' 
(Ch. 9) 

(2) ' is freed from objections and further confirmed 
by experiments.' (Ch. 10) 

b. ' The second supposition ': " the blood under the 
influence of the arterial pulse enters and is im- 
pelled in a continuous, equable, and incessant 

" Harvey, Works, ed. cit., ch. 9, p. 48. 


stream through every part and member of the 
body, in much greater abundance than were suffi- 
cient for nutrition, or than the whole mass of in- 
gesta could supply " "^ 

(1) 'is confirmed/ (Ch. 11) 

(2) * circulation of blood confirmed from it.' (Ch. 

c. * The third supposition ': " the veins in like manner 
return this blood perpetually to the heart from all 
members of the body " ^^ 

(1) ' confirmed and that there is a circulation of 
blood from it.' (Ch. 13) 
3. ' The conclusion of the demonstration concerning the 
circulation of the blood.' (Ch. 14) 

B. Confirmation of Conclusion that the Blood Circulates 
(Ch. 15-17) 

1. 'The circulation of the blood is confirmed by likely 
reasons.' (Ch. 15) 

2. ' The circulation of the blood is proved from conse- 
quences.' (Ch. 16) 

3. ' Motion and circulation of the blood is confirmed by 
those things that appear in the heart and which are 
clear from anatomical dissections.' (Ch. 17) 

In the Introduction (Part 1, B, 1) Harvey paves the way 
for his new theory by showing that the existing theory is un- 
satisfactory. He states in the opening paragraph that " In dis- 
cussing the motion, pulse, action, use and utility of the heart 
and arteries, we should first consider what others have said on 
these matters, and what the common and traditional viewpoint 
is. Then by anatomical dissection, multiplied experience, dili- 
gent and accurate observation, we may confirm what is rightly 
stated, but what is false make right." Harvey then carefully 
examines the beliefs of his contemporaries in a series of seven- 

" Ibid. " Ibid. 


teen dialectical propositions and replies. He concludes, " From 
these and many other considerations it is plain that what has 
been said on the motion and use of the heart and arteries must 
seem obscure, inconsistent, or impossible to the thoughtful 
student. It will therefore be proper to investigate the matter 
more closely, to study the motion of the heart and arteries not 
only in man but in all animals possessing a heart, and to search 
out and find the truth by frequent vivisections and by constant 
ocular inspection." 

This doxographic approach is distinctly Aristotelian,'^ and 
establishes that one should not lean on man as the final author- 
ity.^^ In Ch. 1, he indicates that nature, despite the difficulty 
of extracting answers from her, is the final authority. 


'" It is part of Aristotle's methodology to examine dialectically existing opinion 
before proceeding to the scientific investigation of things. Examples of this pro- 
cedure are found in Physics, Bk. 1, ch. 2; Generation and Corruption, Bk. 1, ch. 1; 
The Soul., Bk. 1, ch. 2, and elsewhere. The following passage from On the Heavens 
states some of the reasons for the procedure: " Let us start with a review of the 
theories of other thinkers; for the proofs of a theory are difficulties for the contrary 
theory. Besides, those who have fu-st heard the pleas of our adversaries will be 
more likely to credit the assertions which we are going to make. We shall be less 
open to the charge of procuring judgment by default" (Bk. 1, ch. 10, 279 b 6-11). 
" We may convince ourselves not only by the arguments already set forth but 
also by a consideration of the views of those who differ from us ... If our view 
is a possible one . . . and [what] they assert is impossible, this fact will be a 
great weight in convincing us . . ." (Bk. 2, ch. 1, 283 b 30-a) . All translations 
from Aristotle are from the Oxford edition of his works. 

^' The true Aristotelian tradition may be gathered from the following statements: 

" We had perhaps better consider the universal good and discuss thoroughly 
what is meant by it, although such an inquiry is made an uphUl one by the 
fact that the Forms have been introduced by friends of our own. Yet it would 
perhaps be thought to be better, indeed to be our duty, for the sake of maintaining 
the truth even to destroy what touches us closely, especially as we are philosophers 
or lovers of wisdom; for, while both are dear, piety requires us to honour truth 
above our friends." (Aristotle, Nicomachean Ethics, Bk. 1, ch. 6, 1096a 11-16). 

" He who believes Aristotle to be a god ought to believe that he never made a 
mistake. But whoever thinks him to have been a man must admit that he was as 
liable to make mistakes as the rest of us." (St. Albert the Great, Physicorum lib. 
VIII, tr. I, cap. 14, ed. Borgnet, III, p. 553). 

" Unless a man holds truth dearer than friends, he will be ready to pronounce 
false judgments and to bear false witness for the sake of friends. But that is 
immoral. All men ought to hold truth dearer than friends, because all men have 
the use of reason. But this duty is particularly binding on all philosophers, be- 


In subsequent chapterS^ Harvey begins to record his reading 
of the book of nature. In Chapters 2-5, he reports what she 
says about the heart and arteries. By obtaining the true attri- 
butes of these critical components of the cardiovascular system, 
their motion, pulse and action, he will be in a position subse- 
quently to elucidate their use and utility. " For if none of the 
true attributes of things have been omitted in the historical 
survey " states Harvey's mentor Aristotle, " we should be able 
to discover the proof and demonstrate everything which ad- 
mitted of proof, and to make that clear, whose nature does not 
admit of truth." Aristotle emphasizes in this same passage 
that " in each science the principles which are peculiar are 
the most numerous. Consequently it is the business of experi- 
ence to give the principles which belong to each subject. I 

cause they profess to teach wisdom, and wisdom is nothing else than the knowl- 
edge of truth . . . Truth is, indeed, divine for it is found fundamentally and 
primarily in God. That is why Aristotle insists on the sacredness of the duty of 
holding truth dearer than friends . . . Plato is of the same opinion. For, once, 
when setting aside a theory of his master, Socrates, he declares that truth must 
be our supreme concern. And elsewhere, he declares: Socrates is, indeed, a friend 
of mine, but truth is a greater friend. And in a third text, he declares that one may 
make little of Socrates, but one must make much of truth." (St. Thomas Aquinas, 
In I Ethic, lect. 6, nn. 76, 78) . 

^* This is another expression of the true Aristotelian position. " God, like a good 
teacher, has taken care to compose most excellent writings that we may be in- 
structed in all perfection. ' All that is written,' says the Apostle, ' is wi'itten for our 
instruction.' And these writings are in two books: the book of the creation and 
the book of the Holy Scriptures. In the former are so many creatures, so many 
excellent writings that deliver the truth without falsehood. Wherefore Aristotle, 
when asked whence it was that he had his admirable learning, replied: ' From 
things, which do not know how to lie.' " (St. Thomas, Sermo 5 in Dom. II de 
adventu, ed. Vives, Opera Omnia, XXIX, p. 194). 

William Harvey, who, on the one hand, makes clear that " the authority of 
Aristotle has always such weight with me that I never think of differing from 
him inconsiderately " (Harvey, Anatomical Exercises on the Generation of Animals, 
Ex. 11, ed. cit., p. 207), also states that " 'Wlioever, therefore, sets himself to 
opposition to the circulation, because [he] regards it as in some sort criminal to 
call in question disciplines that have descended through a long succession of 
ages, and carry the authority of the ancients; to all these I reply: that the facts 
manifest by the senses wait upon no opinions, and that the works of nature bow to 
no antiquity; for indeed there is nothing either more ancient or of higher authority 
than nature." (Second Exercise to John Riolan, ed. cit., p. 123) . 


mean for example that astronomical experience supplies the 
principles of astronomical science: for once the phenomena 
were adequately apprehended, the demonstrations of astron- 
omy were discovered. Similarly with any other art or science. 
Consequently, if the attributes of the things are apprehended, 
our business will then be to exhibit readily the demonstrations."^® 

Again Aristotle emphasizes that " each set of principles we 
must try to investigate in the natural way, and we must take 
pains to state them definitely, since they have a great influ- 
ence on what follows. For the beginning is thought to be more 
than half of the whole, and many of the questions we ask are 
cleared up by it." ^'^ 

Harvey, of course, as an Aristotelian, does not limit himself 
to man. To get at the heart of the matter and of man he must 
be interested in the hearts of other animals. His aim is to get 
at the true nature of the heart. His interest is not descriptive. 
He is not interested in this heart or that with the variations in 
numbers of chambers or differing associations with lung or gills, 
but in the heart universally considered, prescinding from the 
variations that are found in nature. He refers to cold blooded 
animals as well as to warm blooded: toads, snakes, frogs, snails, 
shellfish and fish. In all it has been estimated that he worked 
with about 80 species of animals .^^ 

That this is a methodological approach and not simply the 
insatiable curiosity of a field biologist is made clear from the 
quote from Aristotle that appears on the title page of Prelec- 
tiones, from the fifth of the canons which Harvey lists for 
his own guidance at the beginning of his lectures, and from a 
passage from Harvey that appears in De Motu. 

The Aristotle quotation states, " The fact is that the inner 
parts of man are to a very great extent uncertain and unknown, 
and the consequence is that we must have recourse to a con- 

''^ Prior Analytics, Bk. 1, ch. 30, 46 a 18-27. 
^^ Nico-machean Ethics, Bk. 1, ch. 7, 1098 b 4-9. 

'^ William Harvey, Prelectiones, ed. cit.. Introduction by a Committee of the 
Royal College of Physicians of London, p. vi. 


sideration of the inner parts of other animals which in any- 
way resembles that of man." ^- 

The fifth canon emphasizes that one should systematically 
study other animals " according to the Socratic rule " for this 
will permit one to refute and correct errors in natural phi- 
losophy, and to discover the use, action and dignity of things, 
and thereby obtain for anatomy knowledge of the causes of the 
parts, the ends, their necessity and use. The Harvey passage 
is as follows: 

Since the intimate connection of the heart with the lungs, which 
is apparent in the human subject, has been the probable occasion 
of the errors that have been committed on this point, they plainly 
do amiss who speak and demonstrate the parts of animals generally 
(as all anatomists commonly do) from the dissections of man alone, 
and at that dead. They obviously act no otherwise than he, who, 
having studied the form of a single republic, should set about a 
general discipline of polity; or who, having taken cognizance of a 
single farm, should imagine that he has scientific knowledge of 
agriculture; or who, on one particular proposition attempts to 
syllogize the universal. Had anatomists only been as conversant 
with the dissection of the lower animals as they are with that of 
the human body, the matters that have hitherto kept them in a 
perplexity of doubt would in my opinion, have met them freed 
from every kind of difficulty.^^ 

It should be seen here that in his dedication to comparative 
anatomy, to Socrates' and Aristotle's rule, Harvey differs from 
the modern scientist. The latter directs this branch of biology 
primarily to taxonomy or to the elucidation of evolutionary his- 
tory. The Socratic rule, on the contrary, is directed at eliciting 
an essential definition through the use of the inductive method. 
Socrates, according to Aristotle, was interested in what a thing 
is, its essence, as the starting point for syllogizing. " Two 
things may be fairly ascribed to Socrates," says Aristotle, " in- 
ductive arguments and universal definitions, both of which are 
concerned with the starting point of science." 


'''Aristotle, The History of Animals, Bk. 1, ch. 16, 494 b 21-24. 

*^ Harvey, Works, op. cit., ch. 6, p. 35. 

** Aristotle, Metaphysics, Bk. M, ch. 4, 1078 b 18-30. 


To understand the use and the goal of Grecian and Har- 
vian comparative biology, two things should be understood. 
First, that one has to seek out and know the many. Secondly, 
that knowledge of the many which one has to seek out is the 
" one in the many " — that which is common to the many, that 
commonality which most fully accounts for why the thing is 
as it is. 

To know the many, however, does not automatically result 
in an answer. Modern science suffers from a plethora of the 
many, because of the variety and the high output of sense 
observations from our laboratories. The modern scientist is in 
the position of Meno, who, in answer to Socrates' question. 
What is virtue?, responds that " Every age, every condition of 
life, young or old, male or female, bond or free, has a different 
virtue: there are virtues numberless, and no lack of definitions 
for them . . ." ^^ The modern scientist in the absence of the 
Harvian answer would respond similarly to the question, 
What is a heart .f*, that every species of animal has a different 
heart: there are numberless hearts and numberless definitions. 
But Harvey, following Socrates, prescinds from the many and 
seeks what the heart is " in the universal . . . whole and sound, 
and not broken into a number of pieces." ^® Harvey also follows 
Aristotle, who formally discusses the method of obtaining defi- 
nitions in his Posterior Analytics which, as part of the Org anon, 
was part of Harvey's formal training in logic and scientific 

Unlike the modern whose notion of causality is limited pri- 
marily to the material and efficient causes, Harvey further 
follows Socrates and Aristotle in seeking the fuller explanation 
that comes with the additional knowledge of the formal and 
final causes. 

Socrates in his last days recollects his rejection of this ancient 
error of modem scientists when, as a young man, he, " with a 
prodigious desire to know that department of philosophy which 

^^ Plato, Meno, 71 E-72 A (Jowett translation.) 
"'Ibid., 77 A. 


is called the investigation of nature: to know the causes of 
things, and why a thing is " " registers his disappointment after 
being directed to Anaxagoras who, forsaking any principle 
of order, tried to explain everything by " having recourse to 
air, ether, and water and other eccentricities." ^^ 

Aristotle as a scientist's scientist ^^ and philosopher's philoso- 
pher fully and formally develops this Socratic position in Book 
I of the Parts of Animals. He, too, as if writing against the 
enthusiastic follower of Harvey, who reads but does not under- 
stand him, talks about " the ancient writers, who first philoso- 
phized about Nature as having busied themselves " with " the 
material principle and material cause." *° Aristotle explains, 
on the contrary, that 

if men and animals and their several parts are natural phenomena, 
then the natural philosopher must take into consideration not 
merely the ultimate substances of which they are made but also . . . 
the homogeneous and heterogeneous parts; and must examine how 
each of these comes to be what it is, and in virtue of what force. 
For to say what are the ultimate substances out of which an 
animal is formed, to state, for instance, that it is made of fire or 
earth, is no more sufficient than would be a similar account in the 
case of a couch or the like . . . For a couch is . . . such and such a 
matter with this or that form; so that its shape and structure must 
be included in our description. For the formal nature is of greater 
importance than the material nature.*^ 

Aristotle finally concludes that 

It is plain, then, that the teaching of the old physiologists is 
inadequate, and that the true method is to state what the definitive 
characters are that distinguish the animal as a whole; to explain 
what it is both in substance and in form, and to deal after the same 

" Plato, Phaedo, 96 B. 

"' Ibid., 98 C. 

'' Charles Darwin, Life and Letters, Letter to Ogle, 1882, vol. 3, p. 252: " From 
quotations I had seen I had a high notion of Aristotle's merits, but I had not the 
most remote notion what a wonderful man he was. Linnaeus and Cuvier have been 
my two gods, though in very different ways, but they were mere schoolboys to old 

*° Aristotle, Parts of Animals, Bk. I, ch. 1, 640 b 5. 

" Ibid., 640 b 15-29. 


fashion with its several organs; in fact, to proceed in exactly the 
same way as we should do, were we giving a complete description 
of a couch."*- 

We can see then that Harvey as an Aristotelian is interested 
in function as well as action, in ends as well as means — the 
teleological as well as the mechanical. We shall also see that 
Harvey respects the differentiation as well as the interrelation- 
ship of what has to be known for a full understanding of the 
causes. Part of the modern difficulty in understanding Harvey 
stems from a failure to appreciate Harvey's sensitivity to lan- 
guage, and our insensitivity to the sharply delineated concepts 
w^hich his terminology precisely communicates — concepts and 
terms which are the culmination of a long logical and biological 

The conceptual difficulty can best be seen from the Leake 
translation. In the table of contents: the Latin words dis- 
sectione, in three instances, and ex-perimentis are both trans- 
lated into experiment', dissectio, in another instance, is trans- 
lated into investigation; confirmato is translated into both 
established and proved; probatur is translated into supported; 
and suppositio is translated into consideration and proposition. 
The first sentence of the Introduction of this translation begins, 
" In discussing the movements and functions of the heart and 
arteries, we should first consider . . .". The original Latin, 
however, instead of movement and junctions, has motu, pulsu, 
actione, usu, utilitatibus. 

We can now return more specifically to the manner in which 
Harvey arrived at his revolutionary conclusions concerning the 
motion of the heart and blood. If one turns to the table of con- 
tents above, he will note that whereas the word dissection is 
characteristically found in the chapter headings on the motion 
of the heart and arteries (part 2 A) , the word supposition is 
characteristically found in the section on the circulation of the 
blood (part 3 A) . Dissection, of course, pertains to sense; 
supposition, to reason. One may correctly infer from this that, 

"/62d., 641 a 14-18. 


when it comes to the circulation of the blood, the demonstra- 
tion is logical, not ocular. The absence of magnifying instru- 
ments of sufficient strength at the time made it impossible to 
observe either the circulation of the blood or the continuity of 
the cardiovascular system. It is not implied here, however, that 
the ocular, even if possible, could approach or match the certi- 
tude of the logical demonstration.^^ 

Circulation, as such, is not mentioned in the body of the 
work until Chapter 8, where it is introduced in the form of a 
short review of the argument developed subsequently. Since 
the conclusion that the circulation of the blood is the end result 
of a long reasoning process, the chief function of Harvey's pre- 
ceding chapters is to contribute premises which are ti*ue, 
primary, immediate, better known than, prior to, and the cause 
of the conclusions which follow from them.** In other words, 
it is necessary to establish the motion, pulse, and action of 
the heart and arteries, and the relationship of the lungs to the 
heart and the blood to the lungs first. This calls for the most 
exacting type of sense observations, their verification by col- 
lated findings, and care in the inferences drawn from them. It 
is through such knowledge that Harvey is in a position to ask 
questions leading to the initial idea and final demonstration 
that the blood circulates. 

The first part of Harvey's treatise establishes, contrary to 
the beliefs at the time, that the heart and the arteries in the 
living animal always contain blood: that the proper motion of 
the heart is contraction, not expansion; that its action is pump- 
like, not bellow-like, and that it forcibly expels blood in one 
direction; that contraction, not expansion — systole, not diastole 
— corresponds to the pulse on the chest wall; that the arterial 

** It should not be forgotten that the observations of Swammerdam of the per- 
fectly formed butterfly in the cocoon in 1669, and those of Leeuwenhoek of the com- 
plete outline of both maternal and paternal individuals in the microscopic sperma- 
tozoa in 1677, led to the complete replacement of Harvey's theory of epigenesis by 
the preformation theory, which lent itself to a mechanical explanation of nature, 
and which was to dominate biological thinking through the first half of the eight- 
eenth century. 

"Aristotle, Posterior Analytics, Bk. 1, ch. 1, 71 b 16-22. 


pulse, which in arterial diastole corresponds to carliac systole, 
not cardiac diastole; that cardiac systole is the cause of the 
arterial pulse via the motion it transmits through the blood; 
and that blood from the right ventricle gets to the left ventricle 
through the lungs. 

Since " the one action of the heart is the transfusion and pro- 
pulsion of the blood by mediation of the arteries to the extremi- 
ties of the body," ^^ the question arises as to where the heart 
gets the blood which is the subject of its action. The genesis 
of the belief and the hypothesis that blood circulates is as 

And sooth to say, when I surveyed in various disquisitions by how 
much abundance blood might be lost from cutting arteries, in 
dissections and induced experiments in the living; then the sym- 
metry and magnitude of the vessels that enter and leave the ven- 
tricles of the heart (for nature doing nothing groundlessly, would 
never have given them such proportionate magnitudes ground- 
lessly) , then the ingenious and attentive fitting together of the 
valves and fibers, and the rest of the heart's fabric and many other 
things besides, I frequently and seriously bethought me, and long 
revolved in my mind, by how much abundance blood was trans- 
mitted, and the like, in how short a time its transmission might be 
effected, and not finding it possible that this could be supplied by 
the juices of the ingested aliment without the veins on the one 
hand becoming drained, and the arteries on the other hand getting 
ruptured through the excessive charge of blood, unless the blood 
should somehow find its way from the arteries into the veins, and 
so return to the right ventricle of the heart; I began to think 
whether there might not be a motion as it were, in a circle.^® 

Chapter 9 contains the principal demonstration of the cir- 

A fluid of limited quantity kept in 

perpetual motion in one direction is moved circularly. 

And the blood is such a fluid. 

Therefore the blood is moved circularly. 

In this syllogism according to the Aristotelian logic em- 

" Harvey, Works, op. cit., ch. 5, p. 32. ** Ibid., ch. 8, pp. 45-46. 


ployed by Harvey the middle term is the material cause (i. e. 
limited quantity of fluid) , and the demonstration is " one 
through the material cause." The major premise is a general 
physical theorem proved by Aristotle in Books VII and VIII of 
the Physics, where he shows that perpetual motion of any 
system must be circular in character. The minor premise is a 
definition of the blood derived from Harvey's careful studies 
recorded in his earlier chapters. 

Harvey's conclusion is, as he admonishes a critic on a later 
occasion, " demonstrative and true, and follows of necessity, 
if the premises be true." *^ Therefore he adds that any criti- 
cism of his conclusion cannot be in the area of argument and 
logic, but in the area of observation and experiment which 
supplies the premises. Harvey insists here that " our senses 
ought to assure us whether such things be false or true and not 
our reason, ocular testimony and not contemplation." ^^ That 
Harvey has learned well from Aristotle, who was the father 
both of biology and logic, is evident from Harvey's recognition 
of and respect for the proper spheres of sense and reason. 

The degree to which Harvey's demonstration is Aristotelian 
should be noted further. First, it is an example of the relation- 
ship of a less general science, biology, to a more general and 
fundamental science, physics, to which it is subalternate: a par- 
ticular biological fact is illuminated by a universal physical 
theorem to yield a new biological fact. Secondly, it is an ex- 
ample of the dictum that demonstrations in science are made 
through a definition expressing an essential characteristic. 
Thirdly, contrary to modem thinking, Harvey's demonstration 
does not depend on mathematical measurements but on 
physical proportions, i. e., the proportion of one quantity to 
another on the basis of physical comparison rather than on 
mathematical principles. In stating that Chapter 9 is " the 
first instance of the quantitative method in physiology " and 
that it " introduced the most important method of reasoning in 

*^ Harvey, Second Exercise to John Riolan, ed. cit., p. 133. 

" Ibid. 


science," *° Leake misses Harvey's fidelity to Aristotle's 
method and its reward. Kilgour, in a recent and careful analy- 
sis of Harvey's use of the quantitative method, concludes that 
certainly " Harvey was not concerned with accurate measure- 
ment " and that his estimations were consciously indifferent to 
precision, the essence of the mathematical procedure. He adds, 
" Apparently, quantitative evidence was not important in lead- 
ing Harvey to develop the idea of the circulation because there 
is no quantitation in his Lumleian Lecture notes of 1616." '" 
The computations Harvey supplies, therefore, may be better 
viewed as communicating to the reader — in the manner in 
which a sensible model makes a theory vivid to the reader — 
the physical reality of the disproportion between the amount 
of ingesta and the flow of blood through the heart.^^ 

Finally, it would be amiss not to recogTiize that the demon- 
stration of the circulation of the blood is just an Aristotelian 
step in the elucidation of the nature of the heart, the prime 
component of the cardiovascular system. The ultimate purpose 
of Harvey's treatise is to define the heart upon which the 
motion of the blood is dependent. 

One of the most remarkable chapters in this work of Harvey's 
is the 17th and final chapter. From all the fields opened up by 
the establishment of circulation — physiology, pathology, symp- 
tomatology and therapeutics — he selects his topic: to relate 
the various particulars that present themselves in the ana- 
tomical study of the fabric of the heart and arteries to their 
several uses and causes, " for I shall meet with many things 

*" Chauncey D. Leake, op. cit., ch. 9, p. 74, fn. 1. 

^° Frederick C. Kilgour, " William Harvey's Use of the Quantitative Method," 
Yale Journal of Biology and Medicine, XXVI (1954) , 417-18. 

^^ Some of the thoughts appearing in this article were first presented and in 
part developed at a summer institute for scientists and philosophers conducted by 
The Albert Magnus Lyceum for Natural Science at River Forest, Illinois, July 
1952. A report of this institute is to be found in the publication, entitled, Science 
in Synthesis: A dialectical approach to the integration of the physical and natural 
sciences, by W. Kane, O. P.; J. D. Corcoran, O. P.; B. M. AsUey, O. P.; and R. H. 
Nogar, O. P. (The Aquinas Library, Dominican College of St. Thomas Aquinas: 
River Forest, Illinois. 1953). See pp. 93-108. 


which receive light from the truth I have been contending for, 
and which, in turn, render it more obvious. And indeed I would 
have it confirmed {firmatain) and beautified {exorriatam) by 
anatomical arguments above all others." °" 

This chapter is primarily an elaboration of the formal cause 
of the heart through the re-examination of the heart and the 
vessels — structurally, comparatively, embryologically and func- 
tionally — in the light of the final cause, viz. the circulation of 
the blood. His final statement which closes his treatise is: " it 
would be difficult to explain in any other way for what cause all 
is constructed and arranged as we have seen it to be." 

He establishes what a heart is in his characterization of the 
heart per se as the left ventricle, viz. that ventricle " distin- 
guished by use not position, the one namely that distributes 
blood to the body at large, not the lungs alone." In doing so he 
establishes the connection of the final and formal causes. 

This chapter completes the definition of the heart for 
Harvey, which definition may be expressed in syllogistic form 
as follows: 

An organ which must supply an organ which is so con- 

the body with a steady flow structed as to be able to 

of a fluid whose quantity is produce a circular motion 

proportionately small is of that fluid. 

And the heart has this very function. 

Therefore the heart is: 

1 . An organ which has a pulsating " left " ventricle mth a 
non-regurgitating valvular inlet and outlet and whatever addi- 
tional cardiac parts that conform to the needs of the species 
(the formal cause: the anatomical structure described teleo- 
logically and in detail, i.e., in its relationship to its motion, 
pulse, action, use and utilities, e. g., the arrangement of the 
fibres in the walls, the valves, the braces of the heart; " the 
actions and uses of the heart may be understood from the con- 

^^ Harvey, Works, op. cit., ch. 16, p. 74. 


stitution of its muscular fibers and the fabric of its moveable 
parts " '') , 

2. and is composed of muscular tissue and other tissue com- 
ponents necessary to the parts (the Tnaterial caiise) , 

3. for the sake of circulating the blood (the final cause or 

4. by contraction (the efficient cause of circulation) .^* 

^* Ibid., ch. 17, p. 82. 

^* That the last chapter is an integral and important part of Harvey's classic is 
not the common position. Leake presents a typical viewpoint when he states that 
" The last three chapters add little to the significance of the demonstration " 
(Chauncey D. Leake, op. cit., Translator's Preface, p. x) . But here it seems that 
Leake has a limited appreciation of the purpose of the work as explicitly stated by 
Harvey, and of the true scientific nature of the anatomical exercise employed by 
Harvey. As to the purpose of the work it should first be recalled that the title of 
this classic makes clear that it is an anatomical exercise, and that it concerns 
the motion of the heart as well as the motion of the blood. Secondly, that the 
opening statement of the Introduction states that Harvey is discussing " the motion, 
pulse, action, use and utility of the heart and arteries," and of Chapter 1 that his 
purpose is to discover " the motions, use and utility of the heart." That Leake 
does not appreciate the comprehensiveness of the anatomical exercise is reflected in 
his translation, in which he reduces action, use and utility to junction in the Intro- 
duction, and M5e and utility to junction in Chapter 1. 

If we turn to the anatomical works of Fabricius, who was Harvey's teacher, we 
find the following exposition of the anatomical exercise: "to treat first the dissection 
or description of each organ, then its action, and finally its utilities, and in this 
way present our entire knowledge of the organs as comprised in these three 
divisions." He adds that he has followed " this path the more willingly because 
those distinguished pioneers, Aristotle and Galen, have blazed the trail and, so 
to speak, carried the torch before me on the way." (Fabricius, De Visione, voce, 
auditu, Preface, translated by Howard B. Adelmann, The Embryological Treatises 
oj Hieronymus Fabricius oj Aquapendente, Cornell University Press, 1942, p. 82). 
Fabricius classifies the biological works of Aristotle and Galen in these three 
divisions and states that " The third part, indeed, which discusses the utilities of 
the whole, as well as of the parts of an organ, corresponds to the four books of 
Aristotle's De partibus animalium [and] to that great work of Galen's, De usu 
partium . . ." (ibid., p. 83) . 

When we turn to Aristotle's explication of the third part of the anatomical 
exercise he states that " In the first place we must look at the constituent parts 
of animals. For it is in a way relative to these parts, first and foremost, that 
animals in their entirety differ from one another: either in the fact that some have 
this or that, while they have not that or this; or by peculiarities of position or 
arrangement; or by the differences that have been previously mentioned, depending 
upon diversity of form, or excess or defect in this or that particular, or analogy, or 


NatuFcally, the final and efficient causes are proximate causes 
and are not intended as complete in any sense. In this context 
Harvey's Aristotelian answer to his critic Riolan is pertinent: 
" To those who repudiate the circulation because they neither 
see the efficient nor final cause of it, and who exclaim, Cui 
bono? I have yet to reply, having hitherto taken no note of 
the ground of objection which they take up. And first I own 
I am of opinion that our first duty is to inquire whether the 
thing be or not, before asking wherefore it is (propter quid) ? 
for from the facts and circumstances which meet us in the 

on contrasts of the accidental qualities." For, according to Aristotle " to do this 
[pass on to the discussion of the causes] when the investigation of the details is 
complete is the proper and natural method, and that whereby the subjects and 
the premises of our argument will afterwards be rendered plain." (Aristotle, The 
History of Animals, Bk. 1, ch. 6, 491 b 10-19). 

Galen's position is quoted by Fabricius: "A practical knowledge of the nature 
of each of the members is gained from dissection together with a thorough under- 
standing of its actions and utilities." Galen further adds, in the quotation from 
Fabricius: " Moreover, lest anyone unwisely neglects these aspects or be thought- 
less enough to say that they are not of great consequence, I can truly say this: 
They are of so much importance, that whoever has learned them thoroughly must 
unhesitatingly confess that he has learned and comprehended the whole subject of 
anatomy, which, in my opinion, is nothing but the true and solid foundation of 
all medicine and the absolute and perfect end of natural philosophy." (Fabricius, 
op. dt., p. 83) . 

Galen's statement is clearly in anticipation of criticisms such as Leake's. That 
Leake has this position is in great part explained by the fact that contemporary 
physicians and doctorates of anatomy have been raised on Gray's AnatoTny which 
is entitled Anatomy, Descriptive and Surgical and which is intended for " Students 
of Surgery rather than for the Scientific Anatomist." (Henry Gray, Anatomy, 
Descriptive and Surgical, A New Edition Thoroughly Revised by American Authori- 
ties from tlie Thirteenth English Edition (Lea Brothers, 1896) Preface to the 
Thirteenth English Edition, p. 8) . It can be seen that Gray's Anatomy is a practical 
work ordered to surgery and which only relates the first division of the traditional 
notion of anatomy, namely description, to surgery. 

An understanding of Harvey's procedure then, may be summarized in the words 
of Fabricius: " Now in the second part of this treatise, I must discuss action, since, 
as Galen everywhere testifies, it is not permissible to arrive at the third section, 
which describes the usefulness (utilitates) of the parts, before the actions of the 
organs are understood. For the utilities of an organ always have reference to action, 
and depend upon the action which proceeds from the homogeneous parts of it. For 
this reason, in every organ there is always provided one part which is the prin- 
cipal instrument of its action, that is, a part from which the action proceeds, while 
the other parts of the organ are related to the action as useful assistants." Fabri- 


circulation admitted, established, the use and utilities of its 
institution are especially to be sought." ^^ 

Notwithstanding, Harvey makes clear " the principal use 
and end of the circulation: it is that for which the blood is sent 
on its perpetual course, and to exert its influence continually 
in its circuit, to wit, that all parts dependent on the primary 
innate heat may be retained alive, in their state of vital and 
vegetative being, and apt to perform their duties; whilst to 
use the language of physiologists, they are sustained and actu- 
ated by the inflowing heat and vital spirits." ^® 

The modem reader, of course, will have to understand that 
it would take some time, and the modem development of the 
science of chemistry, before this point could have been made 
in terms of oxygen instead of vital spirits, or amino acids, 
glucose, and fatty acids instead of natural spirits. In the mean- 
time he can have the reassurance from Harvey that " There is, 
in fact, no occasion for searching after spirits foreign to, or 

cius then exemplifies the above distinctions with the eye, in which the crystalline 
lens has the principal utility, and the other parts of the eye, the cornea, the iris 
and the rest, are structures useful for the eye's action through the secondary 
utilities they have for either improving or protecting vision, and concludes: " It 
is now clear from the foregoing that utility is always related to activity, whether 
the usefulness of the organ is sought from its action or from other things either 
consequential or accidental; nor can you inquire into the usefulness of any organ 
unless its action is first known." (Fabricius, The Formed Fetus, Part 2, The 
Action and Usefulness (utilitas) of the parts of the fetus, ch. 1, Adelmann trans- 
lation, ed. cit., p. 276) . 

Harvey's last chapter, which is entitled " The motion and circulation of the blood 
is confirmed by those things that appear in the heart and are clear from anatomical 
dissections," can now be seen as an integral part of the anatomical exercise. In 
the preceding chapters Harvey has established the proper action of the heart, 
as well as its use, the circulation of the blood. This now permits him to look at the 
heart so as to determine formally its utilities, i. e., its abilities to serve, in the 
light of its actions and use. By determining that the formal cause of the heart — 
its utilities — has a one to one correspondence with its action — the efficient cause 
of blood circulation — and with its use, the final cause, namely, the circulation of 
the blood, Harvey can now reflectively confirm the circulation. In this remarkable 
chapter Harvey identifies the principal utility with the muscular left ventricle and 
the secondary utilities with valves, braces, etc. 

^® Harvey, Second Exercise to John Riolan, ed. cit., pp. 122-123. 

^^ Harvey, First Exercise to John Riolan, ed. cit., p. 98. 


distinct from, the blood ": " for " the blood and spirits con- 
stitute one body (like — whey and butter in milk, or heat in 
hot water . . .) ." ^^ 

It should be stressed that Harvey in elucidating the formal 
cause of the heart, as well as the formal cause of the arteries 
and veins, has obtained the efficient cause of circulation and 
the basis for a propter quid demonstration. This is the import 
of his last chapter and his concluding statement quoted above. 


Although Harvey's discovery of the circulation of the blood 
was truly revolutionary, its establishment was strictly tradi- 
tional. Ironically, the greatest opposition to his work came from 
the traditionalists. What accounts for the paradox? 

Most scholastics of the fifteenth and sixteenth centuries so 
admired Aristotle that they ended up slaves to his conclusions 
and caricaturists, rather than disciples, of the methods by 
which he arrived at them. As a result they were very unpro- 
ductive in the natural sciences. 

Modern biologists trace their lineage back to three seven- 
teenth century scientists who revolted from these Aristotelians: 
Francis Bacon, Rene Descartes ^^ and William Harvey. What 

^^ Harvey, Anatotnical Exercises on the Generation oj Animals, Ex. 51, ed. cit., 
p. 502. 

^^ Harvey, The Motion of the Heart and Blood, Introduction, ed. cit., p. 12. 

^^ Descartes was one contemporary who had no difficulty accepting Harvey's 
conclusion. " I need only mention in reply what has been written by a physician 
in England, who has the honour of having broken the ice on the subject (that the 
blood's) course amounts precisely to a perpetual motion." (Rene Descartes, 
A Discourse on Method of Rightly Conducting the Reason and Seeking Truth in 
the Sciences, Everyman's Library, p. 41). He accepted Harvey's conclusion without 
difficulty because it fit in with his mechanistic and mathematized method. His 
method, however, did not protect him from misunderstanding Harvey's demon- 
stration and almost everything that Descartes further said about the motions of 
the heart and blood was in error. (Ibid., pp. 37-43) . 

Harvey, of course, was fully cognizant of Descarte's failure and makes this clear 
in the following passage: ". . . the ingenious and acute Descartes (whose honourable 
mention of my name demands acknowledgments,) and others ... in my opinion 
do not observe correctly . . . Descartes does not perceive how much the 
relaxation and subsidence of the heart and arteries differ from their distention or 


each of these three did was to free himself from the short- 
comings of his contemporaries by a daring innovation. The 
innovation of Descartes was philosophical. He allowed his 
philosophical genius to carry him to the extreme of founding 
a completely new philosophy. The innovation of Bacon was 
pseudo-philosophical. His lack of philosophical genius carried 
him to the extreme of founding a new methodology of investi- 
gation. Descartes paved the way for a whole series of modern 
errors; and Bacon caused the disappearance of methodology in 
those who became his followers. But the innovation of Harvey 
lay in the diligence of his investigation of the Aristotelian prem- 
ises and the profundity of his penetration of Aristotle's method. 
From this novelty — fidelity to the tradition — has come his 
permanent contribution to modern science. It made him both 
an authentic representative of the past and an authentic repre- 
sentative for the future, and establishes him as a model for an 
age that slights sense, as well as for an age that slights reason. 

Herbert Albert Ratner, M. D. 

Loyola University 
Chicago, Illinois 

diastole; and that the cause of the distention, relaxation, and constriction, is 
not one and the same; as contrary effects so they must have contrary causes; as 
different movements they must have different motors; just as all anatomists know 
that flexion and extension of an extremity are accomplished by opposite antagonistic 
muscles, and contrary or diverse motions are necessarily performed by contrary 
and diverse organs instituted by nature for the purpose " (Harvey, Second Exercise 
to John Riolan, ed. cit., pp. 139-140) . 

Part Two 




THE cultivation of the liberal arts and the sciences during 
the twelfth century developed new methods and inves- 
tigated new subject-matters. What was achieved in 
theory and interpretation is obscured by the further trans- 
formation of problems and enlargement of data during the 
succeeding period, the hundred years between the middle of 
the twelfth and the middle of the thirteenth centuries, when 
the scientific and philosophical works of Aristotle and a vast 
body of accompanying commentary, elaboration, and specu- 
lation were translated for the first time. The problem of uni- 
versals and the problem of elements are two highly ambiguous 
signs of the intellectual activity of a period of distinguished 
cultural and scientific renaissance. 

The grammarian, rhetorician, and dialectician of the early 
twelfth century studied texts that had long been available 
more constructively and imaginatively — Latin grammars and 
rhetorics, translations of Aristotle's Categories and On Inter- 
pretation, Porphyry's Introduction, and Boethius' logical trea- 
tises and commentaries — and the twelfth century Book of Six 
Principles attributed to Gilbert de la Porree was assimilated 
with Porphyry's Introduction to the canon of Aristotle's Or- 
ganon. Even the problem of universals was familiar in the 
widely known three questions of Porphyry, After the trans- 
lation of the last four books of Aristotle's Org anon the work of 
twelfth century logicians like Abailard had little pertinence 
to the continuing problems; and, in general, the liberal arts 
of the trivium were turned from interpretative applications 
and constructive theories to demonstrative and speculative 



The encyclopaedist and the cosmologist of the twelfth cen- 
tury likewise worked on texts long available but neglected — 
Chalcidius' translation of Plato's Timaeus and his commentary 
on it, the works of the Platonists Apuleius and Macrobius or of 
Martianus Cappella who furnished bits of the theories of 
Hermes Trismegistus, and finally the eleventh century trans- 
lations of works on medicine or on the nature of man, like 
those of Constantine the African or Alfanus of Salerno in 
which the problem of elements is stated. Thierry of Chartres, 
Peter Abailard, William of Conches (one of whose works is 
sometimes called On the Ele77ients of Philosophy) , and their 
critic William of St. Thierry as well as many other philosophers 
of the early twelfth century used the elements as beginning 
points and ordering principles in their expositions of composites 
as man, the universe, and the sciences; and elements were 
continued in that function in the encyclopaedias of the later 
twelfth and early thirteenth centuries, such as Alexander Neck- 
ham's On the Natures of Things, Thomas of Cantimpre's On 
the Nature of Things, and Bartholomew of Glanville's On the 
Properties of Things. After the translation of Aristotle's scien- 
tific work and of commentaries which put varying interpre- 
tations on his conception of things, neither the data nor the 
theories of these organizations of knowledge were useful in the 
continuing investigations; and, in general, encyclopaedic organi- 
zations of the sciences were turned from the classification of 
the nature and properties of things to the ordering of motions 
and functions according to principles. 

The problem of elements is the counterpart of the problem 
of universals. (1) Science is of the universal; (2) it is derived 
from and applied to particulars; (3) examination of universal 
predicates is therefore involved in questions of existence and 
being, of experience and reason. Conversely, (1) wholes or 
complexes are composed of parts and ultimately parts are 
Composed of simple parts; (2) the nature of parts depends on 
how the whole is conceived; (3) determination of simples is 
therefore involved in a complex of related questions concerning 


the indivisibility of the element, such as, whether the compound 
is divided actually or intellectually; whether the elements so 
produced are corporeal or incorporeal; whether they are indi- 
viduals or classes; and whether they are infinite or finite; 
whether they are characterized only by properties like size, 
shape, weight, and motion or also by other qualities. Questions 
about universals arise from the opposition of different con- 
ceptions of logical and scientific method. Questions about 
elements arise in the opposition of different interpretations of 
data. The problem of universals and the problem of elements 
are important in periods like the twelfth and the fourteenth 
centuries and they are subject to similar resolutions, but the 
differences of disciplines and of information in two such periods 
change the implications of the problems and the considerations 
relevant to their treatment. 

The history of the treatment of elements in the Middle Ages 
reflects the indirect influence of earlier theories of elements and 
repeats in ironic fashion the customary history of Greek phi- 
losophy. Aristotle taught us that the Ionian and Italian philoso- 
phers used the " elements " as principles in their philosophies in 
" lisping anticipations " of his own use of " causes " as prin- 
ciples. We fill in or modify this version of the development 
of thought by giving the elements interpretations suggested by 
the ways in which they are used in cosmological or medical 
accounts of the origin of the universe or the development and 
functions of organisms. Thales' conception of water as a prin- 
ciple is given meaning in application to the structure and origin 
of the universe, and Hippocrates' theory that all natural objects 
are characterized by four qualities — hot, cold, dry, and moist — 
has its obvious applications in physiology and therapy. The 
theories of elements propounded in the medical works of the 
eleventh century and the cosmologies of the twelfth century 
likewise provide the principles of the relevant sciences and 
prepare for the more diversified treatment, in the thirteenth 
century, of principles and sciences devised from the interpre- 
tation of Aristotle's works. 


Aristotle's version of intellectual history depends on his dis- 
tinction of principles, causes, and elements, yet his meaning of 
" elements " is seldom used even when his history is repeated. 
A principle is a " beginning "; all causes and all elements are 
principles, but not all principles are causes or elements, and not 
all causes are elements. Elements are one variety of one of the 
four causes, the material cause. Aristotle defines element as 
the first component part of a thing, indivisible in kind into 
other kinds. The Aristotelian conceptions of " matter " and of 
" kind " have prevented the wide acceptance of this definition, 
for incorporeal as well as corporeal things have matter and a 
thing indivisible " in kind " may be divisible in many ways. 
Aristotle gives three examples to clarify his definition; elements 
of speech, of bodies, and of geometrical or logical proof. The 
Greek word stoicheion means both " element " and " letter." 
The elements of speech or letters are the parts into which 
speech is ultimately divided and which cannot be divided into 
forms of speech different in kind from them: a syllable can 
be divided into parts different in kind, but if letters can be 
divided their parts are likewise letters. The elements of bodies 
are simple parts like water, whose parts in turn are water. 
The elements of geometrical and logical proof are the primary 
demonstrations and the primary syllogisms, which are each 
implied in many demonstrations and which have no parts 
different in kind from them. The elements of demonstrations 
are demonstrations, not propositions or terms. Some people 
use " element " in the broader transferred sense of the small 
and simple and indivisible; the most universal things and 
genera are then thought to be elements, and unity and the 
point to be first principles.^ The first philosophers sought the 
principles of things among the material causes, including the 
four elements; - Leucippus and Democritus said the full and the 
empty, the atoms and the void, are elements; ^ the physicists 

^ Metaphysics, V, 3, 1014a26-bl5. 

* IhH., I. 3, 983b6-984b8. 

* Ihid., 985b3-19. 


posited elements of bodies^ and neglected elements of incorporeal 
things, while the Pythagoreans treated the principles and ele- 
ments even more strangely, for they derived their principles 
from non-sensible mathematical objects and applied them to 
perceptible bodies.* 

Physical elements have an important place in Aristotle's 
organization of the physical sciences. The principles and causes 
of motion are treated in his Physics; elements become important 
in discriminating the kinds of bodies according to their motions 
in his De Caelo; elements are not fixed and changeless, and the 
effects of changes or transmutations of the elements are treated 
in his On Generation and Corruption; the remaining problems 
of phenomena caused by the operation of elements above the 
earth's surface and by the formation of mixtures, compounds, 
and functionally organized wholes are considered in his Meteor- 
ology.^ The division of bodies in the De Caelo is into simples 
(haplon) , which have simple motions, and compounds {sun- 
theton) of those simples, which have composite motions. The 
circular motion of the first body, aither, and of the heavenly 
bodies, is treated in the first two books of the De Caelo; ® the 
straight line motions of the simple bodies, fire and earth, which 
are respectively light and heavy, and of the bodies compounded 
of them, are investigated in the last two books. ^ The definition 
of a bodily element is that into which other bodies can be 
analyzed but which cannot itself be analyzed into parts differing 
in kind.^ The On Generation and Corruption is concerned with 
substantial change rather than with local motion, and the 
transformation of the four elements or simple bodies, fire, air, 
water and earth, is explained by combinations of the primary 
qualities, hot, cold, dry and moist, rather than by the qualities 
light and heavy. 

* Ibid., I, 8, 988b23-990al8. 

^ Aristotle reviews this course of inquiry at the beginniiifj of the Meteorologica, I, 
1, 338a20-339a9. 
« De Caelo, I, 2, 268b26-269bl7. 
''Ibid., m, 1, 298a24-bl2. 
» Ibid., in, 3, 302al5-19. 


The Meteorology finally turns to phenomena less regular than 
the motions of the primary body, aither, below the region of 
the motion of the stars. These include, in addition to meteor- 
ological phenomena in the strict sense, the composition of 
elements into homogeneous bodies and of homogeneous bodies 
into structured or organic bodies. Two of the primary qualities, 
hot and cold, are active, and two, dry and moist, are passive. 
The combinations of elements may be mechanical mixtures 
(sunthesis) or chemical compounds (mixis) . The latter are 
" homoeomerous " bodies, inorganic (gold, silver, stone) , vege- 
table (bark, wood) , or animal (bone, flesh, sinew) , Homoeo- 
merous bodies are distinguished by qualities which act on the 
senses (white, fragrant, resonant, sweet, hot or cold) and more 
intrinsic qualities which, like moist and dry, are passive, such as 
solubility, solidifiability, flexibility, frangibility, plasticity, duc- 
tility, malleability, combustibility, compressibility.^ Homoeo- 
merous bodies are composed of elements, and are in turn the 
material for more complex " non-homoeomerous " bodies. Aris- 
totle's examples of inorganic structured complex bodies are 
artificial objects, like flutes and saws, which have specific 
functions, while his examples of organic complex bodies are 
leaf and root, hands, feet, and eyes." The bodies composed, 
in turn, of non-homoeomerous bodies are men and plants and 
the like. In the course of discussing homoeomerous bodies 
Aristotle makes use of the distinction between masses or cor- 
puscles (onkos) and pores (poros) , which is used later in the 
history of elements and is thought to derive from Democritus' 
distinctions between atoms and void; it is to be observed, 
however, that these particles would have the status of molecules 
relative to simpler atoms or elements. 

Philosophers continued to form theories concerning elements 
after Aristotle, and Aristotle's history of elements as the prin- 
ciples of the early philosophers was usually combined with a 
Stoic or Neoplatonic conception of elements. These were the 

» Meteorologica, IV, 8, 384b24-385al8. 

" Ibid., IV, 10, 388al0-29; 12, 389b23-390b22. 


versions in which the history influenced early Christian thought. 
The Stoics held that the universe, like other wholes, had two 
principles, an active and a passive principle, or an efficient and 
a material principle, and that the universe is ordered by reason 
and providence/^ Plato distinguished and related the operation 
of reason and of necessity in the formation of the universe by 
placing reason in the composition of the world soul and neces- 
sity in the operation of elements. The pattern of later dis- 
cussions of elements as the material parts of a universe brought 
into existence by the efficient or rational causality of God is 
established in pagan and Christian accounts of the history of 
philosophy during the early centuries of the Christian era. 
Almost the same doctrines are given in three related accounts — 
one by Sextus Empiricus, a physician and skeptical philosopher, 
the other two ascribed respectively to the physician Galen and 
to the Christian Clement the Roman — and they are adaptable 
to the Mosaic account of creation.^" The Recognitions of the 
pseudo-Clement were translated into Latin, with modifications, 
by Rufinus and are well-known in various versions during the 
early Middle Ages; the Historia Philosopha of the pseudo-Galen 
is in accord with the treatment of elements in Galen's medical 
works which were translated in the eleventh century. 

Sextus and the pseudo-Galen follow the Stoic division of 
philosophy into three parts, logic, physics, and ethics; and they 
organize their treatment of physics by distinguishing an efficient 
and a material principle .^^ The pseudo-Clement distinguishes 
simples from composites and argues that corporeal wholes 
cannot be accounted for by the elements of which they are 
composed without recourse to a simple cause, rational and 
providential, of the invisible universe which contains the visible 

" Diogenes Laertius, VII, 134 and 138-139. 

^^ Herman Diels (Doxographi Graeci, Berlin, 1889, pp. 251-2) argues that the 
three are so closely related that they must have been derived from a common Stoic 
source composed between the times of Seneca and the Antonines. 

^' Sextus Empiricus, Pyrrhoneiai Hypotyposeis, III, 1, Adversus Mathematicos, 
IX, 4; Galen, Historia Philosopha, 16 (Diels, pp. 608-9) . 


universe/* Sextus undertakes to show that dogmatic views of 
God and of elements are alike untenable; the pseudo-Galen 
enumerates the various philosophic views of elements and of 
God; the pseudo-Clement refutes Epicurus with the aid of 
Plato and sketches the various doctrines of elements before 
treating the problems of their use in explaining the phenomena 
of the universe. The enumerations of theories of elements in 
the three accounts have striking points of similarity/" Similar 
problems are treated — whether the " material " elements are 
" corporeal " or " incorporeal," perceptible by sense or by reason, 
or imperceptible, free of qualities or characterized by qualities, 
finite or infinite. The character of the elements reflects the 
mode of composition used as a model and is sometimes indi- 
cated by use of other terms instead of " element," such as 
" atom," " seed," " root," " minimum," or " molecule." 

The place of elements in the discussion of problems of parts 
and wholes is apparent in each of these accounts. The author 
of The Recognitions, thus, presents himself as one who had 
frequented the schools of the philosophers before he became 
a Christian, and in the dialogue in which elements are discussed, 
the chief speaker, Niceta, acknowledges that he attended the 
Epicurean schools, while one of his brothers studied with the 
Pyrrhonians and the other with the Platonists and Aristotelians. 
He begins his treatment of the origin of the universe by differ- 
entiating all things {omne quod est) into the simple and the 
composite. The simple " lacks number, division, color, differ- 
ence, roughness, smoothness, heaviness, lightness, quality, 
quantity, and, therefore, even limitation." The composite is 
made up of two, three, four, or more components. The simple 
is incomprehensible and immense, without beginning and end, 

^^ Recognitiones, VIII, 9-12, Patrologia Graeca 1, 1375A-6C. 

^^ Sextus Empiricus, Pyrrhoneiai Hypotyposeis, 111,30-32, Adversus Mathematicos, 
IX, 359-64; Galen, Historia Philosopha, 18, pp. 610-11; Clement, Recognitiones, 
VIII, 15, 1378. Sextus goes on to other problems of physical philosophy in Adversus 
MathcTnaticos, Book X — problems of place, motion, time, number, generation and 
corruption — which also involve elements, and a similar enumeration of theories is 
made in connection with generation and destruction, ibid., IX, 310-18. 


without cause, but himself father and creator. Man is able, 
however, to come to awareness of intellectual and invisible 
things from things seen and touched, as is apparent in 

The problem of the origin of the world raises two questions: 
whether it was made or ungenerated; and, if it was made, 
whether it was made of itself or by another. Only the last 
position would provide a place for providence. Niceta argues 
that the world was made by God, and the argument turns 
therefore to the characteristics of the visible world. Bodies 
have two differentiae: either they are connected and solid or 
divided and separate. If the world was made from a solid body, 
it would have to be divided into parts; if it was made from 
diverse parts, they would have to be brought into relation 
and composition. He argues that the universe could not have 
been made from a single body or matter, and that a creator is 
necessary to compound it from two or more bodies. The 
Greek philosophers formed different theories of the principles 
of the universe. Pythagoras said the " elements of principles " 
are numbers; Strato qualities; Alcmaeon contrarieties; Anaxi- 
mander immensity; Anaxagoras equalities of parts; Epicurus 
atoms; Diodorus the incomposite (amere) ; Asclepiades masses 
(onkos) which can be called tumors or swellings; the geometers 
limits; Democritus ideas; Thales water; Heraclitus fire; Diogenes 
air; Parmenides earth; Zeno, Empedocles, and Plato, fire, water, 
air, earth; Aristotle introduced a fifth element, called aka- 
tonomaston or the incompellable, no doubt to indicate him 
who made the universe one by conjoining the elements. The 
" machine of the universe " could not have been set up without 
a maker and director.^® Niceta then refutes the position of 

^^ Recognitiones, VIII, 15, PG 1, 1378A-9A. The enumerations of Sextus and 
Galen are somewhat longer and follow a different order from the pseudo-Clement's 
account, proceeding through the single elements, two, three, four, five, and finally 
other varieties of elements. The list in Sextus' Pyrrhoneiai Hypotyposeis, III, 30-32 
runs: Pherecydes earth; Thales water; Anaximander the infinite; Anaximenes and 
Diogenes of Apollonia air; Hippasus of Metapontum fire; Xenophanes earth and 
water; Oenopides of Chios fire and air; Hippo of Rhegium fire and water; Onama- 


Epicurus, reports the arguments of Plato, and finds support 
in the phenomena of the world — the courses of the stars, 
meteorological occurrences, vegetable, animal, and human struc- 
tures and functions. 

critus fire, water, and earth; the school of Empedocles and the Stoics fire, air, water, 
and earth; the school of Aristotle fire, air, water, earth, and the revolving {kyklo- 
phoretikon) body; Democritus and Epicurus atoms; Anaxagoras homeomeries; 
Diodorus Cronos minima (elachista) and incomposite (amere) bodies; Heracleides 
Ponticus and Asclepiades the Bithynian irregular masses or molecules (anarmoi 
onkoi) ; the school of Pythagoras numbers; Strato qualities. Some of the compexities 
of the problem of elements become apparent in the interpretation of these lists. 
Thus, Sextus elaborates the Pythagorean doctrine that numbers are the principles 
and elements of all things by observing that the Pythagoreans held that the method 
of philosophizing was the same as the m.ethod of linguistic analysis. Language is 
composed of words, words of syllables, syllables of letters or elements (stoicheia) ; 
in the same fashion the true physicist investigates the universe by seeking the 
elements (stoicheia) into which it can be resolved. The advocates of numbers 
(arithmos) as principles (stoicheion) of all things agree with the advocates of atoms 
(atomos) , homoeomeries (homoiomereia) , molecules (onkos) , minima (elachiston) , 
and incomposites {amere) , recognizing that principles must be non-phenomenal, 
non-sensible, intelligible bodies. YAdversus Mathematicos, X, 248-57; cf. Pyrr. Hyp., 
Ill, 151-55, where numbers in turn are generated from the monad (monas) and the 
indeterminate dyad (aoristos duas)]. In the same fashion, Galen emphasizes, in his 
medical writings, the affinity of the atoms of Democritus and Epicurus and the 
molecular masses (onkos) of Heracleides and Asclepiades, even to the extent of 
reducing the differences in the case of Asclepiades to a difference of terms, the sub- 
stitution of onkos for atomos and of poros for kenon. (De Theriaca ad Pisonem, 
cap. 11, Claudii Galeni Opera Omnia, ed. C. G. Kiihn [Leipzig, 1827], vol. XIV, 
p. 250.) Yet the molecules of Heracleides and Asclepiades were frangible or divisible, 
and possessed qualities, and the terms " molecules " and " pore " have an Aristotelian 
derivation which is clearer than their Democritean analogy, for they are terms used 
in the discussion of homogeneous bodies in the Meteorology. Or again, Strato of 
Lampsacus, the successor of Theophrastus as head of the Lyceum, is said to have 
shown tendencies to atomism, yet he is also said to have treated elements as 
" qualities "; this seems to be another case of the assimilation of a philosophy of 
of elements to a philosophy of atoms, for it is clear that in his opposition to 
Platonism, Strato based his analysis on " ultimate components " which he treated 
quantitatively and qualitatively. Doctrines of elements tended to be likened to 
atomism if the operations ascribed to the elements are naturalistic and mechanical; 
elements may be incorporeal and qualitative and still be presented as atomic; if they 
undergo qualitative changes and transmutations, exhibit purposive or teleologicaJ 
orderings, or show effects attributable to God or the world-soul, they are not atomic. 
It is relevant to this transformation of the characterization of elements that Galen 
claimed to have added a fifth instrumental cause (di'hou) to the formal, final, 
efficient and material causes of Aristotle. 


The treatise On the Nature of Man by Nemesius, Bishop of 
Emesa, probably written toward the end of the fourth century 
A. D., was strongly influenced by the medical theories of Galen. 
Nemesius presents man as a conjunction of natures or functions, 
ranging from the inanimate and the irrational to the rational, 
combining the visible and the invisible, and giving evidence 
both of the elements of which he is composed and of the con- 
junctive union in man and in the universe, in both the lesser 
and the greater world, from which the Creator can be inferred. 
Man shares properties with inanimate things, life with animate 
beings, and knowledge with rational beings. He shares with 
inanimate things body and the conjunction of the four elements; 
he shares with plants the nutritive and generative powers; with 
irrational animals he shares, in addition to these powers, volun- 
tary motion, appetite and anger, and the sensitive and respira- 
tory powers; with intellectual natures he shares rationality, 
applying reason, understanding, and judgment, and following 
virtues. He is midway between intellectual and sensible 
essences, conjoined by body and corporeal powers with other 
animals and with inanimate things and by reason with incor- 
poreal substances. The Creator conjoined step by step the 
diverse natures in order to make the universe one and of one 
kind, and this is the best proof that there is one creator of all 
existences.^' God adapted and conjoined all things to all things 
harmoniously, and united into one, through the creation of 
man, invisible and visible things.^^ Nemesius finds the Mosaic 
account of creation bears out this analysis, and he organizes 
his treatment of the nature of man in accordance with it, 
presenting in turn the soul, the union of soul and body, and the 
faculties of man, ranging from imagination and sense through 
intellect, memory, thought, expression, passion, nutrition, pulse, 
respiration, voluntary action, free-will, and providence. 

The body is presented as a conjunction of elements in humors, 

^^ Nemesii, Premnon Physicon a N. Alfano Achiepiscopo Salerni in Latinum trans- 
latus, I, 8-11, ed. C. Burkhard (Leipzig, 1917), pp. 6-7. 
'' Ibid., I, 23, pp. 9-10. 


homogeneous parts, and members.^^ Nemesius defines the cor- 
poreal element {elementum rriundanuin) as the least part in 
the composition of bodies. The mundane elements are four: 
earth, water, air and fire. " They are the first and simple bodies 
relative to other bodies. For every element is of the same kind 
as the bodies of which it is an element. A principle is not of 
the same kind as the things of which it is a principle, but an 
element is wholly of one kind." -" He analyzes the four elements 
by means of the four qualities hot and cold, wet and dry, but 
he argues that these qualities are not elements because bodies 
cannot be constituted of incorporeal things, and he treats the 
problem of the order of elements in the organization of the 
universe by interposition of elements to mediate between con- 
trary qualities. He also expounds the Platonic analysis of 
elements, distinguishing two ways in which he classifies ele- 
ments: (1) by the regular solids, (2) by assigning three 
qualities to each element — fire having sharpness, rarity, motion, 
and earth, at the other extreme, having dullness, density, rest. 
To these he added a third way used by some philosophers, 
who distinguish the heavy elements, earth and water, from the 
light elements, air and fire."^ The elements and the body enter 
into the analysis of the functions of the soul, and Nemesius 
expounds the Galenic theory of the localization of functions: 
imagination in the anterior lobe of the brain," understanding 
in the intermediate lobe,"" and memory in the posterior lobe,"* 
adding that evidence for the localization of these functions was 
derived from observation of brain lesions and diseases affecting 
the brain." 

Nemesius' On the Nature of Man was translated into Latin 
in the eleventh century by Archbishop Nicholaus Alfanus under 
the title Premnon Physicon or Key to Natural Things but with- 
out mention of the name of the author or of the title he gave 

"/6i(Z., IV, pp. 59-61. 

'" Ibid., V, 1-2, p. 62. '" Ihid., XII, 3, p. 87. 

" Ihid., V, 24-25, pp. 67-69. ^* Ibid., XIU, 7, p. 89. 

" Ibid., VI, 4, p. 73. ^^ Ibid., 8-13, pp. 89-90. 


his work. It was translated again in the twelfth century by 
Richard Burgundio of Pisa, who was under the impression that 
it was written by Gregory of Nyssa. Alfanus's version was used 
by Albertus Magnus, and Burgundio's is quoted by Peter 
Lombard and Thomas Aquinas. 

Some remnants of these distinctions are transmitted to the 
Middle Ages by Isidore of Seville. Cassiodorus (490-583) had 
recommended the reading of Latin translations of Hippocrates 
and Galen,"*' but manuscripts of these early translations have 
not been found. He does not treat elements in his Institutiones, 
but a section on the four elements is added in a later inter- 
polation.^^ It deals with the order of elements familiar in 
meteorology from the heavenly bodies to earth, and explains 
the sequence of fire, air, water, and earth, by combinations of 
the properties incorporeal, corporeal, immobile, mobile, sharp, 
blunt (fire is sharp, incorporeal, mobile, as well as hot and dry; 
earth is blunt, corporeal, immobile, as well as cold and dry) 
which are caused by the influence of proximate elements. The 
elements are also equated with regular solids and numbers: 
fire with the pyramid and 12; air with the sphere and 24; water 
with the icosahedron and 48; earth with the cube and 96. In 
a diagram, the four elements, the upper three and the lower 
three are connected by three sets of lines drawn in groups of 
four to points numbered 576 (12 X 48) , 1152 (24 X 48) , and 
2304 (48 X 48) . The text says that the lines indicate ways 
in which the elements by their obvious contacts with each 
other both prepare substances of different species from them- 
selves and are combined because of the diversities in themselves. 
This is the bond binding the union of the world, the relation 
assembling the elements. The interpretation may be based on 

"'Cassiodorus, Institutiones Divinarum et Humanarum Lectionum, I, 31, PL 70, 
1146. He also recommends the reading of Caelius Aurelianus' On Medicine which 
treats the problems of elements. 

" Cassiodori Senatoris Institutiones, ed. R. A. B. Mynors (Oxford, 1937), pp. 


Plato or Macrobius or on St. Ambrose's statement that the 
Greek word stoicheia means joining with each other.^® 

Isidore of Seville (560-636) takes up the elements in his 
encyclopaedic Etymologies, briefly in his treatment of medicine, 
and more fully as ordering principles in his treatment of the 
universe. In medicine the four humors are explained by the 
four elements; blood refers to air, choler to fire, melancholy to 
earth, and phlegm to water."^ Man is composed of soul and 
body; and his living flesh is compacted of the four elements .*° 
The treatment of meteorology and geography opens with suc- 
cessive chapters on the world, on atoms, on elements, on heaven, 
and on the parts of heaven. Atoms are defined as " certain 
parts of the bodies in the world so extremely minute that they 
can neither be seen nor undergo tonne, that is, cutting, for which 
reason they are called atoms." ^^ Isidore adds that there are 
atoms in body, in time, in number, or in language. The list 
recalls Aristotle's list of kinds of elements, but Isidore's criterion 
for atoms is indivisibility: the atom of body is the indivisible 
particle, of time the point or indivisible moment of time, of 
number the unit, of language the letter. The chapter on 
elements begins with a definition of the Greek word hyle as a 
kind of first matter in no way formed but capable of all bodily 
forms. The Greek word for elements, stoicheia, means those 
things which agree with each other in a kind of concord of 
society and communion, since they are said to be joined to 
each other in a kind of natural proportion, and therefore the 
sequence from fire, through air and water, to earth, and the 
sequence back, are causal. All elements are present in all things, 
but a thing is named from the preponderant element. Animate 
beings are distributed among the elements by divine provi- 

"* Ambrose, Hexaemeron, III, 4. PL 14, 176: "... atque ita sibi per hunc cir- 
cuitum et chorum quendam concordiae societatisque conveniunt. Unde et Graece 
stoicheia dicuntur, quae Latine elementuvi dicimus, quod sibi conveniant et 

-* Isidore of Seville, Etymologiae, IV, 5.3; PL 82, 184C. 

'"' Etymologiae, XI, 1; PL 82, 398-9. 

" Ibid., XIII, 2, 472D-3B. 


dence: heaven filled with angels, air with birds, water with fish, 
and land with men and animals. Chapter 5 begins the treat- 
ment of the heavens with the element aether or fire; Chapter 7 
proceeds to meteorology by way of air; Chapter 12 begins the 
treatment of waters with the element water; and Book XIV, 
which is devoted to the earth and its parts, has an opening 
chapter on the element earth. 

The Venerable Bede (672-735) follows a similar order in his 
On the Nature of Things. A fourfold distinction concerning 
the divine creation is made in the first chapter; one phase of 
creation is that the elements of the world were made together 
in unformed matter. In the formation of the world it is 
specified, in the second chapter, that heaven, earth, angels, air, 
and water were made from nothing in the beginning, and the 
elements are used to differentiate the six days of creation. 
Elements enter into the definition of the world in the third 
chapter. The fourth chapter is on the elements and their 
influence on each other and the mixtures they form are stated 
in terms of the qualities heavy and light, hot and cold, moist 
and dry.^" Astronomical questions are introduced by considera- 
tion of the element fire in Chapter 5; the transition to meteor- 
ological questions is made in Chapter 25, on air; waters are 
treated after Chapter 38 on the differentiation of salt and fresh 
waters; geographic questions are introduced by Chapter 45, on 

Bede makes use of the idea of atoms in his treatment of time. 
In Chapter 3 of the De Temporum Ratione, on " the most 
minute spaces of times," he calls the minimum indivisible part 
of time atoms. Days are divided into 12 hours, and hours into 
12 points, 10 minutes, 15 parts, 40 moments — points and minutes 
being measured on clocks, parts on the circle of the Zodiac, 
moments by the swiftest motion of the stars. The least of all 
divisions of time which can in no way be divided further is 
called the atoTn in Greek, that is, the indivisible. Because of 
its smallness it is preceptible by grammarians rather than 

*^ Venerable Bede, De Natura Rerum, I-IV, PL 90, 187-96. 


calculators, for grammarians divide verses into words, words 
into syllables, syllables into feet, and feet into long and short, 
and since it is impossible to divide further, the short foot is 
the atom. Bede rejects the divisions of time proposed by the 
astrologer, and concludes his treatment of atoms by quoting 
Paul on the speed of resurrection: " We shall not all sleep, but 
we shall all be changed, in a moment, in the twinkling of an eye, 
at the last trumpet." ^^ Bede's text, however, reads " atom " 
instead of " moment," and he therefore defines the atom of 
time by the flash of an eye which cannot be divided or cut, 
and which is sometimes called " moment," sometimes " point," 
and sometimes " atom." ^* Bede's interpretation of Paul could 
have been derived from Augustine, and one of the continuing 
sources of information concerning the meaning of atom during 
the Middle Ages was interpretations of the New Testament. ^^ 
The elements of the world, the seasons of the year, and the 
humors of man are distinguished by the same qualities and for 
this reason man is a microcosm or lesser world. Air, spring, 
and blood which grows in spring, are damp and warm; fire, 
summer, and red choler, which develops in summer, are hot 
and dry; earth, winter, and black choler are dry and cold; water, 
autumn and phlegm are cold and damp. Moreover the succes- 
sive ages of man and the different temperaments of men are 
determined by the predominance of one or another of the 

Rhabanus Maurus (748-856) treats the world in Book IX of 
his De Universo in the manner of Isidore of Seville, even to the 

^^ I Corinthians, 15: 51-52. 

" De Temporum Ratione, iii. PL 90, 302-7A. 

35 I 

St. Augustine, Sermo, CCCLXII, 16, 19-18, 20. PL. 29, 1623-25. Augustine 
explains the atom in time by the atom in body. He remarks that many do not 
know what an atom is, and then defines atom from tom,e or cutting, so that atomos 
means what cannot be cut. He uses the division of a stone into indivisible parts to 
clarify the division of a year into like parts. Moreover, he argues that the ictus oculi 
by which Paul explains atomus, does not mean the opening or shutting of the eye, 
but the emission of rays from the eye to what is to be seen, including distant objects, 
such as heavenly bodies. 

*^ De Temporum Ratione, XXXV, 457C-9A. 


extent of repeating in the first two chapters Isidore's treatment 
of atoms and of elements.^' He follows Bede in his treatment 
of time, but his edition of the Epistle to the Corinthians has 
" momentum " instead of " atomum." He therefore adapts 
Bede's definition of " moment," and treats the moment as the 
minimum and smallest time measured by the motion of the 
stars. But he also remarks that another edition of the text 
of Paul has in atomo et in ictu oculi, gives the etymology of 
atomos, and explains that atoms of time are perceptible to 
grammarians rather than to calculators.^^ 

The marks and remnants of older distinctions concerning 
elements are plentiful, but the medical writings which were 
translated during the eleventh century used elements more 
systematically to explain the phenomena of nature and pro- 
vided greater precision of statement and more diversified data 
of application in the use of elements as principles. Constantine 
the African (c. 1015-1087) translated from the Arabic, or 
adapted, several books attributed to Galen, in which elements 
are treated in detail, as well as Isaac Israeli's Book of Elements, 
but the analysis of elements in the Pantegni, an adaptation of 
a portion of the Royal Book of Medicine of Haly Abbas, which 
is the tradition of Galen concerning elements, had a clearly 
marked influence.^" The Pantegni begins, in medieval fashion, 
by reciting the six things which should be known about a book: 
the intention of the book, its utility, its title, what part of 
learning it deals with, the name of its author, the division of 
the book. The author's name is given as Constantine the 
African, who brought the materials together from writings of 
many authors. It was Constantine's ambition to write a book 
covering the whole of theoretical and practical medicine, which 

"Rhabanus Maurus, De Universo, IX, 1 and 2, PL 111, 262A-3A. 

" Ibid., X, 2, 286A-B. 

" Constantini Africani, Opera, Basel, 1536 and 1539. Several of Constantine's 
translations are published among the works of Isaac Israeli, Opera Omnia Ysaac, 
Lyons, 1515. Thus, only the portion of the Pantegni devoted to theory is published 
in the 1539 volume of Constantine's works; both parts. Theory and Practice, are 
in the edition of Isaac. 


would make unnecessary the reading of any other book for 
preparation or supplementation. Medicine, he argues, is more 
necessary and of greater dignity than all the other arts, since 
without health of body rationality is impossible, and \vithout 
rationality science is impossible. But to understand this art, 
dialectic and the arts of the quadrivium must first have 
been mastered. Moreover, medicine covers the whole scope 
of science, for science is divided into logic, ethics, and physics, 
and medicine deals with all three of these parts, but falls 
entirely under none. 

The Pantegni is divided into two parts, Theory and Practice, 
and each in turn is divided into ten parts. Theory is per- 
fect knowledge of things to be seized by intellect alone and 
stored in memory for the control of those things; practice is 
the manifestation of theory in things of sense and in manual 
operations in accordance with understanding of the preexisting 
theory. Theory is divided into three parts — the sciences of 
natural things, of non-natural things, and of things outside 
nature. Practice is the science of caring for the healthy and 
curing the sick with diet, potion, and surgery. Natural things 
are those necessary to the subsistence of bodies and pertaining 
to their contruction or destruction. Natural things have seven 
kinds of parts, three of which are common to sensible and 
insensible things, that is, elements, complexions, and actions, 
and four of which are proper to sensible things alone, that is, 
humors, members, virtues, and spirits. There are six non- 
natural causes — the air about the human body, motion and rest, 
food and drink, sleep and waking, inanition and continence, and 
the accidents of the soul. There are three things outside nature 
— disease, the causes and signs of disease, and the accidents of 
disease. The theoretic portion of the treatise proceeds syste- 
matically from elements to complexions of elements to members 
and virtues of members; then non-natural things and things 
beyond nature are treated. 

The element, as philosophers define it, is a simple and mini- 
mum particle of composite bodies. The elements include fire, 


air, water, earth, but not rocks and metals which, though 
simple to sight are composite to understanding. The elements 
are themselves indestructible, and the destruction of all other 
things consists in their return to the elements of which they 
were composed. Constantine scouts the idea of a single element, 
whether atoms or any one of the ordinary four elements, with 
arguments, ascribed sometimes to Hippocrates, designed to 
show that it is impossible for a single thing to generate things 
diverse from itself without commixture with other things. The 
four elements are the hot, the cold, the dry, and the moist — 
not the qualities simply, rather heat actually perfect is fire; 
actual and perfect cold is water; naturally perfect moistness is 
air; and the perfectly dry is earth. Each element acquires a 
second quality from the element contiguous to it: from the 
motion of the circle of the moon which is next to it, fire acquires 
dryness; air acquires heat from its contiguity to fire; water 
has dampness from the propinquity of air, and earth coldness 
from water. The qualities light and heavy are likewise divided 
among the elements, fire being most light, earth most gross 
and heavy, air and water falling between the two. 

The compounds of elements from which bodies are formed 
are called complexions. They may be of varying degrees, and 
the quality and function of the whole is determined by the 
preponderant element. Sensation is explained by the temper- 
ateness of the complexion of the organs. Thus, nothing would 
be perceived by touch if the organ were not changed into the 
quality perceived; if the organ of touch were not temperate 
it would not distinguish between hot and cold, soft and hard, 
smooth and rough. Man is the most temperate of all animals. 
Unlike the brute which is possessed of a single function, he can 
do all things, and he is rational and intellectual because he can 
understand and distinguish by reason whatever he does. The 
complexions are instruments of nature or of the soul or of both. 
Each animal has instruments of the body in agreement with 
the virtues of the soul, for the government of all bodies is either 
by the soul and nature or by nature alone, that is, nature rules 


in both animate and inanimate bodies, the soul only in animate 
bodies. Certain virtues must be present if the body is to com- 
plete its operations. 

Constantine lists three general virtues: one pertains only to 
nature and is therefore called natural; a second, pertaining to 
the soul, only vivifies and is called spiritual; a third, also per- 
taining to the soul, gives understanding, sense, and voluntary 
motion, and is called animate. The action of natural virtue, 
which consists in generation, nutrition, and growth, is universal 
in animals and plants. Spiritual virtue is common to rational 
and irrational animals, but not to plants; it consists in the 
vivification which is accomplished by the action of the heart 
and the dilation and contraction of the arteries for the con- 
servation of natural bodily heat. The animate virtue is partly 
common to rational and irrational animals, for both participate 
in sense and voluntary motion, and partly not, for only rational 
animals have fantasy, reason, and memory. This analysis per- 
mits the reduction of all actions to kinds of motion, and 
Constantine elaborates the enumeration of six kinds of motion, 
two simple and four complex, all depending ultimately on the 
simple contraries. 

The details of medical theory and practice, for which this 
analytic structure was prepared, are organized relative to the 
means of recognizing and controlling the mixtures of these 
qualities, Constantine is credited with a translation of The 
Book of Degrees (Liber de Gradibus) ascribed to Isaac Israeli 
but of unknown origin, in which medicinal simples are con- 
sidered in terms of their varying degrees of hot and cold, dry 
and moist. Constantine reports four principal grades: a food 
or medicine is in the first degree of heat if it is below that of the 
human body; in the second degree if it is of the same tempera- 
ture; in the third degree if it is somewhat hotter; in the fourth 
if it is extremely hot. The consideration of the contraries is an 
analytical device for the unification of physiology, pathology, 
and therapy. The doctrines of the four elements and the four 
qualities, whose development can be traced from Hippocrates 


through Aristotle to Galen, were at times used for discovery 
or systematization of knowledge and at times as repetitive 
formulae for easy analogies or empty classifications. Their use 
in the twelfth century was as principles employed over a 
broadening scope in intellectual curiosity and on a diversifying 
body of empirical and rational data. 

The framework within which the analysis of elements was 
fitted in the twelfth century was a Platonic conception of the 
universe derived from Plato's Timaeus and Latin Platonists, 
like Apuleius and Macrobius, with echoes of Hermes Tris- 
megistus and the pseudo-Dionysius the Areopagite, a human- 
istic study of the liberal arts in which rhetoric and dialectic 
colored an Aristotelian scheme of categories, syllogisms, and 
topics, and a tradition of interpretation of the Mosaic account 
of creation which used Platonic conceptions and methods 
derived, by way of Augustine and Ambrose, from the Greek 
Hexaemerons and Philo. The medical conception of elements 
lent concreteness, specificity, and empirical detail to the con- 
sideration of the nature of things, but it also accentuated the 
tendency to use a variety of structures or organisms as models 
for the universe or to use the structure of the universe as a 
model for other lesser wholes, and therefore to analogize man 
and universe (microcosm and macrocosm) , human soul and 
world-soul, deliberate action and physical motion, in the treat- 
ment of cosmology, psychology, physiology, geography, and 
history. This merging of Platonism, the liberal arts, and the 
new sciences was one of the distinguishing marks of the school 
of Chartres in the twelfth century. 

William of Conches (c. 1080-1145) , whom John of Salisbury 
calls the most richly endowed grammarian (John's epithet 
opulentissimus has also been interpreted as a reference to the 
high fees of grammarians) , was a grammarian and wrote 
treatises of science and ethics. He was influenced by Thierry 
of Chartres and Peter Abailard in cosmology and theology, and 
he quotes Constantine the African about elements. William 
divides science into two species in his Gloss on Boethius' Con- 


solation of Philosophy: eloquence and wisdom. Eloquence is 
the science of presenting what is known with the proper orna- 
ments of words and sentences; it is a species of science because 
all science consists of only these two parts, knowing things and 
presenting what is known well. Eloquence is not philosophy, 
nor any part of philosophy, but without philosophy, eloquence 
is a hindrance rather than an aid. William's division of phi- 
losophy is Aristotelian rather than Stoic: practical and theo- 
retical, each in turn divided into three parts, practical into 
ethics, economics, and politics, and theoretical into theology 
(the study of incorporeal things) , mathematics (the quad- 
rivium) , and physics (the study of the properties and qualities 
of bodies) . The proper order of learning is from the study of 
eloquence (from grammar through dialectic to rhetoric) to the 
study of practical problems to the study of theoretic problems, 
beginning with bodies in physics and proceeding through mathe- 
matics — arithmetic, music, geometry, astronomy — to the con- 
templation of incorporeal things and to the Creator in theology. 
The Philosophy of the World was written, according to 
William's Preface,*" because he saw so many men arrogating to 
themselves the name of Master, who have dissolved the union 
between eloquence and wisdom, who spend their time sharp- 
ening a sword they never use in battle, and who know nothing 
of philosophy, yet blush to confess themselves ignorant of 
anything and, seeking solace for their lack of learning, proclaim 
to less cautious men that the things they do not know are of 
little utility. 

The use of elements to organize bodies of knowledge and 
empirical data continues to employ two philosophical assump- 
tions: that the invisible things of the world are understood by 
the things that are made,*^ and that the existence of causes 

*° The De Philosophia Mundi or the Peri Didaxeon sive Elementorum Philosophiae 
Libri IV has been ascribed to several philosophers and has been published as the 
work of William of Hirschau, the friend of St. Anselm (Basel, 1531), of the Venerable 
Bede (PL 90, 1127-78) and Honorius of Autun (PL 172, 39-102). The reference is 
to Book I, Praefatio (in the Honorius of Autun edition) PL 172, 41-43. 

*^ The inference from visible to invisible, which is used by the pseudo-Clement 


is proved from consideration of the characteristic of effects/^ 
WiUiam opens his treatise with the definition of philosophy as 
" the true comprehension of things which are and are not seen 
and of things which are and are seen," and specifies that the 
first are incorporeal things, and the second corporeal things, 
whether they are possessed of divine or perishable bodies.*^ 
He treats incorporeal things first — God, the soul of the world, 
demons, and the souls of men. Since God can be known in 
this life, William undertakes to prove his existence to the 
incredulous by arguments from the creation of the world and 
from its daily disposition. The first argument begins with the 
fact that the world is compounded from contrary elements, hot 
and cold, wet and dry. This composition of the world might 
have been effected by nature, or chance, or some artificer. 
Not by nature, since nature flees contraries and seeks similars. 
Not by chance, since simpler constructions, like houses, are not 
made by chance, and, moreover, chance is the unexpected 
occurrence of a thing from a confluence of causes, but nothing 
preceded the world except the Creator. But the artificer was 
not man, since the world was made before man; nor an angel, 
since the angels were made with the world; therefore the 
artificer was God. The second argument, from the daily dis- 
position of things proceeds similarly. Whatever is disposed is 
disposed in accordance with some wisdom, and in the case of 
the world it is not human or angelic but divine wisdom. From 
the daily disposition of things one attains to the divine wis- 
dom, and from the divine wisdom to the divine substance. 

and many of the Church Fathers, finds support in Paul (Rom. 1: 20, "For the 
invisible things of him from the creation of the world are clearly seen, being under- 
stood by the things that are made ") and elaboration in Platonic philosophies. 

*^ The dependence of phenomena perceived by sense or reason on a transcendent 
cause, equally well established in the Christian tradition, finds like support in Paul 
(Col. 1: 16, "For by him were all things created, that are in heaven, and that are 
in earth, visible and invisible ") and its elaboration may have an a ])riori Platonic 
turn, in which man and the world are image, likeness, or imprint and reasoning 
about them proceeds by models, or an a ■posteriori Aristotelian or Stoic turn in 
which phenomena are effects and reasoning about first causes proceeds from effects. 
" De Philosopkia Mundi, I, 1-3, PL 172, 43B-C. 


Philosophers say that in this Divinity, which is maker and 
governor of all things, power, wisdom, and will are present, 
corresponding to the persons of the Trinity, power to the 
Father, wisdom to the Son, and will to the Holy Spirit. 

In this work William only touches on the world soul, enu- 
merating three opinions about it. Some think the world Soul 
is the Holy Spirit, for all things which live in the world 
live by the divine goodness and will which is the Holy Spirit. 
Some think that it is a natural vigor placed by God in the 
world by which some beings only live and others live and 
perceive and think; some, finally, think that it is a kind of 
incorporeal substance which is whole in each body although 
it does not perform the same functions or operations in all 
because of the comparative slowness of some bodies. In his 
Gloss on Boethius, however, William states his own doctrine, 
characteristically combining aspects of the three: the world 
soul is a natural vigor by which all things have their being, 
their motion, their growth, perception, life, reason; its effects 
differ in different subjects; and the natural vigor is the Holy 
Spirit. William's discussion of the third kind of incorporeals, 
demons, is based, as his critics were quick to point out, on 
Plato as well as on Scripture and the Fathers. William argues 
that even Plato's division of good demons (kalodaimones) into 
two genera is not inconsistent with the Scriptural division of 
angels into nine orders, since Plato divides them according to 
the places they occupy and the Bible according to the functions 
they perform. The treatment of the fourth kind of incorporeals, 
souls of men, is postponed to the consideration of man in 
Book IV. 

When William makes the transition from things which are 
and are not seen to things which are and are seen, he warns 
the reader that his manner of presentation must change since 
his exposition will use either statements that are probable and 
not necessary or statements that are necessary and not prob- 
able, " for as philosophers we posit the necessary even if it is 
not probable, and as physicists we add the probable even if 


it is not necessary." ** His claim for his treatment is that 
nothing more probable will be found in the works of " modern 
physicists." Since things which are and are seen are bodies, 
and since all bodies are composed of elements, his starting point 
is with elements as Constantine defines them. " An element, 
therefore, as Constantine says in the Pantechne, is a simple 
and minimum part of any body, simple with respect to quality, 
minimum with respect to quantity." *^ William interprets this 
to mean that an element is " a simple part, which has no 
contrary qualities," which Constantine expands, in order to 
exclude homogeneous wholes, like bones, by adding " a mini- 
mum part, which is a part of something in such wise that 
nothing of the same sort is part of it." Letters are elements 
in like fashion because they are parts of syllables in a way in 
which nothing is part of them. Constantine undertook to derive 
humors from the composition of the four elements, then homo- 
eomeries or " consimilar parts," like flesh and bone, as well as 
organic or " instrumental parts," like hands and feet, from 
humors, and finally, the human body from these two kinds 
of parts. Consequently, the elements are not " things which 
are seen," the earth, water, air, and fire, which are commonly 
called elements, for those are not simple in quality or minimum 
in quantity, but each is seen to contain all the qualities, as 
there is in earth, for example, something of hot, of cold, of dry, 
and of moist. 

William argues therefore that the elements of corporeal things 
or things which are seen are incorporeal or things which are 
not seen. Division is of two sorts: the human body can be 
divided into members and homoeomeries actually, but only the 
understanding divides homoeomeries into humors and into 
elements. The power of the understanding, as Boethius points 
out, is to disjoin the conjunct and to conjoin the disjunct. If it 
is asked where the elements are, the answer is that they are in 
composition of bodies as the letter is in the composition of 
syllables but not in itself {per se) . Some thinkers, like simple 

"■'Ibid., I, 20, PL 172, 48C-D. "/6«Z., 21, 48D-9A. 


minds, know nothing unless they can comprehend it by sense, 
but the investigations of the wise man must be concerned more 
with insensible than with sensible things. The elements are 
simple and minimum parts determined by simple, non-contra- 
dictory qualities, as earth is by cold and dry. The parts which 
are seen are composites in which one of the elementary particles 
dominates, as the composite in which cold and dry particles 
predominate is called earth. If one wishes to apply separate 
names to the two, William says, the particles which are not 
seen may be called the elements, elementa, and the particles 
which are seen may be called the elemented, elevientata, prod- 
ucts or mixtures of elements.'*^ Some philosophers who have 
read neither the writings of Constantine nor those of any other 
physicist say that the elements are the properties or qualities 
of things which are seen, that is, dryness, coldness, dampness, 
and heat. William uses quotations from Plato, Johannitius, and 
Macrobius to prove that the qualities are in the elements, and 
therefore, the elements are not the qualities. Other philosophers 
say that things which are seen are elements, and William argues 
that there is no contradiction between this position and that 
of Constantine, although they treat two different kinds of 
elements. Constantine treats the natures of bodies as a physi- 
cist, and he calls the simple and minimum particles of bodies 
" elements " in the sense of first principles. Philosophers who 
investigate the creation of the world rather than the natures of 
individual bodies call the four parts which are seen " elements " 
because the world is composed of them and they were created 
first. If it is said that these are not elements, because they are 
made of the four elements, and earth, for example, contains 
some water, and that Plato asks how one is to decide during 
the transmutation of elements whether to call it earth or 
water,*' William's reply is that the earth in question is some- 
thing porous and saturated with water, and even if it is dis- 

"Cf. Tlieodore Silverstein, " Elementatum: its appearance among the Twelfth 
century Cosmogonists," Medieval Studies, XVI (1954) , pp. 156-162. 
*■' Plato, Timaeus 49B-C. 


solved in water, it is' not the element " earth " but the 
" earthly," which is " part of the element," which is dissolved. 
Therefore the elements of bodies are the particles and the 
elements of the world are accounted for by their conjunctions 
and mixtures. 

William raises two more questions which have the same 
characteristic of relating the problem of how wholes are com- 
pounded of parts and how intelligible principles are used to 
structure sensible data, that is, how the incorporeal things of 
understanding are related to the corporeal things of sensible 
experience. They are the questions (1) of the composition of 
the universe or of the bonds by which elements are joined 
together in compounds and organisms and (2) of the origin 
of the universe or whether the elements were formed from a 
preexistent chaos or were present in the chaos. Both questions 
raise issues which are philosophic in character about the 
defining properties of elements which are qualitatively simple 
and quantitatively minimum in kind, and about how they 
" are " (corporeal or incorporeal) and " are understood " (sen- 
sible or intellectual) . 

William's treatment of the structure of the universe is based 
on Plato's demonstration that between extreme elements fire 
and earth, two and not more than two elements, air and water, 
are needed to establish the unity and cohesiveness of a uni- 
verse.^* Plato's argument is that that which comes to be must 
be corporeal and therefore visible and tangible, for the basic 
proportion underlying his account of creation is that being is 
to becoming as thought and reason are to opinion and sensa- 
tion. William interprets Plato's statement that Divine Reason 
ordained that the universe be so constructed as to be percep- 
tible to sight and to touch as a consequence of the purpose in 
creation that man should see even with his eyes in the creation 
and government of things the divine power and wisdom and 
goodness, should fear the power, venerate the wisdom, and 
imitate the goodness. But sight is impossible without fire and 

''/?>irf., 31B-32C. 


touch is impossible without earth, and the conjunction of fire 
and earth, which are opposed by contraries (since fire is subtle, 
mobile, and acute and earth is corporeal, obtuse, and immobile) 
required the interposition of one or more middle terms. William 
distinguishes mixture {commistid) , in which neither of the 
contraries remains what it was before, from conjunction (con- 
junctio) , in which both the contraries remain what they were 
before. Conjunction is impossible in the case of active qualities 
(like hot and cold) unless they are separated by a middle term 
to prevent one from dissolving the other. Wishing to conjoin, 
not mix, fire and earth that both would remain what it is, God 
created between the two elements, not one, but two more 
elements, water and air. For if he had placed only water 
between them it would be conjoined to earth more than to 
fire, for it shares corporality and obtuseness with earth and 
only mobility with fire, and that conjunction would not endure; 
similarly, if only air were placed between, it would have 
subtlety and mobility in common with fire and only obtuseness 
with earth. To the objection that if one did not suffice, God 
could make it suffice, William says that he does not put a 
limit on God's power, but he says concerning things which are 
that none could suffice nor could there be anything, according 
to the nature of things, that would suffice. 

Having shown that one would not suffice, he demonstrates 
why there could not be anything that would suffice. Elements 
may be separated by two contrary qualities or by three. 
Between some binary pairs, one element would suffice as a 
middle term; thus, in the case of earth, which is cold and dry, 
and air, which is hot and damp, water (which shares coldness 
with earth and dampness with air) is a term of separation and 
connection. Between ternary terms there is no middle, since 
any element would share one quality with one of the extremes 
and two with the other. Moreover, even if fire and air are 
treated in terms of two rather than three qualities no middle 
could be found since fire is hot and dry, earth, cold and dry, 
and any combination of the two qualities would be identical 


with one of the two elements or the impossible combination, hot 
and cold.*^ Of the six combinations of the four qualities, four 
are possible and determine the four elements; and the remaining 
two combinations, hot and cold, dry and wet, are impossible. 

** The demonstration of the harmony or unbreakable chain of elements binding 
the universe together, dependent on the interposition between fire and earth of two 
and only two elements, goes back to Plato, but the changes in the properties of the 
elements on which the demonstration depends mark changes in the doctrine of 
elements. Plato's argument depends on the nature of proportion and of numbers: 
if the universe had been a plane surface, one middle would have sufficed; since it is 
solid two middle terms are required. Macrobius gives a rough translation of this 
passage, omitting the references to proportions and square and cubic numbers; 
instead he discusses hot and cold, dry and moist. (Commentarii in Somnium 
Scipionis, VI, 23-33) . The Medieval tradition, finally, presents the Platonic analysis 
of elements as permutation of sets of three qualities, elaborated and systematized 
from his account of the properties of elements resulting from the geometric forms 
assigned to them (Timaeus, 55C-56B) . The systematic account of the six qualities 
of the elements is known as early as Nemesius, and scholars have argued that his 
source is a lost commentary of Posidonius on the Timaeus or a lost commentary of 
Porphyry. If the problem is treated in terms of three qualities, the two extreme 
elements of the universe are opposed by sets of contrary qualities — subtle, mobile, 
acute (fire) vs. corporeal, immobile, obtuse (earth) , whereas if it is treated in 
terms of two qualities, the contraries separate the elements in groups of threes, but 
the two extreme elements are not opposed by contrary qualities — hot, dry (fire) 
vs. cold, dry (earth) — and therefore, according to Nemesius (V, 11, p. 64). the 
sequence of elements is not merely an ascent and a descent but a circle, since fire 
shares with earth the quality dry. ^Miatever the origin of the analysis in which each 
element is characterized by three qualities, the Latin writers of the Middle Ages 
learned the distinctions it employs from the Commentary of Chalcidius on the 
Timaeus. The sequence of elements between the two extremes, fire and earth, as 
set forth by Chalcidius, may be schematized as follows — 

Ignis — acutus subtilis mobilis 

Aer — obtunsus subtilis mobilis 

Aqua — obtunsa corpulenta mobilis 

Terra — obtunsa corpulenta immobilis 

The two extreme pairs — fire-air and water-earth — share two qualities and are 
opposed in one; the sequence consists in the change of one quality at each step; 
the two extremes are opposed in all three contrary qualities. Chalcidius' translation 
and commentary (in the manuscripts that have come to us) are incomplete. The 
translation breaks off at 53C, immediately before the analysis of the mathematical 
forms which constitute the elements and of the sequence of the elements relative to 
each other. The Commentary is also incomplete: the list of topics enumerated is 
not completed; nonetheless the treatment of the elements is complete and it runs 
through all three forms of analysis. The theory of the elements as mathematical 


Finally, the sequence of the elements from fire to earth is 
shown to involve an order of lightness and heaviness.^" 

The resolution of the second question, that of the place of 
the elements in the creation of the universe, according to 
William, is also worked out in opposition to a widely held 
position. Almost all philosophers say that the elements did 
not occupy fixed places in the first creation but were mixed 
in one mass and therefore moved up or down together. This 
position is derived from Ovid and Hesiod, but its proponents 
add a reason for it (that the Creator might show how great 
the confusion of things would be if they were not ordered by 
his power and wisdom and goodness) , and they add the 
authority of Plato who said that God reduced the elements 
from an unordered scattering to order.^^ William argues that 
the position is false, the argument invalid, and the authority 
incorrectly interpreted. The position is false because elements 
must be bodies, or spirits, or properties of bodies or of spirits; 
he shows that they cannot be any of these except bodies, and 
bodies occupy place. The argument is invalid because before 
the creation there were neither angels nor men to show how 
great the confusion of things would be. The quotation from 

forms is expounded and elaborated. The theory of the three quahties constituting 
the elements is developed (Platonis Timaeus, Interprete Chalcidio cum eiusdem 
Commentaria, XXI-XXII, ed. J. Wrobel, Leipzig, 1876, pp. 87-8) as commentary 
on Plato's argument that the elements are required to explain how the world is 
sensible (Timaeus 31C; it makes use, however, of distinctions from 55C-56C) , since 
what comes into being must be material and capable of being seen and touched. 
The treatment of the two qualities (hot or cold and dry or moist) constituting the 
elements is part of the analysis of matter (silva or hyle) , which is without qualities, 
and the transmutation of the elements (ibid., CCCXVII-CCCXXIX, pp. 341 fE.) . 
The excerpt on the four elements which appears in Cassiodorus' Institutiones is 
given without derivation (Mynor's note [p. 167] is " Quod unde dictum sit pudet 
me nescire ") . The analysis set forth in the interpolated passage is clearly derived 
from Chalcidius' Commentary on the Timaeus. 

^° William's analysis combines the three modes of treatment of the elements that 
were observed in Nemesius — (1) two qualities, heavy and light, assigned to the 
elements in pairs of elements, (2) four qualties, hot, cold, dry, wet, assigned two 
to each element, and (3) six qualities, obtuse, acute, mobile, immobile, subtle, 
coropreal, assigned three to each element. 

"^ Timaeus, 53B. 


Plato is incorrectly interpreted because Plato did not hold that 
the elements were actually in an unordered scattering, but that 
they could be, and in the first creation they were where they 
now are, but they were thicker, in so far as they were mingled, 
and obscurer in as much as there were no sun, moon, or stars 
to light them. The stars, thus, were made from all four ele- 
ments, the upper elements which are \Tisible and mobile, and 
the lower elements which are obscure and immobile. The stars, 
which are visible, shining, and mobile, have their qualities from 
the interplay of the properties of the elements, and in that 
interplay each of the four qualities is found in the visible forms 
in which the elements appear. According to Constantine each 
of the elements has two qualities, one proper to itself, the other 
from another element; fire hot of itself, dry from earth; air 
damp of itself, hot from fire; water cold of itself, damp from air; 
earth dry of itself, cold from water. 

The stars, being fiery in nature, began to move immediately 
on their generation and to heat adjacent air and, through it as 
intermediary, the further removed water. The various genera 
of animals were created from heated water, birds in the air, 
fish in the water, and other animals and man on the earth. 
The theory of elements gives organization to William's encyclo- 
paedic examination of the world and of its parts. At the 
beginning of Book II, he describes Book I as a summary 
exposition, within the limits of his small powers, " concerning 
the particles of things which are and are not seen and con- 
cerning elements which some teachers present as visible things," 
and he proposes now to take up in turn each element and its 
embellishment (ornatus, i. e., kosmos) . 

The opening chapter of Book II is on ether and its ornatus. 
Fire is the space above the moon, and it is also called ether; 
its ornatus is whatever is seen above the moon, that is, the 
stars, both fixed and wandering. The book presents information 
concerning the planets and astronomical phenomena. The 
opening chapter of Book III is on air which extends from the 
moon to the earth and is damper and thicker nearer to earth. 


The early chapters take up the zones of the air and the effect 
of the heat of the sun raising water to form clouds, and the 
transition from air to water is made in Chapter 14 on the 
tides of the Ocean. The book presents information concerning 
meteorological phenomena, snow, thunder, lightning, tides, 
fountains, and wells. Book IV is devoted to the remaining 
element, and begins with a chapter on earth and the world. 
After sketching some geogi-aphical questions — the qualities of 
earth, its inhabitants, the continents Asia, Africa, and Europe, 
a translation is made to man in Chapter 7. Since the creation 
of the first man, male and female, from dust was treated in 
Book I, William undertakes now to treat " of the everyday 
creation, formation, birth, ages, members of man, and of the 
functions and uses of his members." He begins with the sperm, 
traces man from the womb through infancy, examines his 
organs, digestion, sleep, senses, soul, virtues, and youth and 
old age largely in terms of the fundamental contraries. The 
book ends with five chapters on teaching and the order of 

William argues that man is by nature hot and cold and is 
tempered by the interplay of the four qualities, so that dif- 
ferences of virtue and temperament result from the intensifica- 
tion and remission of the contrary qualities. ^^ He follows 
Constantine's localization of the functions of the mind in the 
three cells of the brain. The anterior cell is called fantastic, 
that is, visual or imaginative, because it is the seat of the 
power of seeing and understanding; it is hot and dry to attract 
the forms of things and colors. The middle cell is called 
logistic, that is rational, because it is the seat of the power of 
distinguishing; it is hot and moist that it may conform to the 
properties of things and distinguish better. The posterior cell 
is called memorial, because it is the seat of the power of 
retaining; it is cold and dry in order to retain better. This 
localization was determined, according to William, by observa- 
tion of wounds of the head in which it was noted that injuries 

" De PhUosophia Mundi, IV, 20; PL 172, 93B-C. 


to one of the cells resulted in the loss of the function associated 
with it without affecting the other functions.^^ Sensation is a 
function of the body which man shares with other animals; 
distinguishing and understanding are functions of the soul, 
peculiar to man. There are three powers of the soul: under- 
standing {intelligentia) by which man perceives incorporeal 
things with the certain reason why they are thus; reason by 
which man perceives in what respects things agree with other 
things and in what they differ; memory by which man firmly 
retains what was known before. 

The doctrine of elements provided William of Conches with 
more than the simple parts from which to construct things, 
organisms, and a universe; they were also principles for the 
examination of the relation of corporeal things perceived in 
sense experience to the incorporeal structures conceived by the 
mind and used to explain the nature of corporeal things. The 
processes of composition and resolution which related elements 
as qualitatively and quantitatively simple parts to composite 
wholes also crossed the line which separates seen from unseen 
and corporeal from incorporeal. William's analyses therefore 
have philosophic interest (since he explores the problems 
involved in these relations) and empirical content (since the 
structures w^hich he abstracts are found embodied in things 
which are and are known) . The elements serve similar func- 
tions in other twelfth century cosmologies, scientific treatises, 
and encyclopaedias, and they provide common principles for 
the work of William of Conches and the work of men like 
Thierry of Chartres and Peter Abailard who influenced him and 
of William of St. Thierry who criticized him. 

Thierry of Chartres was Chancellor of the School of Chartres 
from about 1141 to about 1150. John of Salisbury calls him 
" the most zealous investigator of the arts," and another disciple 
says he was " preeminent among the philosophers of all Europe " 
{totius Europae philosophorum precipuus) . Bernard Sylvestris 
dedicated the De Universitate Mundi to him, and two of his 

" Ibid., IV, 24, PL 172, 95. 


pupils, Herman the Dalmatian (or Carinthian) and Robert of 
Chester (or Katene) , in the dedication of their translation of 
Ptolemy's Planisphere to him, address him as the first anchor 
and sovereign of the second philosophy (the mathematical arts 
of the quadrivium) , the immovable support of studies tossed 
by every tempest, in whom relives the soul of Plato descended 
from the heavens for the blessing of mortals, the true father 
of Latin Studies. 

Thierry says that his method of commenting on the first 
part of Genesis is by distinctions which are literal and according 
to physics. There are four causes of earthly subsistences: an 
efiicient cause, God the Father; a formal cause, the wisdom 
of God, or the Son; a final cause, the benignity of God, or the 
Holy Spirit; and a material cause, the four elements. To say 
In the beginning God created the heaven and the earth is to 
say that he created matter in the first moment of time. Once 
created, heaven could not remain immobile: in the revolution 
which constituted the first day, the highest element, fire, illumi- 
nated the lower element air. In the revolution of the second 
day, fire through the medium of air, heated the lower element 
water, vaporizing it into minute drops which can be suspended 
in air; the firmament was thus placed in the midst of the water, 
air being suspended between a layer of vaporized and a layer 
of condensed water. Since the condensed water below was 
diminished in that process, dry land appeared in the third 
revolution; the action of the heat of the superior air and the 
dampness of the earth produced herbs and trees. In the fourth 
day, the bodies of the stars were created by contraction, caused 
by heat, of the waters above the firmament. Heat was increased 
in the revolution of the fifth day by the motion of the stars, 
became vital, and produced fish in the waters and birds in 
the air. On the sixth day, the vital heat proceeded to earth, 
and the animals of the earth were created, including man made 
in the image and likeness of God. After the sixth day no new 
mode of creation was used, but new creatures were produced 
from the seminal causes inserted in the elements in those first 


stages of creation. Among the elements, fire is an active and 
efficient cause, earth a passive and material cause, while air 
and water are both active and passive, instruments and vehicles 
of causation. Among the seminal causes which determine pro- 
cesses and developments after the formation of the world are 
gravity and lightness which bring the elements into inter- 
relations in local motion.^* 

Thierry proceeds from the creation of the world to an exposi- 
tion according to the analysis of physicists (secunduvi rationem 
physicoruTn) of the motions of heaven and earth as determined 
by the properties and relations of elements. He argues that 
when Moses said that the earth was without form and void, 
and when he used other similar expressions, he was referring 
to the " informity," or rather the " uniformity," of the four 
elements. This " confusion " of elements, which the ancient 
philosophers called matter (hyle) or chaos, is what Moses 
signified by " heaven and earth." 

The informity of those elements then consisted in the fact that 
each of them was almost of the same sort as the others and that the 
differences between them were minimum or almost nothing. There- 
fore that difference was held by the philosophers to be nothing, and 
they called the elements thus confused one unformed matter. Plato, 
however, considering the minimum which separates the elements, 
and knowing that the difference, although minimum, is present in 
the confusion, concluded consequently that matter, that is, the con- 
fusion of elements, underlies the four elements themselves, not in 
the sense that that confusion preceded the four elements in time 
or creation, but in the sense that confusion naturally precedes 
differentiation, as sound precedes word, or genus precedes species.^^ 

When Moses went on to say that the spirit of the Lord moved 
upon the waters (Gen. 1: 2) , he distinguished the operative 
cause from the material cause. The power of the artificer, 
whom he calls the spirit of the Lord, excels and dominates 

'^^ Thierry of Chartres, De Sex Dierum Operibus, ed. M. Haureau, in Notices et 
Extraits des Manuscrits de la Bibliotheque Rationale, Paris, 1888, vol. XXII, Part 2, 
pp. 172-7. 

" Ihid., p. 179. 


matter in order to inform and order it, in a relation similar 
to that which Plato, Hermes Trismegistus, and Virgil found 
between God or spirit or world-soul and matter or hyle or 
world. Having presented the two primordial causes of the 
creation, matter and operative power (inateria et virtus opera- 
trix) , Moses went on to demonstrate how and in what order 
the spirit of the Lord operated on matter, but Thierry pauses 
to examine the knowledge that man can have of the Creator 
from creation. He distinguishes four kinds of demonstrations 
{genera rationum) which lead from things to their creative 
cause — arithmetical, musical, geometrical, and astronomical 
proofs, but our manuscripts break off after an arithmetical 
analysis of unity and equality and their bearing on the existence 
of things. 

Peter Abailard (1079-1142) developed a theory concerning 
the nature of universals in his treatises on logic and dialectic, 
and he drew conclusions concerning the nature of the artificer 
and the elements of the world in the treatises in which he used 
rhetoric or dialectic to interpret statements of Scripture and 
facts of history or to interpret doctrines of prophets and phi- 
losophers. He opens his Commejitary on the Epistle of S. Paul 
to the Romans by observing that all Sacred Scripture has the 
objective of teaching and moving like a rhetorical oration,^® and 
that the two Testaments are therefore divided into three parts: 
the law, to teach what should be done and avoided; the 
Prophets or the Epistles, to dissuade from evils or persuade 
to goods; and the histories, to provide examples. He interprets 
Paul's statement that the invisible things of God are understood 
by the things that are made, to mean that knowledge of the 
universe as a vast fabrication or as effects may lead to knowl- 
edge of its artificer as power, wisdom, and goodness. In his 
interpretation of the passage from Paul, Abailard finds a similar 
treatment of creation in Plato and Cicero; he argues that the 
perception of the power, wisdom, and goodness of the Creator 

^* Comvientariorum super S. Pauli ad Romanos Libri Quinque, Prologus 
PL 178, 783B. 


is the discovery of the marks of the Trinity; and he analogizes 
that knowledge to the perception, when a bronze statue is set 
before the eyes, that the bronze and the bronze statue are the 
same thing essentially and numerically and yet are diverse in 
their properties.^^ His rhetorical method is apparent in his 
Expositio in Hexaemeroji, in which he undertakes a threefold 
interpretation — historical, moral, and mystic — " of the abyss 
of profundity " of Genesis. As first step in the historical inter- 
pretation, one must take into account the fact that Moses 
addressed a carnal and uneducated people and sought to raise 
them to a consideration of divine things. Moses therefore began 
his exposition with the creation and disposition of the world, 
for " God, who is invisible and incomprehensible in himself, 
conveyed to us the first knowledge of himself from the mag- 
nitude of his works, since all human knowledge arises from the 
senses." ^^ To begin with creation is to follow the natural order 
in addressing a carnal people, committed to the corporeal 
senses, and not far advanced in spiritual understanding. 

Christian philosophers had learned from Platonic and Stoic 
philosophers to treat problems of wholes and parts by distin- 
guishing the artificer or the efficient principle causing the unity 
and the material principles compounded into wholes. Abailard's 
exposition of the creation marks off the stages of formation by 
means of the four elements and finds in the structure and 
embellishments of the world evidence for the unity and trinity 
of the Creator. The opening statement of Genesis, " In the 
beginning God created the heaven and the earth," means that 
the four elements were created first, " heaven " signifying the 
light elements, fire and air, " earth " signifjang the heavy 

" Ibid., I, PL 178, 802D-5A. The doctrine of the Trmity is developed in detail 
in Abailard's Theologia Christiana, I, 2 and £f. (PL 178, 1124 fl.) . Abailard says 
at the beginning of the second book of the Theologia Christiana that he has 
assembled in the previous book quotations from the prophets and the philosophers 
concerning the Trinity; in the second book he examines the relation between the 
philosophical disciplines and religion. (Ibid., 1165 ff.) Cf. Introdiictio ad Theo- 
logiam, I, 8-10 and 11. (Ibid., 989C-95B, and 1035 ff.) 

^* Expositio in Hexaemeron, PL 178, 733A. 


elements, water and earth; and they were created " in the 
beginning," because the first confusion or congeries of elements 
constituted the matter for the formation of other bodies. Fire 
and earth marked off the limits within which the other elements 
provided connecting bonds and limiting differentiations, and 
the whole constitution of the world consisted in the four 
elments/® The Trinity is expressed in the beginning of Genesis, 
and is developed more fully in the creation of man in the image 
of God on the sixth day, for it is in power, wisdom, and love 
that the likeness of the human soul to God is apparent.^" The 
moral interpretation is based on the same distinctions as the 
historical interpretation. Much as the confused congeries of 
elements is later ordered, so too man, composed of soul and 
body, but in the beginning unformed and incomposite in moral 
character, is transformed from the initial confusion (symbolized 
by the fluid element water) first by the light of faith, then by 
hope, and finally by charity.®^ The mystical interpretation is 
an allegory of cultural history proceeding through six ages, in 
which the first age of primitive culture without law or art is 
symbolized by the confused congeries of elements, and sub- 
sequent ages follow like analogies to the days of creation, until 
in the sixth age the future is extrapolated from the history of 
the past.®^ 

It is apparent that the problem of elements is a problem of 
parts and wholes, not in the simple sense that a whole is 
compounded of parts, but in the more complex sense that a 
whole persists through changes of parts and that a whole 
is identifiable although characterized by different properties. 
When changing wholes or inclusive wholes are under considera- 
tion, the problem of part and whole becomes a problem of same 
and other. Abailard distinguishes three senses of same and 
other {idem et diversum) : as likeness, as essential sameness 
but not same in number, and as sameness in property,^^ for the 

" Ibid., 733C-7B. " Ibid., 770C-1D. 

•° Ibid., 739B, 760B-1D. " Ibid., 771D-3A. 

" Introductio ad Theologiam, 11, 12, PL 178, 1065. 


examination of data in a universe, which is a whole charac- 
terized by properties of dynamism, wisdom, and goodness, 
requires an analytic device by which to identify the wholes 
which remain the same essentially although characterized by 
different properties. One analogy runs through his works, the 
comparison of the distinction of Persons in the unity of God 
to the distinction of properties in a physical object: in his 
Covimentary on S. Paul he uses the analogy of a bronze statue; 
in his Introductio ad Theologiam, a bronze seal; in his Theo- 
logia Christiana, a wax image. In the later two works he adds 
a third analogy, the characterization of man, to these two.^^ 

Bronze is the " matter " on which an artificer works to form 
a seal; the seal, thus " mattered " (materiatum) and formed 
(formatum) , is " scalable " (sigillabile) , that is, adapted to 
impress an image on a soft substance like wax; when it is 
actually used, it is " sealing " (sigillans) , that is, its act is the 
transfer of the form to another matter. When the wax is being 
sealed, the single bronze substance has three diverse predi- 
cates: bronze, scalable, and sealing; bronze is matter, scalable 
and sealings are " mattered." Abailard argues that the relation 
of the persons of the Trinity is similar: wisdom is a kind of 
power, as the bronze seal is a kind of bronze; benignity reforms 
the image of God in us that we may conform to the image of 
the Son of God, as sealing comes to be from bronze and the 
scalable. In the same way the genus, animal, is the matter of 
the species, man, for man is a kind of animal as the bronze 
seal is a kind of bronze.®^ " Matter " and " mattered " in a 
given image are the same, essentially, yet the matter precedes 
the mattered; and a like precedence is found in each of the 
related pairs of terms — constituent and constituted, cause and 
effect, generating and generated.*^® The distinction and the 
terms in which it is expressed are found in the eleventh century 

** Expositio in Epistolam ad Romanos, PL 178, 804B-5A; Introductio ad Theo- 
logiam, II, 13-14, PL 178, 1068C-70B, 1073A-5A; Theologia Christiana, III, IV, 
PL 178, 1248B-9A, 1288A-90C. 

«^ Introductio ad Theologiam, II, 13-14, 1068C-70B, 1073A-5A. 

*» Theologia Christiana, IV, 1288A-90C. 


translations of Salerno. Alfanus, Archbishop of Salerno, dis- 
tinguished materia from matenatum in his translation of 
Nemesius. After pointing out that some philosophers held that 
the soul is corporeal, while others held it was incorporeal, he 
gives a Neoplatonic refutation of the corporeity of the soul: 
the body needs a principle to hold it together; the principle is 
either incorporeal or corporeal; if it is corporeal, it in turn 
needs a principle to bind its constituents together. If the Stoics 
say that the principle is a motion, one asks what is the power 
or virtue (virtus) which causes this motion. If it is matter, 
the previous arguments are repeated; if it is not matter, it is 
" mattered " (materiatiim) , and the mattered will be different 
from matter, for " what participates in matter is called 
mattered." But if it is not matter, it is " immattered " and 
all body is " mattered." "^ The Stoic distinction of an operative 
and a material cause may, however, be joined to the distinction 
between " matter " and " mattered " without becoming involved 
in the Stoic materialism: " matter " is potentiality and the 
" mattered " is potentiality restricted by a form which confers 
a specific function or potentiality and from which a specific act 
follows, but the distinction does not entail the consequence that 
all things are corporeal. 

William of St. Thierry (1085-1148) made elaborate use of 
the doctrine of elements, but was critical of the use of physical 
arguments to specify properties of God or the Trinity inferred 
from creation. He was the adversary of Peter Abailard and 
William of Conches and called their errors to the attention of 
St. Bernard. In his Disputation against Peter Abailard, his 
criticism of Abailard is that " he loves to think about all things 

'■^ Nemesii, Premnon Physicon, pp. 25-26. The distinction of materia and materia- 
tum used by Abailard, of elementum and dementatum used by William of Conches, 
and of natura naturans and natura naturata, which came into use about the same 
time or a little later, have common origins in translations from Greek or from 
languages which preserve verbal forms of materia, elementum, or natura from which 
passive (and sometimes also active) particles can be formed and recognized. In the 
other languages the relation between matter, mattering, and mattered is lost in 
the circumlocutions of translation of a work which examines that relation and is 
inconspicuous in original inquiries into like problems employing the same data. 


and wishes to dispute about all things, about divine things 
and about secular things equally." '^^ He criticizes Abailard's 
use of power, wisdom, and benignity to differentiate the persons 
of the Trinity. In particular, he criticizes his use of the analogy 
of the bronze seal and the distinction between materia and 
materiatum to explain the relation of the Father and the Son.**^ 
He expresses the wish that Abailard would read the Evangel 
of God with the same simplicity as he reads Plato and that 
he would imitate his beloved Plato, who proceeds cautiously 
and prudently from the creation to the incomprehensibilities 
of the Creator.^" He criticizes William of Conches for adding 
a new philosophy to the theology of Abailard, confirming and 
multiplying whatever Abailard said and adding more that he 
did not say.'^ He says that William of Conches describes the 
creation of the first man philosophically, or rather physically, 
and holds that his body was not made by God, but by nature, 
and that his soul was given to him by God, after his body had 
been made by spirits, whom he calls demons, and by the stars. 
William of Conches seems to him to follow the opinion of 
certain stupid philosophers who say that nothing exists except 
bodies and corporeal things, that God in the world is nothing 
else than the concourse of elements and the harmony or tem- 
perature of nature, and that he is himself a soul in body." 

** Guillelmus Abbas S. Theodorici, Disputatio adversus Petrum Abaelardum ad 
Gaufridum Carnotensem et Bernardum, 1, PL 180, 250A. 

"* Ibid., 3, PL 180, 254C-7C. The analogy is also criticized by St. Bernard. 

'" Ibid., 7, PL 180, 270C-D. 

'^^ De Erroribus Guillelmi de Conchis ad Sanctum Bernardum, PL 180, 333 A. 

" Ibid., PL 180, 339A-40A. Walter of Saint Victor says that " William of Conches 
held that all things are made from the concourse of atoms, that is, of the most 
minute bodies," and that Peter of Poitiers used atoms to prove that the flesh of 
Christ was not in Abraham or Adam. (Contra Quatuor Labyrinthos Franciae, IV, 
25, ed. P. Glorieux, Archives d'Histoire Doctrinale et Litteraire du Moyen Age, XIX 
(1953) , 289.) In the Dragmaticon which is in dialogue form, William of Conches 
replies to his interlocutor's question about Epicureanism, denying that he is an 
Epicurean, but adding that there is no philosophic sect so false that it has no truth 
mixed with its falsehood; the Epicureans are correct in saying that the world is 
composed of atoms, wTong in supposing that the atoms were without beginning and 
that the four bodies of the world were composed by the bombardment of large 


William of St. Thierry is not opposed to the use of the 
doctrine of elements. His treatise On the Nature of the Body 
and the Soul treats its subject physically: Book I is entitled 
" The Physics of the Human Body " and Book II " The Physics 
of the Soul." All animal bodies are formed of earth, that is they 
are composites of the four elements; for the earth, from which 
they are formed, and what they consist of must be distinguished. 
William follows Constantine's analysis, defining each element 
by one quality to which a second quality is added from an 
element adjacent to it, and he quotes the argument of Hippo- 
crates that the animal body would feel no pain if it were 
composed of one element. The elements are transformed into 
one another; they form the humors and nourish them; and the 
" children of the elements " follow the ways of their fathers, 
for the elements operate in the greater world as the four 
elements operate in the lesser world or microcosm, man.^^ 
William differentiates three virtues in the regimen of the body: 
the natural virtue localized in the liver, the spiritual virtue in 
the heart, and the animal virtue in the brain. His analysis of 
these three virtues follows Constantine's position in detail, and 
he shares his conclusions also on the localization of the functions 
of imagination, reason, and memory in the three cellules of the 
brain.'* The five senses correspond to the four humours: sight 
is fiery; hearing, aerial; odor, smoky; taste, watery; and touch, 
earthly. William characterizes the method of his treatment of 
the exterior man as one in which he has considered not only 
the exterior man but also certain things within human bodies 
which are not subject wholly to the senses of man but are 
discerned by philosophers and physicists through reason and 

particles. Peter of Poitiers uses the word " atom " in his argument that the flesh 
of Christ was not in Abraham, because there were not in Abraham as many atoms 
as there have been men descended from him by concupiscence. (Sententiae, IV, 
7, 11, PL 211, 1164C). 

"" De Natura Corporis et Animae, I, PL 180, 695-8C. 

'* Ibid., I, 700A-D and 702A-C. 

" Ibid., I, 707B-708A. 


In his treatment of the soul, William of St. Thierry distin- 
guishes the definition of the philosophers of this world, who 
say that the soul is a simple substance, a natural species, dis- 
tinct from the matter of its body, and possessed of the power 
of life, from the definition of the ecclesiastical doctors, who 
say that the soul is a proper substance created by God, 
vivifying, rational, immortal, but convertible toward good and 
evil. The soul vivifies the body in three manners — for the 
purpose of living only, for the purpose of living well, and to 
provide opportunity for the succession of future goods.^^ God 
made man in his image and likeness, as a sculptor makes a 
statue, combining in him virtues of inanimate things, plants, 
animals, and angels. Moreover, since man is made in the image 
of God, his soul is related to his body as God is related to the 
world: it is everywhere and everywhere whole, whole in natural, 
in spiritual, and in animal operations; ^^ and the image of the 
Trinity is found in man's body and in his soul, for the soul, 
which is one, is also memory, counsel, and will, and the body, 
which is one, is also measurable, numerable, and weighable.'* 

The works translated from Arabic and Greek, the epitomes 
of the translators, and the treatises of Western philosophers 
learned in the new sciences introduced further modifications in 
the doctrine of elements. Avicebron (whose Fons Vitae, in 
Latin translation, uses both elementatum and materiatura) , 
Gundissalinus, Herman of Carinthia, and Adelard of Bath 
discuss the problems of determining simple parts and they use 
them in the classification and analysis of a wide range of data. 
The theoretic aspects of the problem become clear again in 
the exploration of the consequences of alternative approaches 
to elements; but the materials on which the schematisms are 
employed, once the new materials treated in the translations 
have become familiar, tend to fall into reiterative repetitions. 
There is some indication that the distinctions based on elements 
stimulated new observation in some fields, but the evidence is 
ambiguous because the task of assimilating the new materials 

'* Ihid., II, 707-9. " Ihid., I, 702C. " Ibid., II, 722A-23A. 


of the sciences was so great that what seems new is often the 
interpretation of an old text newly acquired. It is ambiguous 
also because the focus of inquiry was turning from the elements 
or natures of things to the principles of motions or functions. 
In that transition, the physical sciences of Aristotle are them- 
selves interpreted in terms of elements rather than of principles. 
Gundissalinus distinguishes natural bodies into simple and com- 
posite and then divides natural science into eight large parts: 
the investigation (1) of what is common to natural bodies, 
simple and composite, as in Aristotle's Physics; (2) of simple 
bodies in heaven and earth, as in the De Caelo et Mundo; 
(3) of the mixture and corruption of natural bodies and the 
generation and corruption of elements, as in the De Generatione 
et Corruptione; (4) of the principles of the accidents and 
passions of elements and composites, as in the De hnpres- 
sionihus Siiperioiibus; (5) of bodies compounded of elements 
and of bodies of similar or of dissimilar parts, as in the De 
hnpressionibus Supeiiorum; (6) of bodies compounded of simi- 
lar parts which are not parts of a body compounded of diverse 
parts, as in the De Mineris; (7) of what is common to the 
species of vegetables and what is proper to each of them, as in 
the De Vegetabilibus; and (8) of what is common to the 
species of animals and what is proper to each of them, as in 
the De Ajiimalibus, the De Anima, and the books included up 
to the De NaturalibusJ^ It is worth observing that the fact 
that the title by which Aristotle's De Caelo was known during 
the Middle Ages was De Caelo et Mundo suggested analogies 
to the opening lines of Genesis concerning the creation of 
the heaven (caelum) and the earth (terra) . Aristotle con- 
ceived the history of natural philosophy to be an evolution 
from elements as principles used by early philosophers to his 
own methodical use of causes as principles. This history is 
repeated in the transition from the eleventh to the twelfth 
century, but ironically Aristotle's natural philosophy enters 
into that transition as a philosophy of elements. 

" Domingo Gundisalvo, De Scientiis, ed. P. Manuel Alonso Alonso (Madrid, 1954), 
pp. 120-6. 


After the first systematic commentaries on the newly trans- 
lated scientific writings of Aristotle had appeared in the latter 
half of the thirteenth century, the problem of elements began 
to emerge again, and all the opposed conceptions were formu- 
lated in terminology borrowed from the Aristotelian writings. 
The discussion of least parts and simples in terms of kinds of 
motion led into theories of minima and viaxima, and of simples 
and composites; the discussion of numbers and mathematical 
bodies as least parts and organizing principles of composites 
and organisms went from Platonic beginnings to mathematical 
elaborations; the Stoic elements and their efficient principles 
and the arbitrary models which used methods familiar to the 
skeptics were known in the Renaissance; the Epicurean atoms 
moving in a void were set forth by Gassendi in the seventeenth 
century. With the progress of medicine, astronomy, and me- 
chanics in the Renaissance attention concentrated on the ele- 
ments as principles again, and Boyle was able to assemble in 
the dialogue of the Sceptical Chymist a Corpuscularian, a 
Peripatetic, and a Spagyrist or modern Chemist, to discuss a 
large variety of theories of elements (including van Helmot's 
theory that all things are water fructified by seeds) . 

The transition from the Renaissance to the seventeenth cen- 
tury is similar in what happened to the treatment of elements 
to the transition from the twelfth to the thirteenth century: 
more was known and the data were richer, but the opposed 
theories followed a similar pattern, and the discussion of 
elements again yielded to the discussion of laws and principles 
of motion — the issue in the seventeenth century was not pri- 
marily between Descartes' vortices, Leibniz' monads, and 
Newton's atoms but between their conceptions of mass and 
motion and their elaborations and applications of laws of 
motion. The Newtonian principles were used to organize a 
system of the world and a system of physical science in the 
eighteenth and early nineteenth centuries, but in the twentieth 
century our attention has turned again to elements and par- 
ticles and to more subtle and better grounded forms of anti- 


nomles and paradoxes of matter and energy, matter and 
antimatter, machine and organism, simple and composite, 
motion and rest. We have nothing to learn concerning the 
substance of the twentieth century problem from what was 
known about elements in the twelfth century or in the Renais- 
sance, but the theoretic characteristics and consequences of the 
opposed positions were thoroughly elaborated in the earlier 
periods in statements which have echoes in contemporary 
problems, and the ironical turn of history which transformed 
rather than solved the problems of the earlier periods is prepara- 
tion which might be useful for like transformations in the 
problems faced today. 

Richard McKeon 

University of Chicago, 

Chicago, Illinois. 



THE philosophical problem with which we are here con- 
cerned may briefly be formulated thus: Whether in 
one and the same individual, remaining essentially 
one, there are many substantial forms or only one. 

A concrete thing of matter and form, the crwoXov, is one 
essence and one nature, but it possesses several perfections and 
activities. It is, in fact, a body, corpus, and it is such and such 
a body, a stone or a tree or a horse. A tree is a body, but it is a 
determinate body, quite different from a stone or a horse; 
besides being a corporeal thing, it is also a living thing. Now, 
as Boethius has it, it is the form that confers on matter the 
actual being: ovme esse ex jorma est.^ A substantial form 
imparts an essential perfection, and an accidental form a rela- 
tive or qualified perfection. Assuming that substantial form is 
the determining principle of a composite being, the difficulty 
arises of how to account for the various essential perfections of 
an individual. Does one substantial form give one perfection 
only, so that we have to look for as many substantial forms 
as there are perfections and activities; or does a single form 
suffice to determine the thing in its own nature, thus endowing 
it with all its perfections and activities. f^ A stone is a corporeal 
thing as much as a piece of iron, and man is as much a living 
being as a tree or a horse; but as a horse possesses some per- 
fections which a tree has not, for example, sensitive life, so man, 
besides having nutritive and sense powers, is also endowed with 
an intellective soul. 

The whole point of the discussion, therefore, comes to this: 
Is a man — let us say rnan, for it was in connection with the 
human soul that the vexed question was first stated — a living 

^Boethius, De trinitate, c. 2 (The Theological Tractates, ed. H. F. Stewart and 
E. K. Rand. London, 1926, p. 8; PL 64, 1250 B). 



being by virtue of a distinct nutritive soul, an animal through 
a distinct sensitive soul, and finally rational by an intellective 
soul; or does he owe to one single substantial form, the intel- 
lective soul, not only his being a man, or rational, but also 
his being an animal, a living thing, and a corporal substance? 
If with Aristotle one holds (i) that prime matter is a com- 
pletely passive potency without any actuality of its own what- 
ever; (ii) that privation is the disappearance of the previous 
form, and, consequently, has no part at all in the composition of 
the substance; and (iii) that substantial form is absolutely the 
first determining principle, which makes the thing to be what it 
is, the only root of actuality, unity and perfection of the thing; 
then, consistent with his stated principles, the conclusion forced 
upon us is that in one and the same individual there can 
be but one single substantial form: other forms, that come 
after the first, are simply accidental and not substantial forms. 
Since the thing is already constituted in its own being, they 
cannot give substantial being, but exclusively accidental or 
qualified being; they do not confer upon the concrete thing its 
own definite and specific kind of being, e. g., man, but only a 
qualified or relative state of being, for example, of being fair 
or dark, big or small, and the like. 

On the other hand, if one contends (i) that primary matter is 
not absolutely passive and potential, but possesses in itself 
some actuality, no matter how incomplete or imperfect it may 
be: an incohatio farmae, or any active power; (ii) that priva- 
tion does not mean the complete disappearance of the previous 
form, so that matter is not stripped of all precedent forais in the 
process of becoming; or (iii) that substantial form either meets 
with some actuality in prime matter or does not determine the 
composite wholly and entirely, but only partially; from all this 
it will necessarily follow that there are in one and the same 
individual plurality of forms. 

Briefly, the utimate philosophical issue resolves itself as 

(a) Do the various substantial forms, as imparting different 


essential perfections and virtues, remain actually and simul- 
taneously in a composite, which is essentially one, whether in 
juxtaposition, in co-ordination, disposed hierarchically, or in 
any other way implying actual persistence? 

(b) Or must all previous forms pass away with the coming 
in of the more perfect substantial form, in such a wise that 
they are in the crvvoXov only virtually as implied, synthetized, 
and comprised in the higher form, each essential perfection 
being gathered up into the unity of a single form, which alone 
gives to the individual its ultimate and specific determination? 

The problem may be, and in fact had been, approached from 
two angles: the psychological and the metaphysical. Regarded 
psychologically, the problem was restricted to living beings, 
especially to man. Considered metaphysically, it was raised 
from as many aspects as there are things composed of matter 
and form, whether living or lifeless bodies (mixta) , or simply 
from simple logical relations, such as genus and species viewed 
as matter and form, and their mutual predication. 

The question was not fully elaborated all at once, but slowly 
and by degrees. The starting-point was whether the nutritive, 
the sensitive and the rational principles in man are one soul, 
one substance, or three distinct souls or substances. 

To avoid confusion, it is important to bear in mind that the 
problem of the unity or plurality of the human soul is a dif- 
ferent question from that of the unity or plurality of substan- 
tial form, whether in man or in any composite. Naturally 
enough, if there is plurality of souls, a jortiori there must be 
plurality of substances or forms. Substance, philosophically 
speaking, is equivalent to form. But the latter question is a 
more complex one; that is, assuming that there is in man one 
soul only, and even that the soul is the form of the body so as 
to constitute one essence, it still remains undecided whether the 
determining principle is one only or whether there are required 
as many principles, or forms, as there are perfections and 

There is a general consensus among scholars that it was St. 


Thomas Aquinas who gave to the problem of the unity of sub- 
stantial form its full significance. It is equally agreed that the 
question cannot have originated with him, since it was current 
in the schools as early as the first decades of the thirteenth 
century, though, it is true, it then turned on a single instance, 
namely whether the nutritive, the sensitive and the rational are 
in man one soul, one substance, or three distinct souls or sub- 
stances. (We have already observed that to say substance is 
the same as saying form) . Further, it should be admitted that 
many of the masters, who held that the three principles are in 
man not only one soul, but also one substance, did not fully 
grasp all its implications. Albert the Great was, perhaps, the 
first to see the general and wider principles involved; yet he 
too neither stressed the point nor deduced all the logical con- 
clusions. With Aquinas, on the contrary, the debate entered a 
new phase. Refusing to regard it merely as a psychological 
theory, he considered it as fundamentally metaphysical, based 
on the principle of contradiction; he thus gave it stability, uni- 
versality and full value. Since it is essentially metaphysical, it 
concerns the total range of matter-form composites, without 
exception, holding good not only in psychology, but also in 
logic, in the philosophy of nature and by inference in theology 
as well. It is precisely here that Aquinas' original contribution 
to the problem lies. Still, granted that St. Thomas' predecessors 
and contemporaries, chiefly because of their somewhat imper- 
fect grasping of metaphysical principles, did not clearly per- 
ceive all the issues involved, the fact remains that the problem 
itself, in its psychological aspect, had already been discussed 
and propounded in the schools of Paris and Oxford for at 
least half a century before St. Thomas' time. And if in reality 
there were two contrary opinions, one must have been in sup- 
port of plurality of substances, or forms, and the other in sup- 
port of the unity of substance, or form. There is no alternative 

The aim of this paper is not to discuss in detail the philo- 
sophical issues of the problem, but to attempt to trace its 


origins and to consider its impact on the early masters in Paris 
and Oxford. 

* * 

The origin of the problem under discussion is obscure. On 
the assumption that it could arise only on the basis of Aristo- 
telian principles, it would serve no purpose to search for its 
beginning before the rediscovery of the libri naturales and the 
Metaphysics. The twelfth-century thinkers, failing to under- 
stand the problem of change and becoming, could not perceive 
the value of the question of forms. They posited primary mat- 
ter, not as the potential principle of which things are essentially 
constituted, but rather as a chaotic mass of the four elements, 
as something actual, and therefore already informed.- Simi- 
larly, they had no clear notion of the distinction between sub- 
stantial and accidental forms. The substantial form was, for 
them, not the constitutive principle by which things are what 
they are, but more truly the collection of all the attributes by 
which a thing is discriminated from other things.^ With a con- 
fused notion of matter and form, the question of the unity or 
of the plurality of substantial forms does not even arise. The 
times were not yet ripe for so refined a discussion. 

To trace, then, the origin of the dispute and to investigate 
how and when the Schoolmen came for the first time into 
contact with it, we must turn to another field of inquiry. 

In the height of the conflict against Aristotelianism in the 
last decades of the thirteenth century, there appeared a list 
entitled Errores philosophorum, written, in all probability, by 

* See, for example, Alanus de Insulis, Distinctiones dictionum theologicalium, s. v. 
silva (PL 210,944 C); see also s. v. aqua (704 A); and Regulae de sacra theologia, 
reg. 5 (626 A). 

^ " Forma dicitur proprietas rei, unde Boetius: ' Considerat enim corporum 
formas,' id est proprietates." Alan de Insulis, Distinctiones, s. v. forma (796 D) . 
" Forma est quae ex concursu proprietatum adveniens a qualibet alia substantia 
facit suum subiectum aliud." Nicholas of Amiens, De arte seu articulis catholicae 
fidei, Prologus (PL 210,597-8). Cf. among others, M. Baumgartner, Die Philosophie 
des Alanus de Insulis itn Zusammenhange mit den Anschauungen des 12. Jahr- 
hunderts (B.G.P.M., II. 4). Miinster i. W., 1896, particularly pp. 47-60. 


Giles of Rome,* in which Aristotle and Avicenna are made re- 
sponsible for the thesis: Quod in quolihet composito sit una 
forma substantialis tantum. The author, who is on the whole 
familiar with the facts, argues that the unity thesis is a logical 
inference of the Aristotelian doctrine on change and movement. 
For, since the coming-to-be of a thing never takes place without 
the passing-away of another, and one substantial form is never 
introduced unless the one which preceded it is expelled — seeing 
that the matter of all things material is the same — it follows 
that there are no more substantial forms in one composite than 
there are in another. Nay if one stresses this point rightly, it 
seems necessary to maintain that there is in all compounds one 
substantial form only: and indeed this appears to be the Phi- 
losopher's position. In fact, in the Metaphysics, Book VII, in 
the chapter ' On the unity of definition,' he states that the 
attributes in the definition are one, not because they are present 
in one thing, but because they constitute one nature, one thing. 
If he means one thing composed of many forms, this view may 
be tolerated, but if he means one simple nature and that in the 
concrete thing there is one form only, then it is false .^ 

Doubtless in the Aristotelian system there can be no room for 
the theory of plurality of forms. St. Thomas more than once 
pointed out that haec positio (plurality of forms) secundum 
vera philosophiae principia quae consideravit Aristoteles est 

* Giles of Rome Errores Philosophorum, ed. J. Koch (Milwaukee: Marquette 
Univ., 1944). 

^ Among Aristotle's errors: "11. Ulterius, quia per viam motus nunquam est 
generatio unius, nisi sit corruptio alterius, et nunquam introducitur una forma 
substantialis, nisi expellatur alia, cum eadem sit materia omnium habentium earn 
(De gen. et corrup., I. 3, 319 a 33-b 5; c. 5, 320 b 12-14), sequitur ex hoc quod non 
sint plures formae substantiales in uno composito quam in alio. Immo qui bene pro- 
sequitur viam istam, videtur esse ponendum in omni composito unam formam sub- 
stantialem tantum; et ista videtur via Philosophi. Unde VII° Metapliysicae, 
capitulo ' De unitate diffinitionis,' vult partes diffinitionis non esse unum (Z. 12, 
1037 b 22-27) , ' quia sunt in uno,' sed quia dicunt unam naturam. — Quod si intel- 
ligit unam naturam compositam ex pluribus formis, posset tolerari; sed si intelligit 
unam naturam simplicem, et quod sit in composito una forma tantum, falsum est." 
Ibid., p. 8. And in the summa errorum: "11. Quod in quolibet composito sit una 
forma substantialis tantum." p. 12. 


imposdbilis.^ Yet, since at the earliest stage the question was 
not discussed under this aspect, we are still far from knowing 
how and when the Schoolmen became aware of the problem. 

We get nearer with Avicenna, who, according to the Errores 
'philoso'phorum, explicitly maintained that est una tantum 
forma suhstantialis in coinpodto. As a matter of fact, this 
thesis stands at the head in the enumeration of Avicenna's 
errors. Indeed, in his Metaphysics, section II, in the chapter 
' On the division of corporeal substance,' Avicenna holds that 
the form of the genus is not made specific through anything 
extrinsic. By this he implies that the form of the species is 
not some essence besides the essence of the form of the genus. ^ 
This is a clear statement of the unity thesis. Elsewhere too, 
as for instance, in the Sufficieiitia, Avicenna firmly expresses the 
same view: one and the same substantial form makes matter a 
definite kind of body and a body: Non est alia jorma qua ignis 
est ignis et qua est corpus.^ 

None the less, the weight of these arguments was felt only 
at a later and more developed period of the debate. At all 
events, we can trace its very beginning to Avicenna's Liher 
sextus naturaliuTn, or De anima, translated into Latin at 
Toledo in the second half of the twelfth century by Dominic 
Gundissalinus and his associates, who also rendered into Latin 
Algazel and Ibn Gebirol's Pons vitae. Avicenna argues from 
the unity of the human soul to its substantiality. Since it is 
the soul that makes man what he is and constitutes him in his 
species, if there were in man diverse souls, man would be in 
diverse species.^ Moreover, he posits unequivocally that the 

' Cf. among others, St. Thomas Aquinas, De s'piritualihus creaturis, a. 3 (ed. 
L. W. Keeler, Romae: Gregorianum, 1938, p. 42) . 

' " 1 . Avicenna autem similiter videtur errasse ponens unam formam in com- 
posite, ut patet in Il° tractatu Metaphysicae suae, capitulo * De divisione sub- 
stantiae corporeae ' (ed. Venetiis, 1508, fol. 76ra) , ubi vult quod forma generis non 
specificetur per aliquod extrinsecum. Per quod innuitur quod forma speciei non sit 
aliqua essentia praeter essentiam formae generis." Ibid., pp. 24-26. Summa: "1. 
Quod est tantum una forma substantialis in composito." p. 34. 

^ Avicenna, Sufficientia, II, c. 3. 

' " Anima ergo perfectio est subiecti quod est constitutus ab ea. Est etiam 


human soul, while possessing a multiplicity of powers, namely 
vegetative, sensitive and rational, is essentially one; for it is 
one and the same principle that gives life and movement, and 
governs and acts in man/° 

Gundissalinus is known to us not only as a translator, but 
also as an author. His treatises, in which he made full use of 
his own translations, chiefly of Avicenna and Gebirol, are 
important not so much for his personal contribution to medieval 
thought — for he is rather a compiler than an original thinker — 
as for his being the first to utilize and attempt a systematic 
exposition of the new learning, thus opening up fresh subjects 

constituens speciem et perficiens earn. Res enim habentes animas diversas fiunf 
propter eas diversarum specierum, et fit earum alteritas specie non singularitate; 
ergo anima non est de accidentibus quibus non specificantur species, nee recipiuntur 
in constitutione subiecti. Anima enim est perfectio substantiae, non ut accidens." 
De anima, I, c. 3 ( ed. cit., fol. 4ra) . I have collated Avicenna's text with Bodleian 
Library, Oxford, MS Bodl. 463 (S. C. 2456). 

^° " Postea autem declarabitur tibi quod anima una est ex qua defluunt hae vires 
in membra, sed praecedit actio aliquarum, et consequitur actio aliarum secundum 
aptitudinem instrumenti. Ergo anima quae est in omni animali ipsa est congregans 
principia sive materias sui corporis, et coniungens et componens eas eo modo quo 
mereantur fieri corpus eius; et ipsa est conservans hoc corpus secundum ordinem quo 
decet, et propter eam non dissolvunt illud extrinseca permanentia, quamdiu anima 
fuerit in illo, alioquin non remaneret in propria sanitate." Ibid., fol. 3vb. Cf. P. V, 
cap. 7, fol. 27r S. — Deviating, however, from his own principles, Avicenna held 
that the substantial forms of the elements remain entire in the mixed bodies, an 
inconsistency which cannot be explained save by assuming that he did not foresee 
all the consequences implied in his premises. See Sufficientia, I, c. 10, fol. 19rb; 
Metaph., VIII, c. 2, fol. 97vb-98ra; De anima, IV, c. 5. Cf. St. Thomas, Summa 
tkeologiae, I, q. 76, a. 4 ad 4. It has also been urged that Avicenna's theory on 
the forma corporeitatis is in support of the pluralist view. That it may be inter- 
preted as advocating pluralism is beyond doubt. In this sense it was understood 
and criticized by Averroes. The phrase itself is ambiguous, and because of its 
ambiguitj' it was avoided by Aquinas. Nevertheless, it seems to have a different 
meaning in Avicenna, as M.-D. Roland-Gosselin (Le " De Ente et Essentia " de s. 
Thomas d'Aquin [Bibliotheque Thomiste, VIII; Kain, 1926] pp. 104 fl.) , A. Forest 
(La structure metaphysique du concret selon saint Thomas d'Aquin [Etudes de 
Philosophic medievale, XIV; Paris, 1931] pp. 189 ff.) and others maintain. At any 
rate, Avicenna himself did not use it, it seems, in the sense assumed by the 
pluralists, namely as meaning the first substantial form that makes matter to be a 
body apart from, and previous to, its specific form. His teaching, that it is one 
and the same substantial form which makes matter a definite kind of body and a 
body, remained unaltered. 


of inquiry and new approaches to old problems. It was through 
his treatise De anima, together with Avicenna's Liher sextus 
naturalium, that the question concerning unity of form reached 
the schools. 

Gundissalinus deals with the question in Chapter IV: Anima 
an una vel multae, a faithful echo of Avicenna's An sit una an 

Following Avicenna closely, Gundissalinus discusses two dis- 
tinct questions. The first is whether in all living beings there 
is one single soul which, though in itself one substance, in virtue 
of its manifold powers performs the function of vegetative life 
in plants, of sensation in animals, of intellect and reason in 
man. Thus, a single rational soul produces, according to its 
various powers, vegetation alone in the bones, hair and nails, 
in other parts of the body sensation and movement, and in the 
brain intellect and reason. Or again, to use a simile, just as 
one and the same solar ray causes different effects in different 
things, hardening the clay and melting the wax, so one and the 
same soul, according to diversity of bodies, operates diversely, 
bestowing upon some mere existence, upon others sensation, 
and making others rational beings.^^ 

The other question propounded here is whether in man the 
vegetative, the sensitive and the rational are three distinct souls 
and substances, or one soul and one substance only. It is 
obvious that the former topic is not to be confused with the 
latter; they are two distinct problems. 

The first opinion, qualified as erroneous, is rejected (hunc er- 
rorejn ita destruunt philosophi) . Gundissalinus argues against 
it that these three are in reality not only three powers, but 
three souls specifically distinct from each other, the vegetative 
which is in plants alone, the sensitive which is in brute animals, 
and the rational which is in man. The evidence that they are 
distinct from each other is that each one possesses a separate 
existence; hence one cannot be the other. The vegetative is like 

^^ " The Treatise De Anima of Dom'micus Gundissalinus," ed. J. T. Muclde, 
Mediaeval Studies, II (1940), 44. 


the genus to its species; it is therefore in plants as well as in 
animals; but plants and animals are specifically diversified. 
Nevertheless, from the fact that each taken separately is speci- 
fically distinct, it does not follow that they are also distinct 
subsances when they are united. For instance, a palm tree and 
a vine are both a tree, that is, they are endowed with vegetative 
soul, a power of self-nurishment and growth. Yet for a palm or 
a vine there is not required another soul in addition to the 
vegetative soul, namely, the soul of a palm or of a vine. It is 
one and the same soul that makes the living, growing tree a 
palm or a vine.^" 

Likewise the three vital powers, vegetative, sensitive and ra- 
tional, exist in man. Taken separately, each one is a substance 
distinct from the other, but this is not the case when they are 
jointly existing in man. As the sensitive includes the vegetative 
and has something else besides, that is, sensitivity, so the 
human soul is one single substance {cum sit una simjjlex sub- 
stantia) , implying in itself, not only the rational but also the 
vegetative and the sensitive, not however as distinct substances 
{nan tamen tres substantiae sunt in homine) , but simply as dis- 
tinct powers. Moisture and heat, taken separately, are dif- 
ferent, but conjoined in vapor they make one single thing,^^ 
The higher soul presupposes the lower, without which it can- 
not exist. Neither can the sensitive exist without the vegeta- 
tive, nor the rational, in its turn, exist without the vegetative 
and the sensitive. But the lower form, when conjoined with the 
higher, has not a separate existence, but is implied in the higher, 

" Ibid., pp. 44-45. 

^' " Quamvis autem omnis anima sit substantia et hae tres simul sint in unoquo- 
que homine, quoniam in homine est anima vegetabilis, et sensibilis, et rationalis, 
non tamen tres substantiae sunt in homine; humana enim anima, cum sit una 
simplex substantia, habet vires animae vegetabilis et vires animae sensibilis et 
vires animae rationalis; similiter et anima sensibilis habet vires animae vegetabilis. 
Et quamvis hae vires diversae sint inter se, ita ut una earum non praedicetur de 
altera, quippe cum unaquaeque earum sit species per se, tamen nihil prohibet eas 
simul haberi ab anima rationali. Quemadmodum, quia invenimus humorem in aere 
non separatum a calore, non tamen idcirco necesse est ut humorem et calorem qui 
sunt in aere non habeat aliqua una forma vel aliqua una materia. Sic et de viribus 
animarum." Ibid., p. 45. 


since the higher possesses all that the lower has and something 
more besides: the higher the soul, the greater the power, the 
more comprehensive its virtue. The power which supervenes, 
being stronger, becomes the principle of that which preceded 
and remains the only principle and cause of all the powers 
and virtues operating there. Similarly with regard to the sen- 
sitive and rational souls, just as when the sensitive soul super- 
venes, the vegetative is superseded, so with the appearance of 
the rational soul all the operations both of the vegetative and 
of the sensitive are effected by the rational. The latter vir- 
tually includes the former, not in the sense that we can dis- 
tinguish in the sensitive two souls or substances, and in the 
rational three, but in the sense that one single soul, the highest, 
has the power to produce all the operations performed by the 
vegetative and the sensitive souls.^* 

Gundissalinus reaches the same conclusion in Chapter II, 
when he is discussing the substantiality of the soul. The soul is 
a substance and not an accident, since there is one soul only in 
a living composite, whether it be a tree, an animal or a man. 
To prove, in turn, the unity of the soul, he argues that it is the 
soul that makes man what he is and imparts to him his specific 
nature, for it is the self-same principle that bestows life and 
movement, and governs and acts in man. It is not by reason 
of two or more principles, but by virtue of the self-same prin- 

^* " Quaedam non recipiunt nisi animam vegetabilem tantum, quaedam vero 
amplius quia animalem; quaedam vero multo amplius quia rationalem. Quemad- 
modura si corpus unum ponatur ad solem cuius situs talis esse potest ut non 
recipiat a sole nisi calorem tantum; si vero talis fuerit eius situs ut recipiat 
ab eo calorem et illuminationem, tunc simul calefiet et illuminabitur, et lux 
cadens in illud erit principium calefaciendi illud: sol enim non calefacit nisi radio. 
Deinde si maior fuerit eius aptitudo ut etiam possit accendi, accendetur et fiet 
flamma, quae flamma erit etiam causa calefaciendi et illuminandi simul ita ut 
quamvis sola esset, tamen perficeretur calefactio et illuminatio, et praeter hoc 
calefactio poterat invenire per se sola, vel calefactio et illuminatio sola per se, 
quorum posterius non esset principium a quo emanaret prius. Cum autem omnia 
simul concurrunt, tunc id quod fuerat posterius fit principium etiam prioris et 
emanat ab eo id quod erat prius. Sic ergo dispositionem virium animarum facile 
intelligere poteris, si per corpus calefieri intelligas illud tantum vegetari, et per 
illuminari illud ab anima sensificari, per accendi vero animam rationalem sibi 
infundi." Ibid., p. 46. 


ciple, namely the soul, that an organic body is a body and a 
definite kind of body, that is, an animal or human body, since 
whatever perfection is superadded to an already constituted 
being does not impart a specific being, but merely an acci- 
dental being, or a mode of being. Unless we admit the patent 
contradiction that one and the same being could belong to two 
different species, we must agree that the soul confers on the 
organic composite a complete substantial being, and conse- 
quently that the soul is only one. In fact, as soon as the soul 
departs from the body, the body is no longer an animal or 
human body, but becomes something else, with an utterly dif- 
ferent nature. ^^ Professor E. Gilson has correctly remarked 
that there is complete agreement between Avicenna and Gundis- 
salinus on the concept of the unity of the soul in a composite. ^*^ 

I have dwelt at some length on this point, for it is of no 
mean importance in determining the exact source of the unity 
thesis. It is true that, strictly speaking, the discussion turned 
primarily on the unity of the soul; obviously, as we have 
already noted, a different question from that of the unity 
of substantial form. Nonetheless, Gundissalinus, presenting 

^^ " Nam corpus proprium, in quo existit unaquaeque animarum, scilicet tarn 
vegetabilis quam sensibilis quam etiam rationalis, non est id quod est ex com- 
plexione propria sed ex anima. Anima enim est quae facit illud esse illius com- 
plexionis, nee permanet in complexione propria in actu nisi quamdiu fuerit anima 
in illo. Anima enim sine dubio est causa per quam vegetabile et animal sunt illius 
complexionis; ipsa enim anima est principium generationis et vegetationis. Unde 
impossibile est ut proprium subiectum animae sit id quod est in actu nisi per 
animam. Non enim verum est ut proprium subiectum animae prius constituatur ab 
alio, cui postea adveniat anima quasi non habens partem in eius constitutione vel 
definitione, sicut accidentia quae consequuntur esse rei consecutione necessaria, non 
constituentia illud in actu. Immo ipsa anima constituit ipsum proprium subiectum 
et dat ei esse in actu. Cum vero anima separatur ab eo, succedit necessario cum 
separatione eius alia forma, quae est sicut opposita formae complexionali. Haec 
enim forma et haec materia, quam habebat dum aderat anima, non remanet post 
animam in sua specie, quoniam destruitur eius species et eius substantia quae 
erat subiectum animae." Ibid., chap. 2, p. 41. 

" Les deux philosophes se trouvent done avoir du meme coup une conception 
identique de I'unite de I'ame dans le compose." E. Gilson, " Les sources greco- 
arabes de I'Augustinisme avicennisant," Archives d'hist. doctr. et litt. du M-A., IV 
(1929), 84. 


Avicenna's treatment more systematically, provided the School- 
men with the main elements of the problem by asserting un- 
ambiguously (i) that the vegetative, the sensitive and the 
rational, though three distinct substances when taken sepa- 
rately, are one simple substance when united; (ii) that the 
higher principle includes the lower, which is only virtually 
present when the higher supervenes; (iii) that whatever per- 
fection is superadded to an already constituted being does not 
impart specific being, but merely accidental being; and conse- 
quently (iv) that the vegetative, the sensitive and the rational 
are in man not three distinct substances, but powers. The 
formulation, the arguments and similies set forth by Gundis- 
salinus will become a common patrimony and will be continu- 
ally used in more or less refined fashion by successive genera- 
tions of masters. Some confusion as to the unity of soul or sub- 
stance will linger for a time, but soon philosophers and theo- 
logians will accurately distinguish between the question of the 
unity of soul and the unity of substance or form. 

Turning our attention now to the pluralist theory, Aquinas ^^ 
traced its source remotely to Plato and proximately to Avice- 
bron (Ibn Gebirol) . Both systems issue from the same root, 
both present as reality what is a mere distinction of the mind, 
and one is the sequel of the other.^^ The pluralist theory, in 
fact, follows logically from Platonic presuppositions. Plato 
holds that there are several souls in a body, distinct according 
to different organs and their various vital actions, such as the 
nutritive in the liver, the concupiscible in the heart, and the 
knowing in the brain. ^^ Furthermore, he maintains that the 
human soul is united to the body not as form to matter, but 
merely as mover to the moved, just like a sailor in a boat; and 
again, that man is not composed of soul and body, but that 

^' St. Thomas, De spiritualihus creaturis, a. 3 (ed. Keeler, pp. 40-41) . 

^^ St. Thomas, Summa theoL, I, q. 76, aa. 3-4. " Et haec positio [Avicebron's], 
quamvis videatur discordare a prima [Plato's], tamen secundum veritatem rei 
cum ea concordat, et est sequela eius." De spirit, creat., loc. cit. 

^" Cf. St. Thomas, QQ. dis-p. de anima, a. 11: " Plato posuit diversas animas esse 
in corpore; et hoc quidem consequens erat suis principiis." Also Summa theoL, I, 
q. 76, a. 3. 


man is a soul using a body. In all these cases the resultant 
union would not be essential but accidental. Now in things 
accidentally united there may be plurality of forms without 
any incongruity. 

Nevertheless, the main true source from which the pluralist 
theory has come down to the Schoolmen is undoubtedly Avice- 
bron.-° The keystone of his system is his doctrine of the ' uni- 
versal matter ' (materia universalis) and ' universal form ' 
(fonna universalis) : the two roots from which every thing, 
save God, comes forth and into which it is ultimately resolved. ^^ 
Universal matter is one and the same, and is necessarily devoid 
of every form; it becomes substance by its composition with 
universal form. Substances are essentially different because 
they have diverse forms; each form conferring a special degree 
of being corresponding to its own nature, independently of the 
other. Since every thing possesses its special matter and its 
special form of which it is never stripped, and, at the same time, 
the new added form remains with the previous form or forms, it 
logically follows that in one and the same individual we must 
posit as many substantial forms as there are perfections or 
degrees of being," " It must be taken for granted," he says, 
" that man owes his humanity to the human form, his animality 
to the animal form, his life to the vegetative form, his body 
to the form of corporeity, and his substance to the universal 
form." '' 

^° " Circa ordinem formarum est duplex opinio: una est Avicebron et quorumdam 
sequacium eius." St. Thomas, Quodl. XI, a. 5. Cf. Comm. in 11 De anima, lect. 1 
(ed. Pirotta, n. 225); In 1 Dc gen. et corrup., lect. 10 (ed. Leonina, n. 8); De 
spirit, creat., a. 1 ad 9; a. 3, etc. See M. Wittmann, Die Stellung des hi. Thomas 
von Aquin zu Avencebrol (Ibn Gebirol) , (B. G.P.M., III, 3) Miinster i. Westf., 

Materia universalis et forma universalis . . . haec duo sunt radix omnium et 
ex his generatum est quicquid est, . . . haec natura praecedunt omnia, et in ea 
etiam resolvuntur omnia." Avencebrolis, Fans Vitae ex Arabico in Latinum trans- 
latus ab lohanne llispano et Dominico Gundissalino, primum edidit C. Baeumker 
(B.G.P.M., I, 2-4) Munster i. Westf., 1892-95. I, 5, p. 7. 
'"' Fons vitae, II, 2 (ed. cit., pp. 26-27) . 

Tanquam certum . . . quod forma naturae est aliud a forma animae vege- 
tabilis, et quod forma animae vegetabilis alia est a forma animae sensibilis, et 


As Gimdissalinus in his De anima made known the unity 
thesis of Avicenna, so it was he too who in his other treatises 
popularized Avicebron's theory. In the De processiojie mundi -* 
we meet with the same description of matter and form as in 
Avicebron, whereas in the De imitate ^^ (wrongly attributed to 
Boethius "") he reproduced almost verbatim Avicebron's teach- 
ing on the various degrees of forms. By bringing these theories 
to the fore, Gundissalinus contributed considerably to the 
spread of an utterly un-Aristotelian notion of matter and form 
which is at the base of all pluralism. Again, by proclaiming that 
other Avicebronian tenet, that quicquid iritellectus dividit et 
resolvit in aliquid, com'positmn est ex his in quae resolvitur, he 
provided the pluralists with the fundamental principle on which 
their thesis stands.^^ 

All things considered, we may unhesitatingly conclude that 
the main sources from which medieval speculation drew the 
philosophical problem with which we are concerned were Avi- 

quod forma animae sensibilis alia est a forma animae rationalis, et quod forma 
animae rationalis alia est a forma intelligentiae." Ibid., IV, 3 (pp. 215-216). Cf. 
Ill, 46 (pp. 181-2); V, 34 (p. 320). 

^* Dcs Dominicus Gundissalinus Schrift ' Von detn Hervorgange der Welt ' (De 
processione mundi), ed. G. Biilow (B. G. P. M., XXIV, 3) Miinster, 1925, p. 30: 
" Materia est prima substantia per se existens, substentatrix diversitatis, una 
numero. Item, materia prima est substantia receptibilis omnium formarum." Cf. 
Fo-ns vitae, V, 22 (p. 298) . Also loc. cit.: " Forma vero prima est substantia con- 
stituens essentiam omnium formarum." Cf. Fans vitae, ibid. 

^^ Die dent Boethius fdlschlich zugeschriebene Abhandlung des Dominicus Gundi- 
salvi De Unitate, ed. P. Correns (E.G. P. M., I, 1) Munster, 1891, p. 8: "Quia 
igitur materia in supremis formata est forma intelligentiae, deinde forma rationalis 
animae, postea vero forma sensibilis animae, deinde inferius forma animae vege- 
tabilis, deinde forma naturae, ad ultimum autem in infimis forma corporis: hoc non 
accidit ex diversitate virtutis agentis, sed ex aptitudine materiae suscipentis." Cf. 
Pons vitae, V, 20 (p. 295) . 

** St. Thomas has remarked that the De unitate was wrongly attributed to 
Boethuis: " Dicedum quod liber De unitate et uno non est Boethii, ut ipse stilus 
indicat." De spirit, creat., a. 1 ad 21 (ed. cit., p. 18) . 

^' De processione mundi, ed. cit., p. 4; cf. Fans vitae, II, 16: " Quicquid com- 
positorum intelligentia dividit et resolvit in aliud, est compositum ex illo in quod 
resolvitur" (p. 51). See St. Thomas, loc. cit. Cf. Wittmann, op. cit., pp. 17-18; M. 
de Wulf, Le traite ' De Unitate Formae ' de Gilles de Lessines (Les Philosophes 
Beiges, I), Louvain, 1901, p. 35. 


cenna for the unity thesis and Avicebron for the pluralist 
theory, Gundissalinus being the immediate channel through 
which the same problem reached the schools. 

In thirteenth-century writings A\acebron is expressly men- 
tioned less than Avicenna (the Schoolmen, it seems, were some- 
what shy of referring to him by name) ; yet his influence is not 
to be underrated, chiefly among the so-called Augustinians and 
in the Franciscan school, particularly at Oxford. 

There were, however, other factors which helped to strengthen 
the pluralist theory. Not least among these was the De differ- 
entia spiritus et animae of Costa-ben-Luca,"** the Constabulinus 
of the schools. This short treatise exerted no little influence on 
medieval physiological and psychological thought. From it 
Gundissalinus in his De anima borrowed Plato's and Aristotle's 
definitions of the soul.^^ It helped to sanction the difference 
between ' spirit ' and ' soul ' ^° and to posit an intermediary 
uniting the soul to the body. The soul is united to the body by 
means of a corporeal ' spirit,' which, inasmuch as it comes 
forth from the heart, produces life, breath and beating of the 
pulse; as proceeding from the brain, it causes sensation and 
movement."^ Further, Costa-ben-Luca holds that the three 
powers of the soul, the vegetative, the sensitive and the ra- 
tional, are forms and genera of soul, and may at choice be called 
animae.^- Thus, by introducing an ambiguous teraiinology, he 
rendered an already involved theory even more confused. 

The Liber de causis, springing from the same Neo-Platonic 

^* Excerpta e libra Aljredi Anglici De mofu cordis. Item Costae-ben-Lucae De 
diferentia animae et spiritus liber translatus a Johanne Hispalensi, ed. C. S. Barach 
(Bibl. Phil. Med. Aetatis, II), Innsbruck, 1878. 

^* Cf. Gundissalinus, De anima, chap. 2 (ed. Muckle, pp. 37-41) . 

^° The difference between spiritus and anima is also clearly stated by Isaac 
Israeli in his Liber de definitionibus, translated by Gerard of Cremona, ed. by J. T. 
Muckle in Archives d'hist. doctr. et litt. du M.-A., XI (1937-38), 318-19. 

*^ Costa-ben-Luca, De differentia animae et spiritus, cap. 4 (ed. cit., p. 138) ; 
cf. cap. 1, pp. 121, 124, and cap. 2, pp. 124, 130. 

" Nunc loquarum de virtutibus animae, et dicamus, quod primae virtutes 
animae, quae sunt ei formae et genera, sunt tres: prima, scilicet vegetativa, secunda 
sensibilis, tertia rationalis, et hae virtutes vocantur ad placltum animae." op. cit., 
cap. 3, p. 137. 


source as Avicebron's Fons vitae, supplied a fresh argument in 
support of the pluralist view. We have it from Roland of 
Cremona, that some, to prove that there are three souls in man, 
based their contention on the authority of the book De pura 
honitate, proposition I."" (It is well known that in some ancient 
manuscripts the Liber de causis is entitled De pura honitate.) 
On the other hand, Albertus Magnus adduces this very same 
first proposition to demonstrate that such an assumption is 
untenable. " To admit three souls in man," he argues, " would 
destroy the order of formal causes, which is against the Phi- 
losopher's ^* teaching in the De causis, that the causes are dis- 
posed in a certain order: being, living, sentient, intelligent. For 
in that case the second cause would in no way be influenced by 
the first cause, whereas it is by virtue of that influence that a 
cause is and is a cause." ^^ 

These are the main sources from which the Schoolmen de- 
rived their knowledge of the problem under consideration and 
drew their arguments in favor of or against either opinion. 
Secondary channels, however, concurred to feed the stream. 
We may mention, for instance, the pseudo-Augustinian De 
spiritu et anima,^^ utilized by John de la Rochelle,^' St. x41bert 

*^ '' Et probant illud idem per primam propositionem quae est in libro De pura 
honitate." Text edited by Dom Odon Lottin, 0. S. B., " L'Unite de I'ame humaine 
avant saint Thomas d'Aquin," Psychologic et Morale aux XIP et XIIP siecles, 
2nd edition (Gembloux, 1957) , I, p. 465. 

^* The Liber de causis was attributed to Aristotle in the thirteenth century until 
Aquinas discovered its true origin when William of Moerbeke translated the 
Elementatio theologica of Proclus from the Greek (Viterbo, 18 March 1268) . 

^^ " Hoc autem dato (quod vegetativum, sensitivum, intellectivum sint per sub- 
stantiam separata) , sequuntur duo inconvenientia, quorum unum est. . . . Aliud 
autem est, quod destruitur ordo causarum formalium: quia secunda causa non 
habebit a primaria quod est, et quod causa est. Sunt enim ordinatae causae for- 
males, esse, vivum, sensitivum, intellectivum, ut dicit Philosophus in libro De 
causis." De anima. III, tr. V, c. 4 (ed. Borgnet, V, 418 b) . 

^^ De spiritu et anima, PL 40, 779-832. It was attributed to St. Augustine by 
many in the thirteenth century, but not by St. Thomas. See G. Thery, " L'authen- 
ticite du ' De spiritu et anima ' dans saint Tlaomas et Albert le Grand," Revue des 
Sciences philosophiques et theologiques, X (1921) , 373-377. 

*^ " Dicamus ergo secundum Augustinum in libro De anima et spiritu: ' Una et 
eadem est animae substantia vegetabilis, sensibilis et rationalis, secundum diversas 


and others '« in support of the unity thesis, and by the plural- 
ists for their embryo-genesis theory.^** Medieval thinkers would 
make their approach from various standpoints. Arguments 
were drawn from the most disparate sources; a simile, an obiter 
dictum frequently offered ample matter for speculation. What 
might seem to us quite an insignificant, tentative suggestion 
sometimes gave rise to long and important controversies. It is, 
therefore, not surprising that there were indeed other factors 
which mingled with these to strengthen the development and 
growth of the problem. 

The next question with which we are confronted is when did 
the problem itself reach the Universities of Paris and Oxford.^ 

Although it is beyond doubt that the problem was discussed 
in the schools in the first decades of the thirteenth century, at 
the latest, it would surely be rash, in our fragmentary knowl- 
edge of this period, to assert definitely who were the first 
masters to introduce it. 

It is rather disappointing that Daniel of Morley makes no 
allusion to it in his Pliilosophia.'^° In one so familiar with 
Avicenna and Arabic learning, we should expect to find an 
echo of the discussions held at Toledo on psychological mat- 

potentias diversa vocabula sortitur ' [c. 13, PL 40, 788-9]." La Summa De Anima 
di Frate Giovanni della Rochelle, ed. T. Domenichelli (Prato, 1882) , p. 138. Cf. 
also Richard Rufus of Cornwall, for whom see D. A. Callus, " Two early Oxford 
Masters on the Problem of Plurality of Forms: Adam of Buckfield — Richard 
Rufus of Cornwall," Revue neoscolastique de Philosophic, XLII (1939), 439. 

"* Albertus Magnus, Summa de creaturis, II, q. ,7 a. 1 : " Ex his omnibus accipi- 
tur, quod sententia omnium philosophorum est, quod vegetabile, sensible, et 
rationale in homine sunt una substantia. Et hoc expresse dicit Augustinus in libro 
De spiritu et anima." (ed. Borgnet, XXXV, 90 b) . 

*° De spiritu et anima, cap. 9: " Vegetatur tamen (humanum corpus) et movetur 
et crescit et humanam formam in utero recipit, priusquam animam rationalem 
recipiat. Sicut etiam virgulta et herbas sine anima moveri et incrementum habere 
videmus." (PL 40, 784-5) 

Daniels von Morley Liber de naturis inferiorum et superiorum," ed. K. 
SudhofT, Archiv fiir die Geschichte der Naturioissenschajten und der Technik, VIII 
(1918). See A. Birkenmajer's remarks on this edition, ibid., IX (1920), 45-51. 


ters; but he has purposely, it seems, avoided the subject to 
devote himself entirely to cosmology and astronomy: ostenso 
itaque ex quihus diversitatihus homo constet, turn in anima 
tuiii in cor pore, quoniam ad praesens non spectat negotium in 
huiusmodi diutius jnorari, ad constitutionem mundi, unde 
sermo venit, prius stilum iiiclino.'^^ 

Alexander Nequam taught in Paris at the school of Petit 
Pont in the last quarter of the twelfth century, and about 1190 
was lecturing in theology at Oxford. Seemingly he was in a 
position to know the main questions of the day. Yet in the 
De naturis rerum and in the De laudihus divinae sapientiae 
summing up the problems concerning man, which were then 
current in the schools,*" he has not a word on our topic, though 
he was familiar with the connected question, whether the soul 
and the body are united by means of a medium.*^ Moreover, 
in Books III and IV of his theological work, the Speculum 
speculatio?ium,** he has a short treatise on the soul, which 
would have offered him a good opportunity of introducing the 
point at issue, considering especially his acquaintance with 
Avicenna's De anima. Again, in Chapter XC, De viribus 
animae, he has a long discourse on the powers of the soul, and 
in Chapter XCIV, De sensualitate, under which heading theo- 
logians generally discussed our question, he makes no allusion 

*' Ibid., p. 9. 

*■ Alexandri Neckam De naturis rerum lihri duo, with the -poem of the same 
author, De laudibus divinae sapientiae, ed. T. Wright (R. S.) , London, 1863, cap. 
173, p. 299. Another set of similar questions is found in De laud. div. sap., dist. X, 
p. 499. M.-D. Chenu (" Grammaire et theologie aux XII^ et XIII^ siecles," 
Archives d'hist. doctr. et litt. du M.-A., X (1935-36), 5-28; and " Disciplina. Notes 
de lexicographie philosophique medievale," Rev. So. phil. et thiol., XXV (1936) , 
686-92) has shown the great profit that can be derived from these topics in order 
to trace the origin and development of much medieval speculation. 

** " Nonne maior est contrarietas inter animam et corpus, quae tamen sine aliquo 
medio coniuncta sunt? " De naturis rerum, cap. 16, ed. cit., p. 55. 

^* The Speculum speculationum, written between 1204 and 1213, is extant in 
one manuscript, British Museum, MS Royal 7 F. I. On Alexander Nequam and 
other early masters, see R. W. Hunt, " English Learnmg in the late twelfth 
century," Transactions of the Royal Historical Society, 4th ser., XIX (1936), 19-42; 
D. A. Callus, Introduction of Aristotelian Learning to Oxford (Proceedings of 
the British Academy, XXIX, 1943). 


to it, as though he had never heard of the AristoteHan distinc- 
tion of the vegetative, the sensitive and the rational. 

Alfredus Anglicus, or Alfred of Sareshel, well versed in medi- 
cine and in the natural sciences, was one of the very first to 
make extensive use of the new Aristotelian learning. His De 
motu cordis, dedicated to Alexander Nequam (d. 1217) , was 
introduced in the university curriculum of studies as pars in- 
ferior fhilosophiae naturalis. It contains in a curious mixture 
a large body of doctrine common to Neo-Platonic metaphysics 
and Aristotelian biological and natural philosophy. The re- 
peated assertion that the soul is one only in every living being, 
seems to suggest that Alfred had some inkling of the question. 
He teaches with Aristotle that no living being is without the 
vegetative soul, since nutrition is indispensable for every thing 
that grows and decays: a living being must therefore have 
within itself a principle by which it acquires growth and under- 
goes decay, that is, soul. Animals are not only living but also 
sentient beings. But since one and the same principle, not a 
distinct one, produces life and sensibility, in every living being 
there must be one soul only. Consequently animals have not 
two distinct souls, one vegetative and the other sensitive, for 
from the same soul the operations of life and sensibility arise. 
By one single principle an animal is a living and a sentient 
being .■'^ 

Obviously, this is not an ordered exposition or a thorough 
treatment of the question, which is rather touched upon occa- 
sionally and only in passing; it is more presupposed than ex- 
plicitly and directly stated. The principles upon which the 
structure of the doctrine is built are laid down, the conclusion 
inferred is there; but it is referred to only incidentally insofar 
as it is raised in connection with the general subject matter. 

*^ Des Alfred von Sareshel (Alfredus Anglicus) Schrift De Motu Cordis, ed. 
C. Baeumker (B. G. P. M., XXIII, 1-2), Munster i. Westf.. 1923. " Hanc (animam) 
in quolibet animate unam esse constans est " cap. 13, p. 65; " unius autem una 
est anima " cap. 8, p. 31; " aninia enim animalis simplex et una est; ex ea autem 
tantum vivit et sentit animal; ex una igitur causa. Ex ea igitur animal est. A 
causa igitur uniformi vivit et sentit " cap. 10, p. 43. 


None the less, it is noteworthy that in establishing his point, 
namely, the unity of the soul in every living being, Alfred urges 
the same argument advocated before him by Avicenna, and 
which later will be more elaborately used by Aquinas. 

Turning our attention now to the Paris theologians of the 
period, we meet with no explicit mention of the problem in 
Peter of Poitiers (d. 1205) , in Simon of Toumai (d. 1203) , 
Praepositinus of Cremona (d. 1210) , Robert Curzon, William 
de Montibus (d. 1213) , or Stephen Langton. William of Aux- 
erre (d. 1231) , so keen to turn to profit in his Summa aurea 
(c. 1220) every new topic, and perhaps the first theologian to 
make wide use of the new learning, is equally silent. 

The earliest, to my knowledge, clear and unmistakable ac- 
count is found in the faculty of Arts, in the treatise On the 
Soul of John Blund, written not later than 1210.*" Its main 
source is undoubtedly Avicenna. This treatise, representative 
of both Paris and Oxford, is a striking example of the deep 
penetration in the schools of Avicennian theories, under the 
cloak of Aristotle, at the beginning of the thirteenth century. 
Like Gundissalinus and Alfredus Anglicus, John Blund belongs 
to a period of transition, and joins in the attempt to utilize 
Eastern philosophy in Western thought, linking up the Arabian 
world with Scholasticism, 

The elementary way in which the question is treated points 
unmistakably to its early stage. Its very title, utruvi anhna 
vegetabilis. sensibilis et rationalis sint in homine eadem anima 
an diversae, bears the impress of Avicenna. In the table of 
contents it is described quomodo anima vegetabilis se habeat 
ad animam sensibilem et rationalem. The chief point of the 
discussion, in fact, appears to be more logical than psycho- 
logical, though this is not excluded, namely, whether ' anima ' 
or ' animatum,' the vegetative soul is a genus or a species; and 
if a genus, how it is predicated of its species, namely the 
nutritive soul of animal soul and of rational soul. 

*'See D. A. Callus, "The treatise of John Blund On the Soul," in Autour 
d' Aristotle. RecueU d' etudes ofert a Mons. A. Mansion (Louvam, 1955), pp. 471- 
495. This treatise will be published shortly. 


The debate opens by setting forth the evidence in support of 
the unity view. Three arguments are brought forward: the first 
two are drawn from the univocal predication of ' animatum ' 
and ' substance.' 

(1) Animatum is univocally predicated of a living body, of 
animal and of man. Now a thing is said to be animated inas- 
much as it possesses a soul. Since, therefore, animatum, is predi- 
cated according to the same formal notion signified by the 
name ' animated,' similarly the soul pertains to each thing 
possessing a soul according to the same formal notion. Conse- 
quently, one and the same is the soul of a living body, of animal 
and of man. 

(2) Again, ' substance ' is univocally predicated of body, of 
living body, and of each of its inferiors; and it is specified by 
the addition of gradual differences, such as corporeal, living, 
sentient, and so on. Likewise the soul is specified by the addi- 
tion of vegetative, sensitive, and rational. Now as ' substance ' 
is a genus with respect to its species, so ' soul ' is a genus with 
respect to its species. But it cannot be said that there are many 
substances in one species of substance. For the same reason it 
should not be said that there are three souls in man, but one 
soul only. Accordingly, the vegetative, the sensitive and the 
rational are not three souls, but one soul only. 

(3) ]\Ioreover, if these were three diverse souls, there would 
be in reality three souls in man, which is contrary to Avicenna, 
who teaches that in man it is from the same rational soul that 
the vegetative life, the sensitive life and the rational life are 

That they are diverse souls might be argued as follows: 

(1) If the vegetative, the sensitive and the rational were 
one soul, then as the rational is incorruptible, so also the vege- 
tative and the sensitive souls would be incorruptible; and as 

*' " Si sint diversae aiaimae, contingit hominem habere tres animas in effectu, 
quod est contra Avicennam, qui dicit quod ab anima rationaJi est in homine 
vegetatio, sensibilitas, rationalitas." Cambridge, St. John's College, MS 120, fol. 


the rational soul can be separated from the body, enjoying per- 
petual life, likewise the souls of a tree or of an ass would live 

(2) The second argument aims at proving that ' soul ' is not 
a genus; for, since the genus contains something more than each 
of its species, no genus is equal to its species. Consequently, the 
vegetative, the sensitive and the rational are three distinct 
species, not a genus. 

Blund's answer is that this word soul {hoc nomen * anima ') 
means the genus of the vegetative, of the sensitive and of the 
rational souls. Sensitive soul is a subaltern genus, inasmuch as 
it is a genus with respect to the rational soul, and a species 
of the vegetative soul. But in man there is only one single 
soul which imparts vegetative life, sensitivity and reason.*® 

Doubtless, John Blund's treatment is still quite embryonic, 
and the real issue is more implied than expressed. Nevertheless, 
Blund is a definite witness, not only to the fact that the ques- 
tion was discussed in the schools by the masters of Arts in the 
first decade of the thirteenth century, but also to the fact that 
its first solution was in favor of the unity thesis. Its significance 
lies in this, that we have in this account, however inarticulate 
it may be, some of the same arguments which were later ad- 
vanced in the heyday of the conflict by both opponents and 
defenders: that of the corruptibility or incorruptibility of the 
soul was adduced by all the pluralists, whereas the supporters 
of the unity thesis insisted that it is one and the same prin- 
ciple that gives life, sense and reason to one individual. 

A few years later Roland of Cremona, the first Dominican 
master in the University of Paris (1229-1230) , attests that the 
question had reached the faculty of theology. His statement 
bears considerable weight for its accuracy and conciseness. 

There are, he says, three species of souls: the vegetative soul, 

*^ " Solutio. Dicimus quod hoc nomen ' anima ' significat genus animae vegeta- 
bilis et animae sensibilis et rationalis. Et in homine est una sola anima a qua est 
vegetatio, sensus et ratio. Et anima sensibilis est genus subalternum, quia anima 
sensibilis est genus animae rationalis et species animae vegetabilis." Ibid., fol. 


which is in phmts; the sensitive soul, which is in dumb animals; 
and the rational soul, which is in man alone. Yet there are not 
three souls in man, as some think. According to these thinkers, 
there are really three souls in man: the vegetative, the sensitive 
and the rational. But this is untenable, for of one and the same 
thing there cannot be but one first perfection, since one and 
the same thing can have but one existence {unicum esse) . Now 
all agree that the soul is the perfection of an organized body 
holding life in potentiality. The vegetative soul, therefore, is 
the perfection of this body, and likewise the sensitive and the 
rational soul. It follows, then, that if there were three souls, 
this body would be perfected in virtue of the first perfection, 
which is impossible. Again, if the first endows the body with 
its perfection, the second or the third would serve no purpose.*^ 
Those who claim that there are three souls in man are per- 
suaded by this reason: they see that the embryo, even before 
it is perfected by the sensitive and the rational soul, grows. 
But growth is exclusively caused by the vegetative soul. Con- 
sequently, it seems that the vegetative soul is in the embryo 
before the sensitive and the rational soul. They prove this from 
the first proposition of the book De pwa bonitate. However, 
they labor in vain {frustra nituntur) . The embryo is not self- 
growing or vegetating, but grows in virtue of the mother, inas- 
much as, previous to the infusion of the rational soul, it is in a 
certain manner a part of the mother, since the embryo is united 
to the matrix by cotyledons.^" Accordingly, it remains that the 

** " Neque sunt tres animae in homine, quemadmodum quidam putant. Dicunt 
quod in homine est anima vegetabilis, et anima sensibilis, et anima rationalis. Sed 
hoc non potest stare, quia unius rei unica est perfectio prima, quia unius rei 
unicum est esse. Constat autem quod anima est perfectio corporis organici potentia 
vitam habentis. Ergo haec anima vegetabilis est perfectio huius corporis, et haec 
anima sensibilis, et haec anima rationalis. Ergo habet hoc unicum corpus vi per- 
fectionis primae, quod esse non potest. Iterum, si prima perficit, pro nihilo 
venit secunda vel tertia." Text edited by Dom O. Lottin, Psychologie et Morale 
aux XW et XIW siecles, 2nd edition (Gembloux: Duculot, 1957) , p. 465. 

^^ See, e. g., Alexander Nequam, De naturis reruTn: " Cum enim cotilidonum nexu 
familiari foetus adhaerens matrici quodammodo pars sit ipsius matris " (ed. cit., 
p. 240) ; Albertus Magnus, De animalibus, XVI, tr. II, c. 7: " Qualiter per cottilidi- 
ones fit incrementum embrionis " (ed. Stadler, 1131-3) ; and tr. I, c. 2. 


vegetative and the sensitive in man are not distinct souls, but 
powers of the rational soul.^^ 

Assuredly the development of the problem is as yet at its 
first stage. The discussion turns on the unity or plurality of 
souls in man. The solution gives the impression that it is merely 
outlined and unfinished; it is none the less clear and categorical, 
and the treatment of the whole question is extremely instruc- 
tive, Roland based his reasoning on the Aristotelian definition 
of the soul, regarded as axiomatic. Constat autem quod 
anima est perfectio corporis organici potentia vitarn habentis. 
The argument brought forward is the same one that Aquinas 
will urge and develop to its utmost value in upholding the unity 
of form not only in man, but in all composites: unius rei 
unica est perfectio prima, unius rei urdcum est esse, si prima 
perficit, pro nihilo venit secunda vel tertia. There can be no 
doubt that the first reaction of the Schoolmen in both faculties 
of Theology and of Arts was in favor of the unity thesis: the 
vegetative and the sensitive are not distinct souls in man, but 
powers of the rational soul. 

On the other hand, the same argument from the vital opera- 
tions of the embryo was constantly adduced by the pluralists as 
the most cogent in stressing their view. It is found wherever 
the problem is discussed, often with the biblical text. Exodus, 
21:22, and always with the same physiological reflection. It 
was later corroborated with the authority of Aristotle, De 
generatione animalium, II. 3 {De animalibus XVT. 3, 736 b 
1 ff.) .^" To refute this argument William of Auvergne dedi- 
cated a full chapter to it in his De anima,^^ and in St. Thomas' 
Quaestio disputata De anima, a. 11, to cite one more instance, 
no less than nine objections out of twenty are drawn from the 
embryo-genesis theory. When, however, Roland, trying to 
argue against this view contends that the embryo grows vege- 

^^ " Sensibilis et vegetabilis sunt vires animae rationalis in homine." Ibid. On 
Roland of Cremona, see E. Filthaut, Roland von Cremona O.P. und die Anfange 
der Scholastik in Predigerorden (Vechta i. 0., 1936) . 

^' See the discussion of this point in Albertus Magnus, De animalibus, ad locum. 

" De anima, cap. 4, P. II (ed. Orleans, 1674) , fol. 105 b-106 b. 


tatione matris suae, he is assuming an erroneous fact, though 
it was taught by many physicians in his day.^* 
In conclusion: 

(i) The immediate and main sources of the problem of the 
unity or plurality of souls and substances in man are Avicenna 
and Avicebron. The former stood for the unity thesis in every 
living being; the latter advocated plurality of forms in all 

(ii) The problem was formulated by Dominic Gundissalinus, 
and it reached the schools through him. Under the influence of 
Avicenna he transmitted the unity thesis in his De anima, but 
he popularized the opposite view through his other writings 
drawn chiefly from Avicebron. 

(iii) Various elements of diverse kind mingled with the main 
sources: the Platonic-Galenic teaching on the tripartite dis- 
tinction of the soul and on embryo-genesis; the theory of Costa- 
ben-Luca and of Isaac Israelita on the vital spiritus as distinct 
from the soul and as a medium of union with the body; the 
Liber de causis. All these secondary sources contributed to 
reinforce the pluralist stream. 

(iv) The first reaction of the Schoolmen was in support of 
the unity thesis, both in the faculty of Arts and in the faculty 
of Theology. Theologians in general held the thesis of one soul, 
one substance in man; they held that the vegetative, the sensi- 
tive and the rational in man are not three souls and three 
substances, or one soul and three substances, but one soul and 
one substance. St. Albert the Great voicing their view main- 
tained that " error pessiinus est dicere unius subiecti plures 
esse substantias, cmn illae substantiae non possunt esse nisi 
jormae." ^^ And again: " Hunc errorem hucusque in diem 
sequuntur quidam Latinorum philosophorum, praecipue in sen- 

^* Cf . Albertus Magnus, De animalibus, XVI, tr. I, c. 2, where he ascribes such 
a view to some " de medicorum imperito populo "; St. Thomas, Contra gentiles, 
II, cap. 89. 

"^ De unitate intellectus contra Averroem, cap. 13 (ed. Borgnet, IX, 455 b) . 


sibili, vegetabili et raiionabili, qui dicunt esse diversas sub- 
stantias et unain animam in corpore haminis." ^^ 

(v) With Philip the Chancellor (c. 1230) the problem en- 
tered into its second stage of development. The discussion 
turned, then, not on the unity or plurality of souls, but defi- 
nitely on the unity or plurality of substances, whether the vege- 
tative, the sensitive and the rational are one or three substances 
in man. Theologians discussed it in their commentaries on 
Book II, dist. 17, of the Sentences, and also in their quaestiones 
disputatae and quodlibetales, and later in special treatises. 

(vi) The masters of Arts generally raised the question in 
their commentaries on Aristotle's De anima, at the close of 
Book I or at the beginning of Book II. We have an illuminating 
clue in Adam of Buckfield (c. 1250) as to their procedure in 
setting the question. In this passage (411 a 26-411 b 11), he 
tells us, Aristotle deals with two questions. The first is whether 
the attributes of the soul, namely understanding, opinion, de- 
sire and the like, appertain to the soul as a whole, or whether 
each particular operation is dependent on a particular part; 
that is, whether the soul as a whole thinks, desires, perceives, 
or whether one part thinks, another perceives, another desires. 
The second question is this: Does life reside in one single part 
of the soul, or in more than one, or in all parts.? According to 
some, however, Aristotle's intention is to investigate a different 
problem, namely whether the vegetative, the sensitive and the 
rational are distinct with respect to their operations, or with 
respect to a diversity of substance. Buckfield believes that 
this interpretation is based neither on our translation {jiostram, 
i. e., the Greek-Latin version) nor on the other {aliam, i. e., 
from the Arabic) . Aristotle simply meant to maintain against 
Plato that the soul is not divided into various parts which in 
turn are located in different organs. Since, therefore, the 
problem concerning one or more substances in man was left 
unsolved by the Philosopher, there is room for further inquiry. 

"De anima, I, tr. II, c. 15 (ed. Borgnet, V, 184 a); III. tr. V, c. 4 (417 b ff.) 
et alibi passim. 


Et est hie quaestio: utrum in anima hominis sit eadem sub- 
stantia intellectivae , sensitivae et vegetativae, an sint sub- 
stantiae diversae.^' 

(vii) The question was also raised in the commentaries on 
Aristotle's Metaphysics, particularly in connection with the 
" unity of definition " (Z. 12, 1037 b 22-27) , as quoted in the 
Errores philosophorum {see supra, p. 263) . For instance, we find 
it discussed at great length in an anonymous commentary by a 
secular Oxford master of Arts in the first half of the thirteenth 
century .^^ 

(viii) Finally, the Aristotelian distinction of the soul into 
rational and irrational in the Nicomachean Ethics (I. 13) 
offered another opportunity to theologians and masters of Arts 
to discuss the question. St. Albert was well aware that this 

°' " In hac parte intendit [Aristoteles] de opinionibus aliorum, et sistit sua 
determinatio in prosecutione cuiusdam quaestionis. . . . Cum ita sit, quaestio est, 
utrum omnes istae actiones attribuantur animae secumdum se totam, ita scilicet 
quod secundum se totam intelligat, et secundum se totam sentiat, et sic de aliis, 
an secundum diversas partes sui in diversis membris existentes diversas faciat 
operationes, ut, scilicet, secundum unam partem sui in uno membro existentem 
intelligat, et secundum aliam in alio membro existentem sentiat, et sic de aliis. — 
Adhuc quaerit ulterius, si secundum diversas partes sui in diversis membris 
existens diversas faciat operationes. Tunc est quaestio adhuc, utrum ab una 
illarum partium tantum insit vita animali, aut a pluribus, aut ab omnibus; hoc est 
quaerere, utrum quaelibet pars animae vivificet suum membrum in quo est, aut non. 
Ista tamen quaestio principalis secundum quosdam aliter intelligitur, ita scilicet, 
ut intendat Aristoteles quaerere, utrum anima, cum sit una et eadem secundum 
substantiam et radicem, habeat operationes diversas, an diversificetur substantia 
ita, scilicet, quod substantia vegetativae sit alia a substantia sensitivae, et sub- 
stantia sensitivae alia a substantia intellectivae, sicut et operationes diversae sunt. 
Ista tamen quaestio nee per nostram translationem nee per aliam videtur prae- 
tendi. . . . Cum iam manifestum sit secundum intentionem Aristotelis in hac liltima 
parte quod anima est indivisa secxmdum situm et subiectum, et non videtur esse 
determinatum ab ipso utrum, cum sit indivisa secundum situm et subiectum, simi- 
liter sit indivisa secundum substantiam, propter hoc circa hoc est dubitandum. Et 
est hie quaestio: utrum in anima hominis sit eadem substantia intellectivae, sensi- 
tivae, vegetativae, an sint substantiae diversae." See D. A. Callus, "Two early 
Oxford Masters," ed. cit., pp. 434-5. 

"Although in this commentary the question is discussed in Book IX, it refers 
to the unity of definition. Cf. G. Gal, " Commentarius in Metaphysicam Aristotelis 
cod. Vat. lat. 4538 fons doctrinae Richardi Rufi," Archivum Franciscanum Histori- 
cum, XLIII (1950), 216: " Sed modo quaeri potest: si diffinitum . . ." cf. p. 237. 


topic, strictly speaking, was unrelated to the text. Neverthe- 
less, because there were various opinions, Albert thought it 
fitting to inquire into the question, together with the kindred 
question about whether the powers of the soul are distinct or 
identical with the essence of the soul.^^ We meet with similar 
questions in an anonymous commentary on the Ethica nova by 
a master of iVrts of the first half of the thirteenth century ."^^ 

But by this time, mid-thirteenth century, the debate was 
well advanced, and the treatment of the problem was greatly 
developed. A few years later, the genius of St. Thomas Aquinas 
will bring its solution to full maturity. 

Daniel A. Callus, O. P. 


Oxford, England 

^^ " Quamvis considerare horum differentiam [rationabilis et irrationabilis] non 
pertineat ad banc scientiam, sicut ipse [Aristoteles] dicit, tamen quia de hoc sunt 
opiniones, quaeritur, utrum. . . . See G. Meersseman, " Die Einheit der mensch- 
licheii Seele nach Albertus Magnus," Divus Thomas (Frib.), X (1932) 86 ff. 

"" These questions have been published by Dom O. Lottin, Psychologic et Morale, 
ed. cit., I, pp. 511-12. 



IN the spring of 1271 John of Vercelli, Master General of the 
Order of Preachers, sent a list of forty-three questions to 
three Dominican Masters in Theology for their considera- 
tion. Independently of each other, the three theologians were 
to consider each question carefully and reply promptly keeping 
in mind the directive of the Master General: (i) Do accepted 
authorities, the Sancti, maintain the doctrine or opinion con- 
tained in the articles listed? (ii) Apart from the weight of 
authorities, does the consultor maintain the aforesaid doctrine 
or opinion? (iii) Apart from the consultor 's personal views, 
could the aforesaid doctrine or opinion be tolerated without 
prejudice to the faith? ^ Clearly the purpose of this question- 
naire was to safeguard the truths of faith, even where the 
question raised was one of philosophical opinion or strictly 
natural science, 

St, Thomas Aquinas had previously given his decision on 
most of these questions in two private communiques to the 
lector of Venice, Bassiano of Lodi,- The official questionnaire 
of the Master General contained nothing of importance which 
had not already been considered by St. Thomas in his two 
private replies. The questions are for the most part idle 
curiosities and useless fantasies, as the consultors themselves 
realized. However, the official questionnaire was sent to three 
outstanding Masters in the Order, and not all the questions are 
without interest to the modern reader. St. Thomas' reply to 
the official questionnaire has always been known to Thomists, 
even though little studied. The reply of the second consultor, 

* St. Thomas, Responsio ad jr. Joannem Vercdlcnsem de articulis XLII, prooem., 
ed. R. A. Verardo, O. P., Opuscula Theologica (Turin: Marietti, 1954), I, p. 211. 
In this list the original q. 8 is missing. 

* Responsio ad Lcctorem Venetum de articulis XXX and Responsio ad eundem 
de articulis XXXVI, ed. R. A. Verardo in Opuscula Theologica^ pp. 193-208. 



Robert Kilwardby, later archbishop of Canterbury, was dis- 
covered and published by Fr. M.-D. Chenu, O. P., about thirty 
years ago.^ Now with the discovery and publication of the 
reply of the third consultor, the great St. Albert himself,* we 
are in a position to compare the views of the three Dominican 
Masters point by point. 

Among the relatively few interesting questions in the list of 
forty-three, the first five stand out as particularly important for 
the historian and philosopher of science. They have to do with 
the cause or causes of celestial motion. In the order of appear- 
ance they are as follows: 

1) Does God move any physical body immediately.? 

2) Are all things which are moved naturally, moved under 
the angels' ministry moving the celestial bodies.? 

3) Are angels the movers of celestial bodies.? 

4) Is it infallibly demonstrated according to anyone that 
angels are the movers of celestial bodies? 

5) Assuming that God is not the immediate mover of those 
bodies, is it infallibly demonstrated that angels are the 

movers of celestial bodies.? 

To the casual reader these questions, too, might appear to be 
useless in this age of scientific progress. Angels, it is frequently 
thought, have no place in a discussion of scientific questions. 
Some Catholic scientists, and even some Thomistic philosophers 
feel considerable embarassment at the mention of angels; they 
would rather not mention them at all, or at least not mention 
them as having anything to do with the real world in which 
we live. In medieval literature the problem of celestial movers 
was not created by theologians, nor did it take its origin in 
any point of Catholic faith, although St. Thomas was keenly 

' M.-D. Chenu, O. P., " Les Reponses de s. Thomas et de Kilwardby a la con- 
sultation de Jean de Verceil (1271)," in Melanges Mandonnet (Bibl. Thomiste 
XIII: Paris 1930), vol. I, pp. 191-222. 

* James A. Weisheipl, O. P., " The Problemata Determinata XLIII Ascribed to 
Albertus Magnus (1271)," in Mediaeval Studies, XXII (1960), 303-354. 


aware of the guiding role of faith in this matter. The problem 
of celestial movers was entirely a scientific one having many 
ramifications. But here, as in other problems of medieval 
science, it is not sufficient to know what a particular author 
maintained. It is far more important to understand the scien- 
tific problem in its philosophical context and to evaluate the 
arguments leading to the solution proposed. After all, the best 
of medieval science is not to be found in the lapidaries, herbals 
or bestiaries of the Middle Ages; least of all is it to be found in 
pious legends, sermons or morality plays. Rather it is to be 
found in the speculative commentaries, treatises and disputa- 
tions of the schoolmen. These writings, emanating largely 
from various faculties of the university, are not readily intelli- 
gible to modern readers, as anyone who has tried to read them 
can testify. To understand the writings of medieval authors 
one needs a considerable background in the sources, a specu- 
lative competence to follow the argumentation, and a famili- 
arity with medieval practice. Neither the questionnaire of the 
Master General nor the replies of Albertus Magnus, Thomas 
Aquinas or Robert Kilwardby can be evaluated correctly with- 
out reference to the sources, the argumentation and medieval 

In a review of Chenu's edition of Kilwardby 's reply to the 
questionnaire, Fr. Mandonnet noted the similarity between the 
view of Robert Kilwardby and that of John Buridan, the 
fourteenth century proponent of " impetus " to explain violent 
motion. Inspired by the thesis of Duhem's J^tudes sur Leonard 
de Vinci (3™^ serie) , Mandonnet was quick to point out the 
modernity of Kilwardby 's universal mechanics.^ This sug- 
gestion was developed at some length by Fr. Chenu in a special 
study devoted to the origins of " modern science." ® Whatever 
may be said of the validity of Duhem's well-known thesis, one 
may perhaps doubt the utility of isolating a particular medieval 
thesis — in this case one of dubious modernity — to extol the 

^P. Mandonnet, O. P., Bulletin Thomiste, III (1930), 137-9. 
' M.-D. Chenu, O. P., "Aux origines de la ' Science Moderne,' " in Revue des Sc. 
Phil, et Theol., XXIX (1940), 206-217. 


modernity of medieval science. Even if there should happen 
to be considerable similarity between some aspect of medieval 
science and a current scientific view, this would be no more 
than an interesting curiosity, unless we come to grip with an 
objective philosophical problem and analyze the issues his- 
torically and scientifically. 

A short paper such as this cannot sketch even in broad out- 
lines a picture of medieval astronomy or the history of its 
development.' All that can be attempted here is an examina- 
tion of the problem as seen by each of the three Dominican 
Masters consulted by the Master General, and an explanation 
of the views proposed, especially in their response to the oflficial 
questionnaire. Since our purpose here is to understand the 
medieval view, we need not be concerned about the true his- 
torical intent of ancient sources, but only about how the 
medieval schoolmen interpreted them. That is to say, it is not 
essential here to understand what Plato, Aristotle, Ptolemy or 
Al-Bitruji really meant; it is essential only that we understand 
what St. Albert, St. Thomas and Kilwardby thought them to 
mean. There is always the possibility that these great school- 
men misunderstood or misinterpreted their sources, but this 
makes little, if any, difference to the medieval view of the 
scientific problem. 

Preliminary Observations 

In the traditional division of the speculative sciences derived 
from Plato and Aristotle, astronomy occupied a peculiar posi- 
tion. By astronomy we do not mean the elementary calculation 
of movable feast days, the Epact or the Golden Number; nor do 
we mean identification of the signs of the zodiac or prognosti- 
cations from conjunctions. By astronomy is meant the theo- 
retical sciences which attempts to make celestial phenomena 
intelligible by means of mathematical principles. The peculiar 
position of this theoretical science can be recognized clearly in 
the writings of the three consultors. 

'' An outline can be found in P. Duhem, Le Systeme du Monde (Paris: Hermann, 
1954). vol. III. 


In the first place, astronomy was classified with optics, 
mechanics, harmonics and other scientiae mediae between the 
sciences of pure mathematics and natural science.^ As a sci- 
ence intermediate between mathematics and physics, astronomy 
was considered from three points of view. First, it was con- 
sidered in relation to the higher science of mathematics, to 
which it is subalternated and on which it depends for its scien- 
tific validity. Astronomy, it was said, accepts as established 
all the conclusions of geometry and applies them to the known 
measurements of celestial phenomena. In this consideration, 
astronomy and the other scientiae mediae " have a closer 
affinity to mathematics, because what is physical in their con- 
sideration functions as something material, while what is 
mathematical functions as something formal." ^ Intelligibility 
in every science was taken as derived from the principles, the 
formal element, as contrasted to the material element which is 
the conclusion, or fact now understood scientifically.^" We 
know that mathematical astronomy did not begin until Eu- 
doxus of Cnidos accepted the challenge from Plato " to find out 
what are the uniform and ordered movements by the assump- 
tion of which the phenomena in relation to the movements of 
the planets can be saved." ^^ The obviously irregular motions 
in the heavens, tabulated for centuries before Plato, could not 
be made intelligible except by reducing them, at least in theory, 
to perfectly regular movements of geometric spheres. In other 
words, astronomy was taken formally to be a mathematical 
type of knowledge, extending to measurable quantities of 
celestial phenomena, such as size, distance, shape, position and 

Considered in its own right, astronomy was presented as a 
true speculative science, demonstrative within its own limits. 
Unless there be some true demonstrations in astronomy, true 

* St. Thomas, In I Post. Anal, lect. 1, n. 3; In II Phys., lect. 3, n. 8; In Boeth. 
de Trin., q. 5, a. 3 ad 5-7; Sum. theol., I-II, q. 35, a. 8; II-II, q. 9, a. 2 ad 3. 

* In Boeth. de Trin., q. 5, a. 3 ad 6; Sum. theol, II-II, q. 9, a. 2 ad 3. 

"/n / Post. And., lect. 41, n. 11; Sum. theol, II-II, q. 1, a. 1; q. 9, a. 2 ad 3. 
" Simplicius, De caclo, ed. Heiberg (Comm. in Arist. Graeca, VII) , p. 488, 18-24. 


causal dependencies between principle and conclusion, this 
knowledge would not deserve the name of science. The mathe- 
matical principles of astronomy are themselves demonstrated in 
one of the purely mathematical sciences. Moreover, in theory 
" mathematical principles can be applied to motion," ^~ and 
sometimes the application is clear. But very often geometrical 
figures and principles must be assumed as applicable to the 
celestial phenomenon under consideration, as in the case of 
Eudoxus' four spheres to explain the motions of Jupiter, Cal- 
lippus' seven spheres and Ptolemy's epicycle. Nevertheless, the 
relationship between the principles assumed, even assumed as 
applicable, and the celestial phenomenon to be saved can be 
one of necessity. This connection of necessary dependency of 
the conclusion on the assumed principles is sufficient to estab- 
lish astronomy as a demonstrative science. It was in this sense 
that St. Thomas and St. Albert interpreted Aristotle's state- 
ment that, " It is the business of the empirical observers to 
know the fact, of the mathematicians to know the reasoned 
fact." ^^ Between the mathematical principle and the quantified 
aspect of the fact, there may well be a propter quid relationship, 
that is, the immediate, proper and convertible middle term of 
the measured facts of the conclusion may be the mathematical 
principle invoked. To this extent astronomy should be called, 
and was called a true science subalternated to mathematics. 
To be sure, astronomical science fell far short of the ideal of 
scientific knowledge described by Aristotle in the Posterior 
Analytics. It did not demonstrate through the immediate, 
physical cause of celestial phenomena; at best, it demonstrated 
through a kind of extrinsic formal cause (secundum causam 
formalem remotam) of the natural phenomena." Even this, as 
has already been suggested, is most often in a tentative, dia- 
lectical and hypothetical manner. 

Considered in relation to the physically real celestial bodies 

^^ St. Thomas, In Boeth. de Trin., q. 5, a. 3 ad 5. 

"^^Post. Anal., 1, c. 13, 79a2-3. St. Thomas, In I Post. And., lect. 25, n. 4; St. 
Albert, Lib. I Post. Anal, tr. Ill, c. 7. 

" St. Thomas, In I Post. Anal., lect. 25, nn. 4 & 6. 


and their movements, astronomy was recognized fully as hypo- 
thetical. The true causes of celestial motion are extremely 
difficult for any science to discover. " These matters into which 
we inquire are difficult since we are able to perceive little 
of their causes, and the properties of these bodies are more 
remote from our understanding than the bodies themselves are 
spatially distant from our eyes." ^^ Simplicius, and possibly 
Plato before him, was aware that the aim of astronomy is to 
give 3ome rational account of celestial phenomena, saving all 
the known facts {'X(i)(,eLv ra ^aivoixeva) .^"^ But as it turns out, 
all the known facts of astronomy can be explained by a variety 
of hypotheses. Of course, when a new fact is discovered which 
cannot be accomodated by the existing hypothesis, then some 
new hypothesis must be devised to account for the new fact. 
St. Thomas, commenting on the homocentric spheres of Plato 
and Eudoxus, observes: 

The hypotheses which they devised (adinvenerunt) are not neces- 
sarily true, for although the appearances are saved on the assump- 
tion of those hypotheses, one does not have to say that they are 
true, because the phenomena of celestial bodies may perhaps be 
saved in some other way not yet known to man.^'^ 

An astronomical hypothesis which accounts for all the known 
facts is indeed worthy of provisional credence. But every 
astronomical hypothesis by its very nature was considered by 
St. Thomas to be provisional and indemonstrative. Speaking 
of this type of reasoning, St. Thomas notes: 

Reasoning is employed in another way, not as furnishing an 
adequate proof of a principle, but as showing how the existing 
facts are in harmony with a principle already posited; as in astron- 
omy the theory of eccentrics and epicycles is considered as estab- 
lished, because thereby the sensible appearances of celestial move- 
ments can be explained; it is not, however, as if this proof were 

" St. Thomas, In II De caelo, lect. 17, n. 8. 

Cf. P. Duhem, " Sc^fetj/ ra ^aLPo/Meva. Essai sur la notion de theorie physique 
de Platon a Galilee," Annales de philosophie chretienne (Paris), 4 serie, VI (1908), 
113 ff., 277 flf., 352 ff, 482 ff., 561 ff. 

^' St. Thomas, In II De caelo, lect. 17, n. 2. 


[demonstratively] adequate, since some other theory might explain 

The tentative and hypothetical character of astronomical 
theories was commonly recognized from the thirteenth century 
onward, that is, after the acceptance of both Aristotle and 
Ptolemy in Latin translation. The homocentric hypotheses 
of Eudoxus and Callippus were taught in the faculty of arts 
together with the Ptolemaic hypotheses of epicycles and eccen- 
trics. The schoolmen frequently discussed the preferability of 
one over the other in their commentaries on Aristotle. 

This brings us to the second peculiar characteristic of astron- 
omy recognized in the Middle Ages, namely that mathematical 
astronomy was ordained to the discovery of true physical causes 
in nature. The mathematical character of astronomy was 
clearly evident to the schoolmen. But as mathematical, it 
abstracted from all questions of efficient, final and material 
causality; its concern was with the quantitative formalities of 
celestial phenomena related functionally to assumed mathe- 
matical principles. [Astronomi] non considerant motum caeles- 
tium secundum principia Tnotus, sed potius secundam numerum 
et mensuram quantitatis suae.^^ This being the case, one might 
have expected such an abstract science to be an end in itself, 
a purely speculative science sought for its own sake. In actual 
fact, however, this was not the view of Albertus Magnus, 
Thomas Aquinas or Robert Kilwardby. These three men, it is 
true, did not consider the functional use of astronomy in the 
same way, but they did consider astronomy to have a func- 
tional use in discovering real physical causes beyond quantity. 

In the Second Book of the Physics Aristotle had raised the 
problem concerning the relation between the mathematical 
sciences and natural science.-" Taking the case of astronomy, 
Aristotle posed the dialectic: astronomy is obviously a part of 
mathematics, but it is also a part of natural science since it 

^* St. Thomas, Sum. theoL, I, q. 32, a. I ad 2. 

" St. Albert, Lib. XI Metaph., tr. 11, cap. 10, ed. Borgnet (Paris: Vives, 1890- 
1899), VI, 628a. 
'" Arist., Phys. II, c. 2, 193b22-194al2. 


considers the sun, moon and stars; therefore mathematics also 
is a part of natural science. In reply Aristotle distinguished 
purely mathematical definitions from those of natural science; 
this is sufficient to establish the sciences as distinct. In confir- 
mation Aristotle pointed to the quasi-physical character of 
optics, harmonics and astronomy, which he called to, ^vo-tKajxepa 
Twv fiadrjixaTcov (Phys., II, 2, 194a7) . Modern translators give 
the more probable rendering of this phrase as " the more 
physical of the branches of mathematics." It was in this sense 
that Averroes (text. comm. 20) and St. Albert (ibidem) had 
understood the text, William of Moerbeke, however, rendered 
this phrase with equal grammatical correctness as magis physica 
quam matheviatica. This translation presented St. Thomas 
with the opportunity of explaining how astronomy, harmonics 
and optics pertain, in a certain sense, rather to natural science 
than to mathematics: 

Sciences of this kind, although they are intermediate between 
natural science and mathematics, are here described by the Philoso- 
pher as more natural than mathematical, because each thing is 
denominated and specified by its ultimate term; hence since investi- 
gation in these sciences terminates in natural matter, though by 
means of mathematical principles, they are more natural than 
mathematical. . . . Hence astronomy is more natural than mathe- 

Both St. Albert and St. Thomas recognized two tj^es of 
astronomy: mathematical astronomy, such as was studied by 
Eudoxus, Ptolemy and others, and physical astronomy, such as 
Aristotle discussed in the Physics and De caelo et mundo. This 
latter astronomy was considered an integral part of natural 
philosophy. Unlike mathematical astronomy, physical astrono- 
my attempts to discover all the physical causes of celestial 
phenomena, the ultimate efficient and final cause as well as the 
material and intrinsic formal cause. For Albert and Thomas 
physical astronomy alone indicates the real system of the uni- 
verse. The difficulties involved in discovering the real system 

" In 11 Phys., lect. 3, nn. 8-9. See also Sum. theol., II-II, q. 9, a. 2 ad 3. 


of the universe, the moving causes of celestial motion, their 
number and order, are obvious. Consequently this part of 
natural philosophy abounds with tentative views and argu- 
ments, having need of mathematical astronomy to suggest 
possibilities. Discussing the number of celestial movements, 
Aristotle himself realized the need of " that one of the mathe- 
matical sciences which is most akin to philosophy, namely of 
astronomy." ^" He was unable to determine the exact number 
of distinct celestial motions, but he tentatively adopted the 
astronomical hypotheses of Callippus minus eight uncertain 
motions, taking the number of spheres to be forty-seven. From 
this he argued that " the unmovable substances and principles 
also may probably be taken as just so many; the assertion of 
necessity must be left to more powerful thinkers." "^ That there 
must be many movements and movers was accepted by St. 
Albert and St. Thomas as certain, but their exact number was 
hypothetical and not essential to the argument pursued.^* 

In other words, for St. Albert and St. Thomas mathematical 
astronomy and the other physical parts of mathematics are 
considered as ordained to the discovery of physical causes in 
natural philosophy. The mathematical sciences are, as it were, 
the dialectical preparation for the real demonstrations in na- 
tural philosophy. Since all mathematics, even the more physi- 
cal parts of mathematics, prescind from motion and sensible 
matter,-^ they are that much removed from reality and need 
to be evaluated by that science which studies nature as it really 
exists, in Tuotu et inabstracta. That is to say, the mathe- 
matical sciences are subordinated to and ordained to the phi- 
losophy of nature. Consequently, " if there were no substance 
other than those which are formed by nature, natural science 
would be the first science." ^^ 

" Metaph., XII, c. 8, 1073b4-5. 
"/fete?., 1074al5-17. 

" St. Albert, Lib. XI Metaph., tr. II, c. 17 & c. 27; St. Thomas, In XII Metaph., 
lect. 9, n. 2565; lect. 10, n. 2586. 
"Boethius, De Trinitate, c. 2. 
''"Metaph., VI, c. 1, 1026a28-29, and XI, c. 7, 1064b9-10. 


Robert Kilwardby, on the other hand, represents a different 
tradition in medieval thought.-" His is the Platonic tradition of 
Robert Grosseteste, Pseudo-Grosseteste and Roger Bacon, 
which considered natural science ordained to the mathematical, 
and mathematics ordained to metaphysics. The Platonic hier- 
archy of the sciences was seen to correspond to a real priority 
of forms in nature, not, of course, existing apart from sensible 
reality, but within physical bodies. Thus motion and sensible 
qualities, the object of natural science, are radicated in the prior 
forms of pure quantity, the object of mathematics; the forms 
of quantity, in turn, are radicated in the prior form of nude 
substance, the concern of metaphysics. Kilwardby, discussing 
the four mathematical sciences, sees a perfect hierarchy of 
priority and dignity among the mathematical forms. The 
lowest of all the mathematical sciences is astronomy, for it con- 
siders celestial motion through the principles of geometry; hence 
astronomy is prior to and more abstract than natural science. ^^ 
Since discrete quantity is simpler and prior to extension, all 
the sciences which deal with number are prior to geometry. 
Among these the lower is the ideal harmony of numerical 
proportions; the science of numerical harmony, therefore, is 
prior to geometry.-'' The highest and most abstract of all the 
mathematical sciences is arithmetic, or algebra, quia ipsa ut 
sic, nulla aliarum indiget.^° Thus arithmetic, the sciences of 
pure number, is quasi mater aliarum [scientiarum].^^ But as 
Kilwardby failed to distinguish the numerical " unity " dis- 
cussed in mathematics from the entitative " unity " convertible 
with being, he said that it belongs to the metaphysician to 
explain the cause of plurality in mathematics.^" 

It may perhaps be a fair interpretation of Kilwardby 's mind 

"'' See my " Albertus Magnus and the Oxford Platonists," in Proceedings Am. 
Cath. Phil. Assoc, XXXII (1958), 124-139. 

^** Kilwardby, De ortu scientiarum, cap. 16 ad 1. Meiton College, Oxford, MS 
261, fol. 25v. 

^* Ibid., cap. 24 ad 4, fol. 32ra. 

*Ubid., cap. 19, fol. 27va. 

'^Ibid., cap. 22, fol. 28vb. 

^'^Ibid., cap. 24 ad 1, fol. 29rb; also cap. 14 ad 2, fol. 24vb. 


to say that if there wefe no metaphysics, arithmetic would be 
the supreme universal science. This contrast, however, with 
the view of St. Albert and St. Thomas is not perfectly symetri- 
cal, since Kilwardby did not consider metaphysics to rest on 
the real existence of " substance other than those which are 
formed by nature." Nevertheless a clear contrast can be seen 
between the Platonic orientation upward from nature to mathe- 
matics and the Aristotelian orientation subordinating mathe- 
matics to natural philosophy. St. Albert and St. Thomas both 
defended the autonomy of natural science within the limits of 
its own piincipia propria illuininantia, distinct from meta- 
physics and superior to mathematics.^^ 

The third peculiar characteristic of astronomy recognized in 
the Middle Ages was the special role it had in the discovery of 
God's existence. This characteristic was not entirely new. In 
pagan mythology the celestial bodies were themselves con- 
sidered gods or at least the inhabitation of the gods. Pagan 
philosophers such as Plato and Aristotle did not hesitate to call 
celestial bodies divine. Ptolemy himself saw in astronomy the 
only secure path to theology: 

For that special mathematical theory would most readily prepare 
the way to the theological, since it alone could take good aim at 
that unchangeable and separate act [God], so close to that act are 
the properties having to do with translations and arrangements of 
movements, belonging to those heavenly beings which are sensible 
and both moving and moved, but eternal and impassible.^ 


Al-Bitruji, St. Albert frequently points out, had this advantage 
over the complicated system of Ptolemy that he considered 
all celestial motions to be derived from a single first mover, who 
is God.^^ For Kilwardby the path to God rose more tortuously 

''^Cf. J. A. Weisheipl, " Albertus Magnus and the Oxford Platonists," ed. cit., 
pp. 136-139. 

^* Ptolemy, Almagest, Bk. I, chap. 1, trans, by R. C. Tahaferro (Great Books of 
the Western World, 16; Chicago, 1952), p. 6. 

^^ Al-Bitruji, De motibus celorum, III, 10-14, trans, by Michael Scot, ed. Francis 
J. Carmody (Berkeley: Univ. of California, 1952), pp. 79-80; St. Albert, Prob- 
Jeviata Determinata, q. 1, ed. cit., p. 321; Liber de causis, I, tr. IV, c. 7, ed. 
Borgnet X, 426b-427b; lib. II, tr. II, c. 1, ed. Borgnet X, 479b-480a et alibi. 


from nature through astronomy, geometry, harmonics, arith- 
metic to the One of metaphysics; for him the proper subject 
of metaphysics is God precisely as the first cause of all plurality, 
material and immaterial .^^ 

St. Albert's view of the matter is most interesting. Through- 
out the Metaphysics and Liber de causis St. Albert repeatedly 
rejected the " Platonic view " which would admit into philoso- 
phy certain separated substances totally unrelated to celestial 
movement. " The statement of certain Platonists that there 
exist separated substances not related to movable bodies, is 
entirely outside the realm of philosophical discourse, since this 
cannot be proved by reason." ^^ The separated substances 
called angels by Avicenna, Algazel, Isaac and Moses Maimoni- 
des have nothing to do with celestial movement or with celestial 
bodies; they are independent intermediaries between God and 
man. For Albert the only demonstrative way to separated sub- 
stances and to God is through the study of celestial motions. 
Consequently not only are angels, as revealed in Sacred Scrip- 
ture, outside philosophical discussion, but the intellectus uni- 
versaliter agens of celestial motions can be none other than 
God. That is to say, the first cause of the primum mobile and 
its diurnal motion is God, and not an intermediary. That God 
is " the immediate natural mover " of the universe in its 
diurnal motion is taken by St. Albert as true and demonstrated 
among those who know anything about philosophy .^^ 

Whatever modern Thomists may have to say about the 
famous quinque viae of St. Thomas, it cannot be denied that for 
Thomas all the proofs progress from terrestrial phenomena 
through celestial phenomena eventually to God. The question 
of angels in St. Thomas' philosophy will be considered later. 
For the present it is important to establish only that in St. 
Thomas' proofs celestial phenomena do have an important 
part to play. This is not to say that the validity of those proofs 

Cf. Kilwardby, De ortu scientiarum, cap. 26, fol. 32rb-va. 
''' St. Albert, Liber XI Metaph., tr. II, c. 17, ed. Borgnet VI, 638a; cf. Proble- 
mata determmata, q. 2, ed. cit., pp. 323-327 

** St. Albert, Problemata determinata, q. 5, ed. cit., p. 328. 


depend upon the antiquated astronomy of the Middle Ages. 
The principle of each proof has universal validity and the line 
of argumentation transcends all astronomy, ancient, medieval 
and modem. Nevertheless to see the proofs as St. Thomas saw 
them, it is necessary to accept, at least historically, the system 
of the universe as he understood it. 

There can scarcely be any doubt that St. Thomas' first proof 
is derived historically from Aristotle's Physics and Meta- 
physics. This is clearly evident in the detailed analysis pre- 
sented in Summa contra gentiles, I, c. 13, where Aristotle is 
explicitly cited as intending to prove the existence of God ex 
parte motus duabus viis. The first way is a paraphrase of 
Phys. VII, c. 1 to VIII, c. 5, text. 35; the second corresponds to 
Phys. VIII, c. 5, text. 36, to the end. The first starts mth the 
example of solar movement and ends disjunctively with Plato's 
self-mover of the first sphere or Aristotle's separated mover of 
the whole. The second starts with various types of self-movents, 
showing how all must be reduced to some primum movens se 
quod sit sempiternum, and ends with God as a self-movent. 
" But since God is not a part of any self-movent, Aristotle in 
his Metaphysics further discovers from this mover which is a 
part of a self-movent, another mover entirely distinct, who is 
God." Two objections to the Aristotelian argument are easily 
handled. The first, that it assumes the eternity of motion con- 
trary to the Catholic faith, is shown to be irrelevant, for it 
makes no difference whether or not motion is eternal; there is 
still need of an adequate mover. The second, that Aristotle 
assumes the animation of celestial bodies contrary to the view 
of many, is likewise shown to be irrelevant, for even if the celes- 
tial bodies are animated, one must still conclude according to 
Aristotle's principles to an unmoved mover entirely separated 
from bodies. A simplified form of this manifestior via is the 
only one presented by St. Thomas in his Compendium theo- 
logiae for Brother Reginald of Pipemo. 

The involvement of celestial bodies in the other proofs for 
God's existence is not so patent in the text of St. Thomas. 
However, it ought to be obvious that the argument from effi- 


cient causality includes the universal agency of celestial bodies 
operating in elementary bodies and in animal reproduction: 

Even among naturalists it is admitted that above those contrary 
agencies in nature there is a single first agent, namely the heaven, 
which is the cause of the diverse motions in those lower bodies. 
But since in the very heaven there is observed a diversity of posi- 
tion to which the contrariety of lower bodies is reduced as to a 
cause, [this diversitj^] must further be reduced to a first mover who 
is moved neither 'per se nor per accidens.^^ 

Similarly the argument from possible and necessary beings 
includes not only terrestrial necessities and contingencies, but 
also the sempiternal celestial bodies and spiritual substances, 
which are radically necessary beings. Their necessity for being 
can, indeed, be seen as derived; therefore beyond them there 
must exist an absolutely necessary being whose necessity is in 
no way derived. *° The Platonic, or more specifically, the Avi- 
cennian *^ argument concerning perfections clearly includes the 
immutable celestial bodies in the participated inequality of 
being and goodness, an inequality which needs to be derived 
from a single source which is essentially being, goodness and 
supreme perfection. The fifth argument likewise includes the 
influence of celestial bodies and separated intelligences on 
natural operations.*" Natural terrestrial operations, influenced 
by celestial motions, the light and heat of the sun, are appar- 
ently purposeful operations of nature; all such operations of 
nature require the direction of intelligence {cypus naturae est 
opus intelligentiae) . 

Historically, then, the five proofs of St. Thomas for the exist- 
ence of God involve celestial bodies and their movement as 
he understood them. Therefore a careful consideration of celes- 
tial phenomena in the physics of St. Thomas is not without 

^* St. Thomas, De pot., q. 3, a. 6. 
*° St. Thomas, De pot., q. 5, a. 3. 
*^ De pot., q. 3, a. 5. 

*'' De verit., q. 5, a. 2; Sum. contra gentiles, I, cap. 13. Cf. Averroes, In II Phys., 
comm. 75. 


value to the modern Thomist, however much the modern 
Thomist may wish to adapt the traditional arguments. 

To understand the problem of celestial movers in medieval 
physics, it is necessary to present the views of Albertus Magnus 
and then those of Robert Kilwardby before examining the cru- 
cial problem in the doctrine of St. Thomas. 

St. Albert the Great 

For St. Albert both physics and metaphysics attain the 
existence of God, but under different formalities and in different 
ways. Physics, although it demonstrates through all the real 
causes in nature, is primarily concerned with the efficient and 
material cause: " if we have said anything about the form or 
about the end [in physics], this was only of form insofar as it is 
mobile and of end only insofar as it is the termination of the 
motion of a mover." " But metaphysics deals with substantial 
being and its causes; therefore in metaphysics " we directly 
show that the first efficient cause is the universal end, that 
from him flow all mobile substances, and that he is like a leader 
of an army with respect to the universe." ** This task is proper 
to metaphysics, and in this respect nothing is borrowed from 
natural science. It is true that natural science proved by way 
of motion the absolute immobility of the first mover, but it did 
not reveal him prout ipsum est causa universi esse et forma et 
finis. This is proper to metaphysics. Hence, Albert concludes, 
it is evident that metaphysics is a loftier contemplation by far 
than physics. 

The task of physics is to explain all changes in nature, both 
terrestrial and celestial. Terrestrial movements, alteration, 
generation and corruption can be explained in large measure 
by the celestial bodies, but since these celestial bodies them- 
selves are moved, the ultimate source of this movement must 
itself be immovable. This ultimate unmoved mover, proved 
in the Physics, is considered by St. Albert to be God, the 

" St. Albert, Lib. XI Metaph., tr. I, c. 3, ed. cit., VI, 584b. 
" Ibid. 


Christian God. But the approach is different in metaphysics. 
Since the term of terrestrial movement and alteration is 'per se 
the generation of a substantial being/^ and since the substantial 
being of the very heavens must be produced, beyond the physi- 
cal universe there must exist a pmicipium universi esse, who is 
the efficient source of being, the formal principle of all being, 
and the universal end of all things.*'' Hence it belongs to both 
physics and metaphysics to consider celestial phenomena and 
God, but physics considers these through the principles of 
motion {secundum pnncipia motus) , while metaphysics con- 
siders these through the principles of being (essendi) . In other 
words, the natural philosopher arrives at the existence of God 
as the first mover, but the metaphysician arrives at His exist- 
ence as the efficient cause, the formal principle and the ultimate 
end of all being. 

This does not mean, Albert points out, that the metaphysi- 
cian gives the propter quid reason for changeable substance, and 
the physicist the quia, as some would have it. " For if the 
physicist borrowed from the metaphysician, it would follow 
that physics is subalternated to first philosophy, which from the 
opening pages of this science we have shown to be false." *'' 
Thus physics and metaphysics are each autonomous sciences 
with special principles of investigation proper to each. How- 
ever, unless it is first demonstrated in physics that there exists 
some real separated substance, there is no need for the sub- 
sequent investigation called metaphysics. The Platonists, 
Albert repeatedly points out, postulated ideas and mathe- 
matical entities separate from matter in order to explain 
sensible being; but these cannot exist apart from matter, and 
if they did, they could not be responsible for motion in the 
universe.*^ Therefore if some separated substance exists to be 
studied in metaphysics, this substance can be demonstrated 



St. Albert, Lib. VIII Pkys., tr. II, c. 4, ed. cit.. Ill, 572a. 

St. Albert, Lib. XI Metaph., tr. I, c. 3, ed. cit., VI, 584b-585a. 
" Ibid. 

" St. Albert, Lib. XI Metaph., tr. I, cc. 4 & 8; lib. 1, tr. V, cc. 8, 12 & 14; lib. 
VII, tr. II, c. 3, et alibi. 


only as the cause of motion, specifically as the cause of celestial 

St. Albert accepted the order of celestial spheres commonly 
taught by the Arabian astronomers. The spheres were con- 
sidered generically to be ten in number: the primum mobile 
causing diurnal movement of the whole universe, the sphere of 
fixed stars, the spheres of Saturn, Jupiter, Mars, the Sun, 
Venus, Mercury, the Moon, and the terrestrial sphere of active 
and passive elements.*^ It was well understood by all that each 
so-called sphere was subject to many distinct motions, each of 
which required some kind of mover. But it was simpler to 
talk in terms of the clearly visible planets, the fixed stars and 
the unseen cause of diurnal motion, than in terms of the precise 
number of celestial motions postulated to save the appearances 
of each planet. Similarly, it was understood among the better 
informed that the notion of " sphere " was postulated to 
regularize the errant motions of the planets and to give intel- 
ligibility to their complicated movements. Those spheres were 
no more " solid," contrary to some modern interpretations, 
than the familiar sphere of terrestrial change. 

In the view of Avicenna each sphere was moved and ruled 
by a separated substance, whatever may have been the number 
of distinct movements required for each planet. It is within 
this context that St. Albert discusses the problem of celestial 
movers. But Avicenna further identified those intelligences and 
the proximate mover {anima nobilis) with angels .°° St. Albert, 
as has already been noted, was unwilling to identify the sepa- 
rated substances of the philosophers with the angels of Sacred 
Scripture. Further, the tenth intelligence for Avicenna was the 
intellectus agens hominum, which ruled the terrestrial realm of 
mutable substances by infusing forms from without. This dator 
formarum was invoked by Avicenna to explain the apparent 
generation of new substances in the world of nature. St. Albert 

*' St. Albert, Problemata determinata, q. 2, ed. cit., p. 324; see ibid., note 9. 

'° An excellent discussion of this has been given by Henry Corbin in his 
Avicenna and the Visionary Recital, trans, by W. R. Trask (New York: Pan- 
theon, Bollingen Series 66, 1960), pp. 46-122. 


repeatedly rejected the Avicennian innovation with sound 
Aristotelian arguments, which need not concern us here. 

The real problem for St. Albert was the obvious difference 
between terrestrial changes arising from nature and celestial 
motions which could not arise from nature. The term " nature " 
is a technical one and it designates that " principle of motion 
and rest in those things to which it belongs properly {per se) 
and not as a concomitant attribute (per accidens) ," " Tech- 
nically it was contrasted with soul {anima, ^vxr]) and with 
intelligence (intelligentia, vov<;) , particularly in Platonic and 
neo-Platonic writings; and it was also contrasted with art 
{ars, Texvy]) and with chance (casus, avroixaTov) by Aristotle. 
Nature as an intrinsic principle always acts in a determined 
manner for a predetermined end.^^ This nature must always be 
efficiently produced by some generator of the form. Once this 
natural form has been generated by an efficient cause, that 
nature spontaneously moves toward the unique end propor- 
tioned to it and rests in the possession of the end. " Hence 
place and motion are given by the generator just as the form is, 
but the form is given principally, while place and motion are 
given per consequens, just as proper accidents are given to the 
form by generation." °^ Moreover, strictly speaking, " nature " 
designates the internal power of inanimate substances {natura 
non est nisi virtus inanimatae suhstantiae) .^* Finally, nature 
is a source of individual attainment, and not of transient ac- 
tivity. Hence " locomotion is never derived [efficiently] from 
nature as ' the principle of motion and rest in those things to 
which it belongs properly and not concomitantly,' as defined 
by Aristotle in Physics II; for which reason, as we have said, 
locomotion must be derived either from the generator or from 
one removing an impediment or from a soul." ^^ In other words, 

"Aristotle, Phijs., II, c. 1, 1921b21-23. Cf. James A. Welsheipl, "The Concept 
of Nature," in The New Scholasticism, XXXVIII (1954), 377-408. 
" Cf. Albert, Lib. VIII Phys., tr. II, c. 4, et passim. 
^^ Ibid., ed. cit.. Ill, 572a-b. 

" St. Albert, Lib. XI Metaph., tr. I, c. 13, ed. cit., VI, 604. 
^° St. Albert, Problemata determinata, q. 2, ed. cit., p. 325. 


since celestial motions do not attain any end, these motions 
cannot arise spontaneously from the nature of celestial bodies. 
For St. Albert, as for Plato and Aristotle before him, celestial 
motions must be derived immediately from some kind of soul, 
or self-mover. 

Comparing the views of Plato and Aristotle,^® Albert notes 
that both agree on three points: (i) that all natural motions 
must be reduced to some self-movent; (ii) that a celestial body 
cannot move itself, but must be moved by a spiritual substance 
which is either a soul or an intellect; (iii) that the spiritual 
mover of the body must itself be indivisible, without magni- 
tude, possessing adequate power to move the celestial body. 
However, Albert notes, Plato and Aristotle differ on two essen- 
tial points: (i) Plato considered the conjoined mover to be the 
ultimate mover, while Aristotle considered this soul to be the 
instrument of a higher intellect entirely separated from all mat- 
ter; (ii) Plato considered the celestial soul to be perpetual and 
descendent from the stars, while Aristotle conceived the con- 
joined mover to be produced by the separated intellect and 
moved by it. In other words, Aristotle, according to St. Albert's 
understanding, admitted a conjoined mover for each celestial 
motion, a mover which was somewhat similar to a spiritual, 
intellectual soul, but without sense faculties. This conjoined 
mover explained how a celestial body like the primum caelum 
could be moved perpetually without attaining any end or 
finality intrinsic to itself. However, the conjoined mover itself 
was moved by reason of the celestial body; that is, the anima 
caeli moved concomitantly {per accidens) with the celestial 
body, much as the human soul is moved by the movement of 
the body. Therefore, the anima caeli is a moved mover, needing 
to be moved by another, a substance entirely separated from 
matter not only in definition, but also in existence. The spirit- 
ual anima caeli can be moved only by intellection and desire. 
The initial intellectual light emanating from the subsisting act- 

^» St. Albert, Lib. VIII Phys., tr. U, c. 8. 


ing intellect, giving the soul the idea and the desire to move, 
is the true immediate mover of the universe. 

As St. Albert understands it, when Aristotle speaks of the 
heavens or the celestial bodies, he usually means the composite 
of soul and body, mover and moved; the heavens are for Aris- 
totle animated substances {substantiae animatae) . While it 
is easier to talk of the sun as though it were a simple substance, 
the movement of the sun is complex and due to many animated 
substances. For Aristotle at least the diurnal, longitudinal and 
latitudinal motions are distinct; each of these is caused by an 
animated celestial body. Ultimately these motions of the sun 
and all other planetary motions are due to the diurnal motion 
of the entire universe, the primum caelum, the first animated 
cause of the universe. 

Now the animated substance is the cause not only of inanimate 
substances, but also of their order and motion. According to the 
teaching of the Peripatetics, this animated substance is the corpus 
caeli. Moreover, it was shown in Book VIII of the Physics that the 
first mover, which is a composite of mover and moved, or pushed, 
is the first heaven (primum caelum.) . In this manner it was there- 
fore shown that the animate precedes the inanimate. We have 
likewise shown in that same place at the end of Book VIII of the 
Physics, first that the first mover is absolutely simple, and that this, 
since it is related to the first body as its mover, unquestionably will 
have the character of soul, and not nature (pro certo habebit 
rationem animae et non naturae) , because nature never moves that 
body whose nature it is according to local motion.^^ 

Plato, according to St. Albert, stopped here with the anima 
mundi as God, but Aristotle realized that each soul, since it is 
moved along with the body, must be moved by the desire for 
some absolutely separated intelligence. Thus for Aristotle the 
separated intelligence known and desired by the first animated 
mover is the actual source of all physical movement and the 
ultimate end of every celestial motion. There is, in other words, 
a hierarchy of intelligences proportioned to the various orders 
of animated substances. There is, for example, at least one illu- 

■*' St. Albert, Lib. XI Metaph., tr. I, c. 13, ed. cit., VI, 604b. 


minating intellect for all the animated movers of Venus, another 
for Jupiter, and so forth. The highest separated intelligence is 
the true immediate mover of the entire universe, the primum 
caelum. The mind and will of God are obediently accepted and 
executed by the animated substances, who consequently move 
as moved movers. 

When discussing this matter on his own terms, St. Albert 
prefers to keep three elements distinct: the celestial body, the 
soul-like mover, and the separated intelligence. The reason 
for this is that Albert could not accept Aristotle's concept of 
celestial " souls " as the substantial form of the body. For 
Albert these " souls " could not be the substantial form of an 
inorganic, insensitive body, such as the moon and sun; this kind 
of body would be entirely useless for intellectual processes. 
Consequently these " souls " move the body only as an efficient 
cause, not as a formal cause.^^ In his early work, the Summa 
Parisiensis, Albert was willing to reconcile Aristotle's " souls " 
with the Catholic doctrine of angels."^ Later, however, Albert 
became most insistent that the angels of revelation should not 
be identified with celestial souls or intelligences. According to 
Giles of Lessines, a disciple of St. Albert, Haec est 'positio 
multorum viagnorum et praecise domini Alberti quondam 
Ratisponensis episcopi, oh cuius reverentiam rationes prae- 
dictam positionem confirmantes addidimus.^° Albert's strong 
views distinguishing angels from intelligences and souls were 
shared by Theodoric of Freiberg, another disciple of his.®^ The 

^^ " Nos cum Sanctis confitemur caelos non habere animas, nee esse animalia, 
si anima secundum propriam rationem sumatur. . . . Operatur autem ad corpus 
ut nauta ad navem, hoc est, secundum rationem movendi ipsum et regendi." 
Summa de creaturis, tr. Ill, q. 16, a. 2, ed. Borgnet XXXIV, 443a. In this edition 
" natura " is erroneously printed for " nauta." 

^' " Ita non est contrarium fidei quosdam angelos iuvare naturam in movendo 
et gubernando sphaeras caelorum, quos Angelos moventes sive intelligentias Phi- 
losophi dicunt animus." Ibid., ad 6, p. 445b. 

*° Giles de Lessines, De unitate formae, P. II, c. 5, ed. M. de "Wulf in Les 
Philosophes Beiges, I (Louvain, 1902), p. 38. 

®^ " Est autem et hoc circa iam dicta tenendum, quod dicti philosophi, loquentes 
de mtelligentiis, non loquebantur de angelis, de quibus scriptura sacra loquitur, 
quae loquitur mysteria abscondita a sapientibus et prudentibus et revelat ea par- 


reason for Albert's view is clearly stated in the reply to John 
of Vercelli's questionnaire: the separated intelligence known 
to philosophers is entirely immobile locally, nee mittitur nee 
venit nee reeedit^- This is entirely contrary to what we know 
of Gabriel, Raphael and Michael according to the Scriptures. 
Further, the separated intelligence is known to philosophers 
solely as the cause of celestial motion and of inferior forms, 
while the angels of Scripture are the messengers of God, a 
function which cannot be proved by natural reason.*^' 

To understand St. Albert better, we must consider celestial 
motion itself and its three distinct causes, namely the body, the 
soul-like mover, and the separated intelligence. 

St. Albert clearly insists throughout all his writings that 
celestial motion cannot be accounted for by the nature of the 
celestial body. That is to say, perpetual motion of the spheres 
cannot originate spontaneously from " nature " as from a 
formal principle. Scholastic philosophy, following Aristotle, 
distinguished two uses of the technical term " nature." ®* The 
primary and principal use of the term was to designate an 
intrinsic active source of regular, teleological activity and at- 
tainment; nature in this sense was called a formal principle, 
since form is the ultimate source of these activities. In a 
secondary and analogical sense the innate, passive receptivity 
for the form could also be called " nature," since potency is a 
true principle of change; nature in this sense was called a 
material or passive principle. For St. Albert none of the char- 
acteristics of nature as a formal principle could be verified in 

vulis." Theodoric of Freiberg, De intellectu et intelligibili, P. I,cap. 12, ed. E. Krebs 
in Beitrdge z. Gesch. d. Phil. d. M.-A., Bd. V, heft 5-6 (Miinster, 1906), pp. 132*- 
133*. Cf. ibid., P. II, cap. 34, pp. 164-165*. I am grateful to Fr. William A. 
Wallace, O. P., for allowing me to utilize his transcription of Theodoric's De intelli- 
genciis et motoribus celorum and De corporibus celestibus quoad naturam eorum 
corporalem from MS Vat. lat. 2183. 

^'^ St. Albert, Problemata determinata, q. 2, ed. cit., p. 323. 

"^ Ibid., q. 5, ed. cit., p. 328. 

'* Cf. J. A. Weisheipl, " The Concept of Nature," loc. cit. above in note 51 and 
reprinted in Nature and Gravitation (River Forest: Albertus Magnus Lyceum, 
1955), pp. 1-32. 


celestial motions. Nature as a formal principle always moves 
toward a determined end, and when it has attained it, rests in 
that attainment. " The reason for this is that nature does not 
cause local motion except 'per consequens, for in moving toward 
the form it consequently moves to the place which belongs to 
its form." In the celestial motions there is never any attain- 
ment and possession. " The mover of the heaven never moves 
to any position, but to move out of it again. But to move into 
a position and to move out of it again is not from nature, but 
from soul." ^^ For this reason Albert frequently insisted that 
celestial motions are not from nature, but from intelligence 
(caeli motus non dicitur naturae motus, sed intelligentiae) .^^ 
Albert undoubtedly would have admitted that celestial motions 
are " natural " in the sense of coming from a passive principle, 
the celestial body. But invariably he prefers to deny the natural 
character of celestial motions, insisting always that they are not 
from nature, but from soul or intelligence. Precisely because 
the body itself is not the source of its perpetual movement, 
it is said to be moved. " Everything which is moved has a 
mover conjoined to itself, as was proved in the Seventh Book of 
the Physicsr " 

The nature of the conjoined mover is difficult to determine 
in the wi'itings of St. Albert, largely, no doubt, because Albert 
retained the Aristotelian terminology while denying the sub- 
stantial union of the two " parts " of the sphere. The con- 
joined mover is clearly a spiritual substance, indivisible, and 
separated from all matter, at least in definition .^^ It moves the 
body by its knowledge and desire of something higher.®^ " Since 

*^ " Adhuc autem natura non movet nisi ad unum, et cum pervenerit, quiescit in 
illo. Cuius causa est, quia natura non est causa motus localis nisi per consequens: 
movendo enim ad formam, per consequens movet ad locum qui est illius formae. 
Motor autem caeli non movet unquam ad aliquem situm, nisi moveat etiam ex illo. 
In aliquid igitur movere et ex iUo non est naturae, sed animae." St. Albert, Lib. XI 
Metaph., tr. I, c. 13, ed. cit., p. 605b. 

** St. Albert, Lib. II Phys., tr. I, c. 2, ed. cit., p. 95b. 

" St. Albert, Lib. XI Metaph., tr. II, c. 3, ed. cit, p. 614a; see Lib. VII Phys., 
text et comm. 10. 

«' St. Albert, Lib. XI Metaph., tr. II, cc. 12-13. 

'"Ibid., c. 13, ed. cit., p. 605a. 


every motion of the heaven is according to the form which is in 
the intellect, as the artistic idea is in the mind of the artist, so 
in the intellect of the mover there is the image to be effected by 
its motion; otherwise its motion would be unintentional, a 
chance result and an accident." ^'^ At times St. Albert does call 
this conjoined mover a " soul," particularly the anima nohilis 
of the Liher de causis (prop. 3) . But more frequently he con- 
ceives the mover as a luminous form of intelligence and desire, 
produced by the separated intelligence. " Since the intelligence 
by its light produces every form in its sphere and order, and 
since those forms are its light {lumen) and this light desires 
to produce beings in existence {luTuen desiderans ad esse de- 
ducere) , the proximate mover of the orb moves the orb and by 
moving produces forms in existence." ^^ The conjoined mover, 
therefore, is an intelligent form, but not the " soul " of the 
sphere. " Thus it is evident that the intelligence is not an angel; 
and if it were, it would still not be the proximate mover of any 
celestial sphere." ^^ 

It is important to note that for St. Albert the luminous 
forms, the conjoined movers of celestial bodies, are the true 
causes of everything which is produced within that sphere. 
That is to say, the luminous form, obedient to a higher intelli- 
gence, is the active principle of such mysterious phenomena 
as animal reproduction, and the spontaneous generation of 
living things from inanimate matter." " Every lower motion 
which is in the matter of generable things is reduced to the 
motion of the heavens, which is the cause and measure of lower 
motion by means of (i) the form of the moving intelligence, 
(ii) the form of the celestial orb, and (iii) stellar rays." '* The 
active powers of light, heat, conjunctions of the planets and 
stars are, for St. Albert, instrumental causes of the celestial 
forms whereby the natural powers of the elements can be pro- 

'» Ihid. 

'^ St. Albert, Problemata determinata, q. 2, ed. cit., p. 327. 

" Ibid. 

" St. Albert, Lib. XI Metaph., tr. I, cc. 6 & 8. 

Ibid., c. 8, ed. cit., p. 594a; cf. Problemata determinata, qq. 7-15 and qq. 34-36. 


ductive of higher forms. One can say that these higher forms 
produced preexist in the elements virtually insofar as these 
elements are instruments of celestial movers. Of course, the 
celestial mover is itself a voluntary, intellectual instrument of 
the absolutely first intelligence, which is God. Similarly the 
male sperm virtually and actively contains the living and sen- 
tient souls of the embryo, but only as the instrument of celes- 
tial forces and intelligences. In other words, the natural heat, 
density, mobility and structure of the male sperm are used 
instrument ally by celestial agents to produce an effect higher 
than their own active powers. ^^ It was in this way that St. 
Albert understood and explained the famous Aristotelian 
phrase. Homo ex materia generat hominem et sol. (Phys. II, 
2, 194bl3) .''^ The only qualification which Albert, the phi- 
losopher and theologian, makes to this phrase is the direct 
creation of the human soul.'^ 

Finally, for Albert, the separated movers of celestial bodies 
are the active intelligences {intellectus agens) . Each intelli- 
gence is like a practical intellect of an artist who conceives the 
image to be produced and implants this in his instruments as 
he uses them. The instruments of the active intelligence are 
three-fold, namely the conjoined spiritual mover, the celestial 
body itself, and the inherent powers of terrestrial nature. Con- 
sequently the ultimate mover of each celestial body is, in fact, 
the separated active intelligence proportioned to the spheres. 
Since, however, all celestial spheres depend upon the diurnal 
motion of the first heaven, the absolutely first mover of all the 
celestial bodies is the separated, active intelligence command- 
ing the primum caelum. This absolutely first mover is the 
primum principium universi esse, the cause not only of all 

7« " 

' St. Albert, Problemata determinata, q. 34; De animalibiis XVI, tr. I, cc. 11-13. 
' Quod enim impressiones separatorum a materia generabilium sint in materia 
patet per hoc quod ex materia hominis homo generat hominem, et sol et motor 
solis; et ideo oportet considerare separata in quantum impressiones earum per 
motum caelestium sunt in generabilibus et corruptibilibus." St. Albert, Lib. 11 
Phys., tr. I, c. 11, ed. cit., pp. 113-4. See Averroes, ibid., comm. 26. 

''"' Problemata determinata, q. 33; De nat. et orig. animae, tr. I, c. 5; De animxi- 
libus, lib. XVI, tr. I, cc. 11-12; Summa de creaturis, P. II, q. 5, a. 4. 


motion, but also the absolute efficient cause, formal principle 
and ultimate end of all being. He produces not only the hier- 
archy of conjoined celestial movers, their bodies and motion, 
but he is also the first efficient cause, formal principle and final 
end of each intelligence. The first principle of universal being 
is commonly designated by St. Albert as the intellectus univer- 
saliter agens, who, as has already been noted, is God Himself. 
As first mover of the heavens He is attained in natural science; 
as first cause of being He is attained in metaphysics. 

Once Albert has established in his reply to the Master 
General that angels are not the same as intelligences discovered 
by the philosophers, he can easily dismiss the first five ques- 
tions as fatuous. The existence of angels, the messengers of 
God, cannot be proved in philosophy; they have nothing to do 
with problems of natural science; and even if God were not 
the first mover of the heavens — which He really is — the exist- 
ence of angels would still not be demonstrated. God, for St. 
Albert, is the first cause of celestial motions, not as a form 
conjoined to the universe, but as a separated active intelligence 
commanding the motions of all, " since Aristotle says that the 
first cause moves the first heaven, to the motion of which all 
motions of celestial bodies are referred, as all movements of 
organic members are referred to the movement of the heart." ^^ 
The only body which God moves immediately as conjoined 
to Himself is the body of Christ, joined hypostatically to the 

Robert Kilv^ardby 

The approach of Kilwardby is very different from that of St. 
Albert. Kilwardby, in fact, reflects much more the schools of 
Oxford than those of Paris, despite his own regency in arts at 
Paris (c. 1237-c. 1245) . He had been a Master in Theology of 
Oxford about fifteen years when he was asked to reply to the 
questionnaire of John of Vercelli. We cannot be certain that 
Kilwardby always maintained the views presented in the reply 
of 1271, but we can be certain of his views at that date. 

''^ Problemata determinata, q. 1, ed. cit., p. 321; cf. Aristotle, De caelo et mundo, 
II, c. 2, 284b6-286a2. 


Replying to the first question, Kilwardby explicitly denies 
that God is the immediate mover of the heavens moving either 
eternally or temporally in place: certissime tenendum est et 
asserenduTn quod Deus non movet "priraum caeluTn nee aliquod 
corpus immediate motu localiJ^ He admits that Aristotle 
seems to consider God as the first mover of the eternal spheres, 
" but the truth is that God does not move any body immedi- 
ately " by continual locomotion. If God did move any body 
in this way, He would be either the substantial act of that body 
and a part of the whole or a simple mover like a man on a horse. 
The first alternative is obviously erroneous. The second is 
awkward and unreasonable for it implies that the first heaven 
is moved by violence: secundo modo caelum primuTn videre- 
tur moveri violenter. Kilwardby, however, does admit that 
God can and does move bodies immediately by a certain 
supernatural change, as in creation, the production of light, 
the formation of Eve and similar events. In such events God 
operates without the assistance of nature or angels. Concluding 
his reply to the first query, Kilwardby categorically states: 

From these considerations, therefore, the reply to the question 
must be that God moves no body immediately by continuous 
motion, but only by His word when a body is changed instan- 
taneously so that something supernaturally begins to exist. 

The second question has to do with natural motions and their 
dependence on angelic movers of the celestial bodies. Kil- 
wardby first distinguishes between natural and violent motions. 
Nature is an intrinsic principle of motion; only bodies which 
have such a principle per se are said to move naturally. Mo- 
tions are called violent when their moving force is extraneous, 
the subject contributing nothing to the motion (quando prin- 
cipiwm motivum est extraneum, passo non conjerente) . Among 
natural motions Kilwardby enumerates continuous movement 
of bodies, instantaneous transmission of light, the irascible and 
concupiscible emotions of spiritual beings, and intellectual ac- 
tivity. Clearly, intellectual and appetitive activities of spiritual 

''^ Kilwardby, Responsio, q. 1, ed. Chenu, loc. cit., p. 194. 


beings are not affected by celestial movement; rather, such 
spiritual activities are productive of celestial motion. 

There are for Kilwardby two types of celestial motion. The 
first emanates from celestial bodies in the form of energy and 
light rays affecting all the active and passive powers of ter- 
restrial bodies, both elementary and composite. This cosmic 
influence is produced by the celestial bodies, but the influence is 
subjectively located in terrestrial bodies. " And perhaps if this 
influence of light and energy were withdrawn from elements 
and composites, all active and passive powers of bodies would 
cease to act or react; hence this influence seems to be the 'per se 
cause of natural activity and movement in the elements." ^'^ 
There is, however, another motion located in the celestial body 
itself; this is the continual rotation of the sphere. Kilwardby 
does not consider this rotational movement of the spheres to 
have any direct or proper bearing on natural terrestrial motion. 
Such motions do provide variations of temperature, humidity 
and the like, but this is secondary to the direct cosmic influence 
affecting natural changes. 

Finally Kilwardby proceeds to discuss the crucial question 
of celestial movers. He notes that there are three opinions 
concerning the motion of celestial bodies. The first is that of 
Aristotle and certain other philosophers. Kilwardby 's inter- 
pretation of Aristotle's view is essentially that of St. Albert: 
" celestial bodies are animated, having animal life and intelli- 
gence by which they perceive the will of the first cause, and 
motion in place by which they fulfill the known will of God; 
by this motion of theirs they conserve things and preserve 
generation and the limited being of generable natures." ^^ In 
this view celestial bodies are moved by spirits which are their 
" souls " just as man is moved by his spirit, or soul. It is inter- 
esting to note in passing that the author of Errores philoso- 
phorum does not attribute animation of the heavens to Aristotle 
or Averroes, but exclusively to Avicenna: 


Ibid., q. 2, ed. dt., p. 196. 
*^ Responsio, q. 2 § De tertio. For this part of the reply we rely on the emended 
edition published by Chenu in Revue des Sc. Phil, et Theol. XXIX (1940), 211. 


Again [Avicenna] erred' on the subject of the animation of the 
heavens. For he held that the heavens were animated. He said 
that the soul of the heavens is not only a suitable moving power, as 
the Philosopher and the Commentator were intent upon saying, 
but that a single being is produced by the union of the soul of the 
heavens with the heavens, just as by the union of our soul and 
our body.^' 

Concerning this presumed view of Aristotle, Kilwardby notes 
that it is philosophically sound and supported by reason: 
" since those bodies seem to be more noble than living bodies, 
they ought to have a higher form of life." Nevertheless in 1277 
the Bishop of Paris condemned the proposition " that celestial 
bodies are moved by an intrinsic principle, which is a soul." ^^ 
And St. Albert, as we have seen, clearly rejected celestial ani- 
mation as alien to the Catholic faith. 

The second opinion listed by Kilwardby is in reality that of 
St. Thomas: " others hold that those bodies are moved by 
angelic spirits who govern and move them in such a way that 
they are not their act, or form." Kilwardby dismisses this view 
as unphilosophical, and he remarks, " Nor do I recall it being 
approved by any of the Sancti as true and certain." However, 
Kilwardby does admit in passing that it could be held absque 
error e by Catholics.^* 

Kilwardby 's own view of celestial motion is presented suc- 
cinctly as the third opinion: 

Just as heavy and light bodies are moved to a place in which they 
rest by their own inclinations and tendencies, so celestial bodies 
are moved circularly in place by their own natural inclinations 
similar to weight {quasi ponderibus) in order to conserve corrup- 
tible things lest they suddenly perish and fail. 

Some spheres rotate naturally from West to East, others from 

®° Giles of Rome, Errores phUosophorum, VI: Avicenna, 10, ed. Josef Koch, trans, 
by J. O. Riedl (Milwaukee: Marquette, 1944), p. 31. 

** Chartularium Univ. Paris., ed. H. Denifle, 0. P., I, n. 473, p. 548, prop. 92; 
see also prop. 213. Cf. E. Krebs, Meister Dietrich, in Beitrdge z. Gesch. d. PhU. d. 
M.-A., Bd. V, heft 5-6 (Miinster, 1906), pp. 75-76. 

** Cf. J. A. "Weisheipl, " The Problemata Determinata Ascribed to Albertus 
Magnus," loc. cit., p. 304, note 8. 


East to West, and still others move naturally as epicycles, and 
others on the eccentric. To each planet and orb God gave an 
innate natural inclination to move in a particular way in rota- 
tional motion; to each He accorded an innate order, regularity 
and direction without the need of a distinct agency like a soul, 
an angel or Himself here and now producing the motion. " Just 
as the forces (pondera) of heavy and light move bodies con- 
sistently, not permitting them to stray outside a determined 
path, so it is with the forces of each and every celestial body." 
Consequently rotational motion is as natural to celestial bodies 
as gravitational motion is to heavy bodies. Both arise spon- 
taneously from nature as an intrinsic active principle, instinctu 
proprioruTn ponderum (q. 3) . It was commonly recognized 
among the schoolmen that heavy bodies need nothing more 
than their own generated nature to account for gravitational 
motion; heavy bodies need no conjoined mover to account for 
the continued downward fall.®^ Kilwardby wished to explain 
celestial motions by a similar intrinsic formal principle. Ter- 
restrial bodies are unattached and hence move rectilinearly to 
a place of relative rest. But for Kilwardby the heavens are 
spherical; stars and planets are attached to their proper orbs 
within a sphere. Consequently the only " natural " motion the 
heavens could have is rotational, a continual rotation of each 
orb on its axis. The combination of various rotations on suit- 
able axes together with the required uniform velocity of each 
rotation produced the apparent motion of the planet. Kil- 
wardby thus dispenses with the need of any conjoined or 
separated mover, whether that mover be called a soul, an 
angel, intelligence or God. It is clear from this that Kilwardby 
could not prove the existence of God through physical motion. 
He cannot even prove the existence of a separated substance. 
Because of the great diversity of opinion concerning celestial 
movers, Kilwardby maintained that it is impossible to prove 
that angels move the spheres (q. 4) . Philosophers think that 
they have infallibly demonstrated the existence of spiritual 

*^ Cf. J. A. Weisheipl, Nature and Gravitation, ed. cit., pp. 19-21, 25-28. 


movers for the heavens', but these are certainly not the angels 
discussed by Catholics. Even assuming that God is not the 
immediate mover of the heavens — which according to Kil- 
wardby He is not — it is in no way proved that angels have to 
be celestial movers (q. 5) . Unlike St. Albert, Kilwardby con- 
ceives the physical universe as perfectly self-contained, per- 
fectly " natural," having no need of immaterial agencies direct- 
ing and moving the heavens. His is the closed world created 
by God in the beginning with sufficient innate tendencies to 
move rectilinearly and rotationally. 

This view was not original with Robert Kilwardby. Fr. 
Daniel A. Callus has pointed out that this idea can be traced 
to the earliest days of Aristotelianism in Oxford. Some sixty 
years before Kilwardby's reply, John Blund gave as his con- 
sidered opinion that the heavenly bodies are not moved by 
souls, nor by intelligences, but by their own active nature 
moving orbiculariter.^^ As is commonly known, this opinion 
found favor among many in the fourteenth and fifteenth 

Fr. Chenu saw in Kilwardby's view an anticipation of John 
Buridan's famous suggestion about celestial motions, that an 
impetus (given by God) is also found in the celestial spheres, 
but one which cannot be diminished by resistance, since celes- 
tial matter offers no resistance.®'^ In all terrestrial projectiles 
impetus is diminished and overcome by nature resisting the 
violent force. But in Aristotelian theory celestial bodies could 
offer no resistance, since they had no weight or gravity; they 
were considered completely passive, having " nature " only as 
a passive principle of motion. Consequently Buridan's sug- 
gestion of an initial impetus for celestial motion was a perfectly 
obvious one; it presupposes Aristotle's doctrine of the pure 
passivity of those bodies. In other words, it is precisely because 

** " Dicimus quod firmamentum movetur a natura, non ab anima, et alia super- 
celestia." The full passage is published by Daniel A. Callus, O. P., " The Treatise 
of John Blund On the Soul," in Autour d'Aristote (Louvain, 1955) , pp. 487-9. 

" Cf. Pierre Duhem, tltudes sur Leonard de Vind, III (Paris: Nobele, 1955) , 
p. 42. 


such bodies have no active " nature " that they can, in the 
scheme of Buridan, receive a perpetual impetus for continued 
motion. This is quite different from Kilwardby's conception of 
celestial spheres actively inclined to circular motion, for here 
the " nature " of celestial bodies is an active principle. The 
final result of both views may be similar or even identical, but 
the theoretical foundation of Buridan's theory of impetus for 
the heavens is profoundly dissimilar to the views of Kilwardby. 
Kilwardby's view, however, was common enough in later 
centuries. It was favored particularly by Platonists and semi- 
Platonists. Notably Nicholas of Cusa attempted to explain the 
circular motion of the heavens by an appeal to their orbicular 
shape; their matter, being different from terrestrial matter, 
naturally tended to move orbicularly, that is, by rotating.^^ 
Copernicus himself explained the circular motion of the heav- 
enly bodies by their spherical nature: 

Now we note that the motion of the heavenly bodies is circular. 
Rotation is natural to a sphere and by that very act is its shape 
expressed. For here we deal with the simplest kind of body, where- 
in neither beginning nor end may be discerned, nor, if it rotates 
ever in the same place, may the one be distinguished from the 

For Copernicus, as for Kilwardby before him, the substantial 
form of a spherical body naturally tends to move spherically. 
Surprisingly, for Copernicus the outermost sphere of the fixed 
stars, though spherical by nature, was said to be at rest.^° It 
must be admitted, however, that Copernicus was not concerned 
with explaining the physical causes of celestial motion, as this 
is beyond the scope of mathematical astronomy. 

We may seriously doubt that Kilwardby's reply influenced 
later writers; it certainly did not influence John Buridan. 
Nevertheless it does represent an important medieval view 
concerning celestial motion. 

** Nicholas of Cusa, De ludo globi, lib. I (Basel, 1565), pp. 210-214. 
** N. Copernicus, De revolutionihus orbium caelestium, lib. I, c. 4 (Thorn, 1873) , 
p. 14; also c. 8, pp. 21-24. 
»" Ibid., c. 10, pp. 28-29. 

celestial movers in medieval physics 183 

St. Thomas Aquinas 

The reply of St. Thomas is the shortest and most succinct 
of the three. He adheres strictly to the forma expected, appeal- 
ing to the Sancti (Scripture, Augustine, Pseudo-Dionysius, 
Gregory, Jerome) and evaluating all questions in the light of 
Catholic faith. " It seems to me safer," he says in the prooem- 
ium, " that doctrines commonly held by philosophers which are 
not contrary to the faith be neither asserted as dogmas of faith 
(although they may sometimes be introduced as philosophical 
arguments) nor denied as contrary to the faith, lest occasion 
be offered to men learned in human wisdom to ridicule the doc- 
trine of faith." 

In his important theological treatise, De suhstantiis separatis, 
St. Thomas considers the relative merits of Plato and Aristotle 
on the question of angels.^^ Plato — really Proclus — is under- 
stood by St. Thomas to have postulated various orders of 
spiritual substances between the human soul and God. Under 
God, the supreme unity and goodness, there is the order of 
secondary gods who are the Forms or Ideas eternally radiant. 
Inferior to these is the order of separated intellects, " which 
participate in the above-mentioned Forms in order to have 
actual understanding." Next come the various orders of soul, 
each one inhabiting a certain kind of body. Celestial souls 
animate celestial bodies and move them, in such a manner that 
" the highest of the bodies, namely the first heaven, which is 
moved by its own motion, receives motion from the highest 
soul, and so on to the very lowest of the heavenly bodies." 
Below celestial souls are the demons who inhabit unearthly 
bodies. The lowest intellectual soul is man, who although he 
inhabits a visible body " as a sailor in a ship," also has another 
nobler body belonging to the soul, incorruptible and everlast- 
ing, even as the soul itself is incorruptible. Souls below man, 
such as plant and animal souls, lack intelligence and immor- 
tality. If all these views of Plato were true, notes St. Thomas, 

Cap. 1-4. For the treatise De suhstantiis separatis we rely on the excellent 
English version of Fr. Francis J. Lescoe (West Hartford: St. Joseph College, 1959) . 


then all orders between God and man would be called ' angels ' 
by Catholics. 

The fundamental weakness of Plato's position, as St. Thomas 
sees it, is that it is without proof, for his separated intelligences 
are merely postulated, not demonstrated. " That is why Aris- 
totle proceeded by a more manifest and surer way, namely, by 
way of motion, to investigate substances that are separate from 
matter." St. Thomas' interpretation of Aristotle is substanti- 
ally that of St. Albert and Kilwardby. Since all generable and 
celestial bodies are moved, they must be moved ultimately 
by a substance which is not material. The immaterial soul con- 
joined to celestial bodies is moved concomitantly with the 
body, therefore it is moved by knowledge and desire of abso- 
lutely separated intelligences. " Therefore each of the heavenly 
bodies is animated by its own soul and each has its own sepa- 
rate appetible object which is the proper end of its motion." 
For Aristotle, then, there are as many intelligences as there 
are celestial souls, and as many celestial souls as there are 
motions. It was Avicenna, according to St. Thomas, who er- 
roneously limited the number of separated intelligences to ten, 
thinking that the multiple motions of a planet could be " or- 
dered to the motion of one star." In any case, according to the 
position of Aristotle, between man and God " there exists only 
a two-fold order of intellectual substances, namely the sepa- 
rated substances which are the ends of the heavenly motions, 
and the souls of the spheres, which move through appetite and 
desire." ^^ Aristotle and Plato both agree that all immaterial 
substances have their entire being from God, that they are 
entirely immaterial, and that they are ruled by divine provi- 
dence. They differ, however, with respect to the number and 
precise character of separated substances as well as to their 
relevance to the physical order. 

For St. Thomas the theologian, Aristotle made three serious 
errors concerning angels. First, he erroneously limited their 
number to what could be ascertained by celestial motion; there 


Ibid., c. 2, n. 10; cf. In II De caelo, lect. 18, n. 16. 


is no demonstrative reason why they cannot be more numerous, 
as Catholic theology teaches .^^ Second, he erred by considering 
some to be substantially united to celestial bodies as their soul; 
such a union is unreasonable and contrary to Catholic teach- 
ing.^* Finally, Aristotle erred in considering angels and the 
universe to have existed from all eternity; such eternity cannot 
be demonstrated by reason. ^^ St. Thomas himself never doubted 
that Plato and Aristotle admitted another mode of " coming- 
into-being " besides physical generation for immaterial sub- 
stances and the universe. " Over and above the mode of be- 
coming by which something comes to be through change or 
motion, there must be a mode of becoming or origin of things, 
without any mutation or motion through the influx of being 
{'per iiifluentiam essendi) ." ^^ St. Thomas goes on to say that, 
although Plato and Aristotle did posit that immaterial sub- 
stances and even heavenly bodies always existed, " we must 
not suppose on that account that they denied to them a cause 
of their being." ^^ On this point they did not depart from the 
position of the Catholic faith. 

We can now return to St. Thomas' reply to the official ques- 
tionnaire. His reply to the first three questions simply states 
that God normally rules His creation through intermediaries, 
the lower and more gross bodies being ruled by the higher and 
more subtle. The divine power, however, is in no way limited 
to the order it has established. Assuming that angels are the 

°^ Ibid., c. 2, nn. 12-13; cf. Sum. contra gent., 11, c. 92. 

^* Ibid., c. 18, nn. 100-101; cf. De spirit, creat., a. 5; Sum. contra gent., 11, c. 
91; SuTn. theol., I, q. 51, a. 1; De pot., q. 6, a. 6. 

^^ Ibid., c. 2, n. 14; cf. Sum. theol., I, q. 46, a. 1; Sum. contra gent., II, cc. 31-38; 
De pot., q. 3, a. 17; De aetemitate mundi. 

** Ibid., c. 9, n. 49. 

*^ Ibid., n. 52. For this reason St. Thomas frequently insists that those who 
interpret Aristotle's God as a mere physical mover or a mere final cause are in 
complete error. For St. Thomas Aristotle's God is a causa essendi ipsi mundo, a 
causa quantum ad suum esse, a factor caelestium carporum. " Ex hoc autem 
apparet manifeste falsitas opinionis illorum, qui posuerunt Aristotelem sensisse, 
quod Deus non sit causa substantiae caeli, sed solum motus eius." In VI Metaph., 
lect. 1, n. 1164. Also In VIII Phys., lect. 3, n. 6; In I De caelo, lect. 8, n. 14; 
In II Metaph., lect. 2, n. 295. 


celestial movers, then no learned man can doubt that all natural 
motions of lower bodies are caused by the motion of celestial 
bodies (q. 3) . Dionysius himself notes that the sun's rays 
induce the generation of sensible bodies, generate life itself, 
nurture, strengthen and perfect it. All of this is within the 
power of angels. 

For some reason St. Thomas omitted to answer the fourth 
question directly. It asks whether it is infallibly demonstrated 
according to anyone that angels are the movers of celestial 
bodies. In two earlier replies to the lector of Venice, St. Thomas 
answered this very question in clear terms: 

The books of the philosophers abound with proofs for this, proofs, 
which they consider demonstrations. It seems to me therefore that 
it can be demonstrated that celestial bodies are moved by some 
intellect, either by God immediately or by means of angels moving 

Consequently his reply to the fifth question comes as no sur- 
prise. He categorically insists that if God does not move those 
bodies immediately, then some other spiritual substance is 
demonstrated as mover, either a celestial soul or a separated 
angel. The fundamental reason for this assertion is stated 
clearly: Quod autem corpora caelestia a sola natura sua move- 
antur, sicut gravia et levia, est omnino impossibile.^^ In other 
words, for St. Thomas it is absolutely impossible that circular 
motion be explained by nature as an active (formal) principle 
within celestial bodies. This view is directly opposed to the 
position represented by Kilwardby. 

Throughout all his writings St. Thomas insisted on the essen- 
tial difference between rectilinear motion and rotational motion. 
Rectilinear motions, such as those of heavy and light bodies, 
arise spontaneously from within bodies, from nature as an 
active (formal) principle. Nature in this sense is predeter- 
mined to a certain end and to the means of attaining it. The 

** St. Thomas, Resp. de art. XXXVI, a. 2; also Resp. de art. XXX, ad 4. 
*' St. Thomas, Resp. ad Joan. Vercel., q. 5; cf. Sum. contra gent.. Ill, c. 23 per 


end, therefore, is already within the intentionality of nature as 
form. Once nature has attained the end, it must rest in its 
acquisition, since it is its good. Physically there is no need for 
any " conjoined mover " to account for this motion downward 
or upward. Nature itself spontaneously moves toward the end 
which is its goal. " There is in heavy and light bodies a formal 
principle of its motion, because, just as other accidents pro- 
ceed from the substantial form, so does place and, consequently, 
movement toward place; not however that the natural form is a 
mover {motor) , but the mover is the generator which begot 
such a form upon which this motion follows." "° Therefore 
nature as an active principle is always ordained to rest in the 
possession of some good proper to itself. 

For St. Thomas the profound difference between celestial 
and terrestrial phenomena lay in the motions. The heavens 
move continuously in time, aiming at no rest or possession of 
a goal. Whether the heavens are eternal or created in time is 
not relevant to the question. Likewise it makes no difference 
whether the celestial bodies in motion are real spheres or inde- 
pendent planets; in either case the motion is always ordered 
to further motion. Clearly these motions cannot be striving for 
a rest as yet unattained, since such a rest would be disastrous 
for the celestial body and no nature can desire its own destruc- 
tion as a good. Nor can it be said that the purpose of such 
motion is motion itself. Motion by its very nature is a tending, 
a continual otherness; it has within its very nature a deformity 
which is incapable of being the final cause of any natural agent. 
" Therefore it is impossible that nature intend motion for the 
sake of motion." "^ Now for St. Thomas, if there is no intrinsic 
end attainable by a body in motion, then that motion cannot 
have sprung spontaneously from nature as form. Like the 

100 g(. Thomas, In II Phys., led. 1, n. 4. Also In I De caelo, lect. 18, n. 1; 
II, lect. 2, n. 6; III, lect. 7, nn. 5-9; In II Phys., lect. 5, n. 5; IV, lect. 12, n. 9; 
VIII, lect. 8, nn. 5-7; Sum. cont. gent.. Ill, cc. 82, 84; De pot., q. 5, a. 5. 

^"^ " Impossible est igitur quod natura intendat motum propter seipsum." Sum. 
cont. gent., Ill, c. 23, § 6. Also De pot., q. 5, a. 5: " impossible est quod aliqua 
natura inclinet ad motum secundum se ipsum." 


matter in generable substances, the celestial body must be 
moved by another, by one in continual contact with it. Conse- 
quently celestial bodies have " nature " only in the sense of a 
passive (material) principle, which means the natural aptitude 
to be moved by another. Hence "the motion of a celestial 
body, as far as its active principle is concerned, is not natural, 
but voluntary and intellectual; however, in relation to its pas- 
sive principle, the motion is natural, for a celestial body has a 
natural aptitude for such motion." ^°- In this matter, notes St. 
Thomas, it makes no difference whether we conceive the celes- 
tial bodies to be moved by intellectual substances conjoined 
to the body after the manner of a soul or by one entirely dis- 
tinct like an angel. Non auteTn esset via solvendi, si moverentur 
-per solum naturae impetuTn, sicut corpora gravia et levia^°^ 

It is true that for St. Thomas celestial bodies can have only 
a passive nature whether the mover be a conjoined soul as 
Aristotle wished or a separated angel, as he himself believed. 
Nevertheless in establishing the existence of God along Aris- 
totle's lines, it does make a difference. St. Thomas, as St. 
Albert before him, was well aware that the First Mover of the 
Physics was for Aristotle identical with the First Being of 
Metaphysics XII. That is to say, St. Thomas knew St. Albert's 
interpretation to be correct. However, there is a serious diffi- 
culty. If the celestial movers are not souls, but angels, as St. 
Thomas himself held with the Sancti, then Aristotle's argument 
is not conclusive. A soul conjoined to the sphere is necessarily 
moved per accidens, that is, concomitantly with the sphere. 
Since this kind of mover is insufficient to account for the pri- 
mary source of physical motion, one can validly conclude to the 
existence of an intelligence which is entirely separated from 
matter. And if one erroneously limits the number of spiritual 
substances to the number of celestial movements, then the sepa- 
rated intelligence moving the first animated sphere (primum 
caelum) must be God. On the other hand, if the immediate 

^°'^ Sum. cont. gent., Ill, c. 23, § 8. Also In II Phys., lect. 1, n. 4; in II De caelo, 
lect. 3, n. 2, and lect. 18, n. 1; De pot., q. 5, a. 5 ad 12. 
^°'' St. Thomas In II De caelo, lect. 18, n. 1. 


mover of the celestial bodies is not a soul, then it is in no way 
moved per accidens. This immediate mover could be God Him- 
self or an angel. And if the number of angels is greater than 
Aristotle conceded, then it is impossible to demonstrate that 
God is the immediate mover of the heavens. This is precisely 
the difficulty envisaged in St. Thomas' reply to the fifth ques- 
tion: assuming that God is not the immediate mover, then it 
is indeed demonstrated that an angel is the mover. This as- 
sumption, however, cannot be made on philosophical, much 
less on physical grounds. This is not to say that Aristotle failed 
to prove the existence of God in Meta^physics XII. Quite the 
contrary. St. Thomas was convinced that Aristotle perceived 
that other mode of becoming yer influentiam essendi, whereby 
every spiritual substance is necessarily dependent on the first 
cause of being. It is this other mode of " being moved " that 
St. Thomas sees in Aristotle's conception of the conjoined 
mover of the first heaven."^ It is the totality of movers which 
are in some true sense moved that validates the Aristotelian 
argument for St. Thomas. " Hence, unless the celestial bodies 
are moved immediately by God, they must either be animated 
and moved by their proper souls or be moved by angels, quod 
melius dicitur." 

Concluding his reply to the fifth question, St. Thomas notes 
that there are some philosophers who would have God move the 
first heaven by means of its anima propria, and the other 
heavens by means of intelligences and souls. St. Thomas' 
own view is that God directs the universe through a hierarchy 
of angels, only the lower of which directly move the celestial 

The view of St. Thomas is openly defended in the anonymous 
Quaestio de viotoribus corporum caelestium, a work formerly 
attributed to St. Thomas and still published among his works .^°' 

"*For example, In XII Metaph., lect. 7, nn. 2519-2522; lect. 8, nn. 2539-2543; 
In II De caelo, lect. 18, n. 6. 

"^ Opera Omnia (Parma: Fiaccadori, 1869) , XXIV, pp. 217a-219b. This treatise 
was first published by Thomas Boninsegnius, O. P., in his edition of the Summa 
with Cajetan's commentary (Venice: apud Juntas) in 1588. The first folio an- 


Strangely, there is no known manuscript of this work extant, 
but it seems to be of English origin, written, as Grabmann has 
pointed out, some time after June 1271/°" In it the author 
rejects at length the tradition represented by Robert Kilwardby 
as well as the animation theory presented by Simplicius. The 
author defends vigorously the Thomistic view that celestial 
movers are two-fold: the passive nature of the celestial body 
and the active power of angels ministering to the will of God. 
The medieval views of celestial movers which we have out- 
lined in this paper are rarely considered today. Yet they are 
important for an understanding of St. Thomas, and they do 
have serious implications which deserve the attention of modern 
Thomists, implications of interest to theologians as well as to 
philosophers of nature. 

James A. Weisheipl, 0. P. 

Alhertus Magnus Lyceum 
Dominican Hou^e of Studies 
River Forest, Illinois 

nounced: " Quaestiones duae S. Thomae de Aquino nuper repertae ac in lucem 
editae, una de principio individuationis, altera vero de motoribus coelestium cor- 
porum, quae nuper repertae fuerunt Florentiae in bibliotheca S. Marci." This new 
manuscript was copied for San Marco by order of Cosmo de Medici and notarized 
on June 5, 1587; this document is published on fol. 2r of the edition. Boninsegnio 
rests his argument for the authenticity of the treatise (fol. 2v S.) on the Thomistic 
character of the doctrine and on the credibility of the manuscript, which also 
contained St. Thomas' De potentia. The same scribe had written the two new 
questions on folios 287-290 of the original manuscript, which is now lost. 

"*M. Grabmann, Die Werke des hi. Thomas von Aquin. 3rd ed. (Miinster, 
1949). Beitrdge z. Gesch. d. PhU. u. Theol. d. M.-A., Bd. XXU, heft 1-2, p. 415. 


THE recent appearance of Marshall Clagett's The Science 
of Mechanics in the Middle Ages ^ has focussed atten- 
tion once again on the wealth of material made avail- 
able by scholars in the " Dark Ages " for the development of 
science as we now know it. Concentrating on " the mechanical 
doctrines of the medieval period which were framed in mathe- 
matical terms or had important consequences for a mathe- 
matical mechanics," ^ Clagett reproduces most of the important 
texts in this area and analyzes them for the conceptual content 
that contributed to the revolutionary seventeenth-century 
development. By intent he avoids the study of methodology, 
nor does he attempt to evaluate the complex relationships 
that existed between physics and natural philosophy during 
this period. Yet even these areas have not been without their 
share of attention in the recent literature. Three significant 
studies of medieval scientific methodology have appeared in 
succession,^ and Anneliese Maier has recently concluded the 
fifth volume of her monumental Stiidieji zur Naturphilosophie 
der Spdtscholastik * with some weighty observations on the 
transitional philosophical concepts that gave rise to the new 

* University of Wisconsin Press: Madison, 1959, xxix -\- 711 pp. 
" Ibid., p. xxii. 

'A. C. Crombie's Robert Grosseteste and the Origins of Experimental Science, 
Oxford, 1953; my own The Scientific Methodology of Theodoric of Freiberg, Fri- 
bourg, 1959; and J. A. Weisheipl's The Development of Physical Theory in the 
Middle Ages, London, 1959. 

* Zwischen Philosophic und Mechanik, Rome, 1958, particularly pp. 373-382. The 
five volumes, which we shall henceforth refer to as Studien I, II . . . etc., are 
entitled respectively: I. Die Vorldufer Galileis im 14.. Jahrhundert (1949); II. Zivei 
Grundprobleme der scholastischen Naturphilosophie (1951); III. An der Grenze 
von Scholastik und Naturunssenschaft (1952); IV. Metaphysische Hintergriinde 
der spdtscholastischen Naturphilosophie (1955); and V. Zwischen Philosophic und 
Mechanik (1958). 


192 W. A. WALLACE 

science. All of these works are fruitful sources of study for 
the Thomistic philosopher of science who would evaluate 
modern science in light of the traditional concepts of natural 
philosophy. It is to be hoped that the time will not be long 
before some penetrating studies in this area may help solve the 
stubborn problems that have frustrated and divided adherents 
to the philosophy of St. Thomas during the past several 

Meanwhile these works have also signalized the importance 
of studying manuscript sources to fill the gaps in our knowledge 
of medieval science. Clagett's work, by his own admission, 
would have been quite impossible without the prior paleo- 
graphical efforts of Maier and Moody. It is in a spirit similar 
to that in which the latter research was undertaken that I 
should like to offer this brief study of gravitational motion 
according to Theodoric of Freiberg (c. 1250-c. 1310) . Theo- 
doric's contributions to medieval optics and scientific method- 
ology are sufficiently well known not to require further 
attention, but by some peculiar oversight the views of the 
German Dominican on the problem of gravitation have gen- 
erally not been recorded.® I shall attempt to fill this lacuna by 
a resume of the unedited opusculum De elementis corporum 
naturaliuTn ijiquantum sunt partes mundi,'' which contains 

^ I have in mind the long-standing debate over a so-called " specific distinction " 
maintained by some to exist between Thomistic natural philosophy and modern 
science, which has impeded the study of a host of philosophical problems concerning 
the nature of matter, gravity, mass, energy, light, the elements, etc., all arising in 
modern science. 

* The literature on Theodoric is given in my Scientific Methodology of Theodoric 
of Freiberg (Studia Friburgensia, No. 26) , The University Press, Fribourg: Switzer- 
land, 1959. Miss Maier mentions him in several footnotes throughout her volumes, 
but otherwise has only a brief treatment of his doctrine on the elements in Studien 
III, pp. 58-69, without considering the relation of the latter to falling motion. 

' This opusculum was probably written about the year 1300. Two complete manu- 
script versions are known: Cod. Maihingen (Fiirstliche Bibl. Schloss Harburg, II, 
1 qu. 6), henceforth referred to as M, and Cod. Vat. Lat. 2183, henceforth referred 
to as U. In addition, some fragments of the opusculum are to be foimd in Cod. Vat. 
Lat. 1121, henceforth referred to as T. When a reading of the Latin text is given 
below, it is generally a composite text based on all available manuscripts, as indi- 


Theodoric's complete doctrine on this subject. It is not my 
intention to enter into a detailed analysis of the doctrine 
presented, but rather to sketch the essential content of The- 
odoric's teaching, supporting this by substantial citation from 
the manuscript versions of the opusculum. In thus utilizing 
the space alloted to me, I also forego the opportunity to point 
out possible relationships between Theodoric's doctrine and 
more recent thought on gravitation. I trust, however, that 
the material presented will have some bearing on further 
analyses of the causes of gravitational motion that may be 
forthcoming from Thomistic philosophers. 

Gravity and the Elements 

The elements, for Theodoric, are material components of 
natural bodies, " principles according to the formality of 
matter," or, more explicitly, " whence a thing is materially 
composed." ^ As such, they can be studied by the meta- 
physician, who is interested in them " from the viewpoint of 
their substance, how they pertain to the genus of being pre- 
cisely as being," or they can be studied by the natural phi- 
losopher " insofar as they are natural bodies and accordingly 
related to motion and change." ^ The latter consideration again 
permits of a twofold division, for the natural philosopher may 
investigate them in a way similar to that of the modem 
physicist, insofar as they are " the first parts of the universe," 
or in a way similar to that of the modern chemist, insofar as 
they contain a " principle of transformation by which one 
element can be simply generated from another, or compounds 
formed from elements." " Gravity is of primary interest to the 
physicist, thus characterized, as Theodoric explains in the 
following passage: 

cated with the foliation. I have already furnished a critical Latin edition of the 
prologue and first eight chapters of this opusculum in my Scientific Methodology, 
pp. 324-331. 

® Prologue, (ed. Wallace) pp. 324-325. 

* Cap. 7, p. 329. 

" Ibid. 

194 W. A. WALLACE 

Certain accidents or qualities are in elements as they are parts of 
the universe, namely, gravity and levity, and, deriving from these, 
natural motions either to or from its center. . . , Through such 
motions bodies arc disposed in their proper places in the material 
universe, considering the latter quantitatively in its extensive and 
dimensional integrity as well as in its specific diversity. Such acci- 
dents are in elements as parts of the universe, making up the uni- 
verse precisely as actual, for actual parts are those which have a 
species. Thus it is that gravity and levity are first found in 
[elemental] bodies complete according to species, and that they are 
their very first accidents as parts of the universe. . . . Wherefore, 
if there be any bodies or natures simpler than these, of which the 
forementioned elements might in turn be composed, light and 
heavy would not be proper to such bodies or natures, nor would 
these be parts of the universe specifically and quantitatively, except 
possibly in an originative way.^^ 

Gravity, then, is one of the first qualities of bodies considered 
in relation to other bodies making up the universe, and is 
properly attributable to the elemental constituents of such 
bodies, themselves specifically complete, as the ultimate source 
of their natural or gravitational motions. This suggests for 
Theodoric some observations as to whether gravity is an abso- 
lute quality, or merely relative, and whether it is subject to 
intensification or not. Surprisingly enough, such questions were 
not commonly discussed at the turn of the fourteenth century; 
Ciagett has pointed out that the first evidence of the concept 
" specific weight " is only to be found in the pseudo-Archi- 
medean treatise De insidentibus in humidum, itself dating from 
the thirteenth.^- There is no direct use by Theodoric of the 
quantitative notions found in De insidentibus, but he does 
speak of an " intensity " of gravity, as is clear from the 
folio win 2: citation: 


There is a twofold modality of heavy and light. One is according to 
absolute quality, w^hose formality consists in this, that heavy and 
light are principles of a determinate tendency to some place in the 
universe. Under this formality heavy and light are distinguished in 
bodies in the following way, viz., some are heavy and light simply, 

" Ibid., pp. 329-330. " Op. dt., pp. 93-95, 674. 


as fire and earth, which go to the extremities of straight-line motion; 
others are such comparatively, in the sense that they are heavy or 
light with reference to various boundaries, as air and water. But 
there is another modality of heavy and light which is noticed in 
the intensity of these qualities, whereby it happens that in the case 
of two bodies, even such as tend to the same terminus, one will be 
heavier or lighter than the other, in the sense that one will have 
more weight than the other. And this can result from one of two 
causes, viz., because of the aggregation of more parts of the same 
body, as a larger portion of earth has more weight than a small 
piece; or from the complexion and nature of the body itself, as lead 
or gold is heavier and has more weight than earth or stone of an 
equal size.^^ 

Thus there is in Theodoric's thought a recognition of specific 
weights, although he gives no mathematical treatment of them, 
and in fact is not interested in their effect on gravitational 
motion. His position is rather that the first modality men- 
tioned above, " according to absolute quality," is proper to 
bodies as they are parts of the universe, and this alone deter- 
mines the proper place or region to which a body tends, 
whether it be element or compound. If it is a compound, it will 
tend to a region determined by what is " predominant " in it, 
not by " proportional parts, even an exceeding one." What 
he means by this " predominant " is not too clear: he describes 
it as being " according to the property and nature of the com- 
plexion in which the species of the body is rooted, which itself 
is one and simple." Yet the practical consequence of his view 
is easily discerned, for he holds that " fiery bodies," i. e., 
" shooting stars and comets," tend to the proper place of fire, 
while " earthy bodies " such as " minerals and stones " tend 
to the place of earth." This is clearly in accord with Aristotle's 
doctrine in De caelo et mundo ^^ and itself adds little to the 
latter's development. Had Theodoric been discussing the 

" Cap. 8, p. 330. 

^^ Ibid., p. 331. For the medieval understanding of the expression, "comets tend 
to the place of fire," see Lynn Thorndike's Latin Treatises on Comets Between 1238 
and 1S6S A.D., Chicago, 1950, passim. 

^^ Book IV, chap. 4, 311a30-b3. 

196 W. A. WALLACE 

velocities of fall of such bodies, and not the places to which 
they tend, his elimination of specific weights as of incidental 
importance would have shown rare insight for his time. But 
there is no mention of velocities in this opusculum, and this 
discovery had still to await the researches of Galileo. 

It is by pursuing such a line of thought, however, that 
Theodoric comes to some interesting questions about composite 
motions and how these can be resolved into component parts, 
for which he proposes noteworthy answers. He maintains, in 
accordance with the teaching just proposed, that there are no 
" intermediary places . . . beyond the four places of the four 
primary bodies," although allowing that a particular compound 
might have a proper place to which it tends in " some one of 
these first regions," determined by its " relation to some part 
of the heavens or the horizon." ^^ Against this position he notes 
the objection, already in Aristotle, that simple bodies ought 
to have simple motions and composite bodies composite mo- 
tions. He replies to this by making precise the sense in which a 
motion is " composite " — not because its terminus is composite, 
but rather because " the manner in which it tends to that 
terminus is composite." This manner of tending, he points out, 
need not be composite, for we find that both simple and com- 
posite bodies undergo simple motions " according to the nature 
of the predominant." In fact, he notes, such simple motions 
are what manifest the natures of the simple bodies or elements, 
and it matters little whether the body undergoing motion be 
simple or composite when the motion itself is simple and mani- 
fests the simple nature that is its principle .^^ 

Yet it is a fact that some composite bodies have simple 
natural motions, while others have composite natural motions — 

^* Cap. 10, M 14vb, U 141vb: Non est eciam aliquis locus medius, vel ut ita 
dicam mixtus, preter hec quatuor loca quatuor corporum primorum. Unde neces- 
sarium est omne corpus recti motus ferri ad aliquem istorum quatuor secundum 
predominans, et si fuerit aliquis locus proprius aJicui mixto secundum habitudinem 
ad aliquam partem celi vel orizontis, hie erit pars alicuius istorum primorum locorum 
et presupposita natura ipsius. 

"Cap. 11, M 15ra, U 142ra. 


and this even when living things are excluded and one treats 
only of objects that move precisely as light or heavy. This 
leads Theodoric to a significant question: " Why do certain 
composite bodies move naturally with a simple motion, and 
certain others with a composite motion? " ^^ The answer he 
proposes, while hardly consonant with modern scientific thought 
on the subjects he treats, provides an insight into the way in 
which the medievals explained such divergent motions as those 
of currents, magnets, tides, and heavenly bodies, and may be 
suggestive of analogous approaches available to the natural 
philosopher of the twentieth century for evaluating modem 
theories dealing with these same topics. 

Composite Motions 

In summary form, the general answer that Theodoric gives 
to this question, which he then goes on to elaborate through 
twelve chapters of the opusculum, is contained in the following 

It should be noted that there are many differences among bodies 
that are moved by nature either with composite or simple motions. 
Some are moved as parts of wholes, without being separate from 
such wholes. Others are moved somewhat as wholes themselves, 
and this in a twofold way, for some are moved by an intrinsic 
natural principle, while others are moved by an extrinsic principle, 
as will become apparent when we consider them singly .^^ 

To illustrate the meaning of this observation, we may note that 
for Theodoric the natural motions of fluids, such as those com- 
prising the atmosphere and the hydrosphere, are generally 
composite motions. Some of these are composite in the sense 
that they are motions of the parts of a fluid medium; the 
movement of such a part he resolves into two interacting 

"Cap. 12, M 15ra, U 142ra-b. 

■^' Ibid.: Est sciendum quod corporum que moventur motu composite seu simplici 
per naturam multiplex est differencia. Quedam enim moventur ut partes in toto, 
non tamen separate a toto, quedam autem ut tota quedam, et hoc dupliclter, quia 
quedam moventur ab intrinseco principio naturali, quedam ab extrinseco, ut de 
singulis patebit. 

198 W. A. WALLACE 

components, one impressed on it by adjoining parts, another 
arising intrinsically within the part itself. Other composite 
motions are those of clouds, vapors and winds, when these are 
considered as integi-al wholes apart from any internal move- 
ments that might characterize their parts; such motions he 
analyzes as deriving partly from the intrinsic elements of which 
such wholes are composed, and partly from the forces that 
generate them, which he sees as endowing them with added 
dispositions to fulfill special purposes intended by nature. Still 
other motions, such as those of rivers and whirlwinds, are com- 
posite because of the reaction of the fluid with its boundaries 
or because of the interaction that results when two natural 
motions converge from different directions. In practically all 
of these cases, as we shall see, the natural motion which is 
attributed by Theodoric to the elemental constituents of the 
fluid is a simple, straight-line motion towards the center of 
gravity, while the component that makes the total motion 
composite derives from an outside source and does not come 
directly from the fluid's intrinsic components. 

The case of the complex movement of parts of a fluid medium 
is not particularly noteworthy, except for the fact that Theo- 
doric there uses notions associated with Averroes' solution to 
the projectile problem,-" which may be indicative of his own 
ideas concerning impetus. Theodoric does not commit himself 
to any particular theory of impetus — in fact he explicitly 
refrains from discussing this matter " — but he does speak of 
the influence of the parts of a fluid on each other by which they 
continue to be in motion after the source of their initial dis- 
turbance has ceased." Since the cases of fluid and projectile 

^°Cf. Commentarium in VIII Physicorum (ed. Venetiis, 1550), Tom. IV, 195va- 

"For the Latin text, see Maier, Studien V, p. 290, fn. 1. 

Cap. 13, M 15rb, U 142rb: Tale enim corpus, cum receperit motum in aliqua 
suarum parcium, huiusmodi pars movet aliam vel alias, et sic deinceps, quod absque 
aliquali subinteraccione parcium ad partes fieri non potest, propter talium corporum 
spiritualitatem, ut dicit Commentator super octavum Physicorum. Partes autem sic 
mote et propulse, alias secum trahunt propter continuitatem. Cum autem per 
talem niocionem partes sursum vel alias extra locum suum actu fuerint, quasi per 


motion are quite dissimilar, at least in the sense that the first 
is that of a continuous medium in direct contact with its dis- 
turbing force, while the second is that of an object obviously 
separated from its mover, one should not make too much of 
this argument, but there does seem to be a suggestion here 
of some motive power being communicated to parts of the 
fluid and thus accounting for its continued motion. 

In discussing the motions of fluids considered as wholes, such 
as winds, clouds, mists, rain, etc., Theodoric develops this 
notion further. He considers these as " incomplete entities not 
yet separated from their generator," and maintains that they 
have some motive principle, apart from the intrinsic gravi- 
tational principle associated with their elemental constituents, 
by which they fulfill a particular end intended by nature.-^ 
The gravitational principle, he notes, is analogous to the intrin- 
sic principle that might be induced into a body by the action 
of an altering agent, and here he gives the interesting example 
of a magnet's action on iron, which he observes causes the 
iron " to tend towards it in a straight line wherever it might 
be, whether through air, water, or a metallic container 

" 24 

violentam alterius partis impulsionem vel aUractionem, motu suo natural! redeunt 
rursum ad locum suum proprium et ipse tales partes et impellentes. Et sic per talem 
impulsionem, tractionem parclum, subinteraccionem, fit quedam inundacio talis 
corporis humidi in suis partibus. Quo fit eciam ut non statim cesset huiusmodi 
motus ad cessacionem primi moventis primam partem, quia sicut dictum est huius- 
modi motus componitur ex naturali et violento, qui ex disposicione sibi, ex mutua 
disposicione seu alteracione vel influencia indita, sepius super seinvicem replicantur, 
cum in huiusmodi naturalis motus sequatur violentum, et violentus causetur a 

"■" Cap. 15, M 15rb, U 142rb. 

-* Cap. 16, M 15va, U 142va-b: Et huiusmodi motus per naturam non solum 
competit rebus que moventur ad aliquem naturalium locorum mundi secundum 
determinatam habitudinem ad centrum et circumferenciam mundi, et hoc secundum 
aliquod principium inexistens per mocionem generantis, sed ' eciam sic moventur 
secundum naturam principii inexistentis per approximacionem alicuius corporis 
alterantis seu aliquo modo afficientis ea. Cuiusmodi est motus ferri ad magnetem, 
quod non impeditum, secundum lineam rectam tendit ad ipsum ubicumque fuerit, 
sive per aerem, sive per aquam, sive per vasa metallina, ut patet ad sensum. Sic 
patet de quibusdam compositis qua racione moventur per naturam motu recto, quia 
scilicet moventur per principium intrinsecum. 

200 W. A. WALLACE 

Unfortunately he does not discuss the character of the extrinsic 
principle in this context. However, when attempting later to 
account for the fact that mists arise naturally from ponds and 
move in determined directions, he explains that the generating 
agent " continually induces some natural disposition into such 
bodies," which is not gravity but " which presupposes and 
requires this qualitative principle," and is similarly related to 
a determinate place.^^ Such an added disposition, he observes, 
is the means by which "universal nature " provides for the 
needs of the various parts of the universe, as for example by 
moving rain clouds to particular areas where water is needed.^^ 
The added disposition he also calls a " generative principle," 
and notes that its action is not a violent one, even though 
attraction and propulsion characterize its operation. He would 
prefer to speak of the propulsion as arising from " whatever 
induces the form or disposition which is the principle of the 
motion," and to understand the attraction as being merely 
in the order of final causality.-^ 

Thus Theodoric analyzes certain composite motions found 

^^ Cap. 17, M 15va, U 142vb: Sed si sunt alia aliqua corpora huius inferioris 
mundi que moveantur per naturam motu tortuoso vel composito vel circulari, 
huiusniodi eciam movebuntur ab exteriori principio, et hoc sive a generante, inquan- 
tum videlicet talibus corporibus continue influit aliquam disposicionem naturalem 
qua acquiratur eis continue locus post locum, non semper secundum habitudinem 
recte distancie que attenditur inter centrum et circumferenciam secimdum lineam 
rectam. Talis enim motus principium est generans, secundum quod ingenerat 
corporibus has simplices et absolutas qualitates que sunt gravitas et levitas. Pre- 
diotis autem corporibus aliquando acquiritur locus continue secundum habitudinem 
ad aliquam partem orizontis, ut si surgat aliquis vapor in parte australi et per 
naturam tendat versus septentrionem. Hoc autem fit secundum aliquam aliam 
disposicionem huiusmodi corporibus inditam, que nee est gravitas neque levitas. 
Presupponit tamen et preexigit hoc qualitativum principium, sic inditum per 
naturam, gravitatem et levitatem in corpore in quo est, sicut et locus in quo vel 
ad quem moventur huiusmodi corpora est pars alicuius locorum gravium et levium. 

^"Cap. 18, M 15va, U 142vb-143ra. 

^ Cap. 19, M 15va, U 143ra: Huic motui corporum que moventur per principium 
generativum commune assimilatur motus et nutrimenti per corpus. . . . Intelligenda 
est pulsio et tractio modo predicto proporcionaliter, sicut in predictis corporibus 
partibus mundi, ut scilicet dicatur pellens eo quod dat formam vel disposicionem 
que est principium motus, trahens autem intelligatur secundum racionem et inten- 
cionem finis. . . . 


in nature and attributes their composite aspect to two com- 
ponent principles, one being the gravity or levity of the 
predominant elements of which the bodies are composed, 
accounting for the straight-line component of their motion to 
or from some center of gravity, the other being a natural form 
added to the gravitational principle by a generating force, and 
accounting for the non-linear component of their motion. This 
suggestion is pregnant with consequences if it could be under- 
stood as applying to the case of the heavenly bodies, and the 
question naturally arises if Theodoric, writing at the latest 
in the first decade of the fourteenth century, could have 
anticipated this seventeenth-century development of celestial 

The answer is to be found in another unedited opusculum of 
Theodoric entitled De intelligenciis et motor ibus celorum.^^ 
Here he introduces the notion of composite motions once again, 
and precisely in the context where one might expect him to do 
so, namely, in connection with the astronomical theories of 
eccentrics and epicycles. Theodoric specifically rejects Aver- 
roes' adherence to the literal text of Aristotle, maintaining that 
Aristotle need not be understood as meaning that heavenly 
bodies must revolve in circular orbits exactly concentric with 
the midpoint of the universe, as Averroes interprets him, and 
suggesting that " perhaps he [Aristotle] wished ' center ' to be 
understood more generally, for the natural center of any natural 
circle whatsoever," as opposed to the center of the world. "^ 
His reason for urging a different interpretation of the Aris- 
totelian text is based on " the efficacy of the demonstrations " 
in Ptolemy's Ahnagest; here, as in other places, Theodoric is 
more convinced by the observational evidence " of the astrol- 
ogers " than he is by the authority of Aristotle.^" Granting the 

^® This opusculum was probably written in the first decade of the fourteenth 
century. There are two manuscript copies extant: Cod. Vat. Lat. 2183, henceforth 
referred to as U; and Cod. Vindobon. (Dominikanerkloster) 138/108. Where 
readings of the Latin text are given below, they are based on U. 

"* Cap. 11, U o8va: Fortassis generalius voluit intelligi medium, videlicet, quod- 
cumque medium naturale cuiuscumque circuli naturalis. . . . 

^° Capp. 11 et 14; De elementis, cap. 9 — cf. Scientific Methodology, p. 126. 

202 W. A. WALLACE 

mathematical explanation of eccentrics and epicycles, however, 
he is still at a loss for a physical explanation as to why this 
peculiar motion of the heavenly bodies occurs, and in seeking 
such an explanation has recourse to his concept of " composite 

In this treatment, as in De elementis, there is again a lack 
of quantitative analysis. Theodoric's argument is in fact very 
brief, and merely suggestive of an analogy that might obtain 
between straight-line motions and circular ones when both are 
considered as natural motions. He first notes that there is a 
certain relativity to be found in linear gravitational motions, 
when the principles of such motions are considered precisely as 
related to the surrounding environment.^^ If extrinsic factors 
introduce a type of composition into motions that should be 
simple when explained in terms of their intrinsic principles 
alone, he sees no reason why a similar type of composition 
might not also be found in circular motions: 

If this is the case in such straight-line motions, as has been said, 
it is not extraordinary or incomprehensible to interpret the Phi- 
losopher's [Aristotle's] treatment of circular motion, when he speaks 
of it as rotating about a center, as not to mean the exact center of 
the universe, but the natural center of any natural circle in which 
there is something having the nature of a terminus, as for example 
the mid-point of the revolution, insofar as a revolution includes in 
its very notion movement to a point and away from a point, both 
being vmderstood with reference to the center of the circle. ... If 
therefore different relations to various termini can introduce com- 
position into straight-line motions, so also different centers can 

'^ Cap. 16, U 59ra-b: Quia in talibus transformacionibus que sunt recti motus 
attenditur fercio aliquis terminus — nichil enini tali motu incipit moveri secundum 
naturam quod non potest perveiiire ad terminum secundum naturam intentum — 
hinc est quod in talibus motis secundum diversitatem talium terminorum invenitur 
nonnulla distraccio et aliquis recessus a pura et omnimoda simplicitate, ne talia 
corpora, quamvis habeantur per simplicibus, ad eosdem terminos vel secundum 
eosdem moveantur. Videmus enim alium esse terminum ad quem naturaliter 
movetur ignis in regione sua, quia ad superficiem infimam spere lune, alium autem 
terminum perpendimus ad quem movetur aer in spera sua, qui si esset in spera 
ignis ab ea recedet naturaliter. Et ita videmus diversitatem terminorum in aqua 
et in terra quoad proprias secundum naturam regiones eorum. 


introduce plurality and composition into circular motions, and 
these too can be composed of many circular motions, of which each 
is itself simple and one.^- 

The composition which Theodoric here attempts to explain 
in terms of physical or natural causes is thus not the com- 
position that would result from a straight-line gravitational 
tendency to a center to which had been added a principle of 
tangential motion, as this was to be proposed by Newton in 
the seventeenth century, but rather a composition of rotary 
motions consistent with the geometrical picture of the universe 
already sketched by Ptolemy. What is interesting about Theo- 
doric's view, however, is his willingness to account for the 
deviations from perfect circularity detected by astronomers of 
his time in planetary, lunar and solar motions, by allowing for 
the possibility of different centers of gravity within the uni- 
verse, and this while viewing these centers not merely mathe- 
matically, but also as terms of proper natural motions from 
intrinsic principles. This represents a very definite break with 
the Averroist- Aristotelian tradition, and at the same time pro- 
vides the basis for accomodating Aristotelian thought to a 
plurality of gravitational centers, in the sense of universal 
gravitation as it was ultimately to be understood by Newton. 

Another interesting development of Theodoric's thought 
regarding composite motions is his attempt to explain the 
complex motion of the tides in terms of natural principles. This 

^^ Cap. 17, U 59rb-va: Si inquam sic se habet in istis motibus rectis, ut dictum 
est, quid mirabile vel inconveniens si sic vult intelligi Philosophus illud quod tractat 
de motu circulari, dicens ipsum fieri circa medium, non sumendo medium omnino 
pro centro universi, sed pro quocumque naturali medio cuiuscumque circuli naturalis 
in quo invenitur eciam aliquis habens naturam termini, puta medium centrum 
circa quod volvitur, que circumvolucio includit in se et importat naturam motus 
ad terminum et a termino, quod utrumque intelligitur in respectum ad centrum 
talis circuli. Moveri enim circa centrum est moveri quodammodo ab ipso et ad 
ipsum; unde habet naturam et racionem termini motus. Si igitur habitudo diversa 
ad diversos terminos motus rectos, ut visum est, sic eciam quoad motum circularem 
secundum diversa media centralia, quorum quodlibet habet naturam et racionem 
termini, potest plurificari et componi motus, ut sit motus compositus ex pluribus 
circularibus motibus quorum quilibet in se simplex et unus est. . . . 

204 W. A. WALLACE 

he undertakes to do in the opusculum De elementis, where he 
works out an explanation that is rather ingenious, even though 
quite implausible from the viewpoint of modern science. The 
motion of the tides, for Theodoric, is yet another case where 
" universal nature " provides for the needs of the universe by 
a composite motion, and this by inducing a motive principle 
that comes " effectively " from the heavenly bodies (particu- 
larly the moon) , and " passively " from sea water as being 
naturally adapted to receive this influx/^ The mode of trans- 
mission of the force deriving from the heavenly bodies is based 
on an interpretation of Proclus,^* whereby Theodoric conceives 
of some generic influence, originating with the separated sub- 
stances, as being more and more determined and composed as 
it works down through the heavenly spheres, finally receiving 
its ultimate determination from the moon.^^ Theodoric does 
not regard this influence as an attraction which exerts a pull 
on the sea, but rather conceives it as somehow effecting an 
alteration within the sea water, which makes it expand and 
thus extend its boundaries on land, thereby accounting for the 
rise (and fall) of the tides. 

Interestingly enough, Theodoric proposes a mechanistic type 
of explanation for this motion which is not without empirical 
foundation. As far as he can discern, tidal motions are 
restricted to bodies of sea water, and are not found in fresh 
water.^" Thus he proposes that sea water can be regarded as 

^^ Cap. 22, M 15vb, U 143ra-b. 

^* Cap. 23, M 16ra, U 143rb-va: Sicut dicit Proclus, 135 proposicione et 136 
proposicione, dicit quod omnes illarum substanciarum separatarum potencie de- 
sursum inchoantes, et per proprias medietates procedentes usque ad extrema, 
perveniunt et ad loca circa terrain. . . . Sicut dicit Proclus 54 proposicione, sic: 
omne quod a secundis producitur, et a prioribus et a causalibus producitur eminen- 
cius. — The references are to the Elementatio theologica. Cf. Proclus, The Elements 
of Theology, A Revised Text with Translation, Introduction and Commentary, by 
E. R. Dodds (Oxford: Univ. Press, 1933), Props. 135-6, pp. 120-121, and Prop. 56 
(cited as Prop. 54 by Theodoric), pp. 54-55. 

*^ Cap. 23, M 16ra, U 143rb. 

^* Cap. 24, M 16va, U 144ra: Sufficiant ilia que dicta sunt nonnulla racione, cui 
racioni concordat hoc quod videmus in aquis dulcibus, sive sint fluentes sive sint 
stagna, scilicet, quod non videmus ibi notabiliter eas vaporare et moveri extra 


a mixture of salt and fresh water, which is not strictly a new 
chemical compound, and whose components can therefore be 
separated " by the application of some force." ^' He conceives 
the action of the moon as being such a force, which effectively 
is able to " vaporize " the fresh (or " sweet ") component of 
sea water, thereby causing the whole body of the sea to 
expand and overflow its banks " as the moon approaches the 
meridian." ^^ Thus there are two natural causes of this com- 

consuetum modum suum, quia non est facilis separacio parcium talium aquarum, 
sicut dictum est de aquis que sunt in mari. 

^' Ibid., M 16rb, U 143vb: Quando humida aliqua adinvicem confunduntur, et 
fuerint substancie diversarum naturarum, et fuerit unum eorum subtilius altero et 
passibilius et facilius obediens agenti, faciliter abinvicem separantur, maxima si 
fuerint valde distantis nature, vel si fuerit unum eorum in alio sic virtute, ut possit 
ex eo faciliter generari. Et sic se habent aqua et vinum, que ex hoc aliqua arte 
separantur. Sicut autem dictum est de aqua et vino, sic se habet et in aliis talibus, 
puta in aqua salsa et dulci. Dico autem aquam salsam cuius substancia est sal, 
ut putei salis. Et talis est aqua maris in sui substancia, et propter hoc coquitur 
sal ex eo. Constat autem quod substancia dulcis aque et aqua maris sunt valde 
diverse, et distantis nature in subtilitate et grossitudine multum differentes. Et 
propter hoc, permixta, possunt aliqua vi abinvicem separari. Manifestum est autem 
quod dulces aque pluvium permiscentur mari; omnia enim flumina intrant in mare, 
et multi et maximi imbres et pluvie cadunt in ipsum. Si ergo sicut experimento 
probatur, ars aliqua potest separare vinum ab aqua vel aliquid huiusmodi simile 
facere, multo forcius natura potuit facere et fecit, determinans ad simile faciendum 
unum naturale instrumentum, confluentibus ad hoc, ut premissum est, aliis causis 
superioribus. ' Confluentibus ' inquam, quasi in unam virtutem et naturalem 
potenciam faciendi hoc, cuius effectus apparet in motu sohus lune. — ^For Theodoric's 
teaching that this kind of mixture does not make a strict (chemical) compound, 
see De miscibilibus in mixto, cap. 9 (ed. Wallace, Scioitific Methodology), p. 339. 

^^ Ibid.., M 16rb-va, U 143vb-144ra: Fit per istum modum, videlicet, quod parti- 
bus dulcis aque sparsis per mare, luna, immo totum celum quasi mediante luna 
tamquam per maxime determinatam causam secundum predicta, facit sua virtute 
dictas dulcis aque partes vaporare, secundum Tholomeum, ex supra inducta auc- 
toritate, et resolvi in fumum humide substancie. Hie enim accipiatur hoc modo 
esse vapor, videlicet, fumus humide substancie, quem oportet extendi quantitative 
intra corpus maris ad omnem dyametrum, et sic incomparabiliter ultra corpus ex 
quo vaporat quantitative, id est dimensionaliter, ingrossari. Luna autem appro- 
pinquante ad meridiauum, in quo magis viget natura et virtus operacionis sue, 
huiusmodi partes dulcis aque vaporant, et sua vaporacione extendunt substanciam 
maris cui permixte sunt, et mare sic extensum fluit quasi extra sinum suum et versus 
vacuitatem litoris. Et recendente luna a meridiano circulo a loco ad quem fluxerat, 
mare refluit, et mare sequitur lunam recedentem et euntem versus litus continuum. 
' Sequitm- ' inquam, non secundam eamdem partem sui qua iam fluxerat, sed 

206 W. A. WALLACE 

posite motion, one being the moon as efficient cause, the other 
being the passive nature of sea water, which is capable of 
receiving the moon's influence because of its peculiar material 

Extrinsic Movers 

Having thus accounted for several composite natural motions, 
Theodoric turns to a question which was much agitated by 
medieval scientists, and whose resolution gTadually prepared 
the way for the new mechanics that was to arise with Galileo 
and Newton. This was the problem of identifying the extrinsic 
mover that is responsible for falling motion, i. e., gravitational 
movement to a center. Theodoric has referred previously to a 
" generative principle " as accounting for the composite charac- 
ter of some natural motions; this resembles the traditional 
Aristotelian doctrine that the generator is the per se cause of 
simple natural motions, and thus the question arises whether 
Theodoric also regards the generator as being the effective 
principle that moves a body falling in straight-line gravitational 
motion. Theodoric's answer to this question is negative. While 
developed in the context of Aristotle's natural philosophy, his 
solution is again representative of a transitional type of rea- 
soning that in some ways anticipates the development of 
sixteenth-century mechanics, and on this account, at least, is 
worthy of note.^^ 

Theodoric's line of argumentation is directed principally 
against those who interpret Aristotle to mean that gravitating 
bodies are moved by the generator in the sense that they have 
their form and species from the generator, and just as they 
have these, so " they have all the natural accidents which 
follow from the species, one of which is natural motion with 
respect to place." *° Such was not an uncommon interpretation 

secundum aliam sui partem que in loco continuo ad presenciam lune vaporat et 
extenditur et fluit, sicut dictum est. . . . 

^^ See Maier, " Das Problem der Gravitation," Studien III, pp. 143-254. 

*°Cap. 28, M 16vb-17ra, T I84r, U 144va: Dicunt autem quidam quod gravia et 
levia et universal iter ea que moventur localiter per naturam in hoc inferiori mundo 


of Aristotle in Theodoric's time, being in fact proposed by 
various of his contemporaries, including Siger of Brabant, 
Godfrey of Fontaines, John Peter Olivi and Duns Scotus.*^ 
But our German Dominican does not regard this explanation 
as consistent with the remainder of Aristotelian doctrine, and 
gives seven arguments why it should be rejected. 

The first is drawn from the processive motion of animals, to 
which Theodoric would apply a similar analysis to the one 
here invoked for the local motion of heavy objects, insofar as 
it too derives from a natural form. This would result in an 
animal's locomotion being caused by its generator (i. e., its 
parent) , which Theodoric calls " absurd." *^ The second argu- 
ment is drawn from a similar application to the heavenly bodies: 
Theodoric merely points out that all metaphysicians agree that 
the latter are moved by another, but no one claims that they 
are moved by their generator .^^ His third argument is for those 
who are dissatisfied with the argument from animal locomotion, 
and is concerned with the motion of the heart and arteries: 
these are clearly vital motions, and as such must come from 
within — therefore they cannot proceed from the generator.^* 

Should one reply to these arguments, moreover, that they 
concern living things whose motions proceed from an active 
intrinsic principle, while falling bodies (as such) are non-living 
and only have a passive principle of motion within them, 
Theodoric will concede the objection. But then his fourth argu- 

moventur a generante, eo quod habent formam que est principium motus a gene- 
rante, a quo sicut habent huiusmodi formam et speciem, sic habent omnia naturalia 
accidencia que consequuntur speciem, quorum unum est naturahs motus secundum 
locum. . . . 

*^ For details, see Maier, Studien III, pp. 158-164. This was also the teaching 
of St. Thomas Aquinas (In II Phys., lect. 1, n. 4; In III De caelo, lect. 7, nn. 8-9; 
In V Metaph., lect. 14, n. 955) , but there are subtleties in Thomas' exposition that 
have been commonly overlooked by historians. For a clear presentation of the 
original Thomistic doctrine and its relation to Arab and late scholastic thought, 
see James A. Weisheipl, O. P., Nature and Gravitation, (River Forest, 1955) , pp. 

" Cap. 29, M 17ra, T 184r, U 144vb. 

" Cap. 30, M 17ra, T 184r, U 144vb. 

" Cap. 31, M 17ra, T 184r, U 144vb-145ra. 

208 W. A. WALLACE 

merit is based on the very passivity of gravitating bodies. By 
the terms of the objection, every passion must be accompanied 
by a simultaneous action, and thus, if the generator is the 
moving agent, it must actually accompany falling bodies " with 
a continual influx of motion," and this " we do not see." *' 
A fifth argument he draws from mathematics. A generator 
causes a triangle, and thus according to the explanation under 
discussion, causes all the natural accidents which flow from its 
quiddity, including that its angles equal two right angles; but 
it is " absurd " to say that the triangle in itself does not have 
this property, and gets it continually from the generator.*^ 

The sixth argument depends on the supposition that fire, or 
any other element, might be eternal, and on this supposition 
would not have a generator. Theodoric maintains that nat- 
urally " it still would be moved up," without the action of the 
non-existent generator.*^ His seventh argument, finally, he 
draws from the nature of motion itself, which is an imperfect 
act and as such requires an " actual mover producing the influx 
of motion." Therefore, if the generator is the mover, " it must 
actually coexist with and touch the object in motion, which is 
contrary to what is apparent to the senses," *^ 

Having thus disposed of a prevalent interpretation of Aris- 
totle, Theodoric turns to his own explanation of what the 
Stagyrite means when he says that falling bodies " are moved 
by the generator as by their principal and essential mover, 
and by whatever removes an impediment as by their accidental 
mover." The interpretation he proposes is based on distinctions 
between substantial and accidental being already developed in 
opuscula other than those now under examination. This doc- 
trine is exposed elsewhere; ^^ here I merely report the distinc- 
tions among accidents that are enumerated in De elementis 
as relevant to the problem of gravitation. 

*^ Cap. 32, M 17rb, T 184v, U 145ra-b. 

"Cap. 33, M 17rb, T 184v, U 145rb. 

^' Cap. 34, M 17rb-va, T 184v, U 145rb. 

" Cap. 35, M 17va, T 184v, U 145rb. 

^''See my Scientific Methodology, pp. 26-32, 80-91, 152-161. 


There are some accidents, notes Theodoric, which are purely- 
accidental in the sense that they have no per se order to any 
causal principle found in the subject by reason of its species, 
nor to the per se cause of the subject (i. e., its generator) , but 
can be present or not without affecting the nature of the 
subject. For example, heat or cold in a stone are purely 
accidental in this way.^° Other accidents are naturally in the 
subject according to its species, either always or for a certain 
time, and have a per se order to some causal principle in the 
subject. This group of accidents is further divisible into two 
types. Some are naturally produced by the subject itself, and 
are found only in things which have a natural diversity of 
parts. The organs of living animals are an example of this 
type.^^ Another type is that of accidents produced by some 
causal principle not itself found in the subject, but which pro- 
duces the subject (e. g., the generator) . These accidents are 
found per se and naturally in homogeneous things, of which an 
example is wetness in water. Since they cannot come from any 
intrinsic principle, but must come from an extrinsic one, and 
this cannot be the end, they must be produced by the efficient 
agent of the subject, which is the generator.^- The per se 
accidents of which Theodoric is here speaking come " under the 
essential order of the generator," and are produced by the same 
action which terminates in the substance or nature of the 
subject, so that they do not need any other essential mover 

^° Cap. 36, M 17va, T 184v, U 145va. 
" Cap. 37, M 17va, T 184v, U 145va. 

52 . 

'Cap. 38, M 17vb, T 184v-185r, U 145va-b: Alia vero accidencia secundum 
naturam que reducuntur ad aliquod principium causale, non quidem repertum in 
subiecto, sed quod est ipsius subiecti causa factiva, puta generans. Et ista sunt 
omnia ea accidencia que secundum naturam et per se insunt rebus homogeneis, ut 
sunt humidum et frigidum virtuale in aqua, frigidum et siccum virtuale in terra, 
grave et leve, et similia. Hec igitur, quia insunt per naturam et sunt per se acci- 
dencia, necesse est ea reduci tamquam in causam aliquid eorum que sunt subiecti 
per se et secundum naturam. Nee hoc potest esse aliquid intrinsecum, secundum 
predictam racionem. Igitur oportet quod principium eorum sit aliquid extrinsecum, 
quod sit per se causa subiecti. Finis autem non est principium factivum alicuius 
rei, sed mo vet per intentionem solum. Relinquitur ergo efficiens sive generans esse 
talium encium factivum principium. 

210 W. A. WALLACE 

to educe them from potency to act, as would be the case if 
they were produced through alteration.^^ 

In this division, then, the first group of accidents are such 
that, when not present in the subject, the subject is simply 
in potency to them. This means for Theodoric that even when 
all impediments are removed, they are still not actually present 
in the subject, but require an extrinsic agent to educe them 
from potency to act, and this agent further presupposes a 
subject already existing with this potency.'* The second class 
of accidents, found in the organic world, also presupposes a 
subject already constituted in a determined species. Since, 
however, they come to be from some causal principle within 
the subject itself, they likewise are not made actually present 
by the generator, although their principle is from the gene- 
rator.^' As to the third class — which is of main interest here 
insofar as it includes gravity and levity — it is manifest that 
their subjects are not simply in potency to them, although it 
might happen that the subject be accidentally in potency to 
them should they be blocked by an impediment, if the accident 
be of such type that it could be impeded. But in any case 
they do not require an essential mover to educe them from 
potency to act. They are already generated with the species, 
and their essential mover was the generator while actually 

^^Cap. 39, M 17vb, T 185r, U 145vb. 

" Cap. 40, M 18ra, T 185r, U 146ra. 

" Ibid. 

^^ Cap. 41, M ISra, T 185r-v, U 146ra-b: Ea autem que sunt tercii generis, 
secundum es que predicta sunt de hoc genere, manifestum est quod res habens suam 
completam speciem non est in potencia simpliciter et per se ad aliquam talium disposi- 
cionem, sed forte erit in potencia secundum accidens, scilicet propter impedimentum, 
si fuerit talis disposicio cui possit accidere impedimentum. . . . Hinc est quod 
gravia et levia habencia suam speciem non moventur nisi a motore accidentali qui est 
removens prohibens, et non a generante, si vere et proprie loquamur de huiusmodi 
motis et motuum eorum principiis. Sed tunc solummodo et vere moventur a gene- 
rante ad huiusmodi naturalia accidencia, cum per mocionem generantis secundum 
substanciam exeunt de potencia ad actum sue forme substancialis. Actio enim 
generantis, ut predictum est, simul terminatur ad speciem rei et huiusmodi per se 
accidencia. . . . 


This supplies Theodoric's basic answer to the difficulty pre- 
sented by falling bodies. Heavy bodies already have their 
gravity from their generator or essential mover. They do not 
need the generator's action any further once they are generated; 
all that they henceforth require is an accidental mover to 
remove any impediments. Once such impediments are removed, 
gravity is immediately and actually present, and the subject 
is not in potency to it in any way, either accidentally or 

This still leaves unanswered the question as to what is the 
efficient principle of the motion which follows from gravity. 
As Theodoric has just shown, this is not the generator, nor is it 
the falling body, nor is it the " disposition " which the body 
acquires, nor can it be a " natural consequent " of its specific 
nature, nor can it be whatever removes the impediment to its 
motion (i. e., its accidental mover) , which merely functions 
in a negative way.^® Rather, in considering such an existential 

^^ Cap. 42, M 18rb, T 185v, U 146rb: Ex predictis liquet quod ea que insunt a 
generante, constante re ipsa secundum suam speciem et cessante omni impedimento, 
postquam eciam res separata fuerit a generante, mox acquisita sunt rei et statim 
insunt, ut ostendit Philosophus in quarto Physicorum de propriis locis gravium et 
levium. Non enim iam manet res ipsa in potencia aliquo modo ad huiusmodi 
disposiciones; quia non accidentali, eo quod non sit impedimentum, nee essenciali, 
propter dictam racionem, scilicet, quia res habens suam speciem non est in potencia 
essenciali ad aliquam talium naturalium disposicionum. Hinc est quod ea que 
secundum dictum modum insunt, sunt forme vel nature habentes se per modum 
habitus circa subiectum, quorum esse est totum simul et in indivisibili, quum in 
instanti talia acquisita sunt rei, sive in termino generacionis, sive eciam post, 
remoto impedimento. . . . 

^® Cap. 45, M 18vb, T 185v, U 146rb-147ra: Constante re secundum suam speciem, 
et impedita per aliud ne possit esse in sua naturali disposicione, si removeatur 
impedimentum, movere potest; quid sit per se agens et faciens rem esse in tali 
disposicione.'' Generans enim non facit, eo quod res iam ponitur separata a generante. 
Nee res ipsa seipsam agere potest ad huiusmodi disposicionem, secundum predicta. 
Nee ipsa disposicio seipsam facit in esse, cum ipsa nondum sit, et non ens non 
ducit seipsum ad esse. Nee potest inesse per naturam cuiusdam consequencie. . . . 
Actus autem non complet potenciam secundum racionem consequendi, absque factivo 
principio actu agente. . . . Nee sufficit dicere quod movens per accidens, id est, 
removens prohibens, hoc faciat; non enim sufficit ad productionem seu factionem 
rei non existentis solum removere impedimentum factionis, nisi sit aliquid actu 
per se faciens. 

212 W. A. WALLACE 

thing as motion, itself an acquisition of being, Theodoric holds 
that another factor must be taken into account, and this is the 
dependence of things on a principal essential cause, not only 
for their coming-to-be, but also for their continued being. In 
his own words: 

It must be understood that things able to be generated, considered 
with respect to their acquisition of being, have a twofold relation 
to the cause generating them: first, according to the conversion 
of potency to substantial act, which has the formality of a coming- 
to-be; secondly, according to the act acquired through the gene- 
rator's causality, which is the formality under which it is already 
constituted in being. In both these ways a thing comes under the 
essential ordering of its generating cause. I wish ' generator ' to be 
understood here as the per se and essential and principal cause of 
the substance of the body, so as to exclude any instrumental cause 
or other causes that may be accidental. I also understand ' essential 
ordering ' to be that by which a thing depends essentially on its 
cause, which not only holds for its coming-to-be . . . but also for 
the perfection of its act once acquired. . . ,^^ 

His thought here has a definite Neoplatonic flavor, although it 
is not without some affinity to the Thomistic analysis of divine 
causality, for Theodoric conceives the principal essential cause 
as that which sustains and connects the whole natural order, 
that on which natural things depend for " a certain continua- 
tion of their being through a continual influx " deriving from 
it as an essential cause.''" The influx of this cause is what 

^* Cap. 46, M 18vb, T 185v, U 147ra: Sed considerandum quod res generabiles, 
quantum ad acquisicionem sui esse, dupliciter se habent ad causam dantem esse per 
generacionem: uno modo, secundum exitum potencie ad actum substancialem, et 
sic habet racionem eius quod est fieri; alio modo, respicit huiusmodi causam 
secundum racionem actus acquisiti per talis cause causalitatem, et secundum hunc 
modum res est in facto esse. TJtroque autem istorum modorum, res stat sub ordine 
essenciali cause generantis. Volo autem intelligi generans quod est per se et essen- 
cialis et principalis causa substancie rei, ut excludatur causa instrumentalis, vel 
eciam alie cause, si que sunt accidentales. Dico autem ordinem essencialem quo res 
per suam essenciam dependet a sua causa, quod quidem non solum convenit rei 
secundum suum fieri, scilicet, quantum ad accepcionem sui esse quoad exitum 
potencie ad actum per mocionem generantis, sed eciam attenditur in causa huiusmodi 
ordinis secundum perfectionem iam acquisiti actus. . . . 

®° Ibid.: Non est aliud quam quedam ipsius esse continuacio per continuum ipsius 
cause influxum per essenciam. . . . 


sustains every natural substance in being. It is also, for 
Theodoric, what gives it actuality during its transitional stage, 
or sustains its motion: 

The influx of this cause is found not only when the thing has been 
constituted in being, but also in a certain way in its changing, for 
otherwise the influx would already have ceased, and if this were 
the only action of the universally first cause, then the being of the 
thing would not be restricted to a certain and determined period.*^^ 

Thus Theodoric's solution reduces simply to this, that the 
efficient principle of gravitational motion is the first principal 
cause in the order of nature, or, in other words, " the motion 
of which we are treating is reducible, as to its principal cause, 
to the essential cause of the substance of the body in motion." ®" 
The singular merit of Theodoric's solution would appear to 
lie in the fact that he has simplified the search for the cause 
of gravitational motion by eliminating the generator altogether, 
as not being in the direct line of efficient causality effecting 
the motion. Thus he does not consider it correct to say that 
the generator is the cause of such motion by the form he puts 
in the falling body. This, for him, is to confuse the meta- 
physician's way of looking at the problem with that of the 
natural philosopher. From the point of view of the natural 
philosopher, the generator is the motive principle in the pro- 
duction of the body; once the body is produced, the only 
principle of its motion that need concern him is the accidental 
mover, which removes any impediments that might restrain 
an efficient causality deriving directly from the principal essen- 
tial cause of the universe. He considers further that there is 

*^ Cap. 46, T 185v: Huiusmodi igitur cause influxus non est solum in facto esse, 
sed eciam est in fieri quodammodo, alioquin iam olim cessasset influere, et si hec 
asset solum causa universaliter prima, tunc esse rei non clauderetur certa et deter- 
minata peryodo. — The manuscript versions all give different readings for this chapter, 
and none is clear and unambiguous. I give here only the reading as found in T, 
which is the briefest and most intelligible. The English above is not a literal trans- 
lation, but conveys what I believe to be the sense of the passage, as far as this is 

*^ Cap. 46, M 18rb, T 185v, U 147rb: Motus huiusmodi de quo agitur reducitur 
Kicut in causam principalem in causam videlicet essencialem substancie rei mote. 

214 W. A. WALLACE 

" a twofold accidentality to be noted in such motions, both 
coming from whatever restrains or impedes bodies of this type; 
one is an [accidental] potency by which it ' happens ' that they 
can be moved; the other by which it ' happens ' that they are 
moved successively, for otherwise, once all impediments are 
removed, they would move instantly." ^^ Unfortunately Theo- 
doric does not elaborate this very interesting observation, but 
immediately adds the colophon and explicit, bringing his opus- 
culum on the elements to rather an abrupt close. 

As to the precise mechanics favored by Theodoric for ex- 
plaining the quantitative aspects of gravitational motion, one 
can only adduce indirect evidence. Two views were current 
among his contemporaries, one deriving from Averroes, which 
would have the velocity of fall directly proportional to the 
motive force and inversely proportional to the resistance of 
the medium, the other deriving from Avempace and having 
the velocity proportional to the difference between the motive 
force and the resistance of the medium.*'* Theodoric seems to 

"' Cap. 47, M 18vb-19ra, T 185v, U 147rb: Sed ex hoc frustium uititur quis recti- 
ficai'e errorem suum quo asserit huiusmodi moveri a generante eo modo qui improba- 
tus est, scilicet, in habeiido formam seu speciem a generante. Aliud est reducere aliquid 
in aliud sicut in causam essencialem, secundum consideracionem primi philosophi, 
qui considerat rerum essencias secundum racionem suarum quidditatum; aliud est 
querere de alicuius principio motivo, secundum quod physicus liabet considerare. 
Unde aliquid potest reduci in causam propriam secundum quod primus pliilosophus 
considerat, quod non potest reduci in ipsam ita quod ipsa sit principium motivum. 
Et sic se habet in proposito quantum ad motus gravium et levium, ut patet ex 
prehabitis. Unde generans non est principium motivum nisi quando actu movet per 
generacionem rei. Est autem principium causale [tale U] eciam postquam generavit, 
sed removens prohibens est principium motus, attamen per accidens inquantum 
physicus considerat de motu, videlicet, inquantum motus. Et secundum istum 
modum cucurrit questio proposita de motibus gravium et levium, et negatur quod 
moveantur a generante. Sed est hie advertenda duplex accidentalitas in motibus 
istorum, et utraque est a prohibente seu impediente huiusmodi mobilia. Una est 
secundum potenciam ad motum qua accidit eis moveri, alia est qua accidit eis 
successive moveri; alias enim, remoto omni impedimento, mutarentur in instanti, 
ut predictum est. Hec igitur sufficiant de dementis mquantum sunt partes mundi; 
alibi enim de ipsis tractatum est inquantum sunt miscibiiia et partes mixti. 
Explicit. . . . 

"^For details, see Maier, " Platonische Einflus!.-! in der scholastischen Me- 
chanik.'," Studien V, pp. 237-285. 


favor the Averroistic explanation, as evidenced by this text 
where he explicitly rejects Avempace's solution: 

It is obvious from what has been said that Avempace's position, 
which the Commentator [Averroes] treats in the context of the 
fourth book of the Physics, is false. This states that if all impedi- 
ments be removed, taking away even corporeal media through 
Avhich heavy and hght bodies move, supposing imaginatively that 
the medium were void, that nonetheless heavy and light bodies 
would be moved by nature with a determinate velocity and slow- 
ness in time. According to the foregoing, however, this is only 
possible where the mover and the thing moved are actually distinct, 
and where the mover is also actually conjoined to the moved 
according to a determinate proportion between the power of the 
mover and the thing moved, as is the case with animals and 
heavenh^ bodies. This would also render false the demonstration 
of the Philosopher [Aristotle] in the fourth book of the Physics, 
where he shows that heavy and light bodies do not move in a void, 
as the Commentator sufficiently explains, nor need we delay over 

Theodoric's treatment of gravitational motion is consistently 
concerned with the natural or physical causes of such motion, 
and is devoid of quantitative or mathematical considerations. 
In this respect his methodology in mechanics is significantly 
different from that found in his optical studies, where experi- 
mental and mathematical techniques reached their highest 
development within the hochscholastik period. This difference 
was noted in my earlier study, where I assigned it to the 
obscurity of the principles available for explaining gravita- 
tional motion (and chemical change) , forcing Theodoric to 
remain at the qualitative and dialectical level when treating 
these matters.®® Yet the conclusion need not be draAvn that 
Theodoric's opuscula were without value for the later develop- 
ment of the science of mechanics. Both Maier and Clagett 
have shown how the mid-fourteenth century opuscula of writers 
like Buridan began to change the ' climate of opinion,' and 

"^ Cap. 44; Latin text given by Maier, Studien V, p. 246, fn. 14. 
"" Scientific Methodology, pp. 127, 246-247. 

216 W. A. WALLACE 

prepare the way for the seventeenth century development, by 
considering gravitational force and impetus less as the cause 
of mechanical motion and more as an efect of the motion 
itself.°^ Theodoric had not yet arrived at this conception, but 
he perhaps cleared the way for it by eliminating gravity (and 
its generator) entirely from the realm of efficient causality. 
In this endeavor, and particularly in his attempt to point out 
existing confusions between a physical and a metaphysical 
approach to such problems of mechanics, Theodoric had some- 
thing distinctive to offer to early fourteenth century physics. 

W. A. Wallace, 0. P. 

Dominican House of Philosophy, 
Dover, Massachusetts. 

"'' Studien V, pp. 380-382; Sdence of Mechanics, pp. 548-678. 


Clarke's Notes to Rohault's Traite de Physique 


SAINIUEL CLARKE, the son of a prominent Norwich 
family, was just sixteen when in 1691 he entered Gonville 
and Cains College, Cambridge. A quarter of a century 
earlier Roger North had remarked on " a general inclination, 
especially of the brisk part of the university," ^ to follow the 
teaching of Descartes; in 1691 Clarke found Cartesian phi- 
losophy established and his own tutor, John Ellis, a " zealot " 
for it." 

One of the reasons for the Cartesian success had been the 
excellent textbook on physics published in 1671 by Jacques 
Rohault, a Cartesian whose ability as a teacher had been 
partly responsible for the vogue for science in the French 
capital. His Traite de Physique ^ had been quickly translated 
into Latin by Theophile Bonet, and an edition of this trans- 
lation was published in London in 1682. Edition after edition 
of the Traite continued to appear in both French and Latin,* 

^R. North, Autobiography, Univ. Lib. Cambridge, MS. Baker 37, fol. 163-163v. 
Cited in M. H. Curtis, Oxford and Cambridge in Transition (Oxford, 1959), p. 257. 

^ B. Hoadley in Samuel Clarke, Works (London, 1738) , I, p. i. 

^ For accounts of Rohault's work and especially of the Traite de Physique, see 
P. Mouy, Le Developpement de la Physique Cartesienne (Paris: Vrin, 1934) , pp. 
108-138, and R. Dugas, La Mecanique au XVIP siecle (Neuchatel: Editions du 
Griffon, 1954) , pp. 252-263. 

* Mouy's account of these editions (op. cit., p. 137) has many errors. George 
Sarton's " The Study of Early Scientific Textbooks," Isis XXXVIII (1947-8) , 137- 
148, is more satisfactory. A fuller list is as follows: 

French editions, published in Paris: 1671 (1st ed.), 1672 (2nd ed.), 1676/5 

(3rd ed. corrigee) , 1676 (4th ed., reveiie & corrigee) , 1682 (4th ed., tres- 

exactement reveue & corrigee), 1683 (6th ed.) , 1692 (6th ed., tres-exactement 

reveue & corrigee), 1705, 1708 (12th ed.) , 1723, 1730. 

French editions published in Amsterdam: 1672, 1676. 

Latin translation by Bonet: 1674, Geneva: 1682, London; 1682, Amsterdam, 

with notes of Le Grand; 1700, Amsterdam, with notes of Le Grand. 

Latin translation by Clarke and with his notes: 1697 (1st version of notes), 



but although still unrivalled, it was by Clarke's day becoming 
seriously out of date. Leaving aside Newton's optical papers 
(1672-6) and his epoch-making Principia (1687) , several im- 
portant works on Cartesian physics had appeared since 1671/ 
and the many observations and experiments carried out, 
especially by Fellows of the Royal Society, had led to numerous 
detailed improvement in knowledge. Another reason for dis- 
satisfaction in Cambridge was the poor quality of Bonet's 

In Clarke, Ellis had a pupil of unusual gifts. Before coming 
to Cambridge he had shown promise of the linguistic ability 
that later in life led him to prepare editions of such different 
authors as Caesar and Homer; and at Cambridge he made 
his mark in natural philosophy by defending a Newtonian 
thesis in the Schools.^ His insight into the forbidding Principia 
was shortly to impress no less a figure than William Whiston, 
who later succeeded Newton in his professorship. On meeting 
Clarke, Whiston " was greatly surprised that so young a man 
as Mr. Clarke then was, not much I think above twenty-two 
years of age, should know so much of those sublime discoveries 
which were then almost a secret to all, but a few particular 

London; 1702 (2nd version) , London; 1708 (2nd version, with notes of Le 
Grand), Amsterdam; 1710 (3rd version), London; 1713 (? 2nd version, with 
notes of Le Grand), Cologne; 1718 (3rd version), London; 1739, " 6th edition," 

EngHsh translation of John Clarke with 4th version of Samuel Clarke's notes: 
1723, London; 1728/9, London; 1735, London. 

The various versions of Clarke's notes are discussed below. The term ' edition ' 
is perhaps misleading in this coimexion, for the successive versions are radically 
changed; and it is therefore not appropriate to speak of " the " notes by Clarke. 
Sarton's inability to obtain a copy of the 1697 edition prevented him from realizing 
this. One of the few writers to draw attention to the changes in Clarke's notes is 
F. Cajori, Newton's Principia (Berkeley: Univ. of California, 1934), p. 631. 

^Including Malebranche, La Recherche de la Verite (1st ed., 1674/5), Regis, 
Systeme de Philosophic (1st ed., 1690) , Perrault, Essais de Physique (1st ed., 1680) , 
Le Clerc, Physica (1st ed., 1695). 

* Hoadley in Clarke, Works, I, p. i. 


mathematicians." " Ellfs accordingly suggested to Clarke that 
he should prepare a new Latin translation of the Traite.^ 

This invitation put Clarke in something of a dilemma: for 
on the one hand he knew, as Ellis did not, that Newton's 
Principia had not only made serious inroads into the Cartesian 
position, but had in practice developed a rival cosmology; yet, 
on the other hand, neither Newton's lectures nor his book had 
had much impact on the university, and an improved Car- 
tesian textbook was an urgent necessity. If Whiston's memory 
for dates is accurate, Clarke's doubts must have persisted into 
1697, the very year in which his translation appeared, for it 
was then that he introduced himself to Whiston in a Norwich 
coffee-house " to ask my opinion about the fitness of such a 
translation. I well remember the answer I made him, that 
' since the youth of the university must have, at present, some 
System of Natural Philosophy for their studies and exercises; 
and since the true system of Sir Isaac Newton's was not yet 
made easy enough for the purpose, it is not improper, for their 
sakes, yet to translate and use the system of Rohault . . . but 
that as soon as Sir Isaac Newton's Philosophy came to be 
better known, that only ought to be taught, and the other 
dropped.' " ^ Newton stood in far greater need of an inter- 
preter than Descartes; until one was forthcoming, Rohault must 
be taught. 

In the Preface to his 1697 edition, Clarke explains his 
motives. The existing translation is faulty, and he gives 
examples of this. But in addition, he says, he is not a man 
to make an oracle of his author, and although critics have 
failed to discredit many of the things in the book, some parts 
have been overthrown by subsequent experiments and some 
have been emended by later writers. He has therefore supplied 
some short notes, in which he has tried to give " a full answer 
to such objections made against the author as seem not to 

■^ W. Whiston, Historical Memoirs of the Lije of Dr. Samuel Clarke (London, 
1730), p. 6. 
^ Ibid., p. 5. 
^ Ibid., pp. 5-6. 


have any just foundation, and a great many things in natural 
philosophy, which have been since found out by the pains and 
industry of later philosophers, are here selected from the best 
writers; and there are also several things added out of the 
observations of the ancient writers of natural philosophy and 
natural history, where they seem to explain and illustrate 
matters." " 

Clarke was not the first to annotate Rohault's text; Antoine 
Le Grand had provided animadversiones to the edition of 
Bonet's translation published in Amsterdam in 1682. The 
Bonet-Le Grand version was published again in Amsterdam 
in 1700, and Le Grand's notes were later appended to Clarke's 
translation and notes when these were published in Amsterdam 
in 1708 and in Cologne in 1713. In total length the two sets of 
notes are much the same. But whereas those of Le Grand are 
individually of some length, most of Clarke's are slight, and he 
refers to a bewildering variety of earlier authors: to classical 
writers like Aristotle, Pliny, Seneca, Livy, Plutarch and Mac- 
robius, to Cartesians such as Regis, Malebranche, Perrault and 
Le Clerc, and to accounts of experiments by the Accademia 
del Cimento, Hooke and Boyle, as well as to the writings of 
Newton himself. 

Newton is first mentioned in a note to the passage where 
Rohault, following Descartes, concludes from the identity of 
matter and extension that a vacuum is not possible. Clarke 
notes that this is controversa et plena dissensionis inter Phi- 
losophos, and refers the reader to Regis, where he will see that 
the objections brought against Descartes are only slight. 
He then adds, almost as an afterthought: sed lanceTn de- 
primit Clariss. Newtonus, and gives a reference to the Prin- 
cipia.^^ There is another reference to the Principia in a note 
on the propagation of sounds.^^ In the notes to the chapter 

^° Where appropriate, English translations are cited from John Clarke's 1723 
edition. Samuel Clarke made curiously few alterations in his Prefaces, even when 
the role played by the notes he is introducing clearly change. 

" n, p. 187. 

" n, p. 208. 


on light Newton comes more into his own, for Clarke gives 
an account of his work on refraction and its implications for 
the construction of telescopes/^ He also lists phenomena asso- 
ciated with prisms, and after mentioning the views of Descartes, 
Hooke and Barrow, continues: His igitur OTuissis, propero ad 
Clariss. Newtoni Theoriam {nam hypothesim earn appellare 
fas non duco) qua superius memorata phaenomena, aliaque 
omnia luculentissime explicantur. Clarke then shows how 
each of the phenomena can be explained by Newton, and 
concludes with a hint of better things to come: Permulta alia 
omni luce dignissima de colorum natura et proprietatibus 
invenit Clariss. Newtonus, quae aliquando in lucem edere 
dignetur efflagitat orhis literarius.^^ 

In the cosmology of Part II, Newton is quoted for a more 
exact estimate of the shape of the earth ^^ and for the relative 
density of the earth and moon ^®; and in a note on comets 
Newton's doctrine of their essential similarity to planets is 
shown to be consistent with their observed behavior/^ Newton 
is not mentioned in the notes to Part III, on terrestrial phe- 
nomena, and Clarke at no time provided any notes to Part IV, 
on physiology and medicine. 

The reader of Clarke's notes, then, would learn something 
of Newton's prismatic experiments and his doctrine of colors; 
but of his great cosmological synthesis, little more than his 
views on the nature of comets. Newtonian attraction is not so 
much as mentioned. The Cartesian plenum, the three elements, 
Rohault's condemnation of attraction, all are allowed to pass 
without comment. It is true that the notes on the prism and 
on comets are the longest of all, but the other notes of substance 
are usually confined to discussions of the views of Cartesian 
commentators. Clarke gives the views on solidity of Descartes, 
Malebranche and Perrault,^^ the laws of Regis on elastic im- 
pact,^^ the views of Regis, Perrault, Malebranche and Le Clerc 
on rest,-° Perrault's explanation of the direction of free fall, 

" II, pp. 212-3. i« II, p. 227. " II, pp. 191-3. 

^* n, pp. 214-9. " II, pp. 227-30. =» II, pp. 189-90. 

" II, p. 225. i« n, pp. 198-200. " II, pp. 231-2. 



and so on. There is no suggestion of a systematic refutation of 
the text and argument in favor of Newtonian philosophy, 
although historians who have confused the 1697 notes with 
those of later editions have often supposed Clarke to offer just 
this." In fact, the notes are tucked away at the back of the 
book, and are referred to on the title page and in the Preface 
by the diminutive annotatiunculae . They represent the tenta- 
tive first steps of a newly-fledged graduate. 

By 1702, when a second edition was required, Clarke's inten- 
tions had undergone a major change. His notes are now 
enlarged to about a fifth of the length of Rohault's text and 
are dignified with the title annotata. Some of the improvements 
are credited to Whiston and to another Clare physicist, Richard 
Laughton; others indicate Clarke's own interests, as when he 
tells us of some of his experiments ^^; but it is the name of 
Newton that appears on the title pages ^* as the chief source 
of the notes. This promise of a more hostile attitude towards 
the Rohault text is soon confirmed by the notes themselves. 
Thus, when Rohault suggests that the essence of matter consists 
in extension, Clarke retorts that a similar argument would 
make its essence consist in existence, and that it in fact consists 
in impenetrability.^^ Of the identification of matter and space 
he now declares roundly. Hoc quidem falsum est,-^ and he 
dismisses the supposed equal quantities of matter in a vessel 
of lead and a vessel of wax with omnino hoc falsum.^'^ 

On the more constructive side, Clarke now feels at liberty 

^^ Hoadley, who clearly lacks Whiston's personal knowledge of these events, is 
perhaps the first to fall into this error. " His aim was much higher than the making 
of a better translation of it. He resolved to add to it such notes, as might lead the 
young men insensibly, and by degrees, to other and truer notions " (Clarke, Works, 
I, p. ii) . At the other extreme, R. Dugas and P. Costabel date the Newtonian notes 
from the 1723 English edition (Histoire Generale des Sciences, ed. R. Taton [Paris, 
1957-], n, p. 465). 

'^ " I have tried it with quicksilver . . .," notes p. 13; "I have oftentimes ordered 
the glass . . .," notes p. 55. 

^* Plural, because the 1702 edition (like the 1710 and perhaps others) was re- 
issued with a new title page. Newton's name occurs on both. 

" Notes, p. 2. =>« Notes, p. 3. " Notes, p. 4. 



to introduce longer notes, notably of Boyle's hydrostatical 
paradoxes and his experiments on taste, smells and so on.^* 
And, most important of all, he provides a brief but uncom- 
promising exposition of Newtonian gravitation, in his views 
of the cause of which he was further from the Cartesian position 
than Newton at times seemed to be.-'' In Part I he remarks 
in passing that " it is now allowed, that gravity does not depend 
upon the air or aether, but is an original connate and immutable 
affection of all matter," ^° and he develops the theory in a series 
of three notes near the end of Part II. The Cartesian account 
of gravity is now dismissed as " a very ingenious hypothesis," 
and it is Newton who has " established the true system of the 
world beyond all controversy." ^^ His admiration is expressed 
in the highest terms: Newton " in his wonderful book of the 
Mathematical Principles of Natural Philosophy has explained 
the true system of the world, and shown the true and adequate 
causes of all the celestial motions almost beyond the genius 
of a man." ^^ 

Clarke explains that, according to Newton, gravity is asso- 
ciated with every pair of particles, wherever they are, whatever 
the bodies in question, and whatever the time; it is propor- 
tional to the quantities of matter, and inversely proportional 
to the square of the distances. This being so, it follows 
(he says) that gravity is an ultimate fact: " gravity of the 
weight of bodies is not any accidental effect of motion or of 
any very subtle matter, but an original and general law of 
all matter impressed on it by God, and maintained in it per- 
petually by some efficient power, which penetrates the solid 

^^ Hydrostatical paradoxes, notes pp. 23-26. On taste, notes pp. 35-36. On smell, 
notes pp. 36-38. Boyle is mentioned in some ten notes altogether, and Dr. M. Boas' 
remark (Rev. d'Hist. des Sc, IX (1956), 124) that Boyle's experiments are quoted 
almost as often as those of Newton is true of the 1702 notes. 

"* On Clarke's views as expressed in his other works, see H. Metzger, Attraction 
UniveTselle et Religion Naturelle chez quelques Commentateurs Anglais de Newton 
in (Act. Sci. Ind. 623), (Paris, 1938), pp. 113-139. On the relations between the 
views of Newton and Clarke, see A. Koyre, From the Closed World to the Infinite 
Universe (Baltimore: Johns Hopkins, 1957), pp. 300-301. 

'" Notes, p. 18. '^ Notes, p. 80. '^ Notes, p. 72. 


substance of it; for gravity is never in proportion to the super- 
ficies of bodies or of any corpuscles, but always to the solid 
quantity of them. Wherefore we ought no more to enquire 
how bodies gravitate, than how bodies began first to be 
moved." ^^ 

In the other two notes Clarke gives a taste of the power of 
the Newtonian conception. In the first he outlines, informally, 
how gravity explains the first two Keplerian laws of planetary 
motion ^*; in the second he follows Halley in using gravity to 
explain the motion of the tides .^^ Here at last the English 
undergraduate was given a glimpse of the power of the New- 
tonian theory; one wonders what continental readers made of 
these notes when they were republished in Amsterdam in 1708, 
no longer hidden at the back of the book, but displayed as 
footnotes to Rohault's text.^*^ 

Although in the 1702 notes Clarke's views are unmistakable, 
surprisingly large sections of the Rohault text are still allowed 
to pass unchallenged. Sometimes this is because Clarke does 
not yet go out of his way to pick quarrels with his author — 
for example, he does not exploit Newton's teaching on comets 
as an argument against the Cartesian vortices — but sometimes 
it is because Clarke is still hampered by Newton's failure to 
publish a more widely-ranging account of his views. 

In 1704, however, Newton's Opticks at last appeared, and 
it was Clarke himself who prepared the Latin translation of 
1706.^" When a new edition of his Rohault translation was 
published four years later, Clarke made numerous references 
in his notes to the Opticks, many of them accompanied by 

^^ Notes, pp. 81-83. 

''* Notes, pp. 70-72. An improved version of this note, with some mathematics, 
was published in the 1723 edition. 

*^ Notes, pp. 83-85. 

'" The influence, if any, of this early popularization of Newtonian cosmology on 
the continent does not appear to have been studied. Clarke's forthright views on the 
nature of attraction are unlikely to have commended themselves to Cartesian readers. 

*''With additional queries, in particular the one which later became Query 31, 
from which Clarke quotes nearly two dozen passages in his 1710 notes. 

"mining all within ' 225 

lengthy quotations. Soine of these references are in the ex- 
tended comments to the chapters on light, but by no means all. 

Encouraged in his criticisms by this new ammunition, Clarke 
now carries the war into the enemy's camp. His earlier dis- 
cussion of the application of gravity to the motion of planets 
is now preceded by four arguments showing that " the vortices 
of matter in which the planets swim, are mere fictions and 
contrary to the phenomena of nature." ^^ Rohault's paragraph 
headed " that these three elements are not imaginary," pre- 
viously allowed to pass, now has a note beginning " these three 
elements are to be looked upon as fictitious and imaginary." ^^ 
The Cartesian subtle matter is now a " fiction . . . very weak, 
and contrary both to reason and experience." *" At last Clarke's 
notes begin to provide a systematic refutation of the text. 

At the same time the positive teaching in the notes is greatly 
increased. Perhaps nothing illustrates their role in this respect 
better than the inclusion of " six whole dissertations " by 
Charles Morgan, a contemporary of Clarke at Cambridge and 
later Master of Clare College. These were important enough 
to merit republication as a separate tract in 1770, long after 
the Cartesian controversy had been settled in Newton's favor. 
Three of the dissertations, on the motion of falling bodies, on 
the motion of projectiles, and on the descent of bodies falling 
in a cycloid, together form a single footnote occupying over 
a dozen pages of small print and ostensibly provoked by 
Rohault's innocuous remark that falling bodies accelerate.*^ 
Clarke clearly feels that he must take opportunities of com- 
plementing the text over and above what is strictly necessary 
to the establishment of Newtonian philosophy.*" 

One particularly interesting note contains Clarke's doctrine 

="'?. 311. 

'' P. 105, my italics. 

*"?. 25. 

*^ The acknowledgement to Morgan is made in the Translator's Preface. Clarke's 
presentation copy to Morgan is in the possession of Clare College, Cambridge. 

*^ Mouy (op. cit., p. 137) erroneously supposes these dissertations to be by 
Clarke and to be " ses critiques principales." 


of the efficient cause of gravity. " Since nothing acts at a 
distance," he says, " that is, nothing can exert any force in 
acting where it is not, it is evident, that bodies (if we would 
speak properly) cannot at all move one another, but by contact 
and impulse. . . . Yet because besides innumerable other phe- 
nomena of nature, that universal gravitation of matter . . . 
can by no means arise from the mutual imj^ulse of bodies 
(because all impulse must be in proportion to the superficies, 
but gravity is always in proportion to the quantity of solid 
matter, and therefore must of necessity be ascribed to some 
cause that penetrates to the inward substance itself of solid 
matter) , therefore all such attraction is by all means to be 
allowed as it is not the action of matter at a distance, but the 
action of some immaterial cause which perpetually moves and 
governs matter by certain laws." He goes on to quote several 
passages from the Opticks, adding the gloss " not bodily 
impulse " to Newton's " What I call attraction may be per- 
formed by impulse." *^ 

With the publication of the 1710 edition Clarke's notes 
assumed almost their final shape. On the title pages Newton's 
name is actually given greater prominence than those of author 
and editor; the notes have grown to between one-quarter and 
one-third the length of the text ^* with a corresponding increase 
in quality, and they are now displayed as footnotes with 
references in the index.*^ Clarke left these notes unaltered in 
the 1718 edition, which suggests that after his famous contro- 
versy with Leibniz,*'' in which he acted as Newton's champion, 
he saw little reason to alter his opinions — above all, on the 
nature of gravity. But he did make a few minor alterations 

"Pp. 50-51. 

** As the title-page of a reissue accurately observes, they have been increased by 

*^ The continental edition of 1708 has footnotes, but these are not referenced in 
the index. The references in the 1710 edition are presumably to the notes Clarke 
himself regarded as important. 

*" See H. G. Alexander (ed.) , The Leibniz-Clarke Corres^pondence (Manchester: 
Univ. Press, 1956) . 

"mining all within" 227 

in the notes for the English translation published in 1723 
by his brother John: the discussion of Kepler's laws*^ and 
Morgan's dissertation on the rainbow are enlarged,*^ there is 
mention of Newton's view of the origins of novae (taken from 
the 1713 edition of the Principia) /^ and a handful more quo- 
tations are culled from the Queries in the Opticks,^'^ but other- 
wise almost all the changes are echoes of changes in the second 
English edition of the Opticks (dated 1717, but published too 
late for use in Clarke's 1718 notes) . 

The English translation with notes was republished twice, 
in 1728/9 and 1735, and the Latin translation with notes 
appeared in Leiden as late as 1739, over forty years after the 
first set of notes and more than half-a-century after the pub- 
lication of the Principia. Benjamin Hoadley and Whiston both 
testify to the popularity of the Clarke-Rohault text in Cam- 
bridge even after the editor's death in 1729, Hoadley remarking 
with mixed feelings, " To this day his translation of Rohault 
is, generally speaking, the standing text for lectures; and his 
notes, the first direction to those who are willing to receive 
the reality and truth of things in the place of invention and 
romance," " Playfair may well be right in ascribing this popu- 
larity to the dual system of college and university teaching in 
Cambridge "; whatever the views of a college tutor over the 
merits of Descartes and Newton, his students could use Clarke's 
book. The work of Newton's supporters would have been 
difficult indeed, if Clarke had not returned twice to make a 
thorough revision of the hesitant and deferential annotatiun- 
culae of his early graduate days, 

Michael A, Hoskin 

Whipple Science Museum 
Free School Lane, 
Cambridge, England. 

'' n, p. 75. 

*'n, pp. 233-235. 

'II, p. 71. Principia (1713 edition), p. 481. 
^°II, pp. 137-8; II, p. 193. 

°^ Hoadley in Samuel Clarke, Works, I, p. ii; Whiston, op. cit., p. 6. The text was 
also used at Yale until 1743, cf. Sarton, op. cit., p. 145. 
■ Cf. Cajori, op. cit., pp. 631-2. 


Part Three 



DARWIN reared his theory of Natural Selection upon the 
basis of three observable facts in the world of living 
things, and two deductions which he made from these 
observations. The first two observations are the following: 
organisms tend to increase their numbers in a geometrical ratio 
such that, if unchecked, the individuals of a given type of 
organism would quickly become so great in number that no 
country could support them. On the other hand, and this is 
the second observation, the numbers of a given type of organism 
do in fact remain relatively constant. 

The first deduction made from these first two observations 
to account for them is what Darwin called " the struggle for 
existence." For if nature produces more individuals than can 
survive, the greater number of them must, for some reason or 
other, be destroyed. Now this Darwin accounted for by com- 
petition between organisms, resulting in survival of those that 
are sufficiently equipped by their quality, or are favored by 
circumstances, such as the seed that falls on fertile ground. 

Darwin's third observation was that organisms tend to vary. 
His first example is that of variation under domestication, of 
wheat, for instance, of pigeons, of horses, and of hounds. Now 
this is attributed to man's power of selection. These variations 
are intended by man. However deliberate the choice, not all of 
these variations that are brought about are actually the result 
of a deliberate selection — not all. Deliberate choice, improve- 
ment of environment, or cross-breeding, are not all there is to 
this selection. Darwin pointed out that, 

. . . eminent breeders try by methodical selection, with a distinct 
object in view, to make a new strain or sub-breed, superior to any 
kind in the country. But for our purposes, a form of Selection, 
which may be called Unconscious, and which results from everyone 

* These pages are the transcript of a recording. 



trying to possess and breed from the best individual animals, is 
more important. [Notice, the breeding or deliberate improvement 
of, say, the quality of wheat or the quality of horses is accom- 
panied by an improvement that was not intended; that is not 
deliberate, an unconscious selection is taking place.] Thus, a man 
who intends keeping pointers naturally tries to get as good dogs 
as he can, and afterwards breeds from his own best dogs, but he 
has no wish or expectation of permanently altering the breed. 
Nevertheless we may infer that this process continued during 
centuries, would improve and modify any breed, in the same way 
as Bakewell, Collins, etc., by this very same process, only carried 
on more methodically, did greatly modify, even during their life- 
times, the forms and qualities of their cattle.^ 

I have quoted this long passage because of the importance 
of what Darwin calls " Unconscious Selection," unconscious 
" insofar that the breeder could never have expected, or even 
wished to produce the result that ensued — namely the pro- 
duction of two distinct strains." This unconscious selection is 
important to Darwin's second deduction, namely. Natural 
Selection. The distinction which he makes brings us face to 
face with two different types of selection; the first is deliberate, 
with a distinct object in view; the second was unintended 
unexpected, nor even wished for. So far as man's purpose in 
this particular intervention is concerned, the new strains pro- 
duced by the second type are fortuitous. Actually, they are 
products of nature. The natural principle, as distinguished 
from the conscious, deliberate one, is called Natural Selection. 

There is no doubt that Darwin was reasoning here on the 
basis of an analogy or proportion between art and nature, and 
that the term for transition was selection. In other words, 
unconscious selection is first revealed as a by-product, so to 
speak, of conscious selection, and an unconscious selection is 
going on in nature all the time. This was sound reasoning, it 
seems to me, given the observations — particularly the one that 
all organisms tend to vary considerably — which should in fact 

^ Charles Darwin, The Origin of Species, chap. I (New York: Modern Library, 
n.d.). p. 32. 

Darwin's dilemma 233 

be warranted by experience, and in some measure they are. 
(Whether they are or not warranted is none of our concern at 
this moment or in this particular paper.) The point is that 
I see no problem in unconscious selection going on in domes- 
tication and in nature untouched by man. Right now I am 
particularly interested in the analogy and the more so because 
Darwin himself dwells upon it. Between conscious selection, 
and that natural selection which accompanies it but lies outside 
man's intention, Darwin sees a proportion. He makes a tight 
case of it. Listen to this from Chapter Three of The Origin 
of Species. 

I have called this principle, by which each slight variation, if useful, 
is preserved, by the term Natural Selection, in order to mark its 
relation to man's power of selection. But the expression often used 
by Herbert Spencer of the Survival of the fittest is more accurate, 
and is sometimes equally convenient. We have seen that man by 
selection can certainly produce great results, and can adapt organic 
beings to his own uses, through the accumulation of slight but 
useful variations, given to him by the hand of Nature. But Natural 
Selection, as we shall hereafter see, is a power incessantly ready for 
action, and is as immeasurably superior to man's feeble efforts, as 
the works of Nature are to those of Art. 

H Darwin's analogy holds good, it implies that both art and 
nature proceed by determinate ways or means to produce some 
final product. Another point worthy of attention is that to 
Darwin's mind the works of nature are immeasurably superior 
to those of our art or craft. We must not interpret Darwin as 
belie\"ing that art cannot produce certain works that nature 
could not bring about, in which respect art is superior to nature. 
Nature does not amputate a gangrenous foot, supply spectacles, 
or false teeth. Here we can do something that is useful and 
that nature cannot do. Darwin only meant that nature's ways, 
in producing her own works, are immeasurably more subtle, 
and relatively obscure to us, than our own ways and means in 
producing artifacts. Nature's selection is superior to our o\vn. 
That is Darwin's position, and notice that he still calls it 


Before dwelling on this second deduction, namely natural 
selection, let us return for a moment to the first, the struggle 
for existence, which Darwin attributes to every organism. And 
here is where we will encounter our dilemma. We all know 
what the expression " struggle for existence " means as referring 
to man's activity, as when he struggles to get somewhere, say, 
physically, to get up a hill, or against an enemy, or to make 
a living, or to get a job. In this context the word " struggle " 
is quite clear. It can be verified immediately. But what does 
it mean when applied to all organisms, to beasts, and even to 
plants as Darwin holds. '^ He was keenly aware that he was not 
using the expression in its readily verified meaning. And here 
I quote from the very same Chapter Three. 

I should premise that I use this term in a large and metaphorical 
sense including dependence of one being on another, and including 
(which is more important) not only the life of the individual, but 
success in leaving behind progeny. Two canine animals, in a time 
of dearth, may be truly said to struggle with each other which 
shall eat food and live. But a plant on the edge of a desert is said 
to struggle for life against the drought, [and here the meaning of 
" struggle " is going to be somewhat diminished], though more 
properly it should be said to be dependent on the moisture. A 
plant which annually produces a thousand seeds, of which only one 
of an average comes to maturity, may be more truly said to 
struggle with the plants of the same and other kinds which already 
clothe the ground. The mistletoe is dependent on the apple and a 
few other trees, but can only in a far-fetched sense be said to struggle 
with these trees, for, if too many of these parasites grow on the 
same tree, it languishes and dies. But several seedling mistletoes, 
growing close together on the same branch, may more truly be said 
to struggle with each other. As the mistletoe is disseminated by 
birds, its existence depends on them; and it may methodically be 
said to struggle with other fruit bearing plants, in tempting birds 
to devour and thus disseminate its seeds. In these several senses, 
which pass into each other, I use for convenience' sake the general 
term Struggle for Existence. [Italics added.] 

There stands the dilemma. The first one is clearly expressed 
when he says, " I use this term in a large and metaphorical 
sense." This is nonetheless most equivocal. The second is the 

Darwin's dilemma 235 

example of the plant. He allows that a plant struggles, but 
of course a plant does not struggle in the way a dog does; 
and a dog does not struggle in the way a man does to solve 
a problem. Further, we must notice that, still within the 
realm of plants, in one case we can say more truly that they 
struggle than in other cases. But a meaning of struggle is still 
retained somewhat. It is not quite the struggle of a man, it is 
not quite that of a beast, but it is not confined to that of a 
plant merely needing moisture either. One plant can somehow 
compete with another and, as a result, the most favored, 
either by quality or by circumstance, will survive, or its 
progeny. " The mistletoe . . . may methodically be said to 
struggle with other fruit-bearing plants." So that the plants, 
in a sense, truly struggle after all. 

This passage from the Origin of Species reminds us of Aris- 
totle's caution in using the simple term " life." If we compare 
plants to animals, he says, they are not alive; but compared 
with other forms of matter, they are indeed alive. So " alive " 
or " life " are equivocal terms, they have many meanings. 
There is a meaning of life verified in a beast, not verifiable in 
the plant; and one of man, that is not verifiable in a beast. 
Aristotle held that such terms are homonymous by design, 
not by chance (as the word " seal ") . Terms or expressions 
that are equivocal by design are called analogous. Bertrand 
Russell speaks of " systematic ambiguity." But Darwin said 
that he was using " struggle for existence " in a large and 
metaphorical sense. Now analogy and metaphor are not the 
same. I mean that a " large sense," and a " metaphorical 
sense " are not necessarily the same, and that is where we 
run into difficulty." Take for instance the word " light," or 
the word " to see." " To see " means first of all, " to see 
with my eyes." But when you explain to me some problem 

^ Not even those of Darwin's followers who opt for sheer metaphor quite succeed 
in circumventing such words as " good," " favorable," " advantageous," " better," 
" improvement," and the like. This is strikingly borne out in an excellent paper, 
" Darwin and Religion," by Prof. John C. Greene, which appeared in the Pro^ 
ceedings of the American Philosophical Society, CII (1959), 716-725. 


and I say, " Oh I see," I do not mean that I see with my eyes, 
since the figures on the blackboard I see with my eyes are 
not exactly what it is that I understand. Seeing is said here 
of understanding. So "seeing" — the word — is still materially 
the same, but it has a prior meaning, and we use the same 
word because this sameness expresses the passage that our 
mind makes from what we know less to what we know more. 
" To see " is an analogous term. 

Take the word " light " for a second instance: " sunlight," 
" candlelight," " the light of reason," or, " to examine a problem 
in the light of calculus." Is " light " used as a metaphor, or 
as an analogous term? It all depends. If you have changed 
the meaning of the term " light " — extending it to identify this 
new kind of thing that you want to designate by it — if you 
have actually stretched the meaning of the word, then it is 
an analogous term. But if you retain exclusively the first 
meaning of the word as in " candlelight " or " sunlight," and 
have not changed what we call the imposition, then your 
application of this word in the " light of geometry " is a meta- 
phor. An analogous term may have first been used as a 
metaphor, such as the word " tongue " when meant of speech. 
But eventually the word was intended to mean both organ 
and language. " The English tongue," or " la langue fran^aise " 
are not metaphors. But not all metaphors can become ana- 
logical terms. " Brief candle " is a fine metaphor for human 
life, but we would hardly say that our life is such in a large 
sense of " brief candle "; or that a heart is of stone in the 
large sense of stone. Nonetheless Darwin, explaining why he 
uses a metaphor, is actually giving reasons which, to an Aris- 
totelian, make the expression an analogous one, although 
Darwin calls it metaphorical. It is actually analogy and I will 
show you why. We should say " in a large, extended sense," 
as distinguished from a metaphor whose sense has not changed 
when applied to something else, although the mode of signifying 
does change. 

You may now wonder what the purpose is in going into the 

Darwin's dilemma 237 

question of naming as I do. It is my simple intention to show 
what strange views we may be led to, unless we clear up this 
particular problem of naming in connection with the theory 
of evolution — with the theory of evolution, at least as it was 
begun by Darwin. Theories of evolution were around long 
before then, but Darwin can be said to have begun the scientific 
investigation of the problem and to have proposed a scien- 
tifically sound theory, at least for his time. 

One of these strange views — and I should not use the word 
" strange " in too forceful a way — we find in Sir Julian Huxley's 
interpretation of general Darwinian theory. Darwin allowed 
that one plant may be said to struggle " more truly " than 
another plant, according to circumstances, or according to kind, 
or according to the kind of plant or kinds of plants with which 
it has to struggle. Now this is surely very different from saying 
that a stone is more truly a stone than a heart of stone, because 
in the latter case we have not changed the imposition of the 
word " stone "; we have retained the first meaning and applied 
it without imposing a new meaning upon it. There is a change 
in the mode of signifying, but not in the significance of the 
word. For the " heart of stone " is in no sense truly a stone 
at all. But Sir Julian takes Darwin's " metaphorical sense " 
quite literally. Take, for instance, the term tending in " ten- 
dency of all organisms to increase in geometrical ratio." Is 
the word " tendency " used here as a metaphor, or is it taken 
as an analogous term.^ For instance, it is a metaphor in " the 
tendency of a variable to its limit." This is not tendency by 
which a man tends to do this, or tends to do that; or by which 
a dog intends to get the bone. The " tendency of a variable 
to a limit " is in this context plainly a metaphor. 

Sir Julian Huxley writes that " at first sight, the biological 
sector seems full of purpose. Organisms are built as if in 
purposeful pursuit of a conscious aim." But the truth, he adds, 
" lies in those two words ' as if.' As the genius of Darwin 
showed, the purpose is only an apparent one." Darwin's con- 
tribution, according to Sir Julian, consists precisely in this — 


in the discovery that there is no purposeful activity going on 
in nature and that everything must be explained without 
having any resort whatsoever to purpose; and that if there 
appears to be purpose in nature it is only in appearance, so 
that when you use terms that are related to purpose in beasts 
or plants, you are using the term as a sheer metaphor. There 
is no room for a " large " sense of purpose. 

It is not my intention to show here that nature acts for a 
purpose. I merely want to attract your attention to the strange 
antinomies we are led to when we deny purpose in nature. 
I am just going to present the antinomies; my present purpose 
does not extend beyond this. Let me then make four points 
regarding purposeful activity and nature, in the context of 
Huxley's assertions which I have just quoted. 

(1) Sir Julian, along with Lord Russell, is emphatic that 
action for a purpose is clearly recognized in human making 
and behavior. He accepts that man acts for a purpose, acts for 
the sake of something; and this is verified in man's case unmis- 
takably according to both these authors; they are both quite 
critical and accept as little as possible, which is in itself a 
praiseworthy attitude. They say, and allow us to say, that 
man truly acts for a purpose. Far from denying such action, 
Huxley asserts that " the future of man, if it is to be progress 
and not merely a standstill or degeneration, must be guided 
by a deliberate purpose. And this human purpose can only be 
formulated in terms of the new attributes achieved by life in 
becoming human." Purposeful activity is therefore a radically 
new kind of reality that arises uniquely in the case of man. 
It is not to be found in nature itself. Man himself cannot be 
said to have been brought about for the sake of something. 
Yet man, as we have stressed, is in many respects unique 
among animals: a purposeful agent is brought about without 
intent in any possible sense of this word. 

Until this purposeful agent appeared on the scene, " The 
purpose manifested in evolution, whether in adaptation, spe- 
cialization, or biological progress, is only an apparent purpose. 

Darwin's dilemma 239 

It is just as much a product of blind forces as is the falling 
of a stone to earth or the ebb and flow of the tides. It is we 
who have read purpose into evolution, as earlier men projected 
will and emotion into inorganic phenomena like storm or earth- 
quake. If we wish to work towards a purpose for the future 
of man, we must formulate that purpose ourselves. Purposes 
in life are made, not found." 

Sir Julian offers no reason why, though at first sight the 
biological sector seems full of purpose, the purpose manifested 
in evolution is only an apparent purpose. He offers no reason 
for this, but I will explain the seeming plausibility of this 
hypothesis a bit later. 

We must concede that if there is action for a purpose in 
irrational nature, that is, outside of man, it will be very dif- 
ferent from the kind we find in man, to the point where 
purpose or action for a purpose will have a different meaning 
when said of man, when said of beast, and when said of a plant. 
If there is that kind of action in nature, if the term purpose 
is deserved, if it is applicable, it will have to carry a new 
meaning, but a meaning related to and dependent upon the 
one we first imposed. If it is stretchable, as it were, if it can 
be enlarged, then we will have to accept that it will have a 
different connotation in these different cases. 

This we ask of Sir Julian. Is it so obvious that a purpose 
is either human or no pui-pose at all.'' If a purpose is indeed 
either human or no purpose at all, then of course Sir Julian's 
position would be quite irrefutable. He suggests that it is we 
who read purpose into nature, that is, we project into nature 
certain things that are actually characteristic of, and exclu- 
sively found in man. And this is no doubt often the case. But 
are we not being anthropomorphic, we ask, in a more sophis- 
ticated way when we imply that nature's purpose is either 
human or no purpose at all? Isn't that another kind of 
anthropomorphism.'' On the other hand if organisms are built 
by nature in " purposeful pursuits," does this mean that nature 
must have a " conscious aim "? I mean, is purposeful action 


restricted to conscious action? That is a further assumption 
and it ought to be justified. Darwin justified it when he spoke 
of the plant Hving on the edge of the desert. He showed us 
that he was stretching the meaning of the word " struggle for 
existence " and " struggle for survival," a survival, which, of 
course, is understood as a good. Dogs struggle to acquire food 
because they like it. But if a plant is going to struggle after its 
food, can you mean that the plant likes it.'' We assume that 
a plant by definition at least has no sensation, so how could 
the plant like iood? Yet plants struggle, as Darwin points out. 
We have to stretch our words, with Darwin. But Sir Julian 
refuses to stretch them: he does not allow a new, related, 
meaning whose difference is based upon a proportion found 
between the things intended by the same word. 

Allow me to mention in passing the over-emphasis on change 
in Darwin and in Huxley, an over-emphasis which has been 
recently criticized rather ably by Loren Eiseley in a book 
written on the occasion of Darwin's centenary. These thinkers 
have so emphasized the passage from one form of life to another 
that they have lost sight of the remarkable stability that can 
go along with this change. Now the stability of an organism 
needs explanation too, and change alone is not going to explain 
stability. We bring in this example simply to point out the 
idea of what we mean by action for an end in nature or what 
is called final cause, although I am wary of the term final 
cause, so easily misunderstood. It is not found in Aristotle who 
teaches that things act " for the sake of something." " Causa 
finalis " is found in scholastic philosophy. St. Thomas uses it, 
as a matter of fact, but I am wary of it in English because it 
tends to be technical. With Aristotle a man acts for a purpose 
and beasts act for a purpose too; and, while plants do also, 
this is very obscure and we must at any rate extend the 
meaning of purpose. The term " good " has likewise several 
meanings — a whole orderly group of them co-ordinated some- 
how one with the other, all covered by that single term 

good "; as for instance in a " good steak," a " good man." 

Darwin's dilemma 241 

" Good " means sometEing quite different in each case. There 
is not a unique meaning here, but actually many co-ordinated 

(2) Take an organ such as an eye or a tooth. We say that 
eyes are for the sake of seeing, that incisors are for the sake 
of cutting and molars are for grinding. When we say this are 
we using metaphor? We can go way back to Empedocles who 
said that we have eyes not for the sake of seeing but we see 
because we have eyes. Another philosopher said that man is 
the wisest of animals because he just happens to have hands. 
It is far more thorough, I think, to hold that man has hands 
in view of making. Why should one position exclude purpose 
as a cause — I mean a good as " that for the sake of which "? 
Nature acts for a purpose; of course, not exactly in the way we 
do, since there is, after all, a radical difference between nature 
and reason, but in a proportional way: there is a proportion 
between the way we act and the way nature acts. There is no 
true identity, but only a proportion, and an irreducible one, 
between them. Can we accept this? It is not our problem here. 
I merely want to show, in a dialectical way, what we are led 
to when we deny that nature acts for a purpose, even in this 
remote yet analogous sense of the term. 

Now, my question is about this struggle. Does that which 
finally comes about after a certain activity possess the nature 
of good? It is good to have the molars in the back (allow 
me this example from Aristotle) and our cutting teeth in the 
front. Is this disposition produced by a proportional cause or 
by chance? Do we understand why the molars should be in 
the back to gi-ind, why the grinding should go on there and 
the cutting out in front? Do our teeth make sense? If their 
disposition were reversed, it would be unreasonable, it would 
be monstrous. That is how we distinguish monsters from non- 

Now, if we allow that nature produces such end products 
because they are good, we imply that nature acts for a purpose, 
but in doing so we must be aware that we have extended the 
meaning of " end " and " action " and " purpose.'* 


(3) Now, once we have recognized goodness in these things, 
we can still ask whether nature acted " for the sake " of this 
goodness, or whether it came about for no purpose at all, just 
by chance, as some of the ancient philosophers held, in common 
with some more recent ones. The Darwinian philosophers who 
deny action for a purpose in nature should realize that they 
have been anticipated by the earliest philosophers; they are 
somehow regressing to ancient positions. 

Sir Julian's view is that all can be rendered intelligible with- 
out purpose — by blind forces. Just what is meant by " blind 
forces," by " blind," on the one hand, and " forces " on the 
other — not to mention the equivocity or ambiguity of the two 
words taken together in " blind forces " — is not clear. I know 
what a " blind man " is, but a " blind stone " is something 
else — I mean that a stone is not expected to see. This makes 
a considerable difference. I know fairly well what I mean 
when I say that stones have neither eyesight nor understanding 
(and even Sir Julian insists upon the uniqueness of man as to 
understanding and purposeful action) . 

Remember Darwin's plant struggling at the edge of the 
desert. Huxley will state that this struggle and its result are 
the product of blind forces, as in the falling of a stone. Darwin 
did not say this, although he did leave us with a dilemma when 
he stated that he was using " struggle for existence " in a large 
and Tnetaphorical sense. Darwin would not have held that 
stones struggle to fall, and to say that they do would be poor 
metaphor. But if taken as a mere metaphor apropos of living 
things, why should it then be good? What does it convey that 
the fall of a stone does not.'^ If I understand him correctly, Sir 
Julian would make no distinction here. The result is that 
" struggle for existence " said of plants and beasts is not only 
poor metaphor; it is also utterly misleading. We must admit 
all the same that Darwin made it possible for some people to 
to hitch on to a metaphorical sense, which, upon closer analysis, 
turns out to be unfelicitous and unscientific; and for others to 
allow an extended, large, and yet true meaning. He might have 
uiifolded himself a bit more. 

Darwin's dilemma 243 

(4) Fourthly, we are faced with two paradoxes, which I will 
mention briefly. For Sir Julian, Reason ought to be satisfied 
with a theory which seeks to explain everything, including 
Reason itself, as arising from something which has nothing in 
common with Reason, and for a reason no different from the 
reason stones fall to earth. Notice the different meanings here 
imposed upon this word " reason." It means one thing in " man 
is endowed with reason "; it means another in " a man has no 
reason to do this rather than that "; and something else again 
when we say " the man fell for the reason that he slipped on 
a banana peel." Sir Julian does not mean that things occur 
for no reason at all; he intends that outside human activity 
all things occur aimlessly and are accounted for without in- 
voking intelligence behind them. He deserves credit for seeing 
that, if purposeful action be held to exist in nature, this can 
only be on the supposition that nature is the work of an 
intellectual agent — that quodlibet opus naturae est opus ali- 
cujus substantiae iyitelligentis — which is precisely what we hold 
(let it be immediately added that the difficulty of our position 
is not unappreciated by us) . In other words, so far as nature 
is concerned, Sir Julian will understand rational to mean no 
more than reason in " the reason stones fall "; with the conse- 
quence that, compared to human reason or to any other 
understanding or intellectual agency, all the things and events 
of nature proceed from utter unreason, and for no other than 
the reason stones fall to the earth. Human reason itself is 
sufficiently accounted for as a product of blind agency. " Ex- 
planation," " interpreting," " providing proof " can never be 
more than an attempt to show that everything in nature is the 
product of aimless " blind forces." Man, then, the avowedly 
purposeful agent, came about for no purpose at all. This 
unfortunate animal finds itself in the curious position of being 
burdened with all the reason or intelligence there is, and with 
all the purposeful action there is. He alone has reason, for a 
reason which can only be blind .^ 

* " Natural Selection can determine the direction of change, but has no goal. 


Now 1 am all in favor ol' economy in explanation. If the 
existence of what Darwin called " good species " (notice his 
use of the word " good ") can be accounted for by, say, random 
mutations, then random mutations it is. But can these species 
be so accounted for.^^ And, by the way, just what does this word 
" random " mean.?^ I know what it means in " to throw dice 
at random." I deliberately so throw them, just as when I aim 
randomly distributed pellets at a duck. In these cases there 
is no opposition between randomness and purpose. If the word 
must be applied to nature, it will either become a metaphor 
or acquire an extended meaning. And what do certain bi- 
ologists intend when saying that all species are the product of 
random mutations and, in the same breath, that therefore they 
are products of mere chance.'^ Does randomness mean the 
same as chance.'' * If so, we are imposing a new meaning on 

It pushes evolution blindly from behind." Julian Huxley, " Man's Place in Nature," 
in The Destiny of Man (London: Hodder and Stoughton, 1959), p. 19. In the 
Sunday Times (Feb. 3, 1957) Sir Julian writes: " The real wonder of life is the 
fact that the automatic and non-purposeful process of biological evolution should 
eventually have generated true purpose in the person of the human species." 

* Elsewhere I expressed some difficulty in understanding Sir Julian Huxley's 
position in this matter. Take, for instance, the following statement: " Natural 
Selection is an ordering principle. It takes the disorderly material provided by 
' random ' or ' chance ' variation, builds it up into orderly patterns of organization, 
and guides it into ordered paths of change." (" Man's Place in Nature," ed. cit., 
p. 14) As J. W. C. Wand remarks in the same booklet (p. 42) : we believe " that 
' the mechanism which directs the course of evolution ' and its ' ordering principle ' 
are guided by a divine mind to a good and beneficent purpose." Plainly, Sir Julian 
sees no need for such a mind. Still, whether or not randomness and chance are for 
him the same, whether chance here means pure chance or something less than pure 
chance, he indeed insists upon an ordering, guiding principle. Might we, in order to 
avoid all suggestion of purpose, take the " ordering " or " guiding " as having the 
meaning these words would have when a river-bed is spoken of as channelling, and 
as directing and guiding its waters to the sea.'' But the analogy cannot stand. For 
the river-bed too, was somehow formed at random (we would say ex necessitate 
materiae), and the sea itself, is a random distribution. One ought not to ask Sir 
Julian " How do you account for the ordering principle? " for the reply would likely 
be " It's just there." No, we are driven back to the monkeys pounding at random. 
Now, when they allegedly produce all extant literature, are their random poundings 
led to this by an "ordering" and "guiding" principle? Sir Julian must surely 
admit that the terms are now vividly out of place. The principle now cannot be 

Darwin's dilemma 245 

either or both of these terms. Upon what grounds? When we 
throw dice at random, we do not know which sides will in fact 
turn up, though we know the possible alternatives; when we 
aim birdshot at a duck, we do not know which of the pellets 
will actually bring it down, though we may be confident that 
some of them will do the work. Something is known here, but 
there is also something unknown: we are blind as to which 
sides of the dice will turn up, or which pellet or pellets will 
strike. (Notice that we in fact use the random distribution of 
many pellets to compensate for the uncertain course of a single 
bullet.) Now there is also something blind about chance or 
fortune in human affairs. Socrates did not go to the market 
this morning to meet the debtor he had been wanting to meet, 
yet he met him all the same, by chance, for he did not know 
his debtor would be there. So here too there is blindness. 
Could this be the reason randomness and chance are said to be 
one and the same.f* 

I have dwelt for a few moments on Sir Julian's position — 
not irreverently, I hope — merely to point out its paradoxical 
nature. Let me add, in all fairness, that whoever holds that 
nature does act for the sake of something ought to be aware 
of the obvious difficulties of such a position. If it is maintained, 
for example, that a bird builds a nest for the sake of offspring 
as yet unborn, and does so quite unwittingly, it is after all, far 
from obvious how anything that does not as yet exist can 
already be a cause — especially in the case of blind agency. 
Purposeful activity in nature is also readily oversimplified, and 
made to look like the argument concluding et voild pourquoi 
voire fille est jnuette; it is obviously good for a man to have 
hands, but this does not show how he acquired them. Tele- 

anything more than the mere possibility of these particular arrangements of letters, 
which just happen to be meaningful. In virtue of what principle is " a million 
monkeys " meaningiul, and " the slithy toves " not, if both are arrived at by aim- 
less monkeys? Where is the reason why the former and not the latter arrangement 
should be judged favorable? Cf. The Hollow Universe (Oxford University Press: 
London, 1960), pp. 97-110; "Abstraction from Matter" (III) in Laval theologique 
et philosophique, 1960, n. 2, pp. 174-188. 


ological mechanisms may help to explain. Meantime, we must 
remember that the good was first recognized by Aristotle ^ as 
a special kind of cause — the first but most obscure of all causes. 
But though it would be foolish to ignore the difficulties which 
this doctrine must entail, will it be any less foolish to conclude 
that it is therefore unscientific? I fail to see why Natural 
Selection must be understood as devoid of purpose, or why 
" the struggle for existence " is to be taken as sheer metaphor. 

Charles DeKoninck 

TJniversite Laval, 

Quebec, Canada. 

' Plato also considered the good as a cause, but not as a cause sui generis. 



The Meaning of ' Nature ' in the Aristotelian 
Philosophy of Nature 

SOINIETIMES there are many things in a word. If such is 
the case, it is to the philosopher's advantage to trace 
out the relation between the various meanings of a word, 
insofar as the later and secondary significations are to be more 
fully understood only when seen in the light of a primary im- 
position, first and best known to us. The extension of the word 
to include further meanings retaining the relationship to this 
first and most known can be for the human mind a safeguard 
from meaningless abstractions and a reminder of the principles 
and trajectory of our knowing. At the same time, if the order 
is not seen, the extension can be a source of confusion and 

The advantage of bearing this order in mind and the danger 
of ignoring it are of particular importance in the case of the 
word nature; for although it is one of the most common terms 
in philosophy, many of its possible significations have yet to be 
explored more fully. The purpose of this article, accordingly, is 
twofold: (1) to trace out some of the more important meanings 
of this word with a view to determining its particular use in 
the Aristotelian and Thomistic philosophy of nature, and (2) 
to show that even this particular meaning is continually modi- 
fied within the science of nature. Our order of procedure shall 
be as follows: I. After a preliminary review of the meanings of 
nature given by Aristotle in Book V of his Metaphysics, we 
shall turn to his Physics in order to determine more explicitly 
which of these meanings are proper to philosophy of nature. 
II. Next we shall develop certain implications of the definition 
of nature given in the Physics by detailing various ways in 
which nature can be taken as either an active or a passive 
principle. HI. Finally we shall examine the extended meanings 
that the word nature assumes as philosophy of nature is ela- 
borated. To my knowledge the possibility of this progressive 


248 SHEiLAii o'flynn brennan 

enlargement of the term nature corresponding to the gradation 
of mobile beings in the philosophy of nature has not been con- 
sidered: this possibility the present study aims particularly to 


Some Meanings of Natuee 

In Book V, Chapter 4, of his Metaphydcs, Aristotle runs 
through several meanings of (f)vcrL<;, which in Latin becomes 
natura and in English nature. Let us recall them briefly. 

1. Taking ^vcrt? to be derived from ^vea-Oai, "to grow," 
Aristotle gives as the first meaning the genesis of growing 
things. Hence ^vcn? means the process of a thing's coming into 
being by growing from something, as a plant comes into exist- 
ence by growing from a seed. In this sense, then, the word is 
used for the generation of a living being. — Our English word 
nature would not have this meaning, of course, nor does the 
Latin natura, though nativitas, the process of birth, does have 
a similar signification. 

2. Secondly, the word is taken to mean what the growing 
being grows from, a source within the growing being. 

3. From this second sense is derived a more general meaning 
of nature: nature as the intrinsic source, not only of generation, 
but of the primary movement (including any type of change) 
which is in a natural being by virtue of what it is. 

Thereupon, the meaning becomes more determinate, as this 
inner source of movement or change is identified: 

4. First, with the formless primary stuff, of which a natural 
thing consists or out of which it is made. It was in this sense 
that the ancient " physicists " called the elements of natural 
things their nature. 

5. Secondly, with essence or form (ovcrla) , for we cannot say 
that those things which are or come to be by nature have their 
nature unless they have their form and shape, even though the 
matter (that from which they come) is present. 

Aristotle then retraces his steps in order to make certain 


precisions: nature is the primary matter, whether this latter 
be absolutely first or first only in a certain order; ^ and nature 
is the form or essence as well, which is the end of generation. - 

6. By " an extension of meaning," finally, any essence 

{ovcria) is called nature, whether it be the term of generation 

or not, because a nature is one kind of essence. It is in this 

sense that we can speak of the nature of a circle or of an 

immaterial substance.^ 

In conclusion, Aristotle makes the point that it is the form 
that is primarily and most properly nature, for the matter is 
called nature insofar as it is receptive of the form, and genera- 
tion and growth are called nature because they are movements 
proceeding from it: * " And nature, in this sense, is the source 
of movement in natural things, which is in them in some way, 
either potentially or actually." 

^ The examples given by Aristotle are in keeping with the views of certain of 
his predecessors. Thus, for primary matter he gives not his own absolutely 
prime matter, but something composite, one or several of the elements; and for the 
form he gives — quoting Empedocles — not the substantial form, but the primary 
composition of a thing. His purpose obviously was to show that the word nature 
was in fact being used for primary matter and for form whatever these might be 
understood to be. 

' Form, therefore, is a principle of a natural thing as a formal cause and a 
principle of generation as a final cause. 

* It might be noted in addition that form or essence may be called nature, not 
only as an end of generation, but as a source of accidental physical movement or 
change, and that this meaning may be extended to include form or essence as 
principle of movement in a more common sense, including any operation, even 
spiritual. This would give us a more proper sense in which we could speak of the 
nature of an immaterial substance, one closer to the original signification than 
essence taken simply. In his De Ente et Essentia, St. Thomas gives this extended 
sense as one of the meanings of nature (" a thing's essence as ordered to its proper 
activity ") and even indicates that this seems to be what Aristotle means by 
nature in Metaphysics V, where he says that in a certain sense every substance is 
a nature (cf . no. 6, above) . 

* The form of the thing to be generated is a principle of generation as the end, 
whereas the form of the progenitor is the active principle from which the generation 
proceeds, the progenitor being the agent. Generation, of course, implies change 
within the progenitor, the latter being a moved mover. As principle of this change, 
the form is obviously a source of change in that in which it is and as such can 
be taken to be nature. Just how the form of an agent, an active principle moving 
another as such, may nevertheless be termed nature, a principle of change within 
the changing being, will be discussed in the last footnote of this article. 

250 SHEiLAii o'flynn brennan 

Such, in brief, is Aristotle's delineations of various meanings 
of nature.^ It is to be noted that all the senses except the 
last include a relation to movement, and this last Aristotle is 
careful to set off from the others by indicating that it involves 
" an extension of meaning." Nature, then, is to be seen prin- 
cipally as a source of movement in things. 

Before proceeding to the Physics, it is of interest to note 
St. Thomas' introductory comment upon this chapter of the 
Metaphysics: " Though the consideration of [nature] does not 
seem to belong to first philosophy, but rather to natural phi- 
losophy, [Aristotle] nevertheless distinguishes the meaning of 
this word here [in first philosophy] because nature according 
to one of its senses is said of every substance." In this passage 
Aquinas is obviously referring to the extended meaning of 
nature; the other meanings, then, would apparently belong 
properly to philosophy of nature. 

This is precisely what we find when we turn to the Physics, 
Book II, Chapter 1.*' Let us briefly review Aristotle's pro- 
cedure: First he points out that things which exist by nature 
are seen to differ from artifacts in that the former have within 

^ These, of course, are not the only ways in which Aristotle uses the word. For 
a comprehensive list of the meanings of <pv<ns in Aristotle, see H. Bonitz, iTidez 
Aristotdicus (Graz, 1955) . 

" St. Thomas establishes the meaning of nature in philosophy of nature right at 
the beginning of his commentary of the Physics. In lesson 1, Bk I of his com- 
mentary he shows the subject of the science of nature to be that which depends on 
matter for both its being and its definition, as distinct from mathematical en- 
tities and the subject of metaphysics. St. Thomas then explains: " Because every- 
thing that has matter is mobile, consequently the subject of natural philosophy is 
mobile being. For natural philosophy is about natural things, which are those 
whose principle is nature. Now nature is the principle of motion and rest in that 
in which it is. Natural science, therefore, is about those things which have in 
themselves a principle of motion." Natural being is here clearly identified with 
mobile being and mobile being with sensible material being. Nature has the 
meaning, not of what the thing is or the essence simply, but of principle of 
movement or change, such as movement according to place or even of generation. 
Movement, inasmuch as it is given as implying matter, is obviously to be understood 
in the strict sense, as actus imperfecti, and not according to an extended meaning 
which could also include any type of operation, even thought. Otherwise the 
natural and mobile being would not necessarily be a material being, as it is explicitly 
stated to be, since there are operations which do not presuppose matter. 


them a source of movement or change in respect of place or 
size or some quality or other, whereas products of art have no 
inner tendency to change, except insofar as they are made of a 
natural substance. From this he concludes that nature is this 
pnnciple or cause of being moved and being at rest in that in 
which it is, and he adds by way of precision, iri which it is pri- 
marily, in virtue of itself and not accidentally. 

This definition, it will be noticed, is the third meaning given 
in the Metaphysics, but with certain additions. Nature is de- 
fined here not merely as a principle but as a cause as well. 
According to St. Thomas, this is to indicate that nature may be 
either a passive source (principle) or an active source (cause) . 
These two senses of nature will constitute the subject for the 
second part of this article; and in the third part we shall con- 
sider the word primarily. The words in virtue of itself and not 
accidentally, we may note here, are meant to exclude such 
intrinsic principles as the art of medicine in virtue of which a 
doctor cures himself. The movement of being cured belongs 
to the man per se as a patient, not as a doctor; it is only acci- 
dentally that the doctor is also the patient. 

After defining nature, Aristotle proceeds to make certain 
distinctions concerning the use of the word: those things are 
said " to have a nature " which have this principle of movement 
and they are substances; and both the subject which has its 
being from nature and the accidents which are caused by this 
nature are said to be natural or according to nature. 

Nature is then identified, as it is in the Metaphysics, with 
" the first material substratum of all things which have in them- 
selves a principle of movement and change "; and then with 
the form of these tilings, insofar as " what is potentially flesh or 
bone does not have its nature until it receives the form by 
which we define what flesh or bone is." Both matter and fonn 
are nature but each in a different way, and unequally, since 
form is nature even more than matter is: " for a thing is more 
properly said to be what it is when it is in act than when it 
exists only potentially," 

In the Physics, accordingly, nature is seen to be the form 

252 SHEiLAH o'flynn brennan 

insofar as a thing does not have its nature unless it has the 
form " by which we define what the thing is." This form might 
appear to be the essence, taken absolutely, without reference 
to movement, unless we bear in mind what has gone before. 
For Aristotle not only defined nature as a principle of move- 
ment but also stated that those things are said to have a nature 
which have this principle. Accordingly, the form must be taken 
as nature precisely because, in making the thing to be what it 
is, it is the root of its particular activities and its particular 
tendencies to change. It is in this sense that the thing would 
not have a nature if it did not have a form. 

But there is another sense in which the form is nature. The 
natural thing is one that is the result of change, the product of 
a natural process of becoming (which, according to Aristotle, 
was also called ^vo-i?) . The form of a natural being is one that 
fulfills a potency of matter, and it was to this form that the 
matter tended in the process of generation. The form, then, 
as nature, is also an end of movement: " What grows qua 
growing grows from something into something. Into what then 
does it grow.? . . . Into that to which it tends. The form then 
is nature." "^ In time, it is true, the form is at the term of 
generation, but, absolutely considered, it is a principle, and a 
principle prior to the matter according to the essential order 
of things. The form, consequently, whether it be considered as 
the origin of activity or as the end of generation, is nature 
as a principle of movement. (It can also, of course, be nature 
as the active principle in the progenitor jrom which generation 
proceeds. But this sense, mentioned in the passage from the 
Metaphysics and indicated at least at one point in Chapter 2, 
Book n, of the Physics,^ belongs properly to a later stage in 
the philosophy of nature, that which deals with the living 
natural being as such.) 

'Aristotle, Physics, Bk II, ch. 1, 193b 17 et sqq. 

* " Man is born from man, but not bed from bed. That is why it is said that 
not the shape but the wood is the nature of the bed, for, if the bed sprouted, 
not a bed but wood would come up. But if the form is art, so also is the form 
nature; for man is born from man." Physics, Bk. II, ch. 1, 193 h 9 et sqq. 


In short, it is as a principle of movement accepted in the 
strict sense ^ (movement involving a material substratum) 
that nature is identified severally with matter and with form. 
Clearly it is not to be taken either as essence, the root of 
spiritual operations, or as essence without reference to move- 
ment in any sense.^° Nature, in fact, is something proper to 
material beings, since all natural beings are mobile beings and 
all mobile beings are material beings. In this meaning of 
nature, it might be added, we find the basis for distinguishing 
between philosophy of nature and metaphysics as to mobility 
and immobility, materiality and pure inmiateriality. 


Nature as Both an Active and a Passive Principle 

For a fuller understanding of nature, the various ways in 
which it is both an active and a passive principle must be 
examined. It has already been indicated that nature can be 
both active and passive. Does this division coincide exactly 
with the division of nature into matter and form? This might 
seem to be the case since in the commentaries of St. Thomas 
the passive principle is usually associated with matter or what 
is material (piincipium fasdvum et materiale) and the active 
with form or what is formal {princvpium activum et formale) }'^ 
At times, however, St. Thomas identifies the form with a pas- 
sive principle as he often does when he speaks of the intrinsic 
principle of falling bodies.^" We might be inclined to dismiss 
the difiiculty with the distinction that when it is not a question 
of living things both form and matter must be included under 

' This sense is not the strictest since it includes generation and corruption, as 
well as movement taken in the strictest sense involving two positive terms (cf. 
Arist., Physics, Y, ch. 1). It is a strict sense in that it excludes operations such 
as thought. 

^° It could be taken as essence considered as a composite principle of accidental 
movements (strict sense). For example, the composite nature of a living being, 
including both matter and form, is a principle of growing, more adequate than 
either matter or form taken alone. 

" Cf. In VII Metaph., lect. 8, n. 1442Z. 

^^ Cf., e. g., In II Phys., lect. 1, n. 4. 

254 SHEiLAH o'flynn brennan 

passive principle, while principium activum et formate would 
be reserved for the principle by which a thing moves itself by 
itself. But this answer creates difficulties as soon as we observe 
that in other places the principle of falling in heavy bodies is 
explicitly given not as a passive but as an active principle/^ 

The solution to this apparent contradiction lies in an ex- 
planation of what is meant by active principle. The formal 
principle is not necessarily active as in an agent, or in a living 
being in which one part moves another. In the passage in 
which the fonii of a heavy body is said to be an active principle, 
what is meant apparently is not that the form moves the body 
as an agent cause or even that it is a principle by which the 
body moves itself, but that it is the ever-present source of the 
motion — of the activity. In this way, it is distinguished from 
a passive, i. e. receptive, principle which requires for the tran- 
sition into act the presence of an agent, as when water is 
being heated. Even in non-living things, consequently, nature 
may be regarded as an active principle, though in living beings 
it is active in a special way. 

When St. Thomas states, then, that the form of the heavy 
body is a passive principle and explains further that the body 
is moved rather than moves, his intention in these passages, 
evidently, is to distinguish the heavy body from the living 
being.^* For though the falling body moves, and moves indeed 
without the actual influence of an agent cause, it, nevertheless, 
does not move itself in the sense that it is an agent (a mover) 
with respect to itself, as is the living being. The mover in the 
case of the falling body would be the original maker that pro- 
duced the form it has, making it the type of thing it is, with all 
its concomitant characteristics, including its tendency to fall 
when raised from the ground. ^^ 

The passive material principle, on the other hand, is a re- 
ceptive principle. It is especially prime matter with its appetite 

" Cf ., e. g., Contra Gentiles, IV, 97. 

" Cf. Arist., Physics, VIII, ch. 4; St. Thomas, In VIII Phys., lect. 8, n. 7, where 
jmncipium fossivum is distinguished from the principium motivum aut activum. 
^^ Cf . St. Thomas, In II Phys., lect. 1, n. 4. 


for form. We may consider prime matter in general as having 
an appetite for form in general, or as the matter in a particular 
substance (e. g., an acorn) having an inclination to a deter- 
minate form (namely, the form of an oak tree) — the determin- 
ation of the appetite being due, of course, to the form possessed 
(i.e., the form of the acorn) . But the passive material principle 
also includes secondary and accidental principles of receptivity 
as in the case of water, which becomes warm when exposed to 
fire. Such an accidental passive principle, of course, even 
though material (i.e., receptive) , springs as a characteristic 
fundamentally from the substantial form just as does the active 
(or, if you prefer, passive) formal principle of being drawn 
downwards for the stone. 

However, a new difficulty now arises, for to say that nature 
may be merely a passive potency seems to do away with the 
distinction between nature and art. Nature differs from art in 
that nature is an intrinsic, art an extrinsic principle. But if this 
intrinsic principle that is nature may be no more than a passive 
potency, which of course is also required by art, the active 
principle being, like art, extrinsic, where would the difference 
lie.? St. Thomas saw this difficulty, as is evident in his com- 
mentary on Book II of the Physics,^^ where he makes the 
precision that in the case of nature this potency must be a 
natural potency. In Book VIII, ch. 4, of the Physics Aristotle 
distinguishes a violent movement from a natural one by the 
fact that the latter is one to which the thing was in potency. 
St. Thomas comments: " These things are naturally moved, 
when they are moved to their proper acts, to which they are in 
potency according to their nature." ^^ " To their proper acts " 
implies that these things are not in potency to just any acts 
or even to many acts, but to certain determinate acts fixed by 
their nature (i. e., by their form, primarily) — to certain per- 
fections wherein they find their fulfillment. Implied here is an 
order of appetite intrinsic to the things. The passive potency 
in the case of nature, then, involves a determinate inclination, 

^^ Lectio 1, n. 4. " /ra IX Phys., lect. 8, n. 1. 

256 SHEILAH o'flynn brennan 

an appetite, not to be found in the passive potency of art. Al- 
though the potency in the case of the matter of artificial things 
is limited to certain forms (e. g., wood cannot be used in the 
making of any and all artifacts) , nevertheless there is no 
positive inclination to any form. There is simply a non-repug- 
nance. The determination that there is in art must come from 
the extrinsic active principle, from the mind of the artist. The 
potency itself, in the case of art, is a passive potency only 
insofar as there is no repugnance to an act that man wishes to 
impose upon it; it is a potency then only in relation to the 
human mind, a sort of " obediential potency." The natural 
potency, on the other hand, is intrinsically related to an act — 
the act also being considered natural, even though in certain 
cases it can be supplied only by a non-natural agent. 

It was by an application of this principle that St. Thomas 
showed the movement of the heavenly bodies to be natural.^^ 
For although they were moved by forces extrinsic to nature, 
the separated intelligences, nevertheless from the point of view 
of the passive potency, implying a determinate inclination or 
aptitude to circular movement, the movement was said to be 
natural. Another application may be seen in the case of evo- 
lution. Though the active principle must certainly have been 
outside of nature, the whole process would have been natural 
from the standpoint of the passive inclination of matter, always 
" desiring " as an end the more perfect fulfillment of its potency. 
The act conferred was natural, corresponding to a natural 
potency, though the power that conferred it was not.^^ 

It should be noted, moreover, that although the natural 
potency in a thing implies an intrinsic order to an act, giving 
rise to a relation between an appetite and a good, this good 
need not be considered as a perfection of the thing in its own 
particular being. Indeed, in the case of non-living things, it 

'•"Cf. St. Thomas, Contra Gentiles, HI, 23. 

** It might be asked if the active principle in such cases would be an example 
of art cooperating with nature. It seems that it would not be — at least not in the 
strict sense. Art, it seems, cooperates with nature when it acts in conjunction with 
au active principle operating in nature, as is the case with medicine. 


is very difficult to determine just what is the good for them. 
But it is sometimes a different matter if we look at such things 
in the general scheme of the universe. Then their observed 
tendencies to certain acts very often appear as contributing to 
the order and good of the whole, they are seen within the 
framework of the general intention of universal nature. ~° This 
was the case even of the heavenly bodies. One could say that 
they did not tend to movement as to a perfection for them, but 
that such movement was intended by nature for the generation 
of rational beings. By such movement they were constituted 
in their given role of causes of alteration in the universe. The 
tendency known as " gravity " can also be seen as contributing 
to a general order. Even the tendency of water to be warmed, 
sometimes given by St. Thomas as a simple example of an 
intrinsic passive principle of natural movement, could be seen 
as contributing to the good of the whole. 

To complete the general picture, however, the passive 
potency should be seen in relation not only to its act, as we 
have been viewing it, but also to the agent which confers the 
act. In his commentary on Book VII of the Metaphydcs,^^ St. 
Thomas explains natural potencies in terms of forms and 
agents: " The difference between the matter of natural things 
and the matter of artificial things is that in the matter of 
natural things there is a natural aptitude for the form and it 
can be reduced to act by a natural agent; this does not happen 
in the matter of artificial things." (Italics mine.) Indeed, the 
universe may be considered as a whole composed of parts so 
interrelated that they are acting upon one another or being 
acted upon by one another, so that everything according to its 
particular nature is related to something else or to many things 
as either patient or agent, or both, though not of course in the 
same respect — and all for the good of the universe as a whole. 
Thus, to use a simple example, water would be related to both 
fire and the north wind as passive, fire and the north wind to 

" Nature taken as the whole system of interrelated individual natures. 
" Lectio 8, n. 1442Z. 

258 SHEiLAH o'flynn brennan 

water as active. This does not presuppose a determinate in- 
clination in the water either to be warmed or to be cooled," 
but an intrinsic aptitude for either, which, unlike the indifferent 
potency in the wood, as the matter of a table, for example, 
gives rise to a relationship and order to other things in nature. 
The movements resulting from these relations are natural. Art, 
on the other hand, would imply an interference, or at least an 
intervening in this order by the human intellect, extrinsic to 
nature — an intervention, moreover, usually not aimed at the 
fulfillment of a natural (i. e., intrinsic) potency .^^ 

In resume, then, a movement corresponding to an intrinsic 
passive inclination to a determinate act as an end and a good 
is termed natural, even though the active principle be quite 
extrinsic to nature. However, natural movements usually take 
place in subjects having a potency to an act which can be sup- 
plied by a natural agent; in this case, even when the passive 
potency is not a determinate inclination to one act but is rather 
an indeterminate inclination to opposite acts, it is still a case 
of nature insofar as by these potencies the subject is related 
to corresponding agents within nature and the order thus estab- 
lished can be seen as fitting into the general scheme of the 
universe. The order of appetite and good in the universe as a 
whole, then, is what determines whether or not a movement is 


Variations in the Meaning of Nature throughout 
THE Study of Nature 

Returning now to Aristotle's definition of nature given in 
the Physics (Bk. II, ch. 1) , we find that there is a qualifica- 
tion that requires further development, the word 'primarily. 
And it is with a consideration of this point particularly that 

^^ A passive potency in the general scheme of nature can be related to more 
than one agent — even to agents producing opposite effects — and therefore it can 
be ordered to opposite acts, both of which would be a good for the whole. It is the 
active, not the passive, principle, in both animate and inanimate things, that as 
nature is determined ad unum. 

"" An exception could be made for those arts that cooperate with nature. 


we become aware of a special divergence in the use of the word 
nature throughout the philosophy of nature. 

In his explanation of this word, St. Thomas says: " Nature 
is the principle of the movements of composite things, but not 
primarily. Thus the fact that an animal moves downwards 
[i.e., falls] does not proceed from the nature of the animal as 
animal but from the nature of the dominating element.""^ 
Nature, then, is a principle primarily of those movements that 
belong to things in virtue of what is most fundamental in 

Nor is this the only instance in which St. Thomas adverts 
to this idea. When, for example, Aristotle speaks of generation 
as the activity the most natural of all living things, St. Thomas 
explains that it is a movement common to all mobile beings, 
even to the inanimate. ^*^ Again, St. Thomas, speaking of the 
vegetative soul, reserves the term nature for what living and 
non-living things have in common: " Now this principle is not 
nature. Nature does not move in opposite directions, for all 
plants grow not only upwards or downwards, but in both direc- 
tions." ■' It seems, then, that in these passages the soul is taken 
to be nature only insofar as it is the principle of movements 
common to all mobile beings — though in other places of the 
De Anima it is clear that the soul as such is regarded as 

What is most common, of course, is also what is most funda- 
mental in any mobile being; and this, we are saying, is what is 

" In II Phys., lect. 1, n. 5. 

^* John of St. Thomas takes the word jmmarily to mean that the nature of a 
being is not a secondary and instrumental principle, such as an accident would be, 
but a fundamental principle, i. e., substantial. That nature must be primary in 
this sense is readily evident. St. Thomas, however, seems to see another meaning 
in the word jmTnarily. 

^* Aristotle, De Anima, II, 4, 415a22 et sqq.; St. Thomas, In II De Anima, 
lect. 7, n. 312. 

" St. Thomas, In II De Anima, lect. 3, n. 257. 

^^ Cf. Aristotle, De Anima, I, 1; St. Thomas, lect. 2, where it is established 
that the study of the soul belongs to philosophy of nature insofar as the proper 
activities of the soul involve modifications of the body. Also, Aristotle, De Anima, 
Bk. II, 4, 415 b 22 et sqq. where the soul is seen as a principle of movement. 


most natural. "'^ This fact is significant especially in the case of 
living beings where one can distinguish between various types 
of movements, some more fundamental than others. We could 
say that movements such as being generated (in a broad sense) 
and falling would be more natural than growing, and growing 
more natural than sensing, and sensing more natural than 
understanding (which is not natural at all in the strict sense 
given to natural in the philosophy of nature) . 

Now why is it that what is most common and most funda- 
mental is also the most natural.? We have said that nature is 
a principle of movement in that in which it is. It is therefore 
a principle of movement in the mobile — in the moving or move- 
able thing. A mobile thing implies potency and passivity. It 
does not necessarily involve activity; this is the mark of the 
mover. Nature then is intimately related to matter. Though 
form is nature more perfectly than matter is, since matter 
would not be a principle of movement without its relation to 
form, and no being would be a natural being in act were it 
not for form; nevertheless, form is nature only insofar as it 
determines matter, because otherwise it would not be a princi- 
ple of movement at all. Where there is no matter, there is no 
nature. And in the measure that form rises above matter it 
reaches beyond mere nature, as it becomes, first, a principle not 
only of being moved but also of moving, and then a principle 
not only of movement but of operations that are not strictly 
movements at all. 

Let us look more closely at this gradation in natural beings. 
One step above the bottom, we have the plants, differentiated 
from inanimate things by the vegetative soul. Now, this soul, 
like any other, even the human soul, is most fundamentally 

^* It must be noted that we are taking nature and natural absolutely. Thus, 
absolutely considered, sensing is less natural than growing though relative to the 
animal it is more natural, since it is proper to the animal nature and growing is 
not. Likewise, understanding and willing are more natural for man than sensing, 
though in an absolute sense they are what is least natural in him, if they are 
natural at all, and what is most natural of all is anything he has in common with 
the lowest thing in nature. 


substantial form. As such, it is nature insofar as it was a prin- 
ciple in the generation of the thing of which it is the soul and 
also insofar as it is the principle of movements, such as falling, 
that are natural to mobile beings already constituted. As soul, 
in what is proper to it, it is a principle as well of the vegetative 
operations. These, it is true, are still movements in the strict 
sense, involving activity, passivity and alteration, all in the 
strict sense. However, they are movements in which the 
living being properly moves itself. The soul, unlike any mere 
substantial form, constitutes the being as an agent with re- 
spect to itself. It is still nature, insofar as it is a principle of 
being moved, intrinsic to the moving being. However as an 
active potency, it is a principle of moving rather than of being 
moved, and of moving another as such ^° — in fact, the living 
being moves itself only inasmuch as one part moves another 
part. Thus as an active, motive principle, it has something 
different from and more than mere nature. 

Then, a more perfect soul, the sentient, is capable not only 
of these operations but of sense perception as well, which con- 
sidered in itself, is not movement in the strict sense, but an 
operation that is an actus perfecti.^^ It is movement in some 
sense, however, " a sort of alteration," as Aristotle calls it, for 
it involves a transition from potency to act. If the sentient soul 
is considered to be nature insofar as it is a principle of move- 
ment in a secondary sense, in this respect it can only be nature 
according to an extended meaning. On the other hand, sensa- 
tion involves movement in the strict sense, insofar as it re- 
quires a corporeal organ; and it can result in movement in the 
strict sense, since it can arouse the passions which involve 
bodily modifications and at times also give rise to locomotion. 
Because all these movements are proper to the sentient soul 
as such, it too is properly termed nature. 

'"Aristotle, Metaph., V, 12, 1019al5 et sqq.; St. Thomas comments: "An active 
principle of movement must be in something other than that which is moved." {hi 
V Metaph., lect. 14, n. 955.) 

'^Aristotle, De Anima, III, 7, 431a6 et sqq.; St. Thomas, In III De Anima, lect. 
12, n. 766. Cf. also, De Anima, II, 5; St. Thomas, In II De Anima,, lect. 10 & 11. 

262 SHEiLAH o'flynn brennan 

Finally, an even more perfect soul, the rational, can be a 
principle of intellection which, since it does not require an 
organ, does not involve movement at all. It is an actus perjecti 
and is called movement only because like sensation it requires 
a transition from potency to act. Since the intellectual opera- 
tion is no more than metaphorically movement " (or, at least, 
movement according to an analogical extension even beyond 
that required to include sensation) , the rational soul as its 
principle, considered precisely in this way, is nature only in 
the same improper (or extended) sense. However, because 
the proper operation of the rational soul cannot take place 
without the instrumentality of the senses which do involve 
movement, the study of this soul, also, belongs to philosophy 
of nature. It must be remembered too that there are some 
properly human movements that spring from the rational soul 
AS such— laughing and talking, for example. What is more, the 
soul is an act corresponding to a natural potency, the form of 
a natural body. And it is as a rational soul that it is the form 
of a particular type of body, a human body. In this respect, 
the human soul, even as rational, is properly nature. 

Hence, as the form emerges from matter, the thing which it 
determines rises above passivity, and then above movement, 
and therefore above mere nature also. Not that it loses what 
belongs to nature. It has all this and something more. And, in 
each case, this something more constitutes what is most proper 
to the particular thing, e. g., sensation for the animal, under- 
standing for man. In this sense, then, we can say that what 
is primary or most fundamental in a thing is also most purely 
natural. Indeed, it is what is least perfect in a natural being 
that is also what is most fundamental. And this is also what is 
most common since in nature the more perfect things always 
keep something of the less perfect. 

We might note too, incidentally, that as the form rises above 

^^ Note that in his commentary on the De Anima, I, lect. 10, n. 160, St. Thomas 
says: " In the least proper sense of all, indeed only in a metaphorical sense, is 
movement to be found in the intellect." See nn. 157 to 162 for a distinction of 
the three kinds of movement found in the soul's activities. 


matter, a characteristic of nature, its deterviinatio ad unum, 
diminishes in a proportional degree. Because of their material- 
ity, both non-living things and plants are limited to one form, 
their entitative, natural form. Since one form cannot give 
rise to contrary active inclinations, in this way they are deter- 
mined ad unmn. Already in plants, however, there is a certain 
beginning of indetermination insofar as they can grow up and 
down — their growth being not mere local movement but the 
development of an organism, a body of heterogeneous parts; 
there is a certain spontaneity in that they can adapt themselves 
to varying circumstances. Hence St. Thomas's distinction in 
his commentary on the De Anirna between nature and the 
vegetative soul. As form rises above matter, the thing emerges 
from the purely entitative and becomes capable of the inten- 
tional. As such it is not limited to its own form. The inclina- 
tions of the thing are not merely those springing from its entita- 
tive (natural) form but also those that rise from certain ac- 
quired forms, its forms of knowledge. An animal can have 
now one intentional form, now another, and therefore, can 
have now one tendency, now another. Man, however, can 
possess intellectually at the same time a form and its opposite. 
Hence, precisely as rational, he is above nature insofar as he is 
not at all determined ad unum but must determine himself — 
and therein, by the way, lies his freedom.^^ 

To return now to the development in meaning of nature: it 
might be observed that the variation is based on the different 
senses of two elements in the definition of nature. Nature, it 
will be recalled, is defined as a principle of movement in that 
in which it is. It is an intnnsic principle and it is a principle of 
movement. We have seen that the active principle by which 
living beings move themselves is not in every way intrinsic; ^* 

'* It is interesting to note that although the plant is more determined in its 
operations than the beast and the beast more than man, as to their being the order 
is the reverse: man is more determined than the beast and the beast more than 
the plant. The more perfect the form the more determined a thing is in its 
being and the less determined in its operations. 

^* With respect to this " innerness " of nature we might go even further and 

264 SHEiLAii o'flynn brennan 

furthermore, that the principle of sensation in animals as such 
is not a source of movement in the strict sense and the principle 
of intellection in men has even less reason to be considered as 
a cause of movement. This last extension of meaning, however, 
does not coincide with the sense that is broad enough to include 
even the essence of immaterial substance as root of spiritual 
activity. It is still proper to philosophy of nature, for though 
the operation in question as spiritual is not movement, still as 
the operation of a form in a body, it must take place in con- 
junction with activities that are movements. The rational soul, 
as a form in matter, cannot effectually be a principle of under- 
standing unless it be at the same time a principle of move- 
ment. At this point, however, the extension of the word has 
reached a limit beyond which the meaning would no longer be 
proper to philosophy of nature. 

The word nature, consequently, though it has a sense proper 
to philosophy of nature, admits of a wide variety of meanings 
even within this science. In the Physics, we have seen, nature 
is said most obviously of matter and most properly of form, 
but of both insofar as they are principles of movement in the 
strict sense. Matter is such a principle by its aptitude for form, 
thus implying an inclination to being. Form as fulfilling this 
aptitude, and as an end of generation, is also a principle of 
movement. Once the natural being is in existence, form is 
nature as the active principle of movements necessary for its 
preservation in existence and the attainment of its good in 
general or of movements contributing to the good of the uni- 

consider the active principle of the generating agent relatively to the generated. 
Here the active potency is undoubtedly the mover of another. There is a sense, 
though, in which even this active principle can be called nature, for although it is 
extrinsic to the particular mobile being that is the product of the generation, never- 
theless both mover and moved coincide in the same natural species. (Cf. St. 
Thomas, In VII Metaph., lect. 6, nn. 1386-1393.) What is more, the universe 
could be considered as a whole having heterogeneous parts acting one upon the 
other. In this case, the form that constitutes anything as an agent with respect to 
something else could be considered as a principle intrinsic to the moving whole 
(although extrinsic to the particular thing it moves) and as such could be called 


verse as a whole; and it is the form, too, that accounts for the 
particular passive potencies by which a natural being is related 
to natural agents, fits into the scheme of the universe and thus 
contributes to the good of the whole. As for this whole system 
of interrelated active and passive potencies, it too is commonly 
called Nature. Then, in the study of the soul and subsequent 
treatises, form again is nature, but now as a special type of 
active principle by which the living being can move itself. 
Finally, the form, as soul, is a principle of various activities, 
some more strictly movement than others; and as the meaning 
of movement varies, so does the meaning of nature. But from 
first to last, nature is considered not as essence, nor even as 
principle of operation in the broad sense, but in one way or 
another as principle of movement in the strict sense of the term. 

Sheilah O'Flynn Brennan 

St. Mary's College 
Notre Dame, Indiana 


ORDER is an outstanding characteristic of the man of 
wisdom.^ He is a man who has discovered and observed 
the due order in his reasoning processes. He has im- 
posed a rational order over the acts of his will and emotions. 
And he stands in wonderment at the great order of all nature, 
an order that he himself has not made, but only contemplates.^ 
It is the discovery of order — of logos — in the world that impels 
him to set up a science of nature by which he will understand 
the intelligible necessities and manifold beauties of the uni- 
verse that is his home. 

As a man of wisdom the philosopher of nature seeks not 
only the order inherent in reality itself, but also an order for 
investigating that reality.^ For he realizes that not only the 
exigencies of the real order, but also those of the order of his 
mind will rule the development of his science. When the 
natural philosopher is a teacher as well as a searcher for 
wisdom, he knows that his exposition will have to be modified 
by another order, that required to direct the minds of his 
students to the comprehension of the truths amassed by a 
long tradition of devoted masters. 

No arbitrary plan of investigation nor casual order of treat- 
ment will do justice to the science of nature. There must be a 
definite order that will be the result of the interplay of several 
factors on the science — factors whose demands are essential. 

^ St. Thomas Aquinas, In Mctaphysicarn Aristotelis Commenfaria (ed. Cathala) 
Proemium; In Decern Libros Etkicorum Aristotelis ad Nichomachum Expositio 
(ed. Pirotta), I, 1, n. 1-2; Summa Theologiae, I, 1, 6; I-II, 102, 1; Summa Contra 
Gentes, I, 1; II, 24. 

^ Cf. St. Thomas, In De Physico Atiditu Aristotelis (ed. Leonina) , VIII, 3, n. 3; 
SuTTi. cont. Gent., II, 24. 

* " Processus scientiarum est opus rationis, cujus proprium est ordinare; unde in 
omni opere rationis ordo aliquis invenitur, secundum quern proceditur ab uno in 
jiliud " (St. Thomas, In I De Cado et Mundo [ed. Leonina] Proem., n. 1). 



To ignore these will severely blemish the science achieved and 
particularly the teaching of that science. 

It will be profitable, therefore, to make a synthetic study of 
the principles of order governing the philosophy of nature. 

Two texts of St. Thomas can serve to introduce the question. 

The concept of order includes three elements: first, the idea of 
before and after; hence there is order in all those ways by which 
one thing can be before another, by place, time, and so forth. 
Order also includes distinction, because only distinct things have 
any order. But this is rather presupposed than signified by the 
word " order." The third element is a principle of order, according 
to which order is divided into its species. Hence there is an order 
according to place, another according to dignity, and another 
according to origin.* 

Succession, distinction, and a principle of order: all these 
are pertinent to the consideration of order in the philosophy 
of nature. St. Thomas elaborates on the principle of order in 
the second text: 

Order always has reference to some principle. Therefore, since 
there are many kinds of principle — namely, according to site, as a 
point; according to intellect, as the principle of demonstration; 
and according to each individual cause — so there are many kinds 
of order.^ 

It is the order according to intellect that mainly interests us, 
because we are here considering the problem of ordering a 
science. The principle of that order will in some way coincide 
with " the principle of demonstration." Since demonstration 
is the means for achieving scientific knowledge, the order within 

* " Ordo in ratione sua includit tria, scil. rationem prioris et posterioris; unde 
secundum omnes illos modos potest dici esse ordo aliquorum, secundum quos aliquis 
altero prius dicitur et secundum locum et secundum tempus et secundum omnia 
huiusmodi. Includit etiam distinctionem, quia non est ordo aliquorum nisi distinc- 
torum. Sed hoc magis praesupponit nomen ordinis, quam significet. Includit etiam 
tertio rationem ordinis, ex qua etiam ordo in speciem contrahitur. Unde unus est 
ordo secundum locum, alius secundum dignitatem, alius secundum originem " 
(Super Libros Sententiarum, I, d. 20, 3, 1. Cf. Summa Theol., II-II, 26, 1). 

° Summa Theol., I, 42, 3, transl. A. Pegis, Basic Writings of Saint Thomas Aquinas 
(New York: Random House, 1945). 


natural philosophy will have to conform to the exigencies of 
the logical process of demonstration. Among the many require- 
ments of demonstration is this one, that the principles of a 
demonstration, i. e. the definitions and premises, have to be 
foreknown, even reducible to self-evident propositions, so that 
the mind may be led from the known to the yet unknown. 
The first point of our study will be the order in which the 
mind is led from the known to the unknown. 

The order of learning ® 

The learning process may be likened to the way in which 
nature operates a cure. It may do so through its own intrinsic 
powers, or it may be helped along by the art of the physician 
and the instrumentality of his medicines. By analogy, there are 
two ways of acquiring science. " In one way, natural reason 
by itself reaches knowledge of unknown things, and this way 
is called discovery {inventio) ; in the other way, when someone 
else aids the learner's natural reason, and this is called learning 
by instruction {disciplina) ." ^ There follows from this a funda- 
mental principle of organizing a science. "A similar thing takes 
place in acquiring knowledge (scientia) . For the teacher leads 
the pupil to knowledge of things he does not know in the same 
way that one directs hhnselj through the ^process of discovering 
something he does not know." ® 

Therefore, the via inventionis and the ordo disciplinae coin- 

°L. M. Regis, O. P., Epistemology (New York: Macmillan, 1959), Chap. IV 
" The Angehc Doctor's Method." Chap. XII. " Infalhble Knowledge of Mediate 
Truth." R. Garrigou-Lagrange, The One God (St. Louis: B. Herder Book Co., 
1943) , " The Method of St. Thomas," pp. 9-26. 

'' Truth, 11, 1, transl. J. V. McGlynn, S.J. (Chicago: Henry Regnery Co., 1953). 

* Ibid. Italics ours. St. Thomas teaches the same doctrine elsewhere. " Scientia 
acquiritur dupliciter: et sine doctrina, per inventionem; et per doctrinam. Docens 
igitur hoc modo incipit docere sicut inveniens incipit invenire: offerendo scilicet 
considerationi discipuli principia ab eo nota, quia omnis disciplina ex praeexistenti 
fit cognitioiie (I Poster., 1, 1; 71a), et ilia principia in conclusiones deducendo; et 
proponendo exempla sensibilia, ex quibus in anima discipuli formentur phantasmata 
necessaria ad intelligendum " (Contra Gent., II, 75. Cf. Summn Theol., I, 117, 1; 
In II De Anima, 11, n. 372; De Spir. Great., a. 9, ad 7) . 


cide from the point of view of order. Is there an ordo doctrinae 
that is different from these? Sometimes it is asserted that in 
building up a body of scientific knowledge one would use the 
order of discovery, but in teaching others the fully achieved 
science one would use an inverse order, the order of doctrine. 
Such a position would equate the order of doctrine with two 
other orders: the order of nature or with the via iudicii. 
We shall show that both these identifications are incorrect. 
Actually, the ordo doctrinae and the ordo discipUnae coincide. 
As St. Thomas wrote at a later period of his life, " The names 
' doctrine ' and ' discipline ' pertain to the acquisition of knowl- 
edge. For doctrine is the action of him who makes something 
known; discipline, however, is the reception of knowledge from 
another." ^ The ordo doctrinae is not, therefore, the inverse of 
the via inventionis}'^ In fact, ordo doctrinae should be trans- 
lated " order of teaching." 

Mention has been made of the order of nature or the real 
order. What is the relation between this and the order of 
learning.f^ At the beginning of his commentary on the Physics 
of Aristotle, St. Thomas lays down a principle of learning that 
he reiterates many times in his other works. ^^ Our knowledge 
starts from what is more known to us and proceeds to things 
that are ontologically more perfect and hence more knowable. 
We must start from sensible things, lower in the order of nature, 
but more accessible to our knowledge; it is through these 
sensible things that we ascend to the contemplation of higher 
and ultimately of divine things .^^ Moreover, the study of 

* Exposition of the Posterior Analytics of Aristotle, transl. Pierre Conway, O. P. 
(Quebec: Le Librairie Philosophique M. Doyon, 1956) , I, I, n. 9. 

^° Cf . R. Garrigou-Lagrange, La Realisme du Principe de Finalite (Paris: Desclee, 
1932) , p. 235; P. Coffey, The Science of Logic (London: Longmans, Green and Co., 
1918), n, pp. 15-16. 

"7n I Phys., 1, n. 7-11. Cf. In I Anal. Post., 2, n. 8; In VII Meta., 2, n. 1297- 
1305; Summa Theol., I, 85, 5; In De Trin., 6, 1, ad qu. 1. 

^' " Cum enim omnis disciplina fiat per ea quae sunt magis nota addiscenti, quern 
oportet aliqua praecognoscere ad hoc ut addiscat, oportet disciplinam nostram 
procedere per ea quae sunt magis nota quo ad nos, quae sxmt saepe minus nota 
secundum naturam, ad ea quae sunt notiora secundum naturam, nobis autem 
minus nota" (In VII Meta., 2, n. 1301). 


sensible things is easier than that of immaterial things, and in 
teaching and learning, the preferable order is to start with what 
is easier/' Thus, the order of learning is the inverse of the order 
of nature. 

What is to be said of the via iudicii and the order of learning? 
As a first approach we may note that St. Thomas opposes the 
via iudicii to the via invejitionis,^" the latter of which parallels 
the order of learning. The via inventionis is a procedure from 
the sensible to self-evident principles and thence to the con- 
clusions flowing from them; herein is there a true " discovery " 
of truth. The way of judgment is the inverse of this." It con- 
sists of resolving or analyzing a mediate truth into its principles. 
It verifies and evaluates already acquired knowledge by tracing 
conclusions back to self-evident premisses." Thus, in a science, 
when there has been a chain of demonstrations one following 
from the other, a conclusion can be resolved or analysed back 
to first principles by retracing the course of the demonstrations 
developed through the via inventionis. The way of judgment 
is not then the essential order of learning or of teaching, though 
it is secondarily involved in learning and teaching as the process 
of verification of demonstrations. The way of judgment, how- 

" In V Meta., 1, n. 752; In De Trin., 7, 1, qu. 2, ad 3; In II A7ial. Post., 16, n. 6; 
Summa Theol, II-II, 189, 1, ad 4. 

"De Veritate, 10, 8, ad 10; 14, 1; 15, 1; 22, 2; Summa Theol., I, 79, 8; 9; I-II, 
57, 6; 68 4; II-II, 9, 1. 

^* " Cum autem homo per naturalem rationem assentit secundum intellectum 
alicui veritati, dupliciter peificitur circa veritatem illam; prime quidera, quia capit 
earn; secundo, quia de ea certum iudicium habet " (Summa Theol., II-II, 9, 1). 
The references in the preceding note sufficiently describe the way of judgment. 

^^ The way of invention, from the point of view of content, proceeds by either 
analysis or synthesis, these two terms being used in a variety of ways. However, 
from the point of view of the logical process, invention is synthetic: putting together 
of a syllogism. The way of judgment analyses or resolves a syllogism into its 
elements in order that the intellect may give its assent to the conclusion. On 
analysis-synthesis, cf. L.-M. Regis, "Analyse et synthese dans I'oeuvre de saint 
Thomas," in Studia Mediaevalia in Ilonorem Admodum Rev. Raymundi Joscphi 
Martin (Brugis Flandrorum: De Tempel) ; idem., Epistemology, pp. 422-457; S. E. 
Dolan, " Resolution and Composition in Speculative and Practical Discourse," 
Laved Theologique et Philosophique, VI (1950) , 9-62; F. X. Calcagno, Philosophia 
Scholostica (Napoli: D'Auria, 1950), I, pp. 216-219. 


ever, may seem to be the order of teaching to those who use 
the thesis method in which the conclusion is first presented 
authoritatively and then justified. At most, the conclusion 
should be presented only as a question, the solution of which 
must be arrived at by the way of discovery. 


Distinction of natural philosojjhy from other sciences 

The question of the relation of the real order to the order of 
learning raises the problem of the relation of natural philosophy 
to other sciences, especially to metaphysics, the queen of the 
human sciences. The same material being is known in different 
ways by different sciences. If we are to establish order in 
natural philosophy, then this science must be distinguished 
from metaphysics, theology, and empirical science.^^ 

In many texts St. Thomas explicitly states that metaphysics 
is to be taught after natural philosophy .^^ Metaphysics is, in 
fact, the last of the sciences to be learned, the queen of human 
sciences, the culmination of human wisdom, ancillary to none 
but supernatural theology. Natural philosophy and meta- 
physics are distinct sciences, each with its proper principles. 
Natural philosophy uses proofs with middle terms that contain 
common sensory matter in their definitions. Metaphysics uses 
concepts that are negatively immaterial, that is, containing no 
matter in their definitions, but able to be existentially realized 
either in matter or apart from matter. Two sciences proceeding 
according to such distinct manners of conceptualization are at 
different levels of intelligibility and point up different degrees of 
necessity in their objects. They are thus irreducibly distinct.^" 

^^ The above distinction between invention and judgment is not the same as the 
distinction between inventive logic (largely dialectics) and judicative logic, which 
is concerned with the matter and form of the demonstrative syllogism. Cf. In I 
Anal. Post., 1, n. 6. 

^* " Ordo absque distinctione non est. Unde ubi non est distinctio secundum rem, 
sed solum secundum moduni intelligendi, ibi non potest esse ordo nisi secundum 
modum intelligendi '' (De Pot., 10, 3) . 

'" In III Sent., d. 35, I, 2, 3; In VI Ethic, 7, n. 1209-1211; In Librum de Causis, 
1; In De Trin., 6, 1. 

^"/re / Anal. Post., 41; In De Trin., 5, 1; Summa Theol., I, 85, 1, ad 2. 


Nevertheless, there are close and necessary relations between 
the two sciences. Natural philosophy is preparatory to meta- 
physics,"^ It acquaints the learner with many concepts existing 
in material reality, but able to be extended to a metaphysical 
plane. Notions such as substance and accident, potency and 
act, cause and effect are metaphysical concepts, commensurate 
with being as such; but they are used and studied in natural 
philosophy insofar as they apply to its subject.^^ After be- 
coming acquainted with them at the level of sensory matter, 
where they are relatively easy to grasp, a student can more 
conveniently understand them in their metaphysical context. 
Natural philosophy is preparatory to metaphysics also because 
it proves the existence of immaterial being, without which 
metaphysics would have no formal subject and thus would 
yield its primacy to natural philosophy.^^ 

Even though metaphysics comes later in the order of learning, 
it is first in the order of nature and dignity.^* Therefore, it gives 
an extrinsic guidance to natural philosophy, a guidance that 
the beginner will scarcely realize or one which he will have to 
take on authority. Moreover, the defense of the principles of 
natural philosophy is the function of metaphysics. It is the 
metaphysician who justifies the validity of our knowledge and 
who critically investigates the common principles that other 
sciences borrow and use."^ 

This brief discussion of the relation of the two sciences should 
suffice to justify a few practical points pertinent to our present 
study. Due order requires that purely metaphysical questions 
be eliminated from natural philosophy. Relevant examples 
would be such topics as creation, pantheism, eternity, the glory 
of God as final cause of the universe. The immortality of the 

"/wDe Trin., 5, 1, ad 9. 

"/re IV Meta., 5, n. 591; XI, 4, n. 2206-2210; In II Phys., 5, n. 360. 

"* We have studied elsewhere the relation of natural philosophy and metaphysics: 
" The Formal Subject of Metaphysics," The Thomist, XIX (1956) , 59-74; " Being 
and Metaphysics," The Modern Schoolrnan, XXXV (1958) , 271-285. 

^* In De Trin., loc. dt. 

"' Ibid.; In IV Meta., 5, n. 590-591. 


human soul must not be treated metaphysically in natural 
philosophy; the proof, in order to be physical, must rest on the 
intrinsic incorruptibility of the soul. The de facto question of 
the immortality of the soul, proved from the wisdom and 
goodness of God, must be saved for metaphysics, or at most 
must be presented in natural philosophy in dialectical status. 
The origin of the soul and its status after death are questions 
raised in natural philosophy, but which are unable to be settled 
by the principles of natural philosophy; the metaphysical light 
is necessary .^^ Natural philosophy must always present its 
proofs on the basis of its own principles. Positions should not 
be held because of metaphysical repercussions, but proofs 
should be constructed by the intellectual processing of sensory 
data in the light of properly physical principles. Metaphysical 
proofs can be accepted only as dialectical in the lower science. 
It is true that metaphysics casts a fuller light over the world 
of nature; it gives the ultimate reasons for the truths discovered 
by the physicist. But the distinction necessary for highlighting 
the true nature and order of natural philosophy demands that 
metaphysical insights be presented in the status of footnotes 
or appendices, which are accepted, not as apodictic, but as 
dialectical, until they can be seen in their proper perspective 
within the science of metaphysics. 

Even more important, it is necessary that teachers effectively 
shake off the Wolff-Leibnizian influence and discontinue pre- 
senting natural philosophy as an application of metaphysics. 

^* " Sed quomodo se habeant formae totaliter a materiae separatae, et quid sint, 
vel etiam quomodo se habeat haec forma, idest aniina rationalis, secundum quod est 
separabilis et sine corpore existere potens, et quid sit secundum suam essentiam 
separabile, hoc determinare pertinet ad philosophum primum " (In II Phys., 4, 
n. 10. Cf. In De Sensu et Senato, 1, n. 4; 2, n. 317; In III De Anima, 12, n. 785). 
Just as the above-mentioned questions should be removed from natural philosophy, 
so it would seem that the discussion of the final natural end of man belongs to 
natural philosophy. Every science treats the principles, causes, and properties of its 
subject (In Meta., Proem) . The final end of man is determined by nature (In III 
Ethic., 13, n. 524; VI, 2, n. 1131). It is the ultimate term of the natural motion of 
desire (Ibid., I, 9, n. 197). Ethics borrows from natural philosophy the doctrines 
of man's nature and end; it is, therefore, subalternated to natural philosophy. 


Often the doctrine of hylomorphism, for instance, is treated 
as an application of the metaphysical doctrine of potency and 
act to material things, which implies a genetic primacy of 
metaphysics over natural philosophy. The presentation of 
natural philosophy before metaphysics is important for all 
who would give a synthetic picture of Thomism, even for those 
historians who claim to describe the philosophical doctrine of 
St. Thomas, rather than his theology. 

It is equally essential to distinguish natural philosophy from 
theology. There is no theoretical difficulty to this. But some- 
times the theological interest of authors impels them to give 
undue prominence to problems that have theological import, 
even to treat theological matters in philosophy, such as the 
manner of the Eucharistic presence of our Lord and the possi- 
bility of miracles. The due order and proportion of natural 
philosophy require footnote status for strictly theological prob- 
lems, no matter how worthy or interesting they may be in 
themselves. Special caution must be exercised in taking proofs 
bodily from St. Thomas' theological writings and using them 
uncritically in natural philosophy. The theological light, or per- 
haps a metaphysical orientation, may make a given proof incom- 
patible with the proper method of natural philosophy. Extra- 
contentual arguments are a disservice to natural philosophy. 

Another clarification is necessary for the purposes of keeping 
due order in natural philosophy. What is the relation between 
natural philosophy and modern empirical science .f* This is not 
the place to treat this question ex professo, but we may lay 
down a few propositions. Natural philosophy must not be 
content with mere generalities; it must extend its investigations 
into the realm of the specific. At its general stage it is still 
confused knowledge awaiting further actualization. It must 
apply its light to the whole cosmos and to all its parts. The 
human drive for understanding will not be satisfied with less.^^ 

Modern science's monopoly of detailed phenomena causes 

-'Cf. In I Meteorologicorum, I, n. 1; R. J. Nogar, O. P., "Cosmology without a 
Cosmos," in From An Abundant Spring (New York: Kenedy, 1952), pp. 363-392. 


at least an overlapping, if not a real conflict. A partial resolu- 
tion is certainly possible. Insofar as empirical science is factual, 
its data are required as preliminary to causal demonstration 
at the various levels of natural philosophy, for a rich experience 
is prerequisite to natural philosophy. Insofar as empirical 
science is mathematicized, it is a scientia media distinct from 
natural philosophy.-^ But if mathematics is used as an instru- 
ment for the investigation of facts, and if the facts have thereby 
been certainly established, they may be taken over by the 
natural philosopher and demonstrated in the light of his 
proper principles. From this point of view, mathematicized 
science is instrumental to philosophy.^® Insofar as modern 
science is hypothetical, its relations with natural philosophy 
can be only on the level of a dialectical continuation of phi- 
losophy. At this stage of modern science we can argue that 
there is a de facto influence of philosophy upon the scientist, 
whether it be mechanism, logical positivism, or — are we ana- 
thema for suggesting a desideratum^ — Thomism. At least, if 
nature is to be understood, rather than merely catalogued or 
used, then natural philosophy must shed its light even into the 
dark corners of scientific theory .^° 

One point is most noteworthy. Natural philosophy does not 
depend on scientific theory, but rather vice versa. The doctrine 
of hylomorphism, for instance, is not built on the shifting sands 
of scientific theory. Aristotle elaborated his doctrine long ago 
on the basis of common observation. The discoveries and 
theories of the passing centuries have not overturned that 
doctrine, but rather look to it to introduce intelligibility and 
order into the confused maze of modern facts and theories. ^^ 

^* In De Trin., 5, 3, ad 6. 

'* In I De Coelo, 3, n. 6. 

^^ We have studied the relevance of these principles to the science of psychology 
in "Toward an Integrated Psychology," Proceedings of the American Catholic 
Philosophical Association (1958), 139-148. 

^^ " It is enough for us to remark that rectitude of conscience in scientific research 
has led modern thought to the threshold of the only philosophy which can give a 
reasonable interpretation of the results obtained by experimentation. . . . The 
theory of matter and form, of potency and act, is capable of illuminating the 


Obviously, the order intrinsic to natural philosophy demands 
full clarity on the distinctions and relations obtaining between 
it and empirical science. 

Internal order of natural philosophy 

Once we have ordered natural philosophy in the sense of 
distinguishing it from other sciences, we may turn our inves- 
tigation to its own intrinsic order. In this we have the assis- 
tance of St. Thomas in the various prooemia to his commen- 
taries on the works of Aristotle. 

First, we must make a necessary distinction between the 
order of demonstration and the order of definition. A number of 
books on natural philosophy so divide their matter as to treat 
first of the properties of natural being: motion, quantity, time, 
and place; then as a culmination of that part of natural phi- 
losophy widely called " cosmology," comes a study of the 
nature of material bodies, a determination of the first principles, 
matter and form. The study of the properties is presented, 
explicitly or implicitly, as part of the inductive search for the 
definition of bodies through their first principles. 

Such a process, however, does not do justice to the logical 
doctrine of demonstration. It is propter quid demonstration 
that yields strictly scientific knowledge. The theoretical dis- 
cussions among scholastics on the principles of division of 
sciences presuppose the Aristotelian and classical Thomistic 
concept of science. Scientific knowledge, in this precise and 
technical sense of the word, is not merely a collection of facts 
nor inductive searches ending in definitions. It consists of 
demonstrating attributes, whether properties or causes, through 
the use of middle terms that are both definitions of the subject 
and proper causes of the attributes. There would be no reason 

requirements of modern science with a light which closely agrees with the results 
of experimentation. ... It is easy to catch a glimpse of the great usefulness which 
so profound a philosophy can have in aiding science to clarify the problems of 
nature " (" The Perennial Philosophy and Modem Science," Address of Pope Pius 
XIl to the Intenational Thomistic Congress, September 14, 1955). The Pope Speaks, 
II (1955), 220-221. 


for distinguishing sciences according to the manner of concep- 
tualizing the subject {obiectum jormale sub quo) , if the defi- 
nition of the subject were the terminal point of the science, 
rather than the starting point. The definition is rather the 
very light that reveals the necessary connection of the attri- 
butes with the subject. The definition must be predicated of 
the subject in the minor premiss of a propter quid demonstra- 
tion; it must be shown as the proper cause of the attribute in 
the major premiss. The knowledge of both these premisses is 
prior to the drawing of the scientific conclusion .^^ Therefore, 
the study of the principles of natural being must come at the 
beginning of natural philosophy .^^ 

The order of procedure intrinsic to natural philosophy is set 
out at the beginning of the Physics and of St. Thomas' com- 
mentary on it. We must start with the general characteristics 
of material beings and later proceed to their specific notes.^* 
A reason of pedagogical convenience is given for this: otherwise 
it would be necessary to repeat these truths many times while 
treating the particular manifestations of them.^^ There is also 
a proper reason for this procedure from general to particular. 
A thing is knowable according to its separation from matter; 
this is the principle for the specification of sciences. Even 
within a science the same principle holds for the division of 
parts .^"^ We advance in the scale of knowledge insofar as we 
transcend potency and make manifest more actual notes; in 
other words, we proceed from confused to distinct concepts. 
The more general concepts are more potential; the specific are 
more actual. Therefore, in natural science we must start with 
the study of mobile being in general, with its principles, causes 
and properties. Later, by a process of concretion or application, 

^^ Cf. M. Glutz, C.P., The Manner of Demonstrating in Natural Philosophy 
(River Forest, Illinois: 1956) . 

^^In I Anal. Post., 41, n. 9. Cf. Wm. H. Kane, O. P., "The Nature and Extent 
of Natural Philosophy," The Neio Scholasticism, XXXI (1957) , 85-97. 

^'In I Phys., I, n. 5. 

^'^ Aristotle, Parts of Animals, 1, 1, 639al5-b7. 

^® In De Sensu et Sensato, 1 ,n. 2. 


we treat those mobile beings that are the proper subjects of 
specific types of change.'' The same process of concretion is 
used in the special branches of the science, e.g. psychology 
treats living beings first in general, then in particular. At each 
stage of concretion we must assign the commensurate prin- 
ciples, causes, and properties. The further we proceed in con- 
cretion, the more difficult it becomes to demonstrate facts 
causally, although quite often the final cause of phenomena 
will be apparent, and from it we can " trace the links of 
causation." '^ 

Order to the minds of students 

We have discussed order in natural philosophy from the 
aspect of distinction and priority. Now we must investigate 
it from the aspect of relation to the student. 

A science is a body of knowledge that is intended to be 
communicated to others. It is significant that the word " doc- 
trine," which, when used substantively, signifies a body of 
truths, comes from the word " to teach." The exposition of the 
philosophy of nature can never abstract from this ordination 
to the minds of other men, and so the internal order of the 
science must necessarily envision some audience, whether be- 
giners, graduates, or specialists. We shall confine ourselves to 
considering natural philosophy in relation to the undergraduate 

The most important fact about the undergraduate is that 
he is a beginner in philosophy. He is struggling through a new 
and strange terrain. His insights are superficial; his knowledge 

^^ G. J. McMahon, S. J., The Order of Procedure in the Philosophy of Nature 
(Quebec: La Librairie Philosophique M. Doyon, 1958) Chap. 5-7; C. DeKoninck, 
" Introduction a I'etude de I'ame " in S. Cantin, Precis de psychologie thoiniste 
(Laval University, 1948) pp. xlvi-xlvii, and in Laval Theologique et Philosophique, 
III (1947) 9-65. 

** Aristotle, Parts of Animals, 1, 5, 645al0 The first book of this work gives a 
summary of the method to be pursued in studying the various types of animal life 
from the general to the specific. 645bl-646a6 show how demonstrations are to be 
given in terms of final causes. 


is often largely a memorizing of formulae. He must be helped 
by his teacher to understanding, and this with the aid of a text 
book that features clarity of exposition. The undergraduate 
is not yet prepared for delving into ancient sources; at least, 
he cannot use the works of Aristotle and the commentaries of 
St. Thomas in place of a text book. These are for more 
advanced students. Moreover, these ancient treatises, valuable 
as they are in themselves, are not adapted to the modem 
student, who has had some amount of modern science before 
coming to the study of philosophy. Our exposition of natural 
philosophy must take cognizance of modern science, even 
though philosophy is not founded on scientific theory. We 
must also give at least bowing recognition to the many com- 
peting theories for each thesis in the philosophy of nature, even 
though they may sometimes be little more than historical 

All learning proceeds from previously acquired knowledge. 
This knowledge not only is a starting point; it also conditions 
the acquisition of further doctrine. Because of his previous 
education a student very easily slips into mechanistic modes 
of thought. The concept of formal causality may come hard 
to him. Analogical concepts may be frustrating. The student 
must be gently led into the philosophical mode of thinking. 
Many examples of formal and final causality must be given 
him so that his concepts will be clear and deep. A well-ordered 
exposition of the philosophy of nature must satisfy this need 
of the modern student. 

The presentation of topics within natural philosophy must 
not be given in a cut and dried thesis method. The natural 
relation between a human mind and a not-understood fact of 
nature is expressed in wonderment. As wonderment initiated 
the science of philosophy among the early Greeks, so too it 
will stimulate the individual mind to true philosophical inquiry. 
The order of a science consists in the progress from wonder- 
ment to its contrary, the understanding of causes. ^^ Hence it is 

^' Cf In I Meta, 3, n. 66. 


necessary to arouse this state in the minds of students by 
presenting the topics of natural philosophy as questions, the 
aporia of Aristotle. These questions are hedged in by doubts, 
and it is only in resolving the doubts in the light of certainly 
established definitions and demonstrations that the mind comes 
to rest. Proper order demands that the questions and doubts 
be first proposed. *° The thesis method is not well adapted for 
the first imparting of knowledge, but rather for remembering, 
reviewing, and for disputing. 

The nature of the student's mind demands that a hunt be 
made for all definitions. Definitions have value only when 
one understands how they have been acquired and through 
what kind of defining principles they are stated. Merely to 
state them without justifying them is equivalent to an appeal 
to authority. To state the definition and then to justify its 
elements is to proceed in reverse order. To define after an 
inadequate preparation for the definition is to play the midwife 
to a puny and scrawny brainchild, as Socrates would put it. 
We can learn a valuable lesson by observing St. Thomas pains- 
takingly proceeding through three or four articles before finally 
stating their outcome in a definition. 

The core of science is the propter quid demonstration. All 
else in the science, observations of facts, definitions, quia 
demonstrations, hypotheses and other dialectical material are 
all ordered to propter quid demonstration. This order must be 
made evident to the student. He must be shown how all hinges 
on the first principles of science and how one demonstration 
follows upon another. Particularly, he must be able to evaluate 
the type of demonstration and to situate it in the context of 
the whole science. It must be admitted that one looks far and 
wide before he finds philosophy books that make use of the doc- 
trine of demontration as proposed in the logic texts. The nature 
of the science itself demands this structure, and its order to the 
minds of the students requires that the methodology be empha- 

*" This is, of course, the method of St. Thomas in the Quaestiones Di^putatae and 
in the Summa Theologiae. Cf. R. Garrigou-Langrange, The One God, pp. 9-26. 


sized, both in its abstract principles and in its concrete 
application. Only thus will students be led to philosophic 

It is wisdom that we intend to give our students. Even the 
meager participation of full human wisdom which the phi- 
losophy of nature gives is of great value.^^ Such wisdom is 
communicated to students through a twofold process on the 
part of the teacher, information and formation. The teacher 
is interested in teaching the students to think for themselves, 
to acquire firm habits of correct reasoning, to achieve personal 
insights, to understand rather than to memorize formulae. 
This formation is given, not by abstract exercises, but through 
a process of information wherein the student assimilates the 
wisdom of the ages, the fruits of a rich tradition. There can 
be no question of wasting time by letting untrained students 
try to discover for themselves the wisdom that it took more 
than twenty centuries to acquire. A realistic ordination of 
natural philosophy to the minds of undergraduate students will 
emphasize information by which minds will come into posession 
of the basic doctrines of the science. But if natural philosophy 
is presented with correct order, the cherished goal of formation 
will be achieved in and through the process of information. 

Order, then, is the key-word to the correct presentation of 
the philosophy of nature. Definite order is required by the 
nature of the human mind and its goal of science. Order is 
existent in physical reality and imposes itself on the science 
of that reality. The minds of students of philosophy, condi- 
tioned by special modes of receptivity, require a particular 
ordination of natural philosophy to their own degree of develop- 
ment. We may say, by analogy, that order is the soul of the 
universe, " the form that knits the whole world," *- The con- 
templation of this order in the science of nature will elevate 

" Cf. Contra Gent., II, 1-4. 

*^ Dante, The Divine Comedy, Paradise, Canto 33, 1.92, transl. Lawrence Binyon 
(New York, The Viking Press, 1947) . Cf. Contra. Gent., II, 39; III, 97. 


our minds and hearts, according to the beautiful words of 


The Power primordial and ineffable 
Made with such order all that circling speeds 
Through mind or space, that he who looks on it 
Cannot but taste Him, as thereon he feeds.^^ 

Melvin a. Glutz, C.P. 

Immaculate Conception Monastery 
Chicago, Illinois. 

Ibid., Canto 10, 1 3-6. 


SOME years ago a modern mathematician who had at 
that time become interested in AristoteHan-Thomistic 
philosophy asked me if it would be possible to employ 
symbolic logic to set forth the proofs for the existence of God. 
In the attempt to show him that the difficulties in these proofs 
derived from something other than their logical form, I dis- 
covered that most of the terms I was using meant something 
quite different for him. This was particularly true of the term 
" motion." I, of course, was referring to actus entis in potentia 
inquantum huiusmodi. When I tried to show him how this 
notion required an analysis of matter, form, and privation he 
expressed typical Cartesian astonishment. In the discussion 
which followed he referred to an idea of motion by a neo- 
Kantian which he said fairly well expressed his own concept 
of motion: 

All determination of place ... is a work of the mind: omnis 
locatio mentis est opus. From this point the way is open to Galileo's 
foundation of dynamics: for since place has ceased to be something 
real, the question as to the ground of the place of a body and the 
ground of its persistence in one and the same place disappears. 
Objective physical reality passes from place to change of place, to 
motion and the factors by which it is determined as magnitude. 
If such a determination is to be possible in a definite way, the 
identity and permanence, which were hitherto ascribed to mere 
place, must go over to motion; motion must possess ' being,' that is, 
from the standpoint of the physicist, numerical constancy. This 
demand for the numerical constancy of motion itself finds its 
expression and its realization in the law of inertia.^ 

He also was of the opinion that quite a number of the modern 
scientists and philosophers would agree, at least in general, 
with this idea of motion. I was inclined to agree with him on 

^ Ernst Cassirer, Substance and Function (La Salle, Illinois: Open Court Pub- 
lishing Company, 1923) , p. 362. 



the latter point but on the first one I had to say that such 
motion was " motionless " and that only by using the concept 
developed by Aristotle could we arrive at the prima via. 
Furthermore, while admitting that motion as conceived by 
modern science has a certain validity in the explanations of 
the mathematical physicist, I said that to attempt to make 
this the basis of any kind of a complete explanation of the 
ultimate principles of the universe could lead to a very un- 
acceptable philosophy. I do not recall whether my mathe- 
matician friend was convinced or not. In the present paper 
I would like to elaborate some of these notions. 

Cassirer himself, in his Substance and Function, attempts to 
make this idea of " motionless motion " the basis of a new 
explanation which will replace that of Aristotle. In the first 
chapter he shows how the new developments in logic must 
necessarily replace the logic of the Philosopher, founded as the 
latter was an a now out-moded metaphysics. His conception 
of the Greek synthesis in his analysis of the problem of knowl- 
edge shows his appreciation of the work of both Plato and 

There is no denying that Plato shaped his conception of knowledge 
on the pattern of mathematics, and his theory of ideas not only 
owes separate fundamental insights to mathematics but is deter- 
mined throughout its whole structure by this science. On the other 
hand, his theory far transcends whatever Greek mathematics could 
present in the way of stable results, and Plato seems to have given 
to the mathematics of his time much more than he took from 
it. . . . 

What Plato had done for mathematics, Aristotle did for biology. 
Not only did he conceive of it as a self-contained whole; he was 
the first to provide a conceptual language for its separate parts. . . ? 

What he has in mind here is shown in the rest of his Intro- 
duction to this work. He shows how the work of Descartes, 
Leibniz, and Kant has discovered a new basis for the interpre- 
tation of Nature. As he says: 

" E. Cassirer, The Problem of Knowledge (New Haven: Yale University Press, 
1950), p. 12. 


The Renaissance proved itself in very truth a new birth, in that 
it not only revived the various philosophical theories of antiquity 
but also recovered the spirit by which they had been created. The 
first centuries of the Renaissance were content in general to tie up 
with some doctrine or other. But so long as they sought to establish 
anew the Platonic, the Aristotelian, the Stoic, the Epicurean, and 
the Skeptic systems, all these remained mere heirlooms of which 
it was impossible to take complete possession. Descartes, precisely 
because of his unhistorical temper, was the first to succeed in the 
historic act of liberation. For he never merely took over conclu- 
sions but reembodied in himself the original power of philosophical 
thinking. He filled all science with this power and he thereby 
discovered a new universal form of science, and the Cartesian 
method and the Cartesian system are but the discovery of science 
and establishment of this new form.^ 

That this new approach to science will result in a new "on- 
tology " is shown by his appreciation of the Greek synthesis in 
the very beginning of this work where he says: 

The more deeply reason is absorbed in its own being, and the more 
conscious it becomes of its own true worth, the further it penetrates 
into the Being of things. For there is no sharp line that separates 
truth from reality, thought from Being. This fundamental meaning 
of Greek philosophy is fully realized in Plato. With him the 
problem of being and the problem of knowledge, ' ontology ' and 
' logic ', are bound together in indissoluble unity. 

That this analysis of the Greek achievement has some basis 
in fact would be generally admitted. However, in order to see 
its lacunae more precisely, some further comparison with the 
Aristotelian " synthesis " will be necessary. We might begin 
with the problem of being or " ontology." 

Aristotle studied being in the science which is today often 
referred to as " metaphysics." He called this " first philosophy," 
" theology," and sometimes " the divine science." In his con- 
ception of this discipline there were at least two very important 
aspects: it is a science, and the knowledge of it is in some way 
above the capacity of the human intellect. When he referred 
to it as a science he was speaking in terms of the ideas estab- 

^ Ibid., p. 13. 


lished in the Posterior Analytics. He held that there is a kind 
of knowledge in which the human intellect, starting from prin- 
ciples which it grasps with certitude, is able to arrive at true 
and certain conclusions. When the syllogism of the Prior 
Analytics is employed in this way the result is a demonstration, 
the knowledge is science. We attain this knowledge most easily 
and often in mathematics. It is found in other disciplines but 
with greater difficulty. One study that presented problems 
to this kind of analysis was the science of Nature, another was 
the science of being or first philosophy. 

Heraclitus had said that " Nature loves to hide." Aristotle 
was able to show more clearly why this is so. He discovered 
that the objects studied in this science contained an inherent 
lack of intelligibility. For this reason the student will some- 
times be forced to content himself with an inductive argument 
which will show that a proposition is true without giving a 
scientific reason. At other times he must use an argument 
from analogy. Science in the meaning given that term in the 
Posterior Analytics will be very difficult to arrive at in this 
discipline. Still, Aristotle was convinced that only by building 
on the ideas laboriously worked out in the science of Nature 
would the human intellect be able to come to a knowledge of 
the objects of first philosophy. Here, as Cajetan might say, 
is something which seems to have escaped the notice of many 
modern followers of the Philosopher. There are many today 
who teach that motion is actus entis in potentia inquantum 
hulusmodi. There are not so many who, after presenting this 
notion, go on to explain it along with its properties, time and 
place, and its kinds, both quantitative and qualitative. There 
are even fewer who, after having done this much, go on to speak 
of first motions and first movers. Many teachers today are of 
the opinion that this part of Aristotle's Physics is hopelessly 
tied to the out-dated cosmogony of Greek science. This makes 
it easy for them to ignore totally all the other physical works, 
with the possible exception of his De Anima. Even with this 
last named work there are only a very few teachers who are 


not prepared to use St. Thomas' Summa Theologiae in place of 
the more natural exposition of these principles. However, while 
there are only a few who give much more than lip service to 
Aristotle's treatment of Nature today, the number of those 
who stand ready to expound his metaphysics or first philosophy 
is legion. Some even go further and, with the vague and 
ambiguous notions of metaphysical principles derived from such 
an anti-Aristotelian procedure, attempt to find out how things 
are in Nature. This is truly an attempt to proceed from the 
unknown to the known. Swift's comment on these disciples is 

Having a desire to see those ancients, who were most renowned 
for wit and learning, I set apart one day on purpose. I proposed 
that Homer and Aristotle might appear at the head of all their 
commentators; but these were so numerous, that some hundreds 
were forced to attend in the court and outward rooms of the palace. 
I knew, and could distinguish those two heroes at first sight, not 
only from the crowd, but from each other. Homer was the taller 
and comelier person of the two, walked very erect for one of his 
age, and his eyes were the most quick and piercing I ever beheld. 
Aristotle stooped much, and made use of a staff. His visage was 
meager, his hair lank and thin, and his voice hollow. I soon dis- 
covered, that both of them were perfect strangers to the rest of the 
company, and had never seen or heard of them before. And I had 
a whisper from a ghost, who shall be nameless, that these commen- 
tators always kept in the most distant quarter from their principals 
in the lower world, through a consciousness of shame and guilt, 
because they had so horribly misrepresented the meaning of those 
authors to posterity. . . . But Aristotle was out of all patience 
with the account I gave him of Scotus and Ramus, as I presented 
them to him; and he asked them whether the rest of the tribe 
were as great dunces as themselves.* 

In the study of Being the human intellect also finds diffi- 
culties, according to Aristotle. The obstacle here is not matter 
and its basic unintelligibility, as it was in the science of Nature. 
Rather the very intelligibility of the object studied here so far 
exceeds man's nature that our intellect looking at these objects 

* Jonathan Swift, Gullivers Travels, Part III, ch. VIH. 


is " like the eyes of the owl when in the light of day." The 
Greeks in general, and Aristotle in particular, were very con- 
scious of the fact that while man has an intellect there are 
other intellects in the universe. What is more, they were quite 
thoroughly convinced that the human intellect was the weakest 
of all. It is, I think, a tribute to the Greek genius, especially 
as it was realized in Aristotle, that it was able, by capitalizing 
on its very inadequacies, in some way to overcome its inherent 
limitations. Thus Aristotle showed that a science of first phi- 
losophy could be attained if it is begun on the basis of sound 
doctrine in the study of Nature. That this meant for him not 
only a study of the very general principles but also an analysis 
which would extend to the very elements of which things are 
composed, is well brought out by the commentator on the 
Meteorology of Aristotle. 

It must be considered that the science of this book, and likewise 
of all natural science, should not be despised by man. In fact, he 
who despises it despises himself. And, although many say that 
natural science should not be prized because it has no utility in 
the study of divine things, in which the most blessed life and the 
happiness of man consists, as the Philosopher says in X Ethics, 
still these men deceive themselves. Not only the science of this 
book, but also the whole of natural science, where we consider both 
the common things and those particular and proper to each part, 
is ordered to the study of divine things. This is because we arrive 
at a knowledge of the causes through the manifest and natural 
things which are as effects. This is why the Philosopher in the 
Metaphysics begins with sensible substances and in the twelfth 
book proves the nature of separated substances through argu- 
ments drawn from astronomy.^ 

Thus, while the study of being is in some way above the 
capacities of man, it is this very difficulty which makes it 
appropriate as an ultimate end. In the Greek ideal, man's 
aspirations could only be satisfied in the contemplation of 
things which would in at least a limited way carry him beyond 
his changing, sensible existence. In the Ethics and Politics 

^Anon. in Opera Omnia of St. Thomas, In IV Meteor., lect. 1, n. 2. 


Aristotle works out a modus Vivendi by which man, or at least 
some men, could arrive at an end of this sort. In the last part 
of the Politics he speaks of a speculative life for the whole 
society whereby all citizens would participate in some way in 
this " divine " life. This life would be realized most completely 
in the philosophers. However, even these latter would attain 
only a participation in that more perfect life which exists in 
the separated intelligences. The other members of the society 
would in turn participate, to the extent possible for each, in 
the contemplative life through the philosophers. This would 
be achieved by ordering the whole social conversation to the 
intellectual life, including entertainment, education, law, and 
the arts. Aristotle conceived of music as playing a special role 
in the communication of this life. In this way, since the specu- 
lative life is itself something divine and thus beyond the 
ordinary powers of man, the ultimate happiness of man and 
of society itself would be found by bringing out that which is 
absolutely best in man's nature. 

It would not be quite precise to say that such an idea of man's 
nature and his end is rejected today. Actually, for the most 
part it is not even considered. Most men today, including a 
great many who call themselves philosophers, would be scan- 
dalized by any analysis which seriously considers " separated 
intelligences " and which would attempt, in the purely natural 
order as opposed to the supernatural, to find a place for them 
in any discussion of the end of man. As far as finding man's 
end in the life of the intellect, many would probably admit 
that it is in some way desirable but not very practical.*' 
Furthermore, if man must contemplate let the object be man. 
Such a complete rejection of the Greek ideal can be explained 
very well by carefully considering the concept of motionless 
motion and by studying the kind of philosophy or " world 
view " to which it gives rise when it is considered as the funda- 
mental idea in the study of Nature. This is not to say that 

" This would explain some of the modern confusion in discussions of the 
" liberal " arts. 


such definitions used in modern science are invalid. Quite the 
contrary, they are indispensable if we are to have modern 
scientific research. Any attempt to require the modern mathe- 
matical physicist to use the idea of motion as actus entis 
in 'potentia inquantum huiusmodi would be ridiculous. It is 
equally ridiculous to expect that a philosopher can use the 
scientist's motionless motion and arrive at a world view which 
would satisfy the highest aspirations in man's nature. In fact, 
if the expectation would in any way be taken seriously the 
result could be catastrophic. 

In the Whidden Lectures at McMaster University in 1959 '^ 
Dr. Charles De Koninck showed very clearly that speculation 
based on the definitions of modern mathematical physics does 
not lead us to a knowledge of " Nature and Nature's laws." 
Quite the contrary, we shall have a " hollow universe " devoid 
of Nature and intellect. At first glance this seems opposed 
to what was said earlier about the study of Nature being a 
necessary introduction to first philosophy. This is certainly 
knowledge about nature that the modern scientist is looking for. 
Many modern scientists are not even interested in the practical 
applications of their theories. Their aim is " pure " research 
into the laws of Nature. The use of mathematics in this 
endeavor would apparently even receive the sanction of Aris- 
totle who himself used mathematics in his more particular 
analysis of natural phenomena. Thus, to speak of this specu- 
lation as producing a " hollow universe " would seem to be 
exaggerating differences which are only minor. That this is 
not the case can be seen by examining more closely the object 
and method of the modern scientist. 

In the idea of motion given by Cassirer at the beginning, 
there is the term " place " and " change of place." It is a term 
which the modern scientist or philosopher seldom uses. Instead 
they often use the term " space " which does not mean the same 
thing at all. For Aristotle place is the innermost motionless 

'' Published as The Hollow Universe (Oxford University Press, 1960). 


boundary of what contains.^ For modern science, as Cassirer 
says, " Objective reality passes from place to change of 
place. . . ." This fundamental opposition shows up again in 
the analysis of the notion of " between," In V Physics, chapter 
3, Aristotle defines the terms " together," " apart," " in con- 
tact," " between," " in succession," " contiguous," and " con- 
tinuous." In all but one of these terms the definition given 
applies to mathematical objects as well as to things as they 
exist in Nature. The one exception is the term " between." 
" Between," he says, " is that which a changing thing, if it 
changes continuously in a natural manner, naturally reaches 
before it reaches that to which it changes last." The peculiar 
nature of this term is well recognized by the modern phi- 
losopher. Here is what Cassirer has to say about it: 

The evolution of modern mathematics has approached the ideal, 
which Leibniz established for it, with growing consciousness and 
success. Within pure geometry, this is shown most clearly in the 
development of the general concept of space. The reduction of 
metrical relation to projective realizes the thought of Leibniz that, 
before space is defined as a quantum, it must be grasped in its 
original qualitative peculiarity as an ' order of coexistence ' (ordre 
des coexistences possibles) . The chain of harmonic constructions, 
by which the points of projective space are generated, provides the 
structure of this order, which owes its value and intelligibility to 
the fact that it is not sensuously presented but is constructed by 
thought through a succession of relational structures. ... In this 
sense, modern geometry seeks to free a relation, such as the general 
relation of ' between,' which at first seems to possess an irreducible 
sensuous existence, from this restriction and to raise it to free logical 
application. The meaning of this relation must be determined by 
definite axioms of connection in abstraction from the changing 
sensuous material of its presentation; for from these axioms alone 
is gained the meaning in which it enters into mathematical 

These opposed notions of " motion," " place," and " between " 
arise from a fundamental difference in the respective notions 
of Nature and the natural. 

^Physics IV, ch. 4, 212a 20. ° Substance and Function, ed. cit., pp. 91-92. 


Aristotle, while admitting that " Nature loves to hide " and 
recognizing that knowledge in any scientific way would be very 
difficult to attain here, nevertheless held to its objective reality. 
The modern approach to Nature is well brought out by Cassirer 
in another of his works. After pointing out that modem science 
has exercised a great influence in a practical way on the modern 
world, he says: 

The real achievement of science lies elsewhere; it is not so much in 
the new objective content which science has made accessible to 
the human mind as in the new function which it attributes to the 
mind of man. The knowledge of nature does not simply lead us out 
into the world of objects; it serves rather as a medium in which 
the mind develops its own self-knowledge. . . . One world and one 
Being are replaced by an infinity of worlds constantly springing 
from the womb of becoming. . . . But the important aspect of the 
transformation does not lie in this boundless expansion, but in the 
fact that the mind now becomes aware of a new force within 
itself. . . . The highest energy and deepest truth of the mind do not 
consist in going out into the infinite, but in the mind's maintaining 
itself against the infinite and proving in its pure unity equal to 
the infinity of being. 


If all that is intended here is to show that man's intellect is 
capable of producing an infinity by which it can equal and 
thus in some way overcome the infinity in the processes of 
Nature, there could be no dispute about this. That this is going 
to be used to find out how things are in Nature is easily seen 
by following Cassirer's arguments in the remainder of his book. 
He holds that: 

Both (nature and knowledge) must be understood in terms of their 
own essence, and this is no dark, mysterious ' something,' impene- 
trable to intellect; this essence consists rather in principles which 
are perfectly accessible to the mind since the mind is able to educe 
them from itself and to enunciate them systematically.^^ 

Thus where Aristotle finds something " dark " and " myster- 
ious " in Nature which escapes the power of man's intellect, 

^° Philosophy of the Enlightenment (Princeton: Univ. Press, 1951), p. 37. 
" Ibid., p. 45. 


the modern philosophers and scientists who follow Cassirer 
will see Nature as " perfectly accessible to the mind." 

In his study of Nature and Nature's ways Aristotle often 
uses the principle that " art imitates Nature." In this way 
he was able to discern, in an analogous way, some of the pro- 
cesses by which Nature achieves her end. In fact, even the 
notion that Nature operates for an end is arrived at by this 
reasoning in // Physics. Many moderns, if they are aware of 
this method in his works, often characterize it as " anthropo- 
morphic " and reject it out of hand. This is indeed curious 
because if we compare the results obtained by the " anthropo- 
morphic " method of Aristotle with those of the modern phi- 
losophers for whom Nature is an open book, we should expect 
that the former would find its end in man while the latter would 
have some extrinsic focus. That this is not the case, as least 
for Aristotle, was shown earlier when it was pointed out that 
for him man would have an end in something divine. Man's 
happiness was to be found in the contemplation of that divine 
principle which is the source of all being. When those for whom 
nature is " perfectly accessible to the mind " turn their atten- 
tion to questions of ethics and politics they use notions 
indicating that man is supreme in his determination of his 
goal and that society exists only by some sort of a " social 
contact." With respect to this last notion Fr. Charles McCoy 
has said: 

It may seem curious that the idea of contract be employed to 
express a natural relation. However, the secret of its appropriateness 
is to be found in the fact that the naturalism of this political phi- 
losophy demanded an innate social propensity which could be raised 
to the level of a sufficient explanation of social groupings in such 
a way as to leave no law to be observed which in any sense is 
imposed from without, but to leave only a ' natural law ' which the 
moral subject gives to itself. And nothing is better designed to 
express this kind of naturalness than the idea of contract.^- 

""The Turning Point in Political Philosophy, Avi. Pol. Sc. Rev., XLIV (1950), 
678 ff. 


Thus where Aristotle arrived at a society where man is ordered 
to speculation of things which are above man, the moderns 
place man in a society or " social grouping " which has no law 
" which is in any sense imposed from without." The end of 
man in this latter society will be not the contemplation of the 
world, but will consist rather in remaking the world according 
to the finite capacity of his own intellect. Or, as someone has 
said, " The purpose of philosophy is not to explain the world 
but to change it." 

It seems, therefore, that how we study Nature and how we 
define motion and the ideas used in that study will make an 
important difference in our conception of man and his role in 
the universe. The wordy and confused notion of motion which 
was used by Aristotle in his analysis enabled him to arrive at 
a universe which is open to something higher than man, while 
the clear concept of the motionless motion of modern science 
ends in a " hollow universe," closed about the small and finite 
intellect of man himself. 

Roman A. Kocourek 

College of St. Thomas, 

St. Paul, Minnesota. 


IT has been suggested that for our age the particular riddle 
the Sphinx has set is that of time. Many of the per- 
ennial problems which torment the mind of man are more 
or less involved with time; — to cite but one example: the 
problem of man's free will and God's knowledge of future con- 
tingent events. Though time is the measure of our duration and 
of our activities, it is nevertheless far from clear. An object 
is intelligible only in so far as it is in act. Upon investigation, 
however, time seems to be more potential than actual. The 
past is no longer, the future is not yet, and the only actuality, 
the " now " is not time. 

Modern emphasis on physics has again brought into promi- 
nence this problem of time, but mathematical physics, pre- 
sumably concerned with time, actually deals with its measure- 
ment rather than with its nature. This neglect by physicists 
of the nature of time goes back to Newton who wrote: " I 
do not define time, space, place, and motion, as being well 
known to all." ^ 

The basic text for an understanding of the nature of time is 
Aristotle's Physics, Book Four, Chapter Ten, and the com- 
mentary on it by Saint Thomas Aquinas. Yet even his study 
bristles with difficulties. One of these I have chosen as the 
subject of this paper. Aristotle defines time as "... the 
number of movement according to a before and an after." ^ 
Thus he seems to put the formality of time in number. Now, 
if time is a number and number depends on some mind, it 
would seem that if there were no mind there could be no num- 
bering of motion and hence no time. Aristotle recognized this 
problem as a valid one: " Whether if soul did not exist time 

^ Isaac Newton, Mathematical Principles of Natural Philosophy, Definitions: 
Scholium, trans, by Florian Cajori (Univ. of California Press, 1947), p. 6. 
'Aristotle, Physics, TV, c. 11, 219bl-2. 



would exist or not is a question that may fairly be asked, for 
if there cannot be someone to count, there cannot be anything 
that can be counted, so that evidently there cannot be number; 
for number is either what has been or what can be counted." ^ 

Would we, following the Aristotelian doctrine find ourselves 
forced to hold that prior to the creation of man (or at least 
of a higher animal with memory and hence a knowledge of 
time) there was no time and all things were instantaneous? 
We are cautioned against drawing too hasty a conclusion how- 
ever by these words of Aristotle: "... it is evident that every 
change and everything that moves is in time." * Certainly prior 
to the creation of man things changed and moved, so in Aris- 
totle's own words they were " in time." Such a conclusion 
however seems to contradict his position that if there were no 
soul there would be no time. 

There is some doubt however that this is truly Aristotle's 
position. The above translation is based on a text of William 
of Moerbeke. Aristotle's own text is an uncertain guide because 
it is in such poor condition and because the critical study of it 
is rendered uncertain in that the introduction of a period or a 
comma, missing in the text, would change the meaning. After 
a brief survey of the history of the problem it will be the pur- 
pose of this paper to show that it is more in keeping with the 
thought of Aristotle to hold that time is formally a being of 
nature and not of reason. True, the greater number of phi- 
losophers think that time would not be if there were no soul. 
We shall try to show that it is the thought of Aristotle and of 
St. Thomas that time is an ens naturae and not an ens rationis, 
and to exist even if there were no soul; not indeed perfect in 
being, but rather imperfect, as in motion. 

An investigation of the history of the question shows that 
without doubt Plato believed time to be real: 

Now the nature of the ideal being was everlasting, but to bestow 
this attribute in its fulness upon a creature was impossible. Where- 

' Ibid., IV, c. 14, 223a21-25. 
* Ibid., IV, c. 14, 223a-14-15. 


fore he resolved to have a moving image of eternity, and when he 
set in order the heaven, he made this image eternal but moving 
according to number, while eternity itself rests in unity; and this 
image we call time.^ 

Here Plato identifies time with the motion of the spheres, hence 
a being of nature. Even without an intelligence time would be 
a reality because it is nothing more than the actual movement 
of the spheres. It was precisely on this point, that is, the identi- 
fication of time and movement, that Aristotle criticized Plato 
asking how, if time and movement were the same, we could 
speak of movement being fast or slow. 

Aristotle denied their identity, yet admitted that time and 
movement were always found together. His conclusion was 
that time was the number of movement according to a before 
and after. It is the reality of this number that we are investi- 
gating. As mentioned above, Aristotle's position is doubtful 
and because of the uncertain condition of his text we cannot 
look to him for a satisfactory solution of the problem. His 
text quoted at the beginning, based on William of Moerbeke, 
would seem to put time in the mind and only movement in 
nature. The Latin version of the Arabic also tends to support 
this interpretation. Moreover the renaissance texts render this 
passage in the sense that if the soul is not, there is no time but 
only motion which is numerable. 

In spite of these numerous indications that Aristotle meant 
that if there were no soul there would be no time, it seems that 
his thought is otherwise and in fact seems to require that time 
be in nature even without soul. In support of this thought we 
call attention to the fact that for Aristotle number in the defini- 
tion of time is taken as " numbered " number, (not " number- 
ing " number) , and so a being of nature. Likewise Aristotle 
reduces time to quantity, and places " when " as an accident 
caused by time. 

Among philosophers from Aristotle to Saint Thomas we find 

^ Plato, Timaeus, 37 D, trans, by Benjamin Jowett (New York, 1892), III, 
p. 456. 


almost all holding time to be constituted in its formality by the 

Galen (129-199 A. D.) taught that time was the sucession 
of our perceptions as known. He then places time as a mental 
being which does not exist if there is no soul which perceives. ° 

Plotinus (205-270 A. D.) defines time as the life of the soul 
in movement. It is not to be conceived as outside of soul.^ 

An obscure Boetius on the other hand, thinks nothing pre- 
vents number from being without that which numbers. Thus 
time can exist without soul. Perhaps his position is due to a 
strong Platonic influence.^ 

Themistius (c. 320-390 A. D.) finds fault with Boetius. 
What can be numbered and numbering are correlative; one 
cannot be without the other. If there is no one to number there 
is no numbering and so if there is no soul to number there is no 

Saint Augustine (354-430 A. D.) shows delightful humility 
in acknowledging his ignorance of time: " If no one asks me, 
I know; if I want to explain it to a questioner, I do not 
know." ^° Yet after much analysis he concludes that it is the 
mind which gives time: " It is in you, my mind, that I 
measure time . . . what I measure is the impress produced in 
you by things as they pass and abiding in you when they have 
passed: and it is present." ^^ 

In the sixth century Simplicius expressed his disagreement 
with the thought of Boetius, holding that although the numer- 
able can exist without soul as does movement, yet number and 
hence time can in no way exist without soul. Only movement 
exists in nature, for to consider the prior and posterior belongs 

" Albertus Magnus, Lib. IV Phydcorum, tr. HI, cap. 3, ed. Borgnet, IH, pp. 

'G. H. Turnbull, The Essence of Plotinus (New York, 1934), p. 107. 

^ For this point I am indebted to the unpublished notes of the Rev. J. A. 
Weisheipl, O. P. 

*See note 8. 

^"St. Augustine, Confessions, Book XI, chap. 14 (New York, 1943), p. 271. 

" Ibid., Book XI, chap. 32, p. 283. 


to mind numbering. He therefore concluded that time is a 
being of reason and not of nature/^ 

Averroes (1126-1198 A.D.) , following the Arabic version of 
Aristotle referred to in the beginning of this article, considered 
that the prior and posterior in the definition of Aristotle exist 
only potentially if there is no soul. They are actual if there is 
a soul. If numbered in act there is time in act but, if there is 
no soul, time is only potential. Time has no " to be " in nature 
except in potency. Time is in act only in the operation of the 
mind numbering, whence there is no time formally except in 
so far as the mind numbers according to a prior and posterior. 
This distinction was followed by all the Averroists from the 
thirteenth to the sixteenth century as well as by Saint Thomas 
in his commentary on Book One and Two of the Seiitences.^^ 

In spite of the almost complete unanimity of his predecessors 
on this question Saint Albert showed his great originality, in- 
sisting that the nature of time was something real: ". . . et 
ideo fluxus ille realis erit realiter tevipus." " In developing his 
thought St. Albert said that, to number, three things were 
required: numbered matter, formal number, and the soul effi- 
ciently (not formally) counting. Even if there is no soul, yet 
there is number according to formal being and according to 
numbered number. Now that by which a thing is numbered is 
twofold: that by which it is numbered efficiently (the soul) and 
that by which it is numbered formally. As soon as we have 
multiplicity, discreteness, otherness, we have formal number 
and so "... if there is no soul number is not just potential, 
but it exists according to the habitual form of discreteness of 
numbered things." ^^ Without a doubt St. Albert thought time, 
the number of motion according to a prior and posterior, existed 
formally in nature whether or no there was a soul. 

^~ See note 8. 

" St. Thomas, I Sent., dist. 19, q. 2, a. 1; q. 5, a. 1; dist. 37, q. 4, a. 3; II Sent., 
dist. 12, q. 5, a. 2. 

^* Albertus Magnus, Lib. IV Physicorum, tr. Ill, cap. 16, ed. Borgnet, III, 
p. S40a. 

^^Ibid., pp. 339b-340a. 


The young Thomas of the Sentences thought time dependent 
on the mind: "... the notion of time is in some way com- 
pleted by the action of the soul counting . . ." ^*^ Yet in his 
commentary on the Physics he adopts a quite different position. 
Whether this change was due to the influence of St. Albert we 
do not know. In the commentary on Aristotle's treatment of 
this problem Saint Thomas says: ". . . it is necessary to say 
either that there is no time if there is no soul or to say more 
truly that without the soul time is a kind of being {utcumque 
ens) ." ^^ In explaining this St. Thomas says that if there is 
movement without a mind, so too is there time because the 
prior and the posterior in motion are, and this is just what time 
is, namely the prior and posterior in motion in so far as they 
are numerable. Realizing that it was this " numerable " which 
seemed to demand a soul St. Thomas clarifies its meaning: 
enumeration depends on a mind, but the " to be " of numbered 
things does not depend on mind (unless it be the cause of 
things, such as the divine intellect) . As there can be sensibles 
without sense existing, so the numerable and number can exist 
without numbering.^^ 

Moreover, Saint Thomas questions the validity of Aristotle's 
analogy comparing number and the sensible, i. e. that just as if 
there is no one to sense there is no sensible so if there is no one 
to number there is no number. Commenting on this he says 
that it is forte conditionalis: 

For if there is a sensible, it can be sensed; and if it can be sensed 
there can be someone sensing. But it does not follow that if there 
is a sensible that there is someone sensing. It also follows that if 
there is something numerable there can be someone numbering 
. . . but it does not follow that if there is no one numbering that 
there is not anything numerable.^^ 

To understand how Saint Thomas can hold there is a number 

" St. Thomas, II Sent., dist. 12, q. 5, a. 2. 
" St. Thomas, In IV Phys., lect. 23, n. 5. 
" Ibid. 
" Ibid. 


without someone numbering we must look to the Aristotelian 
concept of number: 

All plurality is a consequence of division. Now division is twofold: 
one is material, and is division of the continuous; from this results 
number, which is a species of quantity .-'^ 

Number is quantity resulting from division in matter; plur- 
ality, discreteness. The plurality in movement, which is time, is 
produced by the present instant actually dividing the move- 
ment according to a before and after — into the past and future 
which are its parts. This instant in dividing is always " other " 
according to the succession of time and movement. 

Time is not number with which we count, but the number of things 
which are counted, and this according as it occurs before or after 
is always different, for the ' nows ' are different.-^ 

From this otherness there results plurality which is time and 
this plurality is present whether or not there is soul to count it. 

The nunc, the instant which divides, is something other than 
the factum esse of movement, — that successive actualization of 
potency which is movement; yet to each factum esse there is a 
corresponding nunc. Plato's error was to identify the two. 

One might ask how, if time is continuous quantity it can be 
defined as number, which is discrete quantity."" In its formality 
it is discrete, it is the " now " dividing and in so far as it is 
dividing the " now " is always different. Yet the " now " is 
also a boundary — the termination of the past and the principle 
of the future and thus realizes the definition of a continuum. 
According to Aristotle: "... the now also is in one way a 
potential dividing of time, in another the termination of both 
parts, and their unity." ^^ 

Like movement, time has a fluid existence; only the instant, 
the division of time, actually exists. Thus Aristotle says of it 

^°St. Thomas, Sum. Theol., I, q. 30, a. 3. 
^^ Aristotle, op. cit., IV, c. 12, 220b8-10. 
^^ Ibid. 
^^Ihid., IV, c. 12, 222al7-19. 


that it exists " barely and in an obscure way " ^* and Saint 
Thomas speaks of it as an " utcuTnque ens," ^^ a kind of being, 
an imperfect being. 

Its perfection, the existence of its parts, past and future, is 
not realized without the operation of the soul. The power of 
retaining the past in memory and of looking ahead to the 
future requires an intellect. "... the totality itself of time is 
obtained through the ordination of the soul numbering the 
prior and posterior in motion . . ." ^" 

It is this aspect which was viewed by the authors cited at 
the beginning of this article. What they failed to see was the 
claim time had to some real being in the actuality of the instant 
which continuously unites the past and future since it is the 
term of the past and principle of the future. 

Sister M. Jocelyn, O.P. 

Rosary College 

River Forest, Illinois 

=* Ibid., TV, c. 10, 217b32-33. 

-^ St. Thomas, In IV Phys., lect. 23, n. 5. 

=^« Ibid. 

Part Four 



MOST biologists today would agree with George Gaylord 
Simpson that, " the factual truth of evolution is taken 
as established and the enquiry goes on from there." ^ 
Yet as Andre Lalande has shown, there are paradoxes in our 
commitment to the theory of evolution,^ and one may face 
them without necessarily opposing the theory itself. One of 
these apparent antinomies is raised by the law of entropy, the 
second law of thermodynamics. Since evolution, at least in 
the living world, is regarded by probably all its advocates as 
an uphill thrust, how can it co-exist with entropy, the so-called 
downhill tendency of the cosmos.? Many observers take the 
view expressed by Norbert Wiener that evolution or entropy 
is only a temporary phenomenon and that in the end entropy 
will exert its universal dominion to end all life processes ^ in 
our universe. But even within scientific cosmology, the solution 
can hardly be so simple. For it has been customary to speak 
of the past and continuing evolution even of the inorganic 
world. Thus in a paper delivered at the University of Chicago's 
Darwin Celebration and significantly entitled, " On the Evi- 
dences of Inorganic Evolution," Harlow Shapley intended " to 
suggest that terrestrial biological evolution is but a rather small 
affair, a complicated sideshow, in the large evolutionary opera- 
tion that the astronomer glimpses." * Has the term " evolu- 
tion," as though it were not already ambiguous enough, been 
extended to cover all the events believed governed by the 
second law of thermodynamics? If this is so and if evolution 

* The Meaning of Evolution (New York, 1951) p. 11. 
^ Les illusions evolutionnistes (Paris, 1931) . 

* The Human Use of Human Beings (New York, 1954) pp. 40-47. L. Whyte 
regards entropy in the title of his book as The Unitary Principle in Biology and 
Physics (New York, 1949) . 

* The Evolution of Life, Vol. 1 of Evolution after Darwin, ed. S. Tax (Chicago, 
1960) p. 23. 



thus becomes a universal cosmic tendency, what becomes of 
entropy and of the opinion that " it is difficult to conceive of 
circumstances that would invalidate the statistical proof of 
the Second Law "? ° Obviously, the paradox suggested by La- 
lande remains unresolved and probably exists in more pointed 
form than the cosmologies of his own day would have urged. 
If the apparent antimony between evolution and entropy is 
to be frankly faced, there is clear need for carefully tracing 
each of the two concepts to their empirical evidence. 

Despite all of its obscurity, entropy is understood well 
enough to be embodied in mathematical equations. Yet evolu- 
tion, even apart from the greater attention paid to it in the 
popular press, is probably easier to illustrate at a physical level. 
All natural change, e. g., the development of an oak from an 
acorn, a frog from a tadpole, and flesh and bone from food 
materials, is in a loose sense of the term an evolutionary process 
in which the better comes into existence.'' Because progress 
is more intelligible in the physical world than the down-hill 
drive of entropy, evolution may be more profitably discussed 


Like other leading ideas in modern science, e. g., the helio- 
centric theory in physics or the atomic theory in chemistry, 
the theory of evolution has analogues going back as far as 
the Greeks, for instance Anaxagora? 7 and appearing in Chris- 
tian writers like St. Augustine with his " seminal reasons." ^ 
Yet the theory of evolution, as we now know it, together with 
the empirical evidence adduced in its favor, is an original 
achievement of modern science. Collingwood, despite his fre- 
quent exaggerations, had an insight in taking the post-New- 
tonian conception of matter to be nature as history.^ Even 

" C. F. von Weizsacker, The History of Nature (Chicago, 1949) p. 57. 
' Sum. cont. Gent., Ill, cc. 3, 4. 

'' Cf. Aristotle's report, Phys., I, 4, 187a20 fF.; the best secondary source on 
Anaxagoras is F. Cleve's, The Philosophy of Anaxagoras (New York, 1949) . 
* Cf. for instance, L.-M. Otis, La doctrine de I'evolution (Montreal, 1950) . 
® The Idea of Nature (New York, 1960) pp. 9 ff.; 133 fl. 


in this modern and history-minded period, it is a well known 
fact that the first evolutionist was not Darwin," In the 
writings of Buffon, Kant, and Laplace there are theories of the 
evolution of the solar system. Buffon, in his monumental work, 
Epochs of Nature (1778) ^^ theorized that the solar system 
originated from a collision between a comet and the sun, and 
he proposed a whole chronology concerning the cooling of the 
earth to its present temperature. Kant held to a nebular 
hypothesis in which an original cosmic dust, subjected to the 
forces of attraction and repulsion, gave rise to the solar system 
as we now know it.^- In 1796, Laplace brought the weight of 
his authority to the nebular theory and reduced the distribution 
of momentum among the apparently evolving planets to New- 
tonian laws. In the spirit of Shapley's remarks, already quoted, 
the notion of biological evolution when it finally caught on 
through Darwin's research and writing, could already be set 
within a larger evolutionary framework. In our own century, 
the study of the galaxy and the discovery, through more power- 
ful telescopes, that there are other galaxies besides our own — 
in fact, billions of them with the most distant believed to be 
six billion light years away — led to the theory that there are 
countless " island universes " and extended the problem of 
cosmology from a study of the solar system to a concern with 
the laws governing the " arrangement, past, present, and future 
of the galaxies in the universe." " 

As we look at the cold facts, there is a whole array of evidence 
that our universe was not always as it now is. There is, for 
instance, radioactivity, the elongation of the moon, the apparent 
succession of living forms as shown by the geological record, 
slight but none the less real irregularities in planetary move- 

" Cf. B. Glass, et al, eds., Forerunners of Darwin 17^5-1859 (Baltimore, 1959) . 

^^ Des epoques de la nature, ed. L. Picard (Paris, 1894), first published in 1778. 

^^ Cf. W. Hastie, Kant's Cosmogony as in his Essay on the Retardation of the 
Rotation of the Earth and his Natural History and Theory of the Heavens (Glasgow, 
1900) . 

^^ H. Bondi, "Astronomy and Cosmology," in What is Science? ed. J. Newman 
(New York, 1955) p. 66. 


ment ^^ which would have an appreciable additive effect over 
a long period of time. But perhaps one of the most crucial, 
because the most cosmic, evidences in this regard is the phe- 
nomenon of the expanding universe. 

To approach the evidence for an expanding universe, it might 
be initially observed that the distances of the nearer stars, 
with respect to a terrestrial observer, can be determined from 
the various angles at which their light strikes the earth in the 
course of the earth's annual movement about the sun. From 
the angles involved, distances can be computed by simple 
trigonometry. But for more distant objects this change of 
angle (parallax effect) is so small that a different method 
must be used, and fortunately another tool is at hand. This 
tool is furnished by the stars called Cepheid variables which 
undergo periodic changes in their visible radiation, rapidly 
increasing in luminosity and then fading back into their original 
brightness. A correlation exists between the brightness of a 
star and its period of pulsation; the longer the period the 
brighter the star. The phenomenon of Cepheid variables, 
named from the star Delta Cephei, the first laiown example 
of such a pulsating star, enables us to know the absolute 
luminosity of the star in question, and when this is compared 
with apparent brightness, the distance of a Cepheid variable 
can be determined. ^^ 

By invoking the periodic law for Cepheid variables, Edwin 
P. Hubble showed that distant nebulae, such as the Andromeda 
nebula, once believed to be part of the Milky Way, are actually 
distant galaxies ^^ — in the case of Andromeda, two million light 
years away. Moreover, this challenge to the older conception 
of a nebula led to the view that the universe is expanding. 

^* Although this irregularity in perihelion is discernible in the case of Mercury 
and is explained by relativity mechanics, it is believed to exist, in a degree too 
small to be observed, in the case of the other planets. 

^^ An explanation of Cepheid variables will be found in A. Eddington, The Ex- 
panding Universe (Ann Arbor, 1958) pp. 7-8. 

^"For Bubble's work, see his The Realm of the Nebulae (Oxford, 1936). 


As in the case of measuring cosmic distances, it may be 
profitable to make a brief summary of the method employed 
to reach the verdict of an expanding universe. This method 
makes use of an analogy between light and sound. When, 
for instance, a fast moving train approaches a by-stander near 
the track there is a rise in the whistle's pitch and, as the train 
recedes, a noticeable lowering of pitch. The physical reason 
given for this phenomenon is the addition and subtraction of 
frequency or wave-length because of the moving sound-source. 
As the train approaches, its own motion is added to that of 
the sound thus making for a shorter wave-length and higher 
pitch of the whistle; as the train recedes, there is a net 
lengthening of the sound wave and hence a lower frequency 
or lower pitch. 

Something similar is believed to happen in the case of light 
waves reaching the earth from distant galaxies. The wave- 
length is shifted toward the red or longer wave lengths of the 
visible spectrum, indicating in the italicized words of George 
Gamow " that " the entire space of the universe populated by 
billions of galaxies, is in a state of rapid expansion, with all 
of its members flying from each other at high speeds." 

The expansion of the universe was proposed as a principle of 
cosmogony by Abbe Georges Lemaitre who postulated a " pri- 
meval atom " in which all the elementary particles of matter 
were densely packed together. Lemaitre regards this Ur-atom 
as an isotope of a neutron.^^ Gamow, who is in sympathy with 
this type of theory, has written: 

The nearest guess is that the overall density of the universe at the 
time was comparable to that of a nuclear fluid tiny droplets of 
which form the nuclei of various atoms. This would make the 
original pre-expansion density of the universe a hundred thousand 
billion times greater than the density of water; each cubic centi- 
meter contained at that time a hundred million tons of matter." 


The Creation of the Universe (New York, 1952) , p. 23. 
The Primeval Atom (New York, 1950) p. 142. 
Op. cit., p. 19. 


Von Welzsiicker who closely resembles Lemaitre and Gamow 
in their cosmologies, speaks of a compressed primeval gas.^° 
Lemaitre, tracing out the history of his exploding primeval 
atom, has computed that if the 

fragmentation occurred in equal pieces, two hundred and sixty 
generations would have been needed to reach the present pulveriza- 
tion of matter into our poor little atoms, almost too small to be 
broken again.^^ 

Summing up his theory on how the primeval atom expanded 
into our present universe, Lemaitre with a flair for the poetic 

The evolution of the world can be compared to a display of fire- 
works that has just ended: some few red wisps, ashes, and smoke. 
Standing on a well-chilled cinder, we see the slow fading of the 
suns, and we try to recall the vanished brilliance of the origin of 

All of these theories, as the opening phrase in the preceding 
quotation reminds us, are evolutionary. Gamow speaks of the 
original Big Squeeze. Such a type of theory points to the 
hypothesis for a beginning of some sort in the history of the 
cosmos we now know. 

The beginning theory is regarded by Sir Edmund Whittaker 
as an argument for Creation, even for Creation in time."^ 
E. A. Milne spoke of a t = and held likewise to a temporal 
beginning of our cosmos.-* With such a conclusion, however, 
and as both of these experts would admit, we pass beyond the 
frontiers of science in the narrow modern sense of the term 
and enter a meta-scientific region. 

The more scientifically orthodox supporters of a beginning 
theory usually do not range beyond the view that there was 
some primeval matrix — an atom, a nuclear fluid, a compressed 
gas — densely packed togther; from this original stuff our uni- 

*" Op. cit., p. 81. 

" Op. cit., p. 78. 

" Ibid. 

'^'^ Space and Spirit (London, 1946) pp. 118-121. 

"'^ Modem Cosmology and the Christian Idea oj God (Oxford, 1952) p. 58. 


verse is said to have arisen by explosion or expansion. Using 
a law projected on theoretical grounds by Lemaitre and con- 
firmed by Hubble, that the recession velocity of a nebula is 
proportional to its distance away, the date of the Big Squeeze 
can be set at about 10^*^ years,"^ although, as Lemaitre argues, 
the velocity of recession may not always have been uniform.'® 

Like the other current cosmological theory to be mentioned 
later, the advocates of a primeval matrix account for the 
known abundances of various elements and must render an 
account of the relative numbers of heavier and lighter elements 
in various places throughout the cosmos. The universe as a 
whole is estimated to be about 55 per cent hydrogen, 44 per 
cent helium, and one percent of the heavier elements. 

In the language of Lyttleton: 

Hydrogen is to be regarded as constituting the primitive material 
of the universe, from which all other elements are somehow formed. 
This conclusion has a highly important implication, because it 
means that in its present state neither the sun nor any similar star 
can produce the heavy elements that are essential for the formation 
of the planets, such as our Earth, in which as we have seen it is the 
heavy elements that are abundant and the hydrogen by comparison 
exceedingly rare.^'^ 

It will not be fruitful, for purposes of this paper, to outline 
the theories, such as supernovation,^^ designed to explain the 
formation and distribution of the heavier elements.-^ It is 
important only to note that this is termed an evolutionary 
process. Shapley writes that " the evolution of matter appears 
to be a synthesis inside the stars of the heavy elements out 
of hydrogen, which is accepted as the primordial, abundant, 
and simple No. 1 element."^" Then too, the whole process 


^® Shapley, art. cit., p. 32. 
"* Op. cit., p. 79. 


R. Lyttleton, The Modem Universe (New York, 1956) p. 137. 

Cf. H. Bondi, The Universe at Large (New York, 1960) pp. 52-55. 
^*E. Findlay-Freundlich, Cosmology (Chicago, 1951) p. 50. 
'° Shapley, art. cit., p. 35. 
^^ In all the discussions of evolution throughout this paper, it is to be understood 


may be regarded as evolutionary for the additional reason that, 
as manifested by the constitution and history of our earth,^^ 
it leads to the appearance and survival of the self-replicating 
macromolecules which are living things. Surely this process is 
a build-up; it is progressive; it is an evolution, and according 
to biologists, it leads, after living things finally appear, to 
higher and higher species. It is proper to speak of the Big 
Bang theory,^^ held by Lemaitre, Gamow, and von Weizsaecker, 
as an evolutionary account. 

Before considering entropy, the down-hill drive in our uni- 
verse, mention must be made of the so-called steady-state 
theory which has grown up in Great Britain and is held by 
such cosmologists as Gold,^* Bondi,^^ Hoyle,^'' and Lyttleton.^^ 
According to this hypothesis, the universe never had a begin- 
ning and therefore did not have to undergo the differentiation 
from a primeval atom. The work done in the never-ending 
expansion of the universe is accounted for by a continuous 
creation. Hydrogen, the " No. 1 element " in the cosmos, is 
created at the rate of one atom per litre of volume every billion 
years. This is Bondi's figure.^^ From hydrogen, other and 
heavier elements are then built up. Bondi further states: 

The expansion of the universe, which can be inferred either from 
thermodynamics or from astronomical observations, would seem to 

that, by the laws of logic, we are dealing only with hypothesis — the best positive 
account we can so far give of how things come to be as they are. We are not dealing 
with fact, as in the proposition, " Man is a rational animal." Yielding to current 
conventions, we have simply used the term " evolution " without grammatically men- 
tioning the logical qualification to be put upon it as only a very strong hypothesis. 

^' Cf. A. Holmes, The Age of the Earth (London, 1937) ; H. Jeffreys, The Earth 
(Cambridge, Eng., 1952) ; E. Bullard, The Interior of the Earth (Chicago, 1953) . 

'^^ "After the full complement of the atomic species had been formed during the 
first hour of expansion, nothing of particular interest happened for the next 30 
million years." Gamow, op. cit., p. 74. 
p. 142. 

'* Cf. E. Mascall, Christian Theology and Natural Science (New York, 1956) 

^^ H. Bondi, Cosmology (Cambridge, Eng., 1952) . 

'* F. Hoyle, The Nature of the Universe (New York, 1950) . 

*' Op. cit. 

'^Cosmology, p. 143. 


lead to a thinning out of material. By the perfect cosmological 
principle [by which Bondi means, roughly, the uniformity of nature] 
the average density of matter must not undergo a secular change. 
There is only one way in which a constant density can be com- 
patible with a motion of expansion, and that is by the continual 
creation of matter.^^ 

The continuous-creation theory must not be confused with 
pair-formation where an electron and a positron are " created," 
as the physicist says, from electric field.*'' And above all, the 
continuous-creation, in view of its proponents, must not be 
regarded as requiring a Creator. As Hoyle writes, " The most 
obvious question to ask about continuous creation is this: 
Where does the created material come from.'^ It does not come 
from anywhere. Material simply appears — it is created." ^^ 
Lyttleton affirms that the appearance of newly created hydro- 
gen " is a property of space itself. . . ." *^ 

By virtue of their theory of continuous creation, the steady- 
state theorists in a sense would have to deny the process of 
evolution we have described above or at least to qualify their 
interpretation of evolutionary cosmogony. For them, the uni- 
verse always was and always will be. As old galaxies recede 
from view, new ones are formed. The work for these processes, 
demanded by the classic formulation of energy laws, is 
accounted for by the continuous creation of the " No. 1 ele- 
ment." In this manner, the steady-state theorists believe they 
can overcome the so-called " beginning " which appears so 
mysterious within the usual canons of scientific investigation. 
But as Milton Munitz has ably argued, the steady-state theory 
does not eradicate the apparently mysterious principles from 
cosmogony. It simply replaces one enigma w^ith another.*^ For 
the continuous creation of new matter is just as mysterious 

«* Ibid. 

^° This is explained by Einstein's E=mc- and does not depart from the principle 
of conservation of mass-energy. 

" Op. cit., p. 123. 

"Op. cit., p. 201. 

*^ " Creation and the ' New ' Cosmology," British Journal of the Philosophy of 
Science, V (1954), 32 ff. 


to the logic usually employed by science as the hypothesis 
of a " beginning." 

A third theory of the origin of the world, based upon the 
notion of a " pulsating universe," may be in the offing.** But 
the two leading cosmologies actually in vogue are the ones 
briefly sketched above, and our concern in this paper will be 
confined to them. Our interest, of course, is their bearing upon 

Despite the comparison by Munitz, the steady-state theory 
has the ring of the gratuitous about it and seems to require 
ad hoc amendments to the usual formulation of the laws of 
thermodynamics. Gamow even believes that there is experi- 
mental argument against the steady-state theory in the evidence 
of Stebbins and Whitford ^^ showing at least some of the 
galaxies to have such a long red shift that their color cannot 
be accounted for by the Doppler effect previously described. 
The reddening is so pronounced that it might seem necessary 
to explain it by inter-galactic dust which scatters light in much 
the same way that the sunset is reddened by our terrestrial 
atmosphere. But this hypothesis would require more dust 
than can be admitted on other grounds. A tenable hypothesis 
seems to be that observed galaxies, in their youth by com- 
parison to their mature period, contained a greater abundance 
of a special type of star (Red Giants) , and if this is the case, 
it is necessary either to accept a developmental view or to patch 
another ad hoc assumption on the steady-state theory to make 
it tenable. 

But even if the steady-state cosmology be entertained as a 
possibility in the light of all the evidence which our unaided 
reason can marshal,**^ it still bears witness to evolution. The 
steady-state cosmologists accept the view that the universe is 

** Finley-Fieundlich, op. eit., p. 56; Shapley, art. cit., p. 33. 

^^ Gamow, op. cit., pp. 33-34. 

*" This conditional acceptance is made in the same spirit that St. Thomas attaches 
to Aristotle's view of an eternal world. As a starting point for the proof for a 
Prime Mover it is the "more difficult" assumption (De Pot., q. Ill, a. 17), and if 
within it, the proof can stand up, it can certainly stand up on a beginning theory. 


expanding. They hold to the formation of heavier elements 
out of hydrogen as one of the general principles for matter's 
development. They re-interpret the evolutionary movement so 
that it is endless in both directions and so that any deficit 
caused by " evolution " is continually being overcome. But 
they do recognize some kind of cosmic advance, and hence our 
later assessment of evolution will include the evolutionary 
aspect of the steady-state theory itself. 

Our only point so far is that the two leading contemporary 
cosmologies are theories of evolution. 


The concept of evolution, an up-hill tendency, forms one part 
of the paradox in modern cosmology; the other is the law of 
entropy, the second law of thermodynamics. This law was 
actually stated by Carnot in 1824 and hence it is also called 
the Carnot principle. Although still invoking the caloric theory, 
Carnot likened a heat engine to a hydraulic system, say a mill 
wheel. The gist of Carnot's argument did not become explicit 
until subsequently, and so his views will be here summarized 
in the later and more polished form taken from other pens.*^ 
In the case of the hydraulic engine, to restore a quantity of 
water to an earlier position at the top of the wheel, energy 
must be supplied to the wheel from some source besides the 
quantity of the water in question. Simplifying the analogy still 
further, let us imagine a source of water and a sink below it. 
To drive the water from the sink back to the source, the water 
and the sink are not enough; we have to supply energy from 
the outside, for instance with a pump or a heater. Were it 
possible, from within any closed mechanical system, to restore 
the system to its initial state after a disturbance of this original 
set of conditions, a perpetual motion machine could be con- 
structed, and one of the ways of phrasing the Carnot principle 

*'' Carnot's principle is discussed in P. Bridgman, The Nature of Thermodynamics 
(Cambridge, Mass., 1950) chap. 2. 


is that it simply rules out a perpetual motion machine of 
this type, 

Carnot likened the behavior of a water system to the flow 
of heat, but the full meaning of his achievement came only 
when Clausius *^ formulated the Carnot principle to read that 
heat, of itself, cannot pass from a cooler body to a hotter one — 
any more than the water in our analogy can flow " uphill." 
But what did Clausius mean by " entropy," — the term he 
introduced to clarify and generalize the second law of thermo- 
dynamics which, in the reading he gave it, simply states: the 
entropy in any closed mechanical system always tends to 
increase to the maximum? 

The strictly mathematical physicist will want to regard 
entropy as " a variable of state " as as " a function of state." 
But this definition, valid as it is within a strictly mathematical 
physics,*^ cannot supply the fundamental physical meaning we 
would like to find. Clausius himself wrote that if we want to 
assign to entropy a proper name, we can 

say of it that it is the transjormation content of the body, in the 
same way that we can say of the quantity TJ that is the heat 
and work content of the body. However, since I think it better 
to take the names of such quantities as these, which are important 
for science, from the ancient languages, so that they can be intro- 
duced without change into all the modem languages, I propose to 
name the magnitude S the entropy of the body, from the Greek 
word e trope a transformation. I have intentionally formed the 
word entropy so as to be as similar as possible to the work energy, 
since both these quantities which are to be known by these names 
are so nearly related to each other in their physical significance that 
a certain similarity in their names seemed to me advantageous.^" 

But what is the " physical significance " of " transformation 
content "? Perhaps we may take a cue from Lindsay and 
Margenau who write, "the quantity we are seeking will be 

Cf. W. Wilson, A Hundred Years of Physics (London, 1950) pp. 37-39. 
For the nature of mathematical physics, cf. In II Phys., lect. 3 (passim) . 
Cf. W. Magie, ed. Source Book in Physics (New York, 1935) p. 234. 


meaningless unless it refers to equilibrium states." '^ Heat 
tends of itself to flow from a hotter body to a cooler one — never 
the reverse — and the flow ends, when the temperatures of the 
two bodies are equal. Entropy is this tendency to equality, 
to equilibrium, to uniformity. 

It will be appropriate later on to spell out more carefully the 
fine-print meaning of equilibrium or uniformity in order to 
show how general this tendency must actually be and to 
indicate that this entropic drive is a dedifferentiation by con- 
trast to the differential structure in an evolutionary process. 
But let us tighten our hold on the meaning of entropy so far 
attained. Our second law of thermodynamics reads that the 
entropy in any closed system always tends to increase to the 
maximum. The augmentation of entropy is a measure of the 
use of energy. In a steam engine, for example, some of the heat 
is dissipated through the machinery and cannot be recovered 
for use; more generally, in any closed system, energy exchange 
always involves in the end a dissipation of heat throughout 
the parts of the system, so that no machine is one hundred 
per cent efficient. 

The second law of thermodynamics thus records the degrada- 
tion of energy and, if our cosmos is finite, the downhill drive 
of the universe itself. The law of the conservation of energy 
expresses the constancy in quantity of the energy involved in 
any closed process; but the law of entropy records the quali- 
tative change in such energy. Some of it passes into a state in 
which it is no longer available for work. In any machine there 
is a loss of available energy because of the dissipation of heat 
through the machine itself. 

Now the law of entropy, like all the laws of thermodynamics, 
is not of merely local significance like an equation that applies 
only to electricity or magnetism. All energy can be converted 
to mechanical energy, and hence all energy transformations — 
thus all the motions in our universe — involve a change of some 
of the energy into unusable heat. In other words, since all 

^^ R. Lindsay and H. Margenau, Foundations of Physics (New York, 1936) p. 215. 


usable energy has a mechanical equivalent and hence can be 
reduced to mechanical energy which in turn, when passing 
from a potential to a kinetic stage, produces unrecoverable heat, 
the law of entropy, though arising out of a study of heat, really 
applies to all closed energy transformations and, if the universe 
is finite, to all cosmic motion. 

This is why Eddington could call the law of entropy " time's 
arrow." " Entropy is a measure of the direction in cosmic 
processes as a whole. It reports that our universe, previously 
claimed to be in evolution, has in reality always been going 
downhill. Slowly it is moving toward uniformity and equi- 
librium where all heat will have have been transformed into 
an unusable state and where, as a result, all further motion will 
become impossible. This is what is meant by the heat-death 
of the universe. 

The law of entropy was being formulated at a time when, 
despite the theory of Daniel Bernoulli and the experimental 
evidence of Count Rumford, the caloric theory of heat was still 
in vogue. About the middle of the nineteenth century the 
kinetic molecular theory of matter, thanks to Joule and Max- 
well, finally became acceptable, and in this perspective, the 
much older idea that heat is a phenomenon of motion was 
finally given quantitative form. The temperature of a sub- 
stance could be correlated to the average kinetic energy of the 
molecules, or more simply put, heat came to be considered as a 
random motion of particles. As such, it is a problem in statistics 
like the throwing of dice or the shuffling of cards. 

Despite all the historical and philosophical interest which the 
study of heat can command, we are interested in the problem 
here only to round off our discussion of entropy. Against the 
background that heat is the random motion of molecules in 
material substances, or that " from the standpoint of the kinetic 
theory, heat is disorganized random mechanical energy, whereas 
mechanical energy proper is directed, ordered," ^^ it is possible 

^- The Nature of the Physical World (New York, 1928) chap. 5. 
"A. d'Abro, The Rise of the New Physics (New York, 1953) I, 398. 


to gain a better possession of the meaning of entropy. Thus 
if entropy is a tendency to uniformity, uniformity itself is one 
synonym for a random aggregation of particles. As a statistical 
equilibrium, such particles have a uniformity of behavior. The 
ideal statistical aggregate is " the same all over." 

Using a different language to reach eventually the same 
conclusion, it can be seen that if heat is a random motion and 
if there is a tendency of a hot body to lose heat to a cooler one 
until the temperature of both are equal, there is a tendency 
between the two bodies to form an undifferentiated or random 
state — in this sense a uniformity — with respect to each other. 
As acquiring more heat, a cooler body acquires more random- 
ness; in other words, an increase of heat means an increase in 
randomness as microscopic particles move about. If there is 
a tendency in the cosmos toward an equality of temperature 
among and within all bodies, this may be described as a ten- 
dency from a less random or differentiated state to a more 
random and undifferentiated state — a tendency from the less 
probable to the more probable. This indeed is another way of 
interpreting the Camot principle. The original constellation 
of things must have been one of lesser probability in the 
vocabulary of statistics, and as time has unfolded, there has 
been a movement from the less probable to the more and more 
probable. And so it will continue in the future. " Order," as 
von Weizsacker has summed it up, 

is a state which can only be realized in a very special way and 
which, therefore, in practice, never originates of itself. Disorder, 
on the other hand, is a generic name for the totality of all states in 
which no definite order is realized; it can thus be realized in a 
thousand different ways. When therefore any change not precisely 
determined takes place in nature, it is to be expected with over- 
whelming probability that it leads from order to disorder and not 
vice versa.^* 

The tendency in our world toward uniformity is thus a 
tendency to randomness, a tendency to disorder, a tendency 

^* Op. cit., p. 168. 


to statistical equilibrium. The commou eud-product of all 
energy reactions is the spread of heat or the increase in ran- 
domness. By contrast to the order, described by von Weiz- 
sacker, which is differentiated and heterogeneous, the random 
or disordered, in the language of thermodynamics, is undif- 
ferentiated and homogeneous. If entropy reigned alone in 
nature, our world would gradually be undergoing a levelling 
influence where difference, or otherness, an essential in all 
motion, would slowly be disappearing. 

There are several qualifications that would have to be put 
upon the law of entropy if the discussion were to become more 
precise than is intended here. 

For one thing within the kinetic molecular theory itself, if 
the particles of a system are truly disorganized, there is a small 
statistical possibility that they may, in their aggregate, move 
" uphill " and this fact has led, as d'Abro suggests, to the 
downgrading of entropy to the status of an approximation.^^ 
Such a view, projected within the classical kinetic molecular 
theory, would be supported for different reasons by the statis- 
tical thermodynamics of quantum theory .^"^ Moreover, Tolman 
suggested that a relativistic treatment of entropy might not 
require the irreversible march toward the " heat-death " of the 
universe." Finally, the steady state theorists restrict entropy 
to local systems and permit the addition of hydrogen, in the 
quantity previously stated, so that the total entropy of the 
universe, far from declining, remains constant, i. e., in a steady 
state.^^ As they deny evolution in its orthodox sense, so the 
steady-state theorists see a universe where entropic losses are 
being overcome. 

Nevertheless, with all of these qualifications, it may still be 
true that the law of entropy — and could we not argue in a 
similar vein concerning evolution.^ — is one of those approxima- 

" Op. cit., I, 399. 

^° But directionality is also indicated by the non-conservation of parity. See the 
article with this title by P. Blackett, American Scientist, XXVII (1959) , 509-514. 
" R. Tolman, The Principles of Statistical Mechanics (Oxford, 1938) . 
" H. Spencer Jones, " Continuous Creation," Science News, XXII (1954) , 29. 


tions, true for the most part as Aristotle ^^ maintained but not 
invested with absohite certitude like the type which post- 
Cartesian physics has been seeking in the physical world. 
Moreover, and as Aristotle also showed in his dialectical evalua- 
tion of his predecessors, approximations can put one on the road 
to reality itself,*'" Thus, there is no intention here of using 
such highly derivative notions as entropy and evolution to 
decide the issue of the fundamental principles in nature; for 
this question is decided at a level far more general than that 
attained by modern science with its specialized techniques of 
experiment and its mathematical apparatus. But within this 
framework, both entropy and evolution may suggest some 
basic truths or reinforce some truths already recognized. 


Several reservations will be useful in order to understand the 
spirit of the ensuing comparisons involving evolution and 

1) However fruitful it might otherwise be to assess the 
methods for studying both evolution and entropy and thereby 
to gain a better hold on the meaning of the results, such an 
excursion into logic and epistemology will not be undertaken 

2) The leading cosmologies of our day are evolutionary. 
This we have seen in the very language of cosmologists them- 
selves. It is apparent in the build-up, a qualitative differen- 
tiation, of the heavier elements from hydrogen ®^ and in the 
final conditioning of the universe to support life in its higher 

^"Phys., II, 5, 196b 10-11. 

'** Ihid., I, 5, 188a 18-29. 

'^ This issue has been raised by E. McMulIin in " Realism in Modern Cosmology," 
Proc. Amer. Cath. Phil. Assoc, XXlX (1955), 137-160. 

" What, then, does this steady-state universe look like? Although it is un- 
changing on a large scale, it is not unchanging in detail. Each individual galaxy 
ages owing to the way its resources of hydrogen are being depleted by its conversion 
into helium inside the stars, and for other reasons." H. Bondi, The Universe at 
Large, p. 43. 


and higher forms. The gradual preparation of matter to sustain 
life would itself be evidence of the evolutionary direction in the 
history of nature. Teilhard has summed up the truly evolu- 
tionary trend, believed discernible throughout the whole cos- 
mos, by his term " complexification." ®^ 

In this light evolution is irreducible to entropy, even though 
both may be universal and correlative; and the techniques to 
measure entropy may not in general be fitted to detect the 
qualitative and finalized character of genuine evolution. We 
may have here an analogue to Bohr's principle of comple- 
mentarity. Nevertheless, evidence for both principles, for what- 
ever conviction it may carry, has become embodied in the 
language of contemporary cosmologists, and is there to see 
even in the outline we have been sketching. 

3) Whether evolution and entropy are absolute and neces- 
sary laws need cause us no scruples in our assessment of their 
meaning. The continued existence of apparently very old living 
forms that did not either evolve or become extinct may be an 
exception to evolution as a truly absolute universal, and there 
are arguments that entropy too is only approximation. But if 
evolution and entropy are true for the most part, they are, 
by such a status alone, entitled to a legal status in scientific 

Will further research modify our current notions of evolution 
and entropy.'' Perhaps it will. But once more these two con- 
cepts must be taken seriously by the philosopher of nature. 
For the philosopher, even though not limited to current experi- 
mental evidence and theory, is bound to take account, to the 
extent that he can, of up-to-the minute scientific findings. If 
he waits until all such results are in, he will wait forever. 
But if he sifts through the reports of the science of his time, 
he may hit upon that element of truth to be found in every 
system of thought "* and, in the case of modern physics, an 
element usually submitted to more or less careful checks. 

"^ Teilhard de Chardin, The Phenomenon of Man (New York, 1959) p. 48. 
^*Meta., II, 1, 993a 30-993b 7. 


This tenuous hold on truth Is all we can expect in exploring 
nature's details. 

With all of these restrictions, what is the problem to be 
treated? It is the paradox mentioned by Lalande more than a 
generation ago and never fully faced, let alone resolved. The 
gist of the problem is that there are two conflicting laws 
reigning in our cosmos. One is the law of evolution leading 
from disorder to order or from uniformity to differentiation. 
The other is the law of entropy which finds the cosmos as a 
whole going from order to randomness and from differentiation 
to uniformity. How can these opposites co-exist? Are we not 
in a position like that of Parmenides who was led to deny 
motion because it seemed to involve irreconcilable opposites? 

Yet, in addition to the undoubted evidence for motion, there 
may also be enough evidence for both evolution and entropy 
to bid us find a corresponding place for both of them in our 
cosmology. In Book I of his Physics, Aristotle found a place 
for the embryonic theory of evolution in Anaxagoras and for 
the quasi-entropy of Empedocles. For all of the early natural- 
ists as serious students of nature saw dimly, Aristotle said, and 
they framed obscurely, some important truths about nature.*'^ 
But they did not push their analysis to the fundamental prin- 
ciples in nature '^^ which are two first contraries and their 

This is not Aristotle's positive argument for primary matter 
and its two first contraries of substantial form and privation, 
and we are applying a similar dialectic to approximate *'^ what 
would be reached scientifically on other grounds. Let us go 
over the dialectic to see how it operates. 

Evolution and entropy, the uphill and down-hill tendencies 
detected by modern cosmology, are contraries. They are oppo- 
sites, and all motion, tends, from different points of view, to 

*^ ". . . for all of them identify their elements, and what they call their principles, 
with the contraries, giving no reason indeed for the theory, but constrained as it 
were by the truth itself." Phys., I, 5, 188b 28-30. 

"^St. Thomas, In I Phys., lect. 10, n. 172 (ed. Angelo Pirotta) . 

*^ This is one reason why dialectic is called tentativa. In IV Met., lect. 4, n. 574. 


be characterized by them both. That is to say, there are no 
processes which tend to be governed by only one of these 
principles, say entropy, while other motions are ruled only by 
evolution. For entropy is generally regarded as universal,"* and 
if modern cosmogony is a witness, equally universal is the 
principle of evolution. Hence, evolution and entropy must 
simultaneously characterize the same change and the same 
changing things. Therefore, the substratum of these two ten- 
dencies must be indifferent to both of them. If it inherently 
possessed one, it would expel the other; and vice versa. 

Such a triadic structure seems to throw us back upon the 
three first principles of change discussed in perennial phi- 
losophy. Evolution is a sign of form; entropy, of privation; 
and the indfferent substratum, of primary matter. We are 
speaking here of signs — not of principles; of effects not of 
causes. For evolution and entropy, if they do signify form 
and privation, are derived and secondary contraries which must 
be traced back to their first principles. But this determination 
of signs and effects is all we are after, here. It is evidence of 
the kind of dualism which has been re-afRrmed in recent physics 
in establishing new bridgeheads between modern science and 
traditional philosophy. 

Teilhard, though not alluding to the substratum we have 
claimed as a necessity to bring evolution and entropy together, 
has reinforced the effort we have made above: 

In every physico-chemical change, adds thermodynamics, a fraction 
of the available energy is irrecoverably ' entropised,' lost, that is to 
say, in the form of heat. Doubtless it is possible to retain this 
degraded fraction symbolically in equations, so as to express that 
in the operations of matter nothing is lost any more than anything 
is created, but that is merely a mathematical trick. As a matter 
of fact, from the real evolutionary standpoint, something is finally 
burned up in the course of every synthesis in order to pay for that 
synthesis. ^^ 

Entropy measures the loss factor, the privation, the exhaust 

"* Von Weizsacker, op. cit., p. 57. "• Op. cit, p. 51. 


of what is "burned up " in the movement toward form. But 
what loses and what gains? It must be a substratum indifferent 
to either process, the subject in which privation and form 
succeed one another. 


Though not concerned with the physical meaning of evolu- 
tion and of entropy but more with logic and pedagogy, there 
is one final observation that may be in place here. For we have 
argued that the philosopher of nature is not dependent on the 
evidence of entropy and evolution to establish his three first 
principles of all change. He knows them because, in the order 
of learning, the analysis of nature on a general level precedes the 
specialized knowledge like that achieved in modern science; 
this pedagogical order is commanded by the very nature of 
human knowing.'" Does our study of evolution and entropy 
lend any confirmatory weight to this order in our reasoned 
knowledge of nature.? 

Let us look at this matter closely, not because it is a physical 
problem but only because evolution and entropy have been in 
focus. Our question, to phrase it properly, concerns the level 
where our reasoned knowledge of nature should begin in order 
to be truly sure of itself. Should it begin with the micro- 
physical, the astrophysical, or at some other level.? 

Our authentic science of nature, sure of where it is starting 
and of the principles it finds there, cannot begin with the 
microphysical. For there may be forces and factors operating 
in the universe at large which will not show up in microphysical 
analysis. Thus, there could be no entropy to a single particle, 
and for the same reason, the scientist could not speak of 
evolution at this atomistic level. Even the biological evolu- 
tionist cannot discuss evolution in the case of single individuals. 
He speaks of populations. " Complete knowledge of the indi- 
vidual events in the history of life," according to Simpson, " is 
absolutely unobtainable, even in principle." '"■ By the same 

^" Summa Theol., I, q. 85, a. 3. 

''^ " The History of Life " in The Evolution of Life, op. cit., p. 121. 


token, the astronomer employs statistics to detect trends in his 
" billions of galaxies." ' " The point is that the over-atomization 
point of view, in terms of the familiar figures of the trees and 
the forest, may lead us to overlook some of the cosmic laws 
which a broader look would reveal . This is especially true when 
our analysis becomes microphysical. 

Shall we begin, on the other hand, with the astrophysical? 
If we do, we will find another source of obscurity. For all our 
knowledge of distant times and places is dependent on what 
we laiow from things on earth, however this knowledge be 
refined and modified later on. If we leap, therefore, to astro- 
physical problems without a prior study of things and events 
within more direct experience, we will lack tested equipment 
to make a realistic sounding of the dark depths to which we 
have plunged. 

Entropy and evolution thus make it relevant to inquire 
where our deliberate possession of natural science should begin. 
And there is no more logical beginning for a truly synthetic 
reading of the book of nature than reason's consideration of 
material things as they are first available in direct experience. 
Such knowledge any scientist must inevitably possess, in how- 
ever uncritical and unobtrusive a fashion, before he resort to 
the special techniques of experiment and mathematics. Using 
knowledge of this type, we have claimed to make evolution 
and entropy not only more physically meaningful than perhaps 
they now are but also consistent with each other. 

Vincent E. Smith 

Philosophy of Science Institute, 
St. John's University, 
New York, N. Y. 

H. Shapley, Galaxies (Philadelphia, 1943) 


Part I: From the Fact of Evolution 

STATEMENTS made by serious students of contempo- 
rary evolutionary theory seem to be, even to this day, 
in open conflict about the " fact of evolution." At the 
Darwin Centennial Celebration held at the University of Chi- 
cago (November, 1959) , the statement was constantly reiter- 
ated: " Biologists one hundred years after Darwin take the 
fact of evolution for granted, as a necessary basis for interpret- 
ing the phenomena of life." ^ Huxley repeated the point: " The 
evolution of life is no longer a theory; it is a fact and the basis 
of all our thinking." " Dr. Sol Tax, chairman of the Convention, 
summed up the panel discussions by extending the concept to 
all areas of scientific endeavor: 

But perhaps most of our schools still teach evolution, not as a fact, 
but as only one alternative among explanations of how the world 
has come to be what it is. No matter what gets done about our 
religious beliefs, this particular phenomenon must now come to an 
end. We cannot deal with the difficult problems of the world unless 
our education takes account of demonstrated einpirical fact. (Italics 
added.) ^ 

However, in one of the most critical papers submitted at the 
Centennial, Dr. E. C. Olson suggests an underlying confusion 
involved in these statements. He writes: 

It is certain that few negative responses would result from the 
simple question " Is the general concept of organic evolution valid? " 

"^ Evolution After Darwin, edited by Sol Tax (Chicago, 1960) III, 107. This 
three-volume work contains the University of Chicago Centennial papers and 
discussions and will be used as a constant reference. Hereafter, the work will be 
signified by the initials EAD. 

Uhid., p. 111. ^Ihid., p. 247. 



were it to be submitted to the biologists working the various dis- 
ciplines today. If, however, a second question were asked, one 
requiring a definition of organic evolution, it is equally likely that 
a varied suite of answers would result, and, if the answers were 
honest, there would be a fair sprinkling to the effect " I don't 
know." * 

After insisting that there is a silent segment of significant num- 
bers among biologists and other scientists who feel that much 
of the fabric of evolutionary theory accepted by the majority 
today is actually undemonstrated or even false, Olson goes on: 

The statement is frequently made that organic evolution is no 
longer to be regarded as a theory, but is a fact. This, it seems to 
me, reveals a curious situation that causes considerable difficulty in 
understanding evolution both among laymen and among biologists 
who are not intimately concerned with its study ... If organic 
evolution can be defined simply and loosely as the changes of 
organisms through successive generations in time, then it can hardly 
be questioned that, within our understanding of the earth and its 
life, evolution has occurred. In this sense it must be considered a 
reality . . .^ 

If, however, the definition of evolution goes further and 
asserts that contemporary synthetic theory (neo-Darwinian, 
mutation-selection) is the theory of evolution, as was done 
many times during the Convention,'' then. Dr. Olson points out, 
that " fact of evolution " must be rejected as unproved and 
invalid. The explanation of how the process of orderly change 
of successive generations through time has been accomplished 
must be dissociated from the statement that such an orderly 
succession has taken place. Only then will many scientists 
accept the proposition " evolution is a fact." ^ 

Olson's critical series of observations in the midst of the 
Centennial discussion of the status of evolutionary theory 
today throws important light upon the confusion which has 
reigned for over a decade about this proposition: " evolution 
is a fact." In 1951, the eminent geneticist T. Dobzhansky 

* Op. cit., I, 525. ^ Ihid., p. 526. « Loc. cit. '' Ibid., p. 527. 


Evolutionists of the nineteenth century were interested primarily 
in demonstrating that evolution has actually taken place. They 
succeeded eminently well. Evolution as an historical process is 
established as thoroughly and completely as science can establish 
facts of the past witnessed by no human eyes. At present, an 
informed and reasonable person can hardly doubt the validity of 
the evolution theory, in the sense that evolution has occurred.* 

Just a few months before this statement was published, Pope 
Pius XII wrote the following statement in the encyclical 
Humani Generis, the Catholic Church's most important and 
explicit comment on the problems connected with evolutionary 

If anyone examines the state of affairs outside the Christian fold, 
he will easily discover the principal trends that not a few learned 
men are following. Some imprudently and indiscreetly hold that 
evolution, which has not been fully proved even in the domain of 
natural sciences (nondum invicte probatuTn in ipso disciplinarum 
naturaliurri ambitu) , explains the origin of all things, and audaci- 
ously support the monistic and pantheistic opinion that the world 
is in continual evolution.^ 

Dobzhanski certainly meant to include the origin of the human 
species by this evolutionary process which he claimed to be an 
indubitable fact. But Pope Pius XII, when he expressed his 
mind on the question of the origin of man from some pre-exist- 
ing living form, again reverted to an expression which seems 
contrary to the statement of the geneticist (and the majority 
of scientists speaking on the question) . After making it clear 
that the Church by no means disfavors the evolutionary inquiry 
into the origins of man from living matter in keeping with 
the most careful research, he adds: 

However, this must be done in such a way that. reasons for both 
opinions, that is those favorable and unfavorable to evolution, be 
weighed and judged with the necessary seriousness, moderation and 
measure . . . Some, however, highly transgress this liberty of dis- 

* Genetics and the Origin of Species, 3rd ed. (New York, 1951) , p. 11. 
® Cf . translation of the Encyclical Letter Humani Generis prepared by The 
Paulist Press, New York, 1950, p. 6. 


cussion when they act as if the origin of the human body from pre- 
existing and living matter were already completely certain and 
proved by facts which have been discovered up to now and reason- 
ing on those facts {per indicia hucusque reperta ac per ratiocinia 
ex iisdem judiciis deducta, jam certa omnino sit ac demonstrata) 


• • • 

On the face of things, there seems to be a fundamental dis- 
agreement between the statements concerning the " fact of evo- 
lution " made by most scientists today and those written in 
Humani Generis. But this apparent disagreement is one found 
not only in the dialogue between the theologian and the 
scientist, or the philosopher and the scientist. There is fun- 
damental ambiguity and apparent disagreement about the 
significance and the validity of the proposition even among 
scientists, as Olson's paper reveals. There cannot be true dis- 
agreement in a dialogue, however, until there is fundamental 
agreement about the meaning of the terms used in the discus- 
sion. Minimal topical agreement must be had: men must agree 
to disagree. 

The proposition " evolution is no longer a theory, it is a 
fact " is valid or invalid depending upon the significance as- 
signed to tw^o terms: " evolution " and " fact." If we disengage 
the series of events called evolution from any discussion about 
the ivay evolution might have taken place, we might begin with 
the definition of evolution set down by Panel Two at the 
Centennial Convention as our constant in the present dis- 

Evolution is definable in general terms as a one-way, irreversible 
process in time, which during its course generates novelty, diversity, 
and higher levels of organization. It operates in all sectors of the 
phenomenal universe but has been most fully described and ana- 
lyzed in the biological sector.^^ 

This definition was agreed upon by Huxley, Emerson, Axelrod, 
Dobzhansky, Ford, Mayr, Nicholson, Olson, Prosser, Stebbins, 
Wright, and, presumably, by all other members of the Con- 

'"Ibid., p. 19. ''EAD, III, 107. 


vention/" Assuming, for the moment, the definition of evolu- 
tion stated here, let us turn our attention to the other undefined 
element of the proposition, the term " fact." 

What is a Fact? 

Although the term is much used (and abused) in ordinary 
speech, the accepted meanings of the word " fact " are greatly 
varied. These variations fall into the following five categories: 

(1) a thing done; deed, specifically, an unlawful deed, crime; 

(2) that which has actual existence; an event; (3) the quality 
of being actual; actuality; as, the realm of fact as distinct from 
that of fancy; (4) the statement of a thing done or existing; as, 
his facts are false; loosely, the thing supposed (even though 
falsely) to be done or to exist; (5) Law: specifically, usually 
in the plural; any of the circumstances or matters of a case as 
alleged; also, that which is of actual occurrence; reality as 
an event.^^ 

The range of meaning here indicates some ambiguity, but a 
fact is, for most people, some deed or event which is known to 
have actually taken place. Analogously and loosely the term 
is applied to events supposed or alleged to have taken place, 
even though the supposition may be unsupported, but in or- 
dinary speech the usual meaning is clear. The term fact im- 
plies an element of certainty, or, at least, the removal of doubt 
about the actual existence of some event. Something is factual, 
or a fact, when it is known, either directly or indirectly, to 
exist or to have existed. One can attain the factual either by 
evidence or by inferences from evidence, but in any case, until 
one can ascribe actual existence to a deed or a thing, the term 
" fact " is not properly ascribed. To the ordinary person, fact 
is contrasted to fiction, fancy, mere supposition, hypothesis, 
guesswork, inconclusive evidence and uncertain or doubtful 

When the student of language begins to investigate the 

^^ Loc. cit. 

^^ Webster's New Collegiate Dictionary, 2nd ed. (Springfield, Mass., 1953) . 

oSi il\y:moxd j. xog.vr 

special and even technical usage of the term "" fact "' in the 
sciences and the arts, he finds the word taking on refined and 
special meanings, sometimes quite incomprehensible and seem- 
ingly contrary to popular usage. Metaphor, analogies and 
sometimes equivocation enter into the use of common terms 
in specialized fields. The term " fact " has not escaped ana- 
logous and even equivocal modification in its use by the sciences 
and the arts.'-^ 

For example, in legal cases, certainty is not required for ad- 
judication. In the words of Hart and McXaughton: 

In a criminal case, guilt need not be found beyond all doubt. The 
trier of the fact must be satisfied of the defendant's guilt only 
" beyond a reasonable doubt." In a civil case, the facts are ordi- 
narily to be found on the basis of " a preponderance of evidence "; 
this phrase is generally defined as meaning simply '* more likely 
than not." The question for the trial judge is whether a " reason- 
able jury " on the evidence submitted could find that the facts 
have been proved by a preponderance of the evidence . . .-' 

That compiling e^^dence and making inferences in criminal and 
ci%*il law cases should have this quality of uncertainty about 
its " facts ■"' is widely known and rather expected. We would 
expect something quite different, however, when we consider 
the e\'idence and inferences proper to the " exact sciences '' 
of physics and chemistri'. In the physical and natural sciences: 

Observation is just opening one's eyes and looking. Facts are 
simply the things that happen; hard, sheer, plain and unvarnished 


At one time in the not too distant past, the meaning of fact in 
the physical and natural sciences did seem to be quite "' sheer, 
plain and unvarnished." The scientist discovered empirical 
facts, formulated laws generalizing the observed facts, and or- 
ganized the laws into s^^lthetic theories."" Without much ad- 

^* Cf. Evidence and Inference, ed. bv D. Lemer (Glencoe, 111.. 1958) . 

' Ibid^ p. 53. 

' E. Mach's words as quoted in X. R. Hanson, Patterns of Discovery. (^Cam- 
bridge, 195S; , p. 31. 

-• Ci. L. de Broglie, Matter and Light (New York, 1939,) p. IS. 

1« ' 


justment, this formula is found in the classical text-books on 
the methodology^ not only of physics and chemistry, but of 
the biological, anthropological, psychological and sociological 
sciences as well. ^Miatever the technique of elaborating laws 
and theories — which might be proper to each discipline — one 
might suppose that a " scientific fact " would be an event, or 
thing, or deed which could be i m mediately and certainlv ob- 
served, or inferred with certitude from technical observation. 
So the classical methodologies of the 19th and early 20th Cen- 
turies seemed to view the use of the term " fact." 

But with the rapid re\'i5ion in the methodology of particle 
physics (micro-physics) due to the indirect techniques neces- 
sary to handle the data, manv remarkable changes have taken 
place in the canonized terms of classical macro-physics, biolog}', 
and the human sciences. Classical meanings attached to such 
terms as causality, fact, law, hj'pothesis, probability, etc. ceased 
to correspond simply with the concepts introduced by the 
micro-physicist. On his level of research, the observations of 
the facts themselves, because of the very indirect techniques of 
experiment he is forced to employ, cannot be disengaged from 
the concepts, assumptions, constructs, analogies and extra- 
polations used to set up the operation of discovery. The 
"thing" studied became a spatio-temporal measurement; its 
" properties " became a description of the processes by means 
of which these measurements are made.^* Fact and inference, 
technique of observation and the event or thing observed, were 
so blended that the classical meanings were radically altered 
in the direction of subjective analog}*. In the light of the 
methodolog^' of micro-physics: 

Observations, evidence, facts; these notions, if drawn from the 
'■ catalogue sciences " of school and undergraduate text-books, will 
ill prepare one for understanding the foundations of particle theory. 
So too with the ideas of theory, h^-pothesis, law. causality and 
principle. In a growing research discipline, inquire- is directed not 
to rearranging old facts and explanations into more elegant 

"F. Renoirte. Cosmology (New York, 1950) p. 118. 


formal patterns, but rather to the discovery of new patterns of 

This ambiguity which has entered into the language of 
science by the operational methods of micro-physics has not 
completely modified the usage of the term " fact " on the level 
of the macro- and the megalo-sciences. There are many scien- 
tific disciplines which still give the term " fact " the meaning 
of something known to have actual existence, something either 
observably or inferentially known to be certain. But the tech- 
niques, terminology and methods of physics have set the pace 
for theoretical scientific thinking for the past three centuries, 
and biologists, chemists, phychologists, anthropologists, soci- 
ologists and even historians have not remained unaffected by 
this change in the fundamental meanings of the basic concepts 
of physics. For our purposes here, it suffices merely to mention 
this increasing tendency for technical scientific language to 
depart from the common dictionary acceptation of such terms 
as " fact " and " observation." 

The Facts of Prehistory 

Returning to the issue of the " fact of evolution," we are 
confronted with another problem. If we accept, for purposes of 
discussion, the definition of evolution set down by the panelists 
at the Darwin Centennial Convention (quoted above) , we find 
ourselves involved in a question which is essentially an his- 
torical one, or, more properly, a problem of prehistory. As T. 
Huxley wrote in 1907: 

Primary and direct evidence in favour of evolution can be furnished 
only by paleontology ... If evolution has taken place, there will 
be its mark left; if evolution has not taken place, there will lie its 

Huxley was speaking of organic evolution, but the problems of 

^^ N. R. Hanson, op. cit., pp. 1-2. 

"" Address on " The Coming of Age of The Origin of Species," in Darwiniana 
(London, 1907), p. 239. 


the origin of life, of the elements, of the earth, the stars, the 
nebulae, etc. are, a jortiori, problems of prehistory. Conse- 
quently, the evidence and inferences brought forward in sup- 
port of these " facts " unwitnessed by human eyes will be 
the kind proper to the disciplines which study historical process. 
Not that the neo-sciences (e. g. neo-biology) cannot offer but- 
tressing arguments for some of the prehistorical inferences, but 
the kind of evidence and inference which constitute the prin- 
cipal argument of evolutionary process is determined and 
limited by the very nature of the problem of prehistory. 

In matters concerning the sciences of prehistory (paleon- 
tology, archaeology, etc.) , two extremes must be avoided: (1) 
expecting more from the kind of evidence and inference than is 
reasonable, and (2) attributing greater stability and reliability 
to the evidence and inferences than is reasonable. In order to 
avoid these excesses, it is necessary to assess properly what kind 
of problem the prehistorian poses, and the power and limits of 
his methodology in seeking solutions. The sciences of pre- 
history are similar to written history in one way, but quite 
dissimilar in another. Perhaps we can best understand the 
problem of discovering " facts " and making " inferences " in 
prehistory by comparing its methods to those of the profes- 
sional historian. 

Scientific history differs from other sciences and arts in its 
subject-matter, its facts, its primary aim, its language, its 
theories and interpretations, its methods and its meaning.-^ Its 
subject-matter is the recorded past, more or less dramatized 
or put into order. The recorded past is a series of indi\ddual 
events, actions, persons, non-recurring for the most part, seen 
in the context of a space- time continuum. The facts are indi- 
vidual, concrete, unrepeatable events made available by the 
witnesses who recorded them. The primary aim of history is to 
reconstruct the events in their individuality, thus resembling a 
literary narrative rather than a scientific treatise. The lan- 

"^ Cf. The Philosophy of History in our Time, ed. by H. Meyerhoff (New York, 
1959) pp. 18-22. 


guage, then, is literary and not scientific. Fact, theory and 
interpretation form a closely knit complex in the historical 
narrative so that there are very few " simon-pure " historical 
facts without some interpretation. 

Historical method is a combination of scientific evidence and 
inference with imagination, insight, and empathy. History 
employs causal and even teleological explanations, shows trends 
and illuminates events, but is not causal in the strict scientific 
sense. The meaning of the series of contingent events and 
their patterns depends upon the theological or philosophical 
assumptions of the historian. Upon most of these statements, 
contemporary historians agree."- Of course, the accent in mus- 
tering evidence and inference will differ with each philosophy 
of history, but we can easily perceive that the historian's 
" facts " are not the facts of common usage. His facts are 
affirmations on record, or inferences from records, that some- 
thing has happened."^ 

We must pass over the debate among contemporary scientific 
historians about the knotty problem concerning the certainty 
or probability of historical evidence and inference."* This we 
know, that the laws of observation and logic obtain in history 
as in every science, and the degree of probability or the attain- 
ment of certitude depend upon the trustworthiness of the 
available witnesses. Obviously, since history cannot be re- 
peated and therefore " tested out " like a scientific experiment, 
the element of conjecture mounts up in this discipline. " His- 
torical facts " lie more in the realm of actual events which 
probably happened, than in the category of actual events which 
certainly happened. The reason is simply that the historical 
method depends so much upon indirect evidence, inferences 
which depend entirely upon the relative trustworthiness of the 
statements of the witnesses. 

If the element of uncertainty prevails in securing evidence 
and making inferences in history, how much more is this the 

'■ Ibid. 

'^ Ibid., p. 124. 


R. G. CoUingwood, The Idea of History (New York, 1957) p. 261. 


condition of scientific prehistory which must draw conclusions 
without the aid of the statements of witnesses. Piggott, in a 
very critical and illuminating paper at the Darwin Centennial 
Convention states: 

What follows from this is, I think, of paramount importance and 
insufficiently recognized: the nature of the evidence dictates the 
nature of the inferences which can be properly drawn from it . . . 
I want to stress here that the past-as-known which is based on 
archaeological evidence is not, and cannot of its nature be, the 
same as the past-as-known based on evidence which involves the 
written record in lesser or greater degree.-^ 

In human prehistory (e. g. archaeology) , what must take 
the place of written records and preserved technological phe- 
nomena is the mental artifact called the raodel. This is a 
human construction based upon extrapolation, interpolation 
and rational analogies to things known to us more directly and 
immediately. Simpson stresses the point that the paleonto- 
logical record of fossil remains of past eras of organic life must 
be read with two factors in mind: (1) the essential tool (in 
reading the record) is extrapolation from what we know in 
neo-biology and present geological formation, an extrapolation 
which has serious limitations and must be carefully regulated; 
and (2) the very nature of the materials makes it obvious that 
the record should not be read with a score of fundamental 

A close reading of both Simpson and Piggott will reward the 
reader with an insight into the limits and the powers of pre- 
history. On the one hand, the warnings and misgivings about 
which Olson, Case and Zuckerman and many others have written 
concerning the conclusions of scientific prehistory are clearly 
borne out." Yet, on the other hand, the reader will be struck 

'^ EAD, n, 87. 
" EAD, I, 129-34. 

27 , 

Cf. Olson, EAD, I, 532-37; E. C. Case, " The Dilemma of the Paleontologist," 
in Contributions from the Museum of Paleontology, Vol. IX, No. 5 (University of 
Michigan, 1951) p. 180; Zuckerman's statements quoted in E. O. Dodson, Evolu- 
tion: Process and Product (New York, 1960) p. 197. 


by the value of the conclusions which are obtained by pains- 
taking methods in this most inaccessible of scientific materials 
— the events which took place millions of years ago, unwit- 
nessed by any human being.^^ A patient study of the methods 
of geology, archaeology and paleontology manifests two signifi- 
cant points: (1) " facts " based upon evidence and inference 
proper to scientific prehistory are sui generis, and, in them- 
selves, highly conjectural and logically tentative; and (2) the 
convergence of prehistoric " facts " with the evidence and in- 
ferences drawn from neo-science (biology, anthropology, etc.) 
yields an unexpected reasonable basis for a series of important 
convictions about what happened during these past eons of 
time. Scientific prehistory should neither be overstated, nor 
underrated, in its ability to resolve some of the problems of 

Fact as a Reasonable Conviction 

Remembering the distinctions made thus far about the way 
the term " fact," whether from evidence or inference, is used 
variously in the sciences depending upon the availability of 
such evidence and inference, it becomes easier to understand 
what is meant by the statement made by Olson, and repeated 
at the Darwin Centennial Celebration: 

Organic evolution — the process of orderly change of successive gen- 
erations through time — does occur and apparently has occurred 
for the total period of life on the earth. There can be many theories 
of how it occurred, each of which may explain part or all of what 
has been observed, and these theories may be in complete conflict 
without invalidating the basic fact of evolution. 


In the first place, Olson recognizes, as do all those who take 
the pains to qualify their conclusions with the appropriate 

"^ Good introduction to the methods of prehistory can be found in G. G. Simpson, 
Life of the Past (New Haven, 1953) and J. R. Beerbower, Search for the Past 
(Englewood CHffs, N. J, 1960) . 

'^ Tendency to underrate scientific prehistory is a limitation of works such as 
G. H. Duggan, S. M., Evolution and Philosophy (Wellington, New Zealand, 1959) . 

"" EAD, I, 527. 


caution, that he is speaking of a " basic fact " of prehistory, not 
of history, not of physics, nor of chemistry, biology, etc. (ex- 
cept in the supplementary sense upon which we shall soon 
elaborate) , Whence comes this general agreement about this 
prehistoric " fact "? Insofar as any conclusion can be drawn 
from the evidence and inference proper to prehistory, every 
reasonable objective doubt has been removed, and the evi- 
dence has converged with such consistency that a firm, reason- 
able conviction has been generated in the minds of those who 
have expertly explored the problem. Le Gros Clark puts it 
clearly this way: 

It is an interesting question, but one which is not easily answered — 
just at what point in the gradual accumulation of circumstantial 
evidence (as we have in evolution) can the latter be accepted as 
adequate for demonstrating the truth of a proposition.'' Perhaps the 
most we can say is that, in practice, this point is mainly determined 
by the multiplicity of independent sources from which this evi- 
dence is derived; if several lines of argument based upon apparently 
unrelated data converge on, and mutually support, the same general 
conclusion, the probability that this conclusion is correct may 
appear so high as to carry conviction to the mind of the unbiased 

Let it be noted that Olson's " basic fact of evolution," like 
Dobzhansky's statement quoted earlier, is in the logical order 
of " probability so high as to carry conviction to the mind of 
the unbiased observer." Without disparaging the logical quality 
of the phrase " fact of evolution," it remains in the order of 
probability , not in the order of certainty. By its very nature, 
evolutionary theory relies on proof and demonstration, the 
inferences of which have all or most doubts removed, but do 
not claim the security that the case could not be otherwise. 
Indeed, for the scientific prehistorian, he might wonder that 
anyone would raise the question whether he meant by the " fact 
of evolution " that it was objectively certain and could not be 
otherwise. He would insist that his science produced proofs of 

^^ " The Crucial Evidence for Human Evolution," in American Scientist, 47 
(1959) 299-300. 


the kind described by Le Gros Clark — so highly probable that 
the unbiased, objective observer must be convinced by the 
convergence of disparate but mutually supporting evidence. 
No more, no less. This is what a prehistoric fact means to the 

In this sense, evolution is a " fact " as opposed to a mere 
hypothesis which has not the documentation sufficient to re- 
move doubt and generate the conviction described. Evolution 
is a " fact " as opposed to a theory among theories of reputa- 
tion, as the " steady-state " theory is opposed to the " pul- 
sating universe " theory in cosmology .^^ Evolution, as defined 
by Olson, abstracting from the various hypotheses concerning 
how the process took place, enjoys the status of having no other 
reasonable natural explanation of the converging evidence to 
oppose it with sufficient evidential support to produce high 
probability or conviction. Evolution is a " fact " as opposed to 
a low degree of probability. On certain levels, e. g. on the level 
of organic evolution, the degree of probability is high. What the 
phrase " evolution is a fact " does not mean, however, is that 
it now enjoys the status of demonstration which generates the 
certitude of direct observation or inference which follows so 
necessarily from that observation that it could not be otherwise. 

Thus it is readily seen how the statements of Dobzhansky, 
Olson, Simpson, Huxley and others at the Darwin Convention, 
who constantly used the phrase " fact of evolution," were not 
unequivocally in opposition to the statements made by some 
philosophers and theologians in their attempts at a dialogue 
upon common issues. The two quotations from Humani 
Generis above, for example, assert that evolution has not been 
fully proved even in the domain of natural sciences and that 
those transgress liberty of discussion who act as if the origin 
of the human body from pre-existing and living matter were 
already completely certain and proved by facts which have 
been discovered up to now and by reasoning on those facts. 
It is of capital importance to understand these statements of 

*" EAD, 1, 32-33. 


Pope Pius XII in the context, not of a biological treatise, but 
of a theological treatise. He was not concerned about bio- 
logical or anthropological methodology; he was not writing a 
paper for the Darwin Centennial Celebration, He was writing 
a theological document, using the language proper to the readers 
to whom it was addressed, namely, the outstanding theologians 
and philosophers of the Catholic Church. He was writing pri- 
marily for those Catholics who were familiar with the logical 
distinctions between those arguments which generate certitude 
and those which conclude only to a degree of probability. The 
reason was evident. Theologians have to evaluate carefully 
the degree of probability of scientific propositions in order to 
place them properly in the context of another source of truth — 
Divine Revelation. 

Pope Pius XII was not questioning the validity of the con- 
cepts of prehistory as synthetic models organizing much of 
organic or even cosmic science; he was not controverting the 
evolution of species or even the possible organic relationship of 
the human body to other primates. He was using traditional 
logical concepts of certitude, probability, rhetorical convictions, 
in order to show that many evolutionary propositions do not 
enjoy certitude but only a limited degree of probability and 
that there are many elements of evolutionary teaching which 
are still seriously controverted — a fact which Olson and others 
took great pains to point out to the Convention. For these 
reasons, therefore, the " fact of evolution " could not be placed 
in opposition to matters of Divine Faith as a truth known to be 
demonstrated with certitude. 

It is manifest from the context of Humani Generis what 
Pope Pius XII wished to do, namely, to call seriously into ques- 
tion whether the " fact of evolution " explains the existence of 
all things and supports the monistic and pantheistic opinion 
that the world is in continual e volution. ^^ He by no means 
contradicts the assertions of Dobzhansky, Le Gros Clark, 
Olson and others that the objective observer, looking without 

^^ Humani Generis, ed. dt., p. 6. 


bias at the converging evidence, must be convinced of the very 
high probabiHty that evolution has taken place. He does not 
address himself to that problem; he merely advises professional 
caution. The proposition he does controvert is that the " fact 
of evolution " applies equally and unequivocally to the origin 
of all cosmic entities; the universe, the nebulae, the stars, the 
elements, life, diversity of organisms, man's body, his mind, 
culture and society, morals, religion, language and art. In fact, 
Humani Generis controverts just what the Darwin Centennial 
Celebration controverted when it manifestly showed that the 
phrase " fact of evolution " applies equivocally to many scien- 
tific disciplines, and to some areas, not at all. Let us see what 
happened at the Darwin Centennial in its application of the 
concept " fact of evolution." 

The Fact of Evolution 

Whether there is presently sufficient converging evidence for 
the reasonable and unanimous (among scientists) conviction 
that monophyletic descent with modification accounts for the 
variety of organic species, including man, on the earth was 
not even discussed at the Darwin Centennial Convention. As 
Simpson wrote in his The Meaning of Evolution (1949) , the 
evidence is in and the case has been fairly adjudicated. As- 
suming two essential propositions: (1) that a natural explana- 
tion, consonant with what we know now in neo-biology about 
organic development, is available; and, (2) that extrapolation, 
analogy and indirect convergent proof be allowed where direct 
proof is unavailable; then, the accumulation of arguments 
found in any good modern text-book on evolution suffice to 
convince the unbiased and objective observer that evolution 
has, in fact, taken place. ^^ 

Indeed, the case for the prehistoric fact of organic evolution 
is a very good one. Biologists no longer question it, that is to 
say, they have no reasonable doubts about the connected series 
of natural events distributing organic species in space and 

^* The Meaning of Evolution (New Haven, 1949) pp. 4-5. 


time. They do debate the relative advantages of the mechan- 
ism of evolution proposed by the neo-Darwinian, the macro- 
mutation-saltation, or some form of Lamarckian theory. But, 
as Olson says, even if one or all of these explanations prove 
inadequate, no one would seriously doubt that the evolutionary 
series of organic events occurred. ^^ What is the basis for this 
assurance .f* 

There is not sufficient space here to give an adequate sum- 
mary of the converging evidence for monophyletic descent with 
modification, and unless the reader realizes the full impact of 
each piece of converging evidence, he is quite likely to take a 
negative and dialectically critical view and reject the evidence 
as logically inconclusive. As a mere dialectician, he is prone 
to ask more of the evidence and the inference than possibly can 
be made available, and fail to appreciate how very convincing 
the evidence, taken together, really is. The following considera- 
tions constitute the essential elements of this converging 

In the first place, the paleontological record needs a natural 
explanation consistent with neo-biology. Reject this propo- 
sition and you place the question of origins outside the domain 
of natural science, and must invoke catastrophic theories, preter- 
natural influences, divine interventions by miracles, etc. which 
would be both bad science, bad natural philosophy and bad 
theology.^" Scientific prehistory shows a series of origins and 
developments from the pre-Cambrian period over 500,000,000 
years ago to the present which leaves no doubt among dis- 
interested observers that there was a series of successive origins 
of plants and animals. Most of the species of plants and 
animals that we know today are quite recent in the fossil record, 

^' EAD, I, 527. 

^* The natural philosopher would abhor a jumbled, disorderly concourse of un- 
related natural events as totally out of keeping with natural laws. Natura non jacit 
saltus. The theologian would abhor the thought of God specially and immediately 
creating, for example, distinct species of finches for each of the several Galapagos 
Islands at different times (multiply this miraculous intervention by the hundreds 
of thousands!) for it goes directly contrary to the theological axiom that God 
ordinarily orders all things wisely through secondary causes. 


and good phyletic sequences of origins have been established by 
scientific prehistory. This series includes the fossil evidence 
for some structural development of homo sapiens. The only 
available natural explanation which does not conflict with the 
natural processes which are manifest in geology and neo- 
biology is the evolutionary one, common descent with modi- 

On the infra-specific level, Ford's field work on the moth 
and the selective forces at work in modifying the species sup- 
ports the concept of natural modification in species and varie- 
ties; Dobzhansky's work (and others) on Drosophila give con- 
vergent support to the theory of common descent with modi- 
fication from the standpoint of mutation of genes and the sur- 
vival of such mutation within the population. On the generic 
level, the amazing series of freshwater molluscs Pauludina can 
be traced in a single 300 foot deposit: nine species with more 
and more complicated shells emerge from one smooth-shelled 
species. Equally significant is the same kind of evidence found 
in English chalk of the Micraster (sea urchin) series. On the 
Family level, the Equidae (horse) series elaborated by Marsh 
and Simpson is most striking. Twelve to fifteen genera of 
horses can be traced with convincing dialectic and fossil docu- 
mentation from the Eocene period, 60 million years ago, to the 
present living genus, Equus. Similar studies, though not quite 
so convincing perhaps, have been made among the ammonites, 
camels, swine, crocodiles and fishes." 

Taken singly, any one series is established with the use of 
a scientific methodology which is vulnerable to the stringent 
rules of demonstrative logic. Yet, remembering the singular 
nature of the problem of origins and the only methods natural 
science has at its disposal, it is not certain demonstrative proof 
that we are after, but that high degree of convergent proba- 
bility which produces conviction and removes all reasonable 

^' Cf. Dodson, op. cit., and especially, the symposium Genetics, Paleontology 
and Evolution, ed. by Jepson, Mayr and Simpson (Princeton, 1949) , 


With the paleontological record objectively before us, and 
the series of simpler forms to the more complex appearing in 
distinct periods of space and time, let us see how all the disci- 
plines of neo-organic science contribute buttressing, yet diver- 
gent, arguments in support of common descent with modifica- 
tion. Again, limited space allows only a schematic summary. 
In biogeography, the area which was so convincing to Darwin, 
we find biogeographical realms, discontinuous distribution and 
exological zones. Within the local areas, we find marvelous re- 
semblance and adaptation to the particular environment. These 
singular conditions can best be explained by common descent 
with modification. How else can the distribution of distinct 
species of finches on the various islands of Galapagos be ex- 
plained, species which so closely resemble the genera of finches 
on the South American mainland.'^ 

In taxonomy, the classification of plants and animals, a mar- 
velously delicate hierarchical relationship is manifested, just 
what would be expected from common phylogenetic descent 
with modification. As Darwin had put it " the only known 
biological explanation for close similarity in nature (among 
organisms) is common descent." ^® This statement is not uni- 
versally true, as more recent studies have shown,^*^ but the 
argument is dialectically sound and weighty. Taxonomic rela- 
tionship is best explained by common descent with modification. 

A similar convergent argument is contributed from the mor- 
phological sciences, e. g. anatomy and physiology. A study of 
the organ systems of animals manifests a phyletic prototype 
which is varied from class to class, family to family, etc. These 
homologies and analogies are best explained by common de- 
scent with modification. In embryology, the student finds that 
individuals of different species (e. g. the hog, calf, rabbit and 
man) pass through embryological stages which are almost 
identical, a fact which is best explained by common decent 

** The Origin of Species, Chapter XIV (6th ed.; Modem Library) , p. 320. 
*^ The trend called " parallel evolution " is described in Simpson's Life of the 
Past, pp. 127 ff. 


with modification. From cytology and biochemistry, other 
arguments are advanced. For instance, protoplasm, blood, hor- 
mones and enzymes show properties which are remarkably 
similar in large groups of animals. This is best explained by 
descent with modification.'"' 

These basic observations and generalizations from the several 
departments of biology could be multiplied and detailed with 
endless documentation, but this summary must suffice to give 
the uninitiated reader some sense of the convergence of argu- 
ment and the buttressing strength of the contribution of neo- 
biology to the general argument of organic prehistory. Again, 
close study of any fundamental textbook on evolution will 
guarantee two important insights: (1) the special kind of 
answer one must expect from a natural investigation of origins 
— its limits, if you will; and (2) within this context, the power 
of the argument, the high probability which the convergence 
of evidence generates among those who view the question of 
origins impartially. 

As a member of the animal kingdom, the species homo 
sapiens is included in the general arguments above. Physical 
anthropology has used the scientific methods of prehistory with 
almost uncanny effectiveness to produce a series of hominoid 
descent with modification comparable to the best phylogenetic 
series among the other mammals. A classification of skulls 
(and other fossilized parts) , based upon several fundamental 
characters, which, taken together, comprise a total morpho- 
logical pattern distinguishing the anthropoid ape skull from 
the hominoid type skull, reveals a graduated series rivalling 
that of Equidae. From Australopithecus (500,000-1,000,000 
years ago) through Pithecanthropus (200,000-500,000) repre- 
sented by Java and Pekin man, Pre-Mousterian (100,000- 
200,000) represented by Steinheim, Fontechevade and Swans- 
combe, Early Mousterian (50,000-100,000) represented by Mt. 
Carmel in Palestine and others in Europe, to Late Mousterian 
and Modern Man (about 50,000) represented by the Neander- 

*" See Dodson, op. cit., for full treatment of these arguments. 


thals on one branch and modern European man on the other, 
we find surprising fossil documentation of descent with modifi- 
cation of the human body.'^ To the physical anthropologist, 
the weakness lies not so much in this series of developments, 
but rather in the lack of fossils connecting Australopithecus 
wdth the fossil hominoids (great apes) of the Pliocene and Mio- 
cene eras. Le Gros Clark admits that mere extrapolation back- 
wards in the absence of concrete fossil evidence is not a satis- 
fying procedure.^" This hiatus is disturbing, but not of such 
proportions as to shake the general conviction that homo 
sapiens is biologically related to the rest of the animal kingdom 
in a natural continuum, even though much important evidence 
remains to be uncovered. What the paleoanthropologist does 
have by way of documentation of the " fact of physical evolu- 
tion " of man is very good. 

The Fact of Cosmic Evolution 

In the Darwin Centennial Celebration papers, as has been 
stated, the question whether evolution is a fact was barely 
alluded to. It was taken for granted. ^^ The issue of the Cen- 
tennial was far more extensive in scope. The burden of the 
papers and the panel discussions was to show that the concept 
of evolution (and especially the neo-Darwinian interpretation) 
was valid in every major scientific discipline. The " fact of evo- 
lution," it was asserted, can and should be extended to the 
origin of mind, culture, life, the cosmos itself and all it contains. 
It was in this extension of evolutionary thought to the problem 
of origins in every field that the Centennial papers. Evolution 
After Darwin, provided expert commentaries of great value. 

A careful analysis of the way the concept " fact of evolu- 
tion " is used in the fields outside biology reveals a fact of con- 
siderable importance. The concept " fact of evolution," valid 
in the matter of organic origins and diversity as described 

*^ W. E. Le Gros Clark, The Fossil Evidence jor Huinan Evolution (Chicago, 
" Ibid., p. 163. " EAD, III, 107. 


above, becomes equivocal as it is applied to the origin of life, 
chemicals, stars, nebulae, mind, language, culture. Neither 
" fact " nor " evolution " retain the same meaning, and the 
evidence and inferences are of another kind, varying from disci- 
pline to discipline. In point of fact, there is gi-eat uncertainty 
that the concept " fact of evolution " is relevant in some areas 
of scientific study. This element of equivocation in terminology, 
in evidence and in inference, is often completely overlooked, 
and the degree of conviction generated in the biological sciences 
is by no means present to the same degree in some of the other 
areas of science. 

This mutation in evolutionary concept as the observer goes 
from one field to the next is of greatest importance in evalu- 
ating the scientific dimensions of evolutionary theory. The 
problem is treated in detail elsewhere,** and can only be touched 
upon here by a few examples drawn from the Centennial 
papers. Applying the hypothesis of evolution to the origin of 
life, H. Gaffron compared the status of the " fact of evolution " 
in biology to that of biochemical biopoesis (the natural origin 
of life from the inorganic) . After admitting the conviction 
generated by convergence of evidence in biology, he states: 

The situation in respect to biopoesis is exactly the reverse. There 
is nice theory, but no shred of evidence, no single fact whatever, 
forces us to believe in it. What exists is only the scientists' wish 
not to admit a discontinuity in nature and not to assume a creative 
act forever beyond comprehension.*^ 

The acceptance of the " fact of evolution " of life from non- 
life is based upon a conviction of an entirely different kind. The 
biologist and the biochemist look across a chasm which is filled 
only by a combination of imagination, extrapolation, human 
faith and a lively hope. This is not to disparage research in 
biopoesis, for out of this combination emerge working hypo- 
theses with which the problem of biopoesis may one day be 

** R. J. Nogar, O. P., " Evolution: Its Scientific and Philosophical Dimensions," 
St. John's University Studies, ed. Vincent E. Smith (Jamaica, N. Y., 1961) Series 3. 
*^EAD, I, 45. 


solved. But today the concept " fact of evolution " cannot be 
applied to the origin of life except in this equivocal sense. Evi- 
dence and proper inference is lacking at the present stage of 

When the concept " fact of evolution " is applied to the 
origin of chemical and physical elements, an even greater 
degree of equivocation on the terms " fact " and " evolution " 
is present. Smart/^ Urey,*^ Fowler ^^ and others are very 
guarded about the extremely hypothetical nature of the knowl- 
edge concerning the formation of the elements of our own 
system. Highly tentative backward extrapolation and reason- 
ing from analogies with our present system of elements, coupled 
with many alternative theories, all enjoying some reputation, 
give another meaning to the phrase " fact of evolution " of the 
elements. As Shapley's paper on the evidence for inorganic 
evolution plainly manifests, the origin of the universe is hardly 
a scientific question at all, and the theories about the course of 
the universe's prehistory alternate between some one-way 
process and a cyclic process, a steady-state and an expanding 
universe depleting its energy.*^ The degree of conviction gen- 
erated in these cosmic sciences is not so great as to rule out 
serious doubts and alternative explanations, and the meaning 
and status of the " fact of evolution " is equivocal. 

Almost without exception, the Darwin Centennial panelists 
and those who submitted papers for Evolution After Darwin 
agreed that when the organic process introduced homo sapiens 
upon the cosmic scene, the concept of the " fact of evolution " 
radically changed. Man may be terminal to a somatic-germinal 
evolution determined in part at least by the forces and mechan- 
isms of selection and mutation which were operative in all the 
other higher animals, but once the species homo sapiens evolved, 
his evolution was no longer to be manifested in human body 

" The Origin of the Earth, Chapter 10 (Cambridge, Eng., 1951). 
*^ The Planets: Their Origin and Development (New Haven, 1952) p. 11. 
*® See the analysis of scientific cosmology in M. K. Munitz, Space, Time and 
Creation (Glencoe, Bl., 1957). 
" BAD, I, 33. 



and gene complexes but rather in psychological potentialities 
Kroeber, Washburn, Howell, Hallowell, Critchley, Hilgard, 
Brosin, Piggott, Steward and Tax asserted in their professional 
contributions that the " fact of evolution " of man's mind, his 
language, his culture, his society, has a very limited and equi- 
vocal usage in comparison to its use in biology, Hallowell 
rejects, with Hilgard, the notion that there are no differences, 
except quantitative ones, betwen the learning of lower animals 
and man," and Steward goes so far as to say: 

This paper is largely an admission of the general uncertainty now 
surrounding the concept of cultural evolution ... In the physical 
and biological universes, evolution implies change which can be 
formulated in principles that operate at all times and places, al- 
though the particular principles of biological evolution differ from 
those of the physical realm. Expectably, or at least by analogy, 
then, cultural evolution should contain its own distinctive prin- 
ciples, which also underlie cultural change. By this criterion, no one 
has yet demonstrated cultural evolution. (Italics added.) 


These papers on cultural anthropology, archaeology, psy- 
chology and language not only show this radical change in the 
concept of evolution as it is applied to man, but they even show 
a strong tendency to ignore the concept of man's prehistory and 
concentrate upon man as he is now known to be the fashioner 
of his own future. Scientifically, man is best known, not in what 
he was in his prehistory, but in what he presently is and does. 
The " fact of man's evolution " is a concept which is most 
equivocal; it is a concept which seems to be becoming obsolete 
in the sciences of human behavior and activity. 


The Fact of Evolution: A Summing Up 

When we hear or read the statement that evolution is now 
no longer a theory but a fact, and should be taught as such, 
a healthy response to the statement should include neither the 
panic of complete and irrational skepticism or denial, nor the 

^"For example, Huxley, EAD, I, 19; Tax, EAD, III, 280. 

" EAD, II, 360. " EAD, II, 182-83. "« EAD, II, 16. 


excessively uncritical naivete of the statement made to science 
teachers attending the last session of the five day Panel at the 
Darwin Centennial Celebration: 

Properly taught, the knowledge which our students gain should 
produce in them a sense of the universality of evolutionary pro- 
cesses, from the prebiological molecular level through the pre- 
human world to man with his physical, mental, and sociocultural 
development, thus integrating the physical, biological, and social 
sciences, and, through history, the humanities. This sense of change 
leads to the habit of " thinking of reality in terms of process " 
rather than in terms of static situations/* 

Careful delineation of the wide varity of meaning attached to 
the concept " fact of evolution " gives us a well focused view of 
both the power and the limits of evolutionary theory. The 
theory is a very complicated combination of univocal, ana- 
logous and equivocal statements, especially when an attempt is 
made to apply it to every scientific area of study. Some of these 
statements are strongly supported by evidence and securely 
drawn inferences; others are hopeful hypotheses and arbitrary 
assertions. Perhaps Beckner's summary of evolution theory in 
biology is a fair evaluation of evolutionary thought in general: 

My own view is that evolution theory consists of a family of related 
models; that most evolutionary explanations are based upon as- 
sumptions that, in the individual case, are not highly confirmed; 
but that the various models in the theory provide evidential sup- 
port for their neighbors.^^ 

Part II: To the Philosophy of Evolutionism 

As long as the " fact of evolution " is understood in its wide 
variety of equivocal senses, variously substantiated with that 
degree of probability presently afforded by the methodology 
used in each scientific discipline, the true value of the diachronic 

"J. C. Mayfield, "Using Modern Knowledge to Teach Evolution in High 
Schools," Graduate School of Education Symposium of the Darwin Centennial 
Celebration. (Chicago, 1960) p. 7. 

" M. Beckner, The Biological Way of Thought (New York, 1959) p. 160. 


concept can be seen. Not only does a process of evolution add 
a dynamic space-time dimension to our understanding of the 
cosmos, but the evolutionary theory also provides a concept 
of synthesis for many disparate scientific approaches. Beckner 

Evolution theory is of philosophical interest because of the way it 
integrates principles of the most diverse sorts, but, in addition, it is 
of interest because here we find the most diverse patterns of concept 
formation and explanation unified in a single theory .^^ 

For many scientists and observers, this quality of unifying 
the work of many sciences, of integrating the explanations and 
approaches of diverse disciplines, is the outstanding contribu- 
tion of evolutionary theory. It is commonly said that Darwin 
did for biology and the life sciences what Newton did for 
classical physics. The very crucial question is raised by Beck- 
ner, and others at the Darwin Convention, whether, in fact, 
evolutionary theory provides an integration by way of a con- 
structural model (or series of models) which is able to embrace 
the research of many sciences, or whether it provides universal 
laws, like Newton's laws of motion, the laws of conservation 
of mass and energy, the laws of thermodynamics. Mental con- 
structs are universalized only in the imagination; universal laws 
are causal and necessitate the events of which they are causal. 
If there is a universal cosmic law of evolution (or laws) , then 
it can be turned into an ultimate philosophical principle of 
the origins of cosmic entities, as some assert. If there is no 
universal cosmic law of evolution demonstrated by science, 
then no such philosophical generalizations are valid and the 
" fact of evolution," so far as a synthetic principle is concerned, 
remains a very useful construct but is non-causal, as others 
assert. The answer to this question is crucial, jor it determines 
whether philosophies or ideologies ^^ of evolutionism have bases 
which are scientifically established in the laws of nature. 

^Ubid., p. 160. 

" For useful distinction between a true philosophy and an ideology, see W. O. 
Martin, Metaphysics and Ideology (Milwaukee, 1959) 


Are There Laws of Evolution? 

If we can model our discussion of natural laws upon the 
methods of physics, the science which has for several centuries 
set the pace for methodological procedure, three closely inter- 
related tasks must be performed in establishing a body of 
knowledge (1) isolate the phenomena to be studied; (2) de- 
scribe unambiguously what is happening; and (3) discern some 
specific permanence in the flux of events under observation. 
By this process, for example, the laws of conservation were 

We have seen how equivocity enters into the very texture of 
evolutionary theory at every level of the " fact." Consequently, 
in this difficult question of prehistory and origins, there is a 
special and sometimes insurmountable difficulty in knowing 
whether the first two conditions above are satisfied. Isolating 
facts of prehistory and describing them unambiguously is, by 
the very nature of the problem, a large order. Assuming the 
most complete and reliable analyses of phylogenies, however, 
can we discern some specific permanence in the flux of events 
under observation.'^ 

B. Rensch takes up the problem of the " laws of evolution " 
in his paper for the Centennial Convention, and the question of 
the direction of evolution was fully discussed.^'' At first sight, 
it seems that in the flow of evolutionary events many laws can 
be formulated: (1) the law of increasing complexity; (2) the 
law of progressive speciation of phyletic branches; (3) the law 
of increasing size; (4) the law of migrations; (5) the law of 
adaptive radiation; (6) the law of irreversibility (Dollo's law) ; 
(7) the law of evolutionary continuity, etc.''° Rensch lists sixty 
different rules which seem to have the quality of regularity, 
and he admits that they can be multiplied indefinitely.*^^ But 

** G. Holton, Introduction to Concepts and Theories in Physical Science (Cam- 
bridge, 1952) p. 278. ^, 

68 >< 



" The Laws of Evolution," BAD, I, 95-116. /< \C»M /^ 

R. Collin, Evolution (New York, 1959) p. 55. -^^'^^^''''''Tr*^*^ 

EAD,T,UO. /oYo^* 


the curious fact about these " laws of evolution " is that they 
have no universal character. They are verified in limited areas 
only and admit of many exceptions. For this reason, biologists 
prefer to call them " rules " and " trends " rather than laws.''" 
More importantly, the rules or trends are not attributes of 
evolutionary process, but are restrictive limitations on the pro- 
cess imposed by the existing fundamental laws of neo-science. 
As Rensch points out: 

The large number of general rules quoted above may be sufficient 
to show that, in spite of primary undirectedness, evolutionary alter- 
ations occur in forced directions to a large degree. After all, every 
generalization in the field of biology means a restriction of evolu- 
tionary possibilities. (Italics added.) 


Dobzhansky confirms this observation that evolutionary pat- 
tern, though showing trends, is historical only, and nothing in 
the known history of life on earth compels one to believe that 
the evolution of organisms is predetermined to change in one 
direction only.*'* All the discussants at the Convention agreed 
that evolutionary process is unique, non-recurrent and irre- 
versible, even though " trends " can be detected which show 
that the process is non-random. The course of evolution shows, 
generally, three stages: diversification, transformation and sta- 
bilization. But the process itself cannot be predicted, is unique 
and contingent, cannot be reversed (by which laws of nature 
are formulated) and is, by its very nature, historical. '^^ 

The upshot of this analysis is of capital importance. The 
laws of nature, which are formulated in the neo-sciences about 
the universe as we now know it, are truly universalized; they 
are the laws of permanence, typical and verifiable by repetition 
and reversibility. The rules of evolutionary process, on the 
other hand, are contingent, non-reversible, unpredictable and 
bear the stamp of restriction based upon the natural laws of 

'" Simpson, EAD, I, 167; Collin, loc. cit. 

"EAD,I, 111. 

" EAD, I, 405. 

*^ G. G. Simpson, The Major Features of Evolution (New York, 1953) p. 312. 


neo-science, the laws of permanence. Strictly speaking, then, 
there is no universal law of evolution: there is only historical 
(jyrehistorical) process. 

Enter: Philosophies of EvolutionisTn 

The importance of this last point cannot be overestimated. 
It is precisely at this major point that evolutionary theory 
provides an illegitimate extrapolation, often quite surreptitious, 
from a partially documented and very useful model called the 
" fact of evolution " into the realm of philosophy or ideology 
based upon an undocumented and thoroughly controverted 
" law of evolution." The supposition of a universal, causal, 
cosmic law of evolution is not a valid inference from any known 
series of natural facts or laws established by science. 

It is absolutely necessary to disengage the philosophies based 
upon this false supposition from the scientific evolution in order 
to clear the air of many ambiguities which impede not only the 
educated person's understanding of evolution, but also the dis- 
cussions among science, philosophy and theology. It is often 
wrongly thought, for instance, that the theological document 
Huinani Generis quoted above is an unenlightened veto of the 
biological " fact of evolution." A close reading, however, will 
show that Pope Pius XII was repudiating, rather, the philoso- 
phies of evolutionism, whether they be mechanistic and mon- 
istic, or dialectical materialism, or the life-philosophies of 
historicism and existentialism.''® Without denying a single piece 
of scientific evidence or a single legitimate inference, and even 
encouraging the useful research into origins of all cosmic en- 
tities including man's body, he was denying that there is a 
shred of evidence from the natural sciences to prove that evo- 
lution is a cosmic law that explains the origin of all things, 
a law which repudiates all that is absolute, firm and immutable 
and gives value only to events and their history .'''' 

Unfortunately, there are many scientists, as well as philoso- 

*' Humani Generis, pp. 6-7. 
"^ Ibid. 


phers and theologians, who fail to draw the line between their 
scientific foundations which are firmly supported by evidence 
and their philosophical, or, more generally, ideological specu- 
lations. At one moment, they speak about biological or an- 
thropological or cosmic evolution, and suddenly, without warn- 
ing — and perhaps without knowing it themselves — they univer- 
salize evolutionary theory into a causal cosmic law and begin 
to draw philosophical conclusions about the universe in which 
we live. To the observer untrained in the logical arts, evolu- 
tionism, historicism, existentialism, mechanistic or even dia- 
lectical materialism may seem to be the necessary consequences 
of contemporary " evolutionary fact." 

A few examples taken from current scientific thinking on the 
subject of evolutionary theory will illustrate this unwarranted 
extrapolation from the " fact of evolution " to the " philosophy 
of evolutionism." Rensch, after enumerating scores of rules of 
evolution, says: 

It was necessary to enumerate these rules, in order to evaluate the 
degree by which the primary undirectedness is changed into a 
forced evolution . . . (Italics added.) ®^ 

He then infers that the evolutionary rules and laws are complex 
manifestations of the universal laws of causality, and that each 
epigenetic development of the process was necessarily deter- 
mined and implicit in the former stages through the universal 
laws of causality.^® His final conclusion follows: 

Summing up, we may assume that the whole evolution of the 
cosmos including the evolution of living beings, was pre-existing in 
consequence of the " eternal " cosmic laws of causality, parallelism 
and logic. However, up to now, such an assumption can be only 
a philosophical working hypothesis.^" 

In Rensch's statement there is some token of warning that 
this inference is really an assumption in the philosophical 
order. Other scientists, however, argue a more direct philoso- 
phy of evolutionism from the data of the " fact of evolution " 

''EAD, I, 110. "EAD, I, 113. '" Loc. cit. 


as though, from the evidence of biological evolution, there is 
but one philosophical inference available: a monistic, mechan- 
istic historical unfolding which is the cause and explanation of 
the origin and diversity of life and living things. Simpson, for 
example, after admitting that inorganic evolution is a special 
case, concludes: 

Evolution is, then, a completely general principle of life and is a 
fully natural process, inherent in the physical properties of the 
universe, by which life arose in the first place (biopoesis) and by 
which all living things, past or present, have since developed, 
divergently and progressively."^ 

The reader will note carefully that the prehistoric process of the 
origin and development of life, including man, is generalized 
into a physical law by which an immanent natural process 
necessitates the present order of living things. Simpson, after 
admitting that the " ultimate mystery," the origin of the uni- 
verse and the source of the laws or physical properties of 
matter, energy, space and time are presently unknown to 
science, goes on: 

Nevertheless, once those properties are given, the theory demon- 
strates that the whole evolution of life could well have ensued, and 
probably did ensue, automatically, as a natural consequence of the 
immanent laws and successive configurations of the material cosmos. 
There is no need, at least, to postulate any non-natural or meta- 
physical intervention in the course of evolution.^ 


He everywhere insists that there are no universal laws of evo- 
lution "^ and that the process of evolution is a unique, irrever- 
sible and directionless historical sequence of events. ^^ Yet here 
he insists that the " fact of evolution," as we know it for 
living things, even in their origin from the inorganic world, 
demonstrates a causal, automatic process resulting from " the 
immanent laws and successive configurations of the material 
cosmos." And with this " demonstration," he rules out scien- 
tifically the possibility of any vitalistic or finalistic explanation 

^' " The World Into Which Darwin Led Us," Science, 131 (Apr. 1, 1960), p. 969, 
" Ibid., p. 972. '" E. g., EAD, I, 167. '* Ibid., p. 173. 


of the evolutionary process. The fact that he goes so far as to 
label any opposition either " lower superstition " or " higher 
superstition " is of rhetorical importance, manifesting clearly 
the personal philosophical intensity of his vie\vs/° 

It is crucial to evolutionary analysis to detect the steps which 
are taken in the mental process by which what is known about 
prehistory can be gradually universalized into a philosophical 
principle of cosmic development without even noticing the ille- 
gitimate inference. In a restricted sense, evolution can be called 
a fact, but we must have a care for equivocation. In no sense 
is evolution a law of the cosmos; it cannot be so generalized. 
Here the false step is taken: 

For, where comparative anatomy offers only probability, paleon- 
tology brings certitude. Paleontology becomes, because of the 
breadth of its conclusions, a truly philosophical science.^ 


By some giant mutation of insight, science demonstrates that 
the historical process is immanently necessitated by the physi- 
cal properties of the elements to produce increasing complexi- 
ties, and that is simply all there is to the process. What began 
as scientific prehistory has suddenly become a life-philosophy 
of historicism, and its basis is " a necessary inference from sci- 
ence itself." A biological theory has become a monistic, mecha- 
nistic, historicist, life-philosophy of the cosmos by an illogical 
leap that remains to most observers completely undetected. 
Huxley finds it easy to draw this conclusion from the scientific 
findings of prehistory: 

All reality is in a perfectly proper sense evolution, and its essen- 
tial features are to be sought not in the analysis of static structures 
or reversible changes but through the study of the irrevocable 
patterns of evolutionary transformations." 

" " The World Into Which Darwin Led Us," ed. cit., p. 973. 

^* M. Vandel, quoted by Msgr. B. de Solages, " Christianity and Evolution," 
translated by H. Blair for Cross Currents from the Bulletin de Litterature Ecclesi- 
astique, no. 4, 1947. 

'''Review of Life of the Past by G. G. Simpson, Scientific American, CLXXXIX 
(1953), 88. 


Philosophies of evolutionism, and they are as old as Hera- 
clitus, are distinct from scientific evolutionary theory, and they 
take various shapes and meanings depending upon their pri- 
mary assumptions. After Darwin, however, the various ide- 
ologies began to be framed in the context of evolutionary 
science, and the names Spenser, Marx, James, Bergson, Le Roy, 
Dilthey and Jaspers come to mind as representing some ex- 
pression of a philosophy of evolutionism."^ It is, in a limited 
sense, true to say that evolutionism, historicism and existen- 
tialism are fundamentally identical expressions on different 
levels of being: cosmic evolution, evolutionism; mankind's 
evolution, historicism; personal evolution, existentialism. The 
emergence of ideological expressions of evolutionism from the 
scientific study of origins and prehistory, the outstanding fea- 
ture of American evolutionary thought in the last decade 
(crowned by the Darwin Centennial in 1959) , results from two 
dangerous tendencies in scientific thought. 

Fundamental Errors 

The first of these is the unrestricted and uncritical use of the 
scientific device of extrapolation. x4.t the Convention, Olson 
warned against its dangers.'^ Simpson declared its limitations.^" 
Piggott is severely critical of every form of extrapolation, 
whether it be interpolation, interpretation, analogy or any 
other form of filling in the gaps of our knowledge with " postu- 
lates which fulfill an emotional need." ^^ Case, Le Gros Clark, 
Gaffron and many others have tried to make explicit the limits 
of this necessary device of scientific prehistory.*' But there is 
no doubt that what often appears in text-books and the more 
popular expressions of current thought on origins is far from 

'* The interrelationship of these ideologies is clearly traced in I. M. Bochenski, 
Contemporary European Philosophy (Berkley, 1957) . 

'" EAD, I, 532. 

^°EAD,I, 121. 

^^EAD, II, 92. 

*^ E. C. Case, op. cit.; Le Gros Clark, The Fossil Evidence For Human Evolution, 
loc. cit.; Gaffron, EAD, I, pp. 44-50. 


critical/^ and the fanciful and unlimited use of extrapolation 
does much to gloss over the highly tentative nature of evolu- 
tionary trends, and, what is worse, seems to give a universal 
status to the " fact of evolution," whereas, in point of fact, 
there is no such cosmic law. 

This first error, the illegitimate use of extrapolation, can be 
corrected by caution in applying the device and, above all, by 
explicating its use so that the basis for inferences can be seen 
clearly. The second error is more deep-seated, both theoreti- 
cally and practically. It is what Maritain calls the gnosticisin 
of history.^* As the discussants at the Darwin Convention 
admitted, the prehistoric process which has been scientifically 
recorded and is called " the fact of evolution " is essentially 
in the genus of history. It is not science in the sense of the 
tested knowledge of reversible natural processes. As Simpson 
put it: 

That evolution is irreversible is a special case of the fact that 
history does not repeat itself. The fossil record and the evolution- 
ary sequences that it illustrates are historical in nature, and history 
does not repeat itself.^^ 

Historians reproach the philosophy of history with four 
capital sins, accusations which throw a bright light upon the 
fallacious extension of authentic scientific evolution to a phi- 
losophy of evolutionism. H. Marrou expresses the indictment 
this way: 

First, its almost inevitably oversimplified, arbitrary and wanton 
approach in regard to the choice of materials, the historical value 
of which is assumed for the sake of the cause; secondly, its self- 
deceptive ambition to get at an a priori explanation of the course 
of human history; thirdly, its self-deceptive ambition to get at an 
all-inclusive explanation of the meaning of human history; and 
fourthly, its self-deceptive ambition to get at a so-called scientific 
explanation of history, the word " scientific " being used here in 

'* Compare with the above, for example, the article " How Life Began," by 
E. A. Evans Jr. in The Saturday Evening Post, Nov. 26, 1960, pp. 25 ff. 
®* On the Philosophy of History, ed. J. W. Evans (New York, 1957) p. 31. 
*° Major Features of Evolution, p. 312. 


this quite peculiar sense, which can be traced back to the sciences 
of nature, that with such an explanation our thought enjoys a kind 
of intellectual mastery over the subject-matter.^° 

This rather vehement reproach can, more quietly, be applied 
to the philosophies of evolutionism. Evolution is an historical 
process, and, as such, it can have no a 'priori explanation; to 
assume one and then arrange materials to document it would 
be false to good scientific method. Simpson admits that the 
record cannot be read without bias, but bias must be reduced 
to a reasonable and defensible minimum,^' Since no true law 
of evolution is discernible, evolution cannot have an all-inclu- 
sive explanation written into its own process to be divined by 
analysis or arbitrary intuition. Evolution is an irreversible 
process and therefore cannot be reconstructed according to 
necessitating laws. Since evolutionary process can neither be 
its own explanation nor reconstructed according to necessitating 
laws, scientific evolution cannot he the basis for any philosophy 
of evolutionism. 

Those who see evolution written into the " laws of nature " 
confuse two things: the necessity of the laws of nature and the 
contingency of the historical events which run their course 
quite naturally. The necessity proper to the laws do not make 
the events necessary. As Rensch observed, the laws of biology 
restrict evolutionary change; the laws of nature are preserva- 
tive, stable, typical, and ever tend to permanence of structure 
and function to the most extraordinary degree .^^ The unique, 
irreversible, non-lawful, historical process which is the sequence 
of contingent events we call evolution is not a law unto itself, 
necessitating all things that it elaborates. Evolution, like any 
history, can be characterized, interpreted or deciphered in a 
certain measure so as to reveal limited general trends, to use 
Simpson's term. But the history does not cause, nor necessitate, 
nor explain the natures or their laws. The cosmos is not merely 

*® Quoted in Maxitain, op. cit., p. 30. 
^'EAD, I, 121. 

'^ EAD, I, 101 

Q a 


its history; mankind is not merely its history; a person is not 
merely his biography. The cosmos and its natures have his- 
tories; mankind has a history; a person has a biography.®'' Since 
the " fact of evolution " can never be more than a partially 
decipherable series of contingent events, it can never be uni- 
versalized into a philosophical principle giving ultimate insight 
and interpretation of the cosmos in which we live or our per- 
sonal being by which we live. Philosophies of evolutionism, or, 
better, ideologies of evolutionism, may appear to be valid infer- 
ences from scientific evolution, but, upon close inspection the 
appearance is an illusion. 

Conclusion: The Rhetoric of Evolutionism 

The evolution of life is no long a theory; it is a fact and the basis 
of all our thinking. (Italics added.) ®° 

By its rhetorical excesses, false philosophy of evolutionism 
can readily be detected. In the statement just quoted, Huxley 
sounds the dominant note of the final phase of evolutionary 
thinking in America, especially prevalent during the past 
decade. Taking the " fact of evolution " beyond extrapolation 
and even beyond the mere philosophy of evolutionism, he 
gives a scientific theory the qualities of a faith with a pro- 
phetic mystique. This is no longer science or philosophy; it is a 
rhetorical formulation of evolutionism into an easily recogniz- 
able personal apologetic. Huxley proclaimed this " new evolu- 
tionary vision " in his Convocation address at the Darwin Cen- 
tennial Celebration: 

In the evolutionary pattern of thought there is no longer either 
need or room for the supernatural. The earth was not created; it 
evolved. So did all the animals and plants that inhabit it, including 
our human selves, mind and soul as well as brain and body. So did 
religion. Religions are organs of psychosocial man concerned with 
human destiny and with experiences of sacredness and transcen- 

89 , 

C. De Koninck, " The Nature of Man and His Historical Being," Laval 
Theologique et Philosophique, V (1949), 271. 
»» Huxley, EAD, HI, 111. 


dence. In their evolution, some (but by no means all) have given 
birth to the concept of gods as supernatural beings . . . they are 
destined to disappear in competition with other, truer and more 
embracing thought organizations.''^ 

To him, scientific evolution not only necessitates a new phi- 
losophy, it inaugurates a new prophetic vision, a new religious 
hypothesis to replace both the old hypotheses of supernatural- 
ism and materialism (Marxian Communism) . He develops his 

I submit that the discoveries of physiologj% general biology and 
psychology not only make possible, but necessitate, a naturalistic 
hypothesis (for religion) , in which there is no room for the super- 
natural, and the spiritual forces at work in the cosmos are seen as a 
part of nature just as much as the material forces. What is more, 
these spiritual forces are one particular product of mental activity 
in the broad sense, and mental activity in general is seen to have 
increased the intensity and importance during the course of cosmic 
time. Our basic hypothesis is thus not merely naturalistic as op- 
posed to supernaturalist, but monistic as opposed to dualistic, and 
evolutionary as opposed to static.''- 

One cannot read the proposal of a new faith called " evo- 
lutionary humanism " in Huxley's Religion Without Revela- 
tion without sensing strongly the rhetorical attributes which 
have accrued to a once scientific dimension of the " fact of 
evolution." Huxley's extension of evolutionary thinking to 
the position of a vision of the meaning of all reality is serious 
because it is done in the name of science. Yet this highly ideo- 
logical and personalized explanation of the universe by cosmic 
history is filled with obvious gloss of analogy, metaphor and 
equivocation. It is extremely subjective, and, in the religious 
sense, apologetical. Time is the synthetic factor and the whole 
burden of his evolutionary philosophy is rhetorically aimed at 
commanding the conviction of the reader in the name and by 
the authority of science. 

It should not be thought that the rhetorical philosophies of 

'^ EAD, m, 252-53. 

"" Religion Without Revelation (New York, 1957) p. 187. 


evolutionism are confined to the exponents of atheistic human- 
ism (Huxley) or atheistic materialism (Marxists) . They take 
many forms, one of which is found in the writings of those who 
claim that the " fact of evolution " necessitates a diametrically 
opposed religious hypothesis, namely, a revealed supernatural 
religion (Fr. Teilhard de Chardin) . The starting point for the 
philosophy of evolutionism is ever the same: 

Is evolution a theory, a system or a hypothesis? It is much more: 
it is a general condition to which all theories, all hypotheses, all 
systems must bow and which they must satisfy henceforward if 
they are to be thinkable and true. Evolution is a light illuminating 
all facts, a curve that all lines must follow.®^ 

The vision which follows in The Phenomenon of Man is quite 
different in what it prophesies from that of Huxley, for, as the 
assumptions are modified, the prehistory of the cosmos tells a 
different story. One story ends with an immanent god, man 
himself; the other ends with a transcendent God, the God of 
the Christian revelation. But the basic rules according to which 
both accounts are fashioned are identical. 

Whether the suppositions be supernaturally revealed truths, 
assumptions of monistic materialism, dialectical materialism 
or humanism, the first step is the elevation of the " fact of 
evolution " to the status of law, a necessary series of scientifi- 
cally demonstrated events. The next step is to elevate the " law 
of evolution " to the level of a narrative world- view to which 
everything else must bow and in the light of which everything 
else must be understood. The third step is to personalize this 
new world view with a highly personalized rhetoric of con- 

In its final stages, the philosophy of evolutionism is an essen- 
tially personalistic, un verifiable intuition, rhetorically involved 
in ideological feeling and emotion, using a life-self-cosmos 
narration as the key to the meaning of reality. The rhetoric 
of evolutionism usually can be distinguished from mere phi- 

** T. de Chardin, S. J., The Phenomenon of Man (New York, 1959) p. 218. 


losophy of evolutionism by the visionary language of the syn- 
thesis. The philosophy of evolutionism can be distinguished 
from the scientific " fact of evolution " by its illegitimate 
extrapolation and claim to universalization. Thus disengaged, 
the fact of evolution can rightly be assessed as one of the most 
significant developments of modern science. 

Raymond J. Nogar, O. P. 

Alhertus Magnus Lyceum 
Dominican House of Studies 
River Forest, Illinois 


UNLESS a modern biologist, who tends to be concerned 
exclusively with the ultra-fine structure of genes and 
the feed-back mechanisms of hormones, has a broader 
outlook fostered by an acquaintance with the humanities and 
a sturdy philosophy, the world becomes a strange unreal uni- 
verse, apparently far removed from the world he once knew. 
This broader view of the universe can have many rewarding 
moments, such as those experienced by this writer while visiting 
the laboratories of Dr. Frank A. Brown, Jr., at the Marine 
Biological Laboratory, Woods Hole, Massachusetts, in the 
summer of 1959. Immediately one felt the impact of a research 
that was as close to the sea as the laboratory itself. Other 
laboratories at the famed MBL had electron miscroscopes, 
television microscopes, radiation scalers, and unique and sophis- 
ticated apparatus of various sorts; but here in the Brown 
laboratory one found much simple, home-made equipment, with 
intact animals going through their paces before a group of 
trained observers. 

Huge water baths regulated the temperature of glass respi- 
rometers which housed crabs with their whole oxygen supply 
contained in plastic bags. Their every breath was registered 
by automatic recording devices. In another room, snails glided 
over a marked course, all unaware that their meanderings were 
being suggested by the motion of magnets manipulated by 
researchers underneath their experimental platform. Fiddler 
crabs in a photographic darkroom regularly changed the color 
of their skin just as though they were still at home on their 
native beaches, becoming white at night and dark in the day- 
time, seeming to possess some sort of magic insight into an 
outer world from which they were completely isolated. Clams 
opened and closed their shells according to a set rhythm and 
made recordings of their activities on special devices, while 



crabs ran to and fro or were quiet during regular intervals of 
time. This was the picture one got while visiting the laboratory 
of one of the outstanding biologists of our time. 

When one questioned the biologists who were performing 
these experiments as to the type of data they were receiving, 
their answers brought many new and interesting facts to light. 
The large repository of accumulated and processed data which 
they possessed and a number of charts they had prepared, based 
on their observations of the behavior and metabolism of the 
plants and animals studied, had led the investigators to the 
conclusion that all these observed activities, despite every effort 
at isolation from the outside, were moving in rhythm with the 
motions of the cosmos. Although the organisms were being 
studied under conditions of temperature, light and other en- 
vironmental factors artificially maintained at an unvarying 
constancy, the plants and animals participating remained some- 
how in perfect accord with major cosmic or geophysical con- 
ditions of the outside world. 

A confirmation of this apparently indestructible harmony 
with the outer world, and even with outer space, arose from 
one summer's observation when the workers were at loss to 
account for the very eccentric results obtained from a certain 
set of experiments. When the meteorologic data corresponding 
to that particular period were consulted, it was discovered that 
the erratic behavior coincided exactly with a sudden and large 
outburst of sunspots! This correlation strengthened their sus- 
picion that their organisms were somehow getting some type of 
" information " from the outside which was not being observed 
in the laboratory. 

Dr. Brown and his associates have published extensively the 
results of their work, and it is very interesting to note the 
evolution of the hypotheses involved as the work progressed 
for a number of years. In particular one is struck by the great 
similarity between the conclusions and e^lanations arrived at 
by Dr. Brown from controlled observations, and the Aris- 
totelian doctrine concerning the influence of the " heavenly 


bodies." The most recent and perhaps the most comprehensive 
review of this work was published by Dr. Brown in a recent 
issue of Science. ^ 

Living organisms, Dr. Brown points out, inhabit a world of 
rhythms.^ The whole physical world, from that of the orbiting 
electrons in the atom to that of our planetary system revolving 
about the sun, shows regular cycles, or periodic changes. There 
are solar, lunar, tidal, monthly and annual cycles, which greatly 
affect the animal and plants; but in spite of the ever-changing 
environment, the organisms maintain a very constant homeo- 
stasis.^ To maintain this marvelous constancy, the organisms 
themselves have " built-in " rhythms that respond to the 
periodic changes in their physical surroundings. There exists 
an abundant literature describing observed rhythmicities of 
various sorts of animals. These rhythmicities appear to be 
inherent, for they persist not only when the animals are in 
their own habitats, but even when they are removed from the 
place where the particular periodicity seemed to constitute an 
advantage for individual survival and that of the species.* 

Perhaps one of the most arresting examples of rhythms is 

^ Frank A. Brown, Jr., " Living Clocks," Science, CXX (1959) , 1535-1544. 

^ Frank A. Brown, Jr., " The Rhythmic Nature of Animals and Plants," Cycles, 
XI (1960) , 81-92. 

^ Walter B. Cannon, The Wisdom of the Body (New York: W. W. Norton, 1932) , 
pp. 20-21; Frank A. Brown, Jr., " The Rhythmic Nature of Life," in Recent 
Advances in Invertebrate Physiology: A Symposium (Eugene, Oregon: University 
of Oregon, 1957) , edited by Bradely T. Scheer. 

* Frank A. Brown, Jr., J. Shriner and C. L. Ralph, " Solar and Lunar Rhythmicity 
in the Rat in ' Constant Conditions ' and the Mechanisms of Physiological Time 
Measurement," Am. Jour. Physiol., CLXXXIV (1956) , 491-496; Frank A. Brown, 
Jr., M. F. Bennett and H. M. Webb, " Monthly Cycles in an Organism in Constant 
Conditions during 1956 and 1957," Proc. Nat. Acad. Sci., XLIV (1958), 290-296; 
Frank A. Brown, Jr., R. A. Freeland and C. L. Ralph, " Persistent Rhythms in O2 
Consumption in Potatoes, Carrots and the Seaweed, Fucus," Plant Physiol., XXX 
(1955), 280-296; Frank A. Brown, Jr., M. F. Bennett, H. M. Webb and C. L. Ralph, 
" Persistent Daily, Monthly and 27-day Cycles of Activity in the Oyster and 
Quahog," Jour. Exp. Zool., CXXXI (1956) , 235-262; Muriel I. Sandeen, Grover C. 
Stephens and Frank A. Brown, Jr., " Persistent Daily and Tidal Rhythms of Oxygen 
Consumption in Two Species of Marine Snails," Physiol. Zool., XXVII (1954), 350- 


furnished by studies made on the color change in the skin of 
the fiddler crab, Uca pugnax.^ Near dawn on the beaches, the 
skin of this crab is observed to begin to darken, becoming 
darkest at noon, while near sunset it begins to blanch, becoming 
lightest at midnight. In its natural habitat the fiddler crab 
begins feeding at dawn, and it is believed that the darkening 
of the skin protects it from the radiant energy of the sun and 
makes it less conspicuous to its predators. When collected and 
taken to a photographic darkroom where light, temperature 
and other environmental factors are maintained constant, these 
crabs continue to change color as if they were still on their 
native beaches, although this color change has no longer any 
survival value. In the course of studying these changes, the 
observers detected not only a diurnal color change produced by 
a diurnal rhythm of melanin dispersion (causing darkening) , 
but also a supplemental tidal color change accompanying a tidal 
rhythm of dispersion. This latter tidal rhythm of darkening 
and blanching was closely related to the feeding periodicity 
and was in phase with the times of high and low tide of the 
crab's natural habitat. So true was this, that crabs collected 
from beaches that had tide times different from those of the 
location of the laboratory where they were observed, main- 
tained their rhythm of color dispersion in step with their former 

Although these diurnal and tidal rhythms held constant in 
the laboratory, they could, nevertheless, be " re-set " out of 
phase with the external solar and tidal times by exposing the 
animals to very low temperatures or to continuous illumination 
over a period of several days. The crabs would then keep the 
regular twenty-four hour cycle and the twelve and one-quarter 
hour cycle, but with a six-hour lag. Thus, instead of beginning 
to darken at six o'clock in the morning, the crabs would begin 
to darken at noon, blanching not at six o'clock in the evening, 

^ Frank A. Brown, Jr., Milton Fingerman, Muriel I. Sandeen and H. M. Webb, 
" Persistent Dirunal and Tidal Rhythms of Color Change in the Fiddler Crab, Uca 
pugnax," Jour. Exp. ZooL, CXXIII (1953) , 29-60. 


but at midnight. This ability to be " re-set " constitutes an 
advantageous adaptive characteristic for the species, making it 
possible for the beginning time of the cycle to be varied in 
harmony with changing physical conditions depending, for 
example, on location. 

Besides rhythms of pigment change, still others were observed 
correlated to the feeding habits of the fiddler crab. Among 
these were the change in rate of oxygen consumption and in 
running activities. With respect to the first, crabs and other 
organisms kept in sealed respirometers showed a daily varia- 
tion in oxygen consumption which coincided with the crab's 
natural feeding times. With respect to the second, wires 
attached to the legs of crabs contained in vessels of seawater 
and connected to mechanical recording devices registered a 
daily fluctuation in activity which coincided with the diurnal 
and tidal running times of the free fiddler crabs on their native 

Rhythms were likewise observed in such diverse organisms 
of the plant kingdom as potatoes, carrots and the seaweed, 
Fucus. Here, too, even when the humidity and barometric 
pressure were considered to be successfully maintained at a 
constant level by the experimenters, there continued to be 
observed a regular pattern of increase and diminution in the 
rate of oxygen consumption for a number of organisms. These 
observations, more than any others, led to the formulation of 
hypotheses indicating that some kind of " information," some 
kind of stimulus, undetected by the observers, was getting 
through to the isolated organisms. The possible roles of ioni- 
zation of air and of various components of cosmic radiation as 
transmitters of this " information " are now under investigation. 
Recent work appears to offer something in the nature of sub- 
stantiation of these explanations. 

This shift of attention to outside " information," outside 
stimuli, marks an interesting new departure. In contrast to the 
tendency to consider each organism as an isolated entity, it 
suggests that outside stimuli, emanating (in the case of cosmic 


radiation) even from outer space, may possibly have a deter- 
mining role in the rhythms of terrestrial organisms. The 
mechanism, or mode according to which these various rhythms 
function has been studied by a number of biologists and bio- 
chemists. Their results indicate that such rhythms as color 
change are due to the action of hormones on the chromatophores 
(pigment organs) in the skins of the crabs and other animals 
studied.** There is evidence in some cases to show that the hor- 
mones themselves are produced consequent to stimuli deriving 
from the central nervous system which has first been stimulated 
by light from without.' When the pigment, under the action 
of the hormones, is dispersed in the chromotophores, the skin 
has a dark color, depending on the color of the pigment; when 
it is undispersed and concentrated, the skin is paler. In addi- 
tion, a kind of mid-w^ay system, the neuroendocrine system, 
has been found to function in many activities which are 

The tendency to look for the basic answers as emanating 
from physico-chemical forces internal to the organism leads 
the biochemist and the dissecting endocrinologist closer and 
closer to the test tube and, it would seem, further and further 
from the actual organism as an entity. In keeping with this 
investigative approach, the persistent rhythms detected in 
organisms were first thought of as produced by purely internal 
processes, by " endogenous clocks." The organisms were pos- 
tulated as possessing inherited mechanisms for the rhythmic 
behavior observed, these " clocks " being considered as running 
on their own frequencies, unaffected by outside environment. 

* Muriel I. Sandeen, " Chromatophorotropins in the Central Nervous System of 
Uca pugilator, with Special Reference to their Origin and Action," Physiol. ZooL, 
XXIII (1950) , 337-352. 

'' Frank A. Brown, Jr., H. Marguerite Webb and Muriel I. Sandeen, " Differential 
Production of Two Retinal Pigment Hormones in Palaemonetes by Light Flashes," 
Jour. Cell and Comp. Physiol., XLI (1953) , 123-144. 

® Francis G. W. Knowles, " The Control of Pigmentary Effectors," in Comparative 
Endocrinology (New York: Wiley & Sons, 1959) , ed. by Aubrey Garbman, pp. 223- 
232; Berta Scherrer, " The Role of Neurosecretion in Neuroendocrine Integration," 
ibid., pp. 134-140. 


It would now seem, however, that while it is true that 
organisms inherit regulatory apparatus, or " feed-back mech- 
anisms " which affect the observed rhythmicity, nevertheless 
these potential mechanisms require first of all to be " set off " 
by some external environmental factor which is functionally 
in the normal environment of the animal or plant. This appears 
in Pfeffer's studies of the so-called " sleep movements " of a 
certain species of bean seedlings. He found that if the seeds 
were germinated in the dark, and if the seedlings were kept 
in the dark, they did not show the " sleep movements." In 
the natural habitat these " sleep movements " consist in the 
drooping of the leaves during the night. Pfeffer could, by 
exposing his " sleepless " plants to a brief period of illumina- 
tion, cause them to assume the same " sleep movements " as 
the plants in nature. Even when returned to continuing dark- 
ness, the plants now persisted in a daily " sleep " rhythm, which 
consisted of a drooping of the leaves during a part of the 
twenty-four hour cycle. ^ 

Dr. William Brett has demonstrated instances similar to that 
of the light-triggered " sleep movements " of the bean seedlings 
in the case of the emergence of flies from their pupal cases. 
If kept through their developmental period in total darkness, 
the flies, whose normal emergence during the twenty-four hour 
cycle is at daybreak, emerge at any and all hours of the day. 
But when such dark-adapted larvae were illuminated at a given 
time with a single flash of light for a period as brief as one 
minute, the flies then emerged for days after from their pupal 
cases at exactly that same time in the twenty-four hour cycle. 
This light-flash was evidently a daybreak-substitute which 
triggered off the rhythmic emergence of the flies at the twenty- 
four hour intervals.^" 

As long as purely " endogenous " clocks, located at a nervous 

* W. Pfeffer, Abhandl. sacks. Akad. Wiss. Leipzig., Math.-Phys. Kl., XXX (1907), 
259, and XXXIV (1915) , 3. Quoted by F. A. Brown, Jr., Sdence, CXXX, No. 3388 
(1959), 1535. 

^^ Frank A. Brown, Jr., " The Rhythmic Nature of Animals and Plants," Cycles, 
XI (1960) , 87. 


and endocrine center, are postulated, with their mechanism 
to be explained purely by physico-chemical means on the 
internal molecular level, the horizon for investigation holds no 
great promise. With the introduction of hitherto disregarded 
or unknown external geophysical forces as possible motivators 
in the periodic physiological processes of animals and plants, 
however, a whole new perspective of research is opened up. 
This new dimension of inquiry and its implications are thus 
presented by Dr. Brown: 

The thesis supported by this article, namely, that during the timing 
of cycle-lengths of the rhythms in animals and plants in so-called 
" constant conditions " the organisms are still continuously receiving 
from the external environment information about the natural geo- 
physical cycles, removes some of the romantic glamor inherent in 
the alternative view that all living things must possess within them- 
selves uncannily accurate clocks capable of measuring, indepen- 
dently, periods ranging in length from the day to the year. On the 
other hand, its implications are tremendous with respect to the 
potentialities involved, through the demonstration that living things 
are sensitively responding to additional kinds of stimuli at energy 
levels so low that we have hitherto considered the living organisms 
completely oblivious to them. These latter potentialities may soon 
loom importantly in many areas of biology and medicine, especially 
in such problems as animal navigation and behavior. 

The demonstration that the physical environment of living things 
is organized temporally in terms of still unknown subtle and highly 
pervasive forces which the living organisms can resolve encourages 
one to speculate that there may be some comparable subtle and 
pervasive spatial organization of the environment which is con- 
tributing at least in a small way towards accounting for geophysical 
distribution or periodic migrations of organisms.^^ 

Dr. Brown was led to his conclusion concerning the con- 
tinuing reception by organisms of unobserved or unknown 
" information " from the external environment by the failure 
of his findings to support currently accepted " laws " in physi- 
ology which did not take such a factor into account. The first 
such finding was the discovery that many of the so-called 

" Ibid., p. 92. 


" persistent " rhythms in animals and plants were independent 
of temperature over wide ranges/' If the rhythms in question 
were purely chemical reactions, as many physiological processes 
are, then there should have been proportionate increases and 
decreases in the rates, for example, of color change, oxygen 
consumption, and activity in the fiddler crab consequent upon 
a raising or lowering of the temperature by ten degrees centi- 
grade. Yet this did not prove to be the case. The rhythms 
continued unaltered over several successive ten degree increases 
in temperature. In addition to this, still another finding con- 
tradicted the concept of purely chemical reactions as the sole 
explanation of observed periodicities, namely, the fact that 
these rhythms appeared to be immune to the action of drugs 
and poisons knowTi to interfere with many different physi- 
ological reactions, especially those involving enzyme activity. 
The mechanisms responsible for the rhythms, it would seem, 
must be regarded as something decidedly more than purely 
chemical reactions. 

A second unassimilable finding seemed to contradict the 
assumption of genuinely " controlled " conditions. Many inves- 
tigators w^ere led to postulate inherent, independent " clocks " 
in organisms because the rhythms continued in their periodicity 
under what were considered to be constantly controlled con- 
ditions of temperature, light, atmospheric pressure and other 
environmental factors. They accepted this explanation in spite 
of the fact that there were experimenters through the years 
who reported data that contradicted the idea of inherent, inde- 
pendent " clocks." Examples of such data, quoted by Dr. 
Brown, are the work of Stoppel in a basement in Iceland, 
Cremer in a deep salt mine in Germany and the two Hempels 
in Lapland. These experimenters showed that under very 
constant conditions of this kind the regular observed rhythms 
were in fact interfered with during the time of the mid-night 

^" Frank A. Brown, Jr., H. Marguerite Webb, Miriam F. Bennett and Muriel I. 
Sandeen, " Temperature-Independence of the Frequency of the Endogenous Tidal 
Rhythm of Vca" Physiol. ZooL, XXVII (1954), 345-9. 


sun/^ The investigators who discovered these very interesting 
exceptions claimed or implied that the rhythms in the bean 
seedlings or insects which they used, depended upon rhythmic 
changes in the environment which, in some manner, still per- 
vade all ordinary so-called laboratory contant conditions. 

Dr. Brown's own observations of an interference in the 
rhythms of oxygen consumption by organisms which correlated 
with changes in outside barometric pressure constituted for 
him the recognition that not only geophysical, but even cosmic 
forces have a governing external influence on the rhythms of 
terrestrial organisms. He states that it was the rhythm in 
oxygen consumption of organisms matching changes in baro- 
metric pressure which led him to consider cosmic radiation as 
a possible factor in the periodicities. Evidence has now been 
obtained to show a definite relationship between the metabolism 
cycles of several organisms and certain fluctuations in cosmic 
radiation.^* Dr. Brown also showed that fiddler crabs exhibit 
a measurable response in the state of their pigmentary systems 
to alterations in the intensity of cosmic ray showers by shield- 
ing the animals with varying thicknesses of lead sheets.^^ 
Other possible factors suggested are the differences of potential 
between the earth and the ionosphere and the various magnetic 

There is good likelihood, judging from the known simultaneous 
influence of such forces as light, temperature and tactile stimuli, 
that if these organisms possess the capacity to respond to one type 
of these relatively low-energy, or diffuse, types of environmental 
stimuli such as are implied by these results [correlation between 
oxygen consumption in organisms and the barometric pressure], 

^^ Frank A. Brown, Jr., " The Rhythmic Nature of Animals and Plants," Cycles, 
XI (1960) . 87; and "An Exogenous Reference-Clock for Persistent Temperature- 
Independent, Labile, Biological Rhythms." Biol. Bull., CXV (1958), 81-100. 

^* Frank A. Brown, Jr., H. M. Webb and M. F. Bennett, " Comparisons of Some 
Fluctuations in Cosmic Radiation and in Organismic Activity During 1954-1955 and 
1956," Am. Jour. Physiol., CXCV (1958), 237-243. 

" Frank A. Brown, Jr., H. M. Webb, M. F. Bennett and M. I. Sandeen, " Evi- 
dence for an Exogenous Contribution to Persistent Diurnal and Lunar Rhythmicity 
under So-called Constant Conditions," Biol. Bull., CIX (1955), 238-254 


they also possess the capacity to respond to a complex of them. 
Supporting such a multiple-factor view is the fact that the forms 
of the rhythms and their monthly variations appear to correlate 
to some extent with the barometric pressure, but at the same time 
have large significant variation at some times of the day and month 
that show little indication of any correlation with pressure.^® 

It was, in effect, the irregular, unexplainable deviations of the 
rhythms that led the investigators, not to discard their data 
as being impossible, but to look for a more primary, or ultimate 
cause of the effects observed. By checking the available meteor- 
ological data, they concluded that living organisms are very 
sensitive to influences from outer space in the form of compo- 
nents of cosmic radiation. These conclusions led the scientists 
to more exciting and fruitful discoveries than had resulted 
previously from more than twenty years of research. 

Dr. Brown's researches point, then, to outside, even extra- 
galactic, influences in the behavior of living organisms, as noted, 
for example, in a periodicity in terrestrial organisms related 
to the occurrence of sun spots, with a variation in color change 
which is affected by the intensity of cosmic radiation. 

One might ask what is so extraordinary about the perception 
that terrestrial organisms are influenced in their behavior by a 
heavenly body such as the sun, or even by cosmic rays ema- 
nating from some unknown source .^^ The effect of the sun upon 
the growth and life cycle of living things is common knowledge. 
More than merely confirming the fact of extra-terrestrial influ- 
ence. Dr. Brown's discoveries clearly demonstrate an order, and 
— in view of the factors studied — an order on a cosmic scale. 
Order is implicit in rhythm, for rhythm presupposes a com- 
bination of variation with constancy. In other words, for 
events to re-occur with a certain regular periodicity, there must 
be a certain fixed pattern beyond the reach of chance which is 
the " clock " for these events; this supplies the " programming." 

The regular periodicity observed by Dr. Brown and his 
associates, a periodicity which, with continuing investigation, 

" Ibid., p. 253. 


appears to be related to causal factors on a more and more cos- 
mic scale, certainly suggests the presence of a real entity or enti- 
ties moving in a constant manner in such a way as to cause 
periodic variation. The hypothesis of ultimate regular motions 
in the universe causing a regular periodicity is, as is known, 
that of Aristotle and St. Thomas Aquinas. This hypothesis 
attempted to explain the simultaneous effect of constancy and 
periodicity as derived from the perpetual, regular, apparent 
motion of the heavenly bodies such as the fixed stars and the 
planets; the periodicity in terrestrial organic life was thought 
to be caused by the apparent northerly and southerly variations 
of the sun and the planets in the zodiacal circle. It should be 
noted that this hypothesis, already in St, Thomas' day, had 
extended beyond the limit of the fixed stars in seeking to locate 
the ultimate corporeal source of cosmic motion, for the detec- 
tion of the precession of the equinoxes required the positing 
of a further motion beyond that of the fixed stars. 


^'^ " From the perpetuity of generation [Aristotle] concludes to the perpetuity of 
celestial motion. . . . He concludes that if something remains the same throughout 
the course of generation, it is necessary for something to remain numerically always 
the same, acting in the same way, in order to cause perpetuity. But nothing in the 
realm of generation and corruption could be a cause of the perpetuity which is found 
in generation and corruption, since none of these things exist always, nor could all 
of them taken together be such a cause, since they do not all exist at one time, 
as is shown in Physics VIII. It remains, therefore, that there must be some 
perpetual agent which acts continuously in a uniform way to bring about perpetuity. 
And this is the ' first heaven ' which moves and resolves all things by a diurnal 

" But since that which continuously acts m the same way solely causes an effect 
which remains constant, while in those things which are generated and corrupted 
there appear effects which do not always remain constant since at one time they are 
generated and at another time corrupted, it is therefore necessary, if there is to be 
generation and corruption in the lower [i. e. terrestrial] beings, to posit some agent 
which varies in its activity. And this agent he states to be the body which moves 
in reference to the oblique circle called the Zodiac. 

" Since this circle declines in both directions from the equinoxial circle, it is 
necessary that the body moving in a circle through the Zodiac be sometimes nearer 
and sometimes farther away, and for this reason it causes contrary effects by its 
nearness and farness. We indeed perceive that those things which are generated as 
the sun approaches are corrupted when the sun recedes, for example, the various 
herbages which come forth in the spring and dry up in the fall. The sun and the 


Needless to say, in considering the suppositions of Aristotle 
as expounded by St. Thomas, it is not a question of urging 
their literal acceptance, since even their authors did not con- 
sider them to be demonstrated.^* Rather it is a matter of 
considering them from the standpoint of their general intellec- 
tual approach, an approach which accords well, for example, 
with findings indicative of universal cosmic rhythms making 
themselves felt in the periodicity of terrestrial organisms, since 
it is an approach sensitive to the over-all rhythmicity of the 
universe felt even in the smallest details of earthly life. This 

other planets move indeed through the zodiacal circle, but the fixed stars are said 
to move around the zodiacal poles, and not around the equinoxial poles, as Ptolemy 
shows. From the motion of these there is caused the generation and corruption of 
all things generated and corrupted, but this is more evident in the case of the 
motion of the sun." St. Thomas, In XII Metaph., lect. 6, nn. 2510-11. 

In another place St. Thomas explains: " One must consider that in the time of 
Aristotle there had not been detected the motion of the fixed stars, which Ptolemy 
sets down as moving from west to east around the poles of the Zodiac at the rate 
of one degree every hundred years, in such a way that a full revolution of the 
Zodiac is completed in thirty-six thousand years." (In II De caelo et mundo, 
lect. 17, n. 7) This is the precession of the equinoxes which today is computed as 
twenty-six thousand years. From the point of view of apparent motion, the fixed 
stars in the various constellations of the Zodiac are in the course of a precession 
from west to east in such a way that the vernal equinox, which several thousand 
years ago took place when the sun was in Aries, now takes place, due to this 
apparent motion of the signs from west to east, in the previous sign, that of Pisces. 
At the present computation the rate of precession would be about 1.4° per hundred 
years. St. Thomas then concludes: " Therefore the ancients laid down the sphere 
of the fixed stars to be the first moving body, and to have only one motion, which 
is the diurnal motion. But on the supposition that the fixed stars move, it is 
necessary for this sphere to move with two motions, namely its own proper motion, 
which is that of the fixed stars, and the diurnal motion, which is that of the 
supreme sphere which is without stars." (Ibid.) I wish to express my gratitude to 
Father Pierre Conway, O. P. for pointing out and translating these and subsequent 
passages from St. Thomas. 

^® " These matters into which we inquire are difficult since we are able to perceive 
little from their causes and the properties of these bodies are more remote from our 
knowledge than the bodies themselves are distant from us in a purely spatial way." 
(Ibid., n. 8) Speaking of the number of planetary motions, St. Thomas says, " We 
shall state what the mathematicians have to say about this. . . . Whatever remains 
unstated, however, shall have to be investigated by ourselves or taken on the 
authority of those who investigate such things or developed later from the facts 
now stated by those who treat these matters." (In XII Metaph., lect. 9, n. 2566) 


point of view is aptly summarized in the celebrated statement 
of Aristotle, " Man is begotten by man and by the sun as well " 
{Physics, II, 194 b 10) ." 

There is a further point of contact in which the observed 
results of natural rhythms and the conclusions of the 'phi- 
losophia perennis would seem to be in accord: the recognition 
of a basic order in the universe. One is not compelled, what- 
ever the urgent extrapolations of the materialist, to accept the 
order observable in a single organism as the result of random 
combinations over a period of billions of years. There is even 
less cogency in the assertion of random events as the cause of 
order when that order involves not the internal mechanism of 
a single organisms, but a whole cosmic network in which the 
individual is seen as a single note pulsating in rhythm with a 
very real " harmony of the spheres." One might accept the 
possibility that a simple melody could result from the random 
spattering of ink on lined paper. Equivalently, by the assertion 
of randomness, one is asked to accept a completely orchestrated 
score of the Jupiter as the result of the same process.-" 

The detection and measurement by the experimenters cited 
of what might be called " cosmic rhythms " is an affirmation 

^' " It is necessary according to the Philosopher to lay down some active mobile 
principle which by its presence and absence would cause variability as to generation 
and corruption in the lower bodies — and such a principle is supplied by the heavenly 
bodies. And therefore whatever, in these lower bodies, generates and moves towards 
specific form acts as an instrument of the heavenly bodies, as in the statement 
that man is generated by man and by the sun as well." Sum. TheoL, I, q. 115, a. 3 
ad 2. 

^** In the dry terms of formal logic, the argument for the chance origin of life from 
the inorganic by random events involves two cases of petitio principii and one of 
the fallacy of consequence. The question is begged first in the assumption that life 
could come from non-life, prescinding from time and any instrumentality. This 
remains to be proved experimentally. It is begged again in the assumption that this 
origin is from chance, and from chance alone. But, by definition, a chance event 
need never happen. 

The fallacy of consequence (If p, then q; but q, therefore p) is involved in the 
argument: If a random event were possible and did take place, then we would have 
living organisms today; but we have living organisms today: therefore. . . . Such 
an inference would be vaild only if it were the only possible inference, but this is 
clearly not the case. 


of order, for rhythm is a species of order. Taking order as 
" the sequence of one thing upon another according to some 
principle," the solar, lunar, tidal (and possibly extra-galatic) 
rhythms of organisms are instances of order. Events in these 
organisms are observed to repeat themselves at certain inter- 
vals: these rhythmic intervals express the principle involved. 

What is the source of this order? There is no theoretical 
reason, nor any experimental data, to hint that the cosmic 
order implied by the rhythms must be the result of random 
events. Rather there is implied what sound science implies in 
all its searchings: the presence of an intelligent and intelligible 
pattern in the uni verse. ^^ 

The discovery of order as in the rhythmicity of fiddler crabs 
and other organisms, far from granting any substantiation to 
the theory of random beginnings, militates strongly against it. 
The tendency of these findings is to suggest, not that the 
observed order is the result of chance, but rather that what 
was thought to be chance is seen to be more likely an aspect 
of order. Thus the interruption of periodicity in fiddler crabs, 
at first considered a random event, later seemed more likely 
to be, when a simultaneous variation of sunspots was learned 
of, an instance of the influence of a certain rhythmicity hitherto 
not considered by the researchers. This is scarcely astonishing, 
for events which may appear to be random to one considering 
only particular causes in a limited range, may be seen to be 
co-ordinated when one becomes conscious of a broader picture."" 

"^ Writers as diverse as Einstein and Aquinas are agreed on this. The familiar 
" Der Herr Gott ist raffiniert, aber boshaft ist er nicht " can be compared with St. 
Thomas' commentary on the Aristotelian dictum, "Art imitates nature." (Phys., II, 
194a20) " The reason why art imitates nature" say St. Thomas, " is that the prin- 
ciple in the activity of art is knowledge. But all our knowledge is received through 
the senses from sensible and natural things; whence we operate in artifacts according 
to the likeness of natural things. But the reason why natural things are imitable by 
art is that the whole of nature is ordered by some intellective principle to its end, 
in such a way that the work of nature is perceived to be the work of an intelligence, 
as it proceeds through determinate means to certain ends, which process art indeed 
imitates in its operation." In II Phys., lect. 4, n. 6. 

*" " It is plain that effects as related to some lower cause appear to have no order 
to each other, but to coincide accidentally, which, if they are referred to a higher 


The experimental determination of rhythmicity indicates a 
more cosmic and universal, rather than a particular base. Such 
indications point away from theories of a random origin of 
organized life, and towards the conviction of a cosmic order 
in which random events have their part simply as normal 
deviations from the rule in a lesser number of cases. Order is 
not known to be the "per se product of chance, and need never 
occur from it. Order does occur from intelligence, as the 
products of human intelligence show. Sound science may well 
suppose a supreme intelligence behind the events of nature. 
Such an intelligence can be demonstrated (though not experi- 
mentally) to be necessarily immaterial, infinite and personal. 

But, the cautious inquirer may ask, could not one suppose 
even the final cosmic, supreme order to be possibly the result 
of chance.? No, for chance cannot be conceived as anything 
other than an exception to order. The supposed supreme 
chance configuration presupposes a more extensive order of 
which it is an exception of lesser degree. Whoever speaks of 
chance implies, whether he acknowledges it or not, an even 
more primordial " order." 

The fascinating researches and challenging results of talented 

comiron cause, are found to be ordered to each other, and not conjoined acci- 
dentally, but simultaneously produced by one fer se cause. If the flowering of this 
herb or that, for example, is referred to a particular force which is in this plant or 
the other, there appears to be no order of one to the other; rather it appears to be 
accidental that when this plant blooms, the other blooms also. And this is because 
the cause of the power of this particular plant extends to the flowering of itself, 
and not to that of another; whence it is indeed the cause that this plant should 
bloom, but not that it should bloom simultaneously with the other. But if reference 
is had to the power of the heavenly body, which is a common cause, the event is 
found to be not accidental, namely that when this flower blooms, the other should 
bloom also, but to be ordered by some first cause ordaining this, which simul- 
taneously moves both herbs to florition." St. Thomas, In VI Metaph., led. 3, 
nn. 1205-6. 

The consideration of angelic knowledge throws light on this conclusion: " The 
angels know all natural causes. WTience certain things which appear contmgent and 
to be accidental when some of their causes have been considered ai-e recognized to 
be necessary by the angels, since they know all the causes involved." St. Thomas, 
De verit., q. 8, a. 12. 


scientists such as Dr. Brown confirm one's opinion of the pro- 
found insights of the perennial philosophy of nature. One 
becomes convinced that a thorough familiarity with the Aris- 
totelian-Thomistic synthesis does not remove one from the 
scientific world of today. It serves rather to put one in tune 
with its most fruitful explorations, as indicated by the direction 
of the findings of Dr. Brown and his colleagues. Far from 
erecting mental blocks, a knowledge of Aristotle and St. 
Thomas can serve only to provide the Catholic scientist with 
thrilling and stimulating perspectives which, while awakening 
a researcher's curiosity, point and beckon towards the First 

Sister Margaret Ann, 0. P. 

College of St. Mary of the Springs, 
Columbus, Ohio. 



MAN lives in a fascinating, kaleidoscopic world, and the 
microcosm that is man is itself a wonderful complex 
of the changing and the abiding. There is constant 
change at every level of his physical and psychological make- 
up. Yet behind this ever-changing phenomenon there is a 
permanent substratum, a human person who undergoes these 

Careful studies have shown that there is a constant turnover 
of much of the body's chemical components. On the neuro- 
physiological level the pulsating brain has been called " an 
enchanted loom where millions of flashing shuttles weave a 
dissolving pattern, always a meaningful pattern, though never 
an abiding one; a shifting harmony of sub-patterns." ^ On 
the chemical level the unending array of mobile patterns is 
well known to biochemists. On the level of man's conscious 
life the constant flux is even more evident: sensory images, 
ideas, desires and emotions tumble over one another in rapid 
succession. The facts of change are so constant and obvious 
as to lead many to doubt the reality of anything permanent. 
Some scientists wonder whether there really is such a thing as 
a -person, for they point out that even the so-called person 
seems to undergo marked changes, sometimes to the point of 
developing a psychosis. Schizophrenia, for example, suggests 
a split of personality. The schizophrenic reveals himself as one 
having a dual personality, at one time revealing the behavioral 
pattern of one personality, and at other times manifesting an 
entirely different personality. But, we may ask, is this a true 
split of the person"^ 

^ C. S. Sherrington, Man on His Nature, 2nd ed. (Garden City: Doubleday, 1953) , 
p. 184. 



It is clear that the psychologist and the ontologist do not 
mean the same thing when, they employ the words " person " 
and " personality." The psychologist, on the one hand, looks 
for thought, emotion and habit patterns which lead to a con- 
sistent and predictable behavior. These for him constitute the 
" psychological person." The ontologist, on the other hand, 
perceives the ontological oneness, even the uniqueness, of an 
existing reality which remains unchanged ontologically through- 
out the constant physical and psychological variations. This 
existential reality, the ontological person, under certain con- 
ditions is capable of manifesting itself differently, not because 
of any radical change in its being, but because of modifications 
in its bodily or mental life. The " person " ontologically under- 
stood is the subject in which the changes occur. It remains 
identically itself throughout aberrations of mind and body. 
The ontological person, therefore, is the fundamental reality 
which originates with conception (or shortly thereafter) and 
remains unchanged until death. Obviously the behavioral 
changes associated with mental illness occur in the ontological 
person, but they are changes oj the psychological person. 
Hence, a schizophrenic is one being, one rational, existent being, 
manifesting more than one emotional and behavioral pattern. 

The ontological person is an autonomous totality composed 
of numerous interdependent functional parts. All the parts live 
by the same life, the unique life of the person, and yet each 
part has its distinctive vital function. Certain functional parts 
are so thoroughly dependent upon others that the distinctive- 
ness of specific functions and parts is not infrequently called 
into question. 

One important problem much discussed today and in the 
past concerns the relation of the mind to the brain. Is the 
mind, as some insist, nothing more than the brain in its func- 
tional capacity.f^ If so, is an injured brain the same as an 
injured mind.f^ Or is the mind a reality distinct from the brain.? 
If so, how do they interact in normal thought, and where is 
the failure causing mental disease.? These and other related 


questions are acute issues today.- In particular, the question 
of the relation of biochemistry to behavior has special relevance 
to the basic issue. If the mind is a reality distinct from the 
brain, how does a chemical compound interact with it? And 
if mental illness is nothing but a malfunctioning of the brain 
(whose function is ultimately dependent upon molecular ac- 
tivity) , how can psychotherapy, that is, a non-chemical treat- 
ment, be effective in reversing an abnormal brain biochemistry? 

The Mind-Body Problem 

Since man first began to philosophize, the precise relation 
between his thinking mind and his tangible body has been 
considered an important problem. Sage, savant and poet, have 
offered explanations, sometimes fundamentally opposed, some- 
times only differently expressed. Plato has left us the metaphor 
of the soul as a charioteer to the body's chariot; Descartes' 
dichotomy of matter and spirit leads to an angelism and a 
division even wider than Plato's. The biologically based solu- 
tion of the Aristotelian tradition has been poetically expressed 
in Gerard Manley Hopkins' " man's spirit is flesh-bound when 
found at best." The materialist solution of dialectical material- 
ism eliminates the problem by calling mind a manifestation of 
matter in motion. We will examine in a subsequent section 
some of the contemporary data and hypotheses concerning 
the relation of biochemical disturbances to abnormal mental 
behavior. Reflection on the data to be presented may help to 
shed some light on the important problem of the mind-body 
relationship. Physiological principles can be introduced as 

Descartes' attempt to establish a philosophy on his Cogito 
ergo sum has made the mind-body problem an insoluble one. 

^S. Kety, "A Biologist Examines the Mind and Behavior," Science, CXXXII 
(1960) , 1861-70; H. W. Magoun, " Early Development of Ideas Relating the Mind 
and the Brain," in CIBA Foundation Symposium, Neurological Basis of Behavior 
(London: Churchill, 1958), pp. 4-27; W. G. Walter, "Adolf Meyer Research Lecture: 
Where Vital Things Happen," American Journal of Psychiatry, CXVI (1960), 673- 


By starting with a subjective foundation for his philosophy, 
Rene Descartes was never able, nor was anyone else able, to 
leave the subjective domain. The objective world of sense 
was forever beyond the reach of mind, and mind beyond the 
reach of sense. His conception of the human soul as something 
so distinct and separate from the living body as to be indepen- 
dent leaves the body and soul two complete entities. It is no 
wonder that physiology and mechanistic psychology soon found 
no place for the ghostly, angelic Cartesian ' soul.' 

A certain parallelism between mental thoughts and physical 
mechanics was taught by Descartes, and a limited influence 
of the mind on body was allowed through the pineal gland. 
Leibniz, however, could see no reason for this limited influence 
of mind on matter, since the two entities were completely 
diverse in nature. Consequently the only parallelism open to 
Leibniz was a harmony between these two, pre-established by 
God. This parallelism was put into a scientific context by the 
psychologists Fechner and Wundt. 

Among modern neurophysiologists, J. C. Eccles, a professed 
Cartesian, has given much thought to the mind-brain problem.^ 
Eccles, following the lead of other investigators,* develops the 
notion that brain and mind liaison takes place primarily in the 
cerebral cortex. According to him this liaison is possible only 
when there is a high level of activity in cerebral tissue. To 
avoid possible misunderstanding Eccles distinguishes the action 
of the mind, or will on the brain from the reverse action of 
the brain on the mind (perception) . He conceives the mind 
as acting on the brain by virtue of the latter's " critically poised 
neurones " which act as hypersensitive detectors of " minute 
spatio-temporal fields of influence " emanating from the will. 
The brain-to-mind action is explained by assuming that the 
spatio-temporal patterned activity of the cerebral cortex can 

^ J. C. Eccles, The Neurcyphysiological Basis of Mind (Oxford: Clarendon, 1953) , 
pp. 261-86. 

* E. D. Adrian, The Physical Background of Perception (Oxford: Clarendon, 
1947); C. S. Sherrington, op. cit. 


act on the spatio-temporal patterning of the mind. There is, 
so to speak, a two-way street: the cerebral detectors can also 
act as transmitters so that the mind can both influence and 
be influenced. 

Eccles' philosophy of mind and brain has not been widely 
accepted. In the first place, it is still a mechanical explanation. 
The mind is assumed to operate on the brain in the same way 
as the brain operates on the mind. In other words, his view 
ascribes to the mind a mode of activity which is proper to 
material things. Descartes at least admitted a real difference 
between thought and mechanics. In the second place, even 
as a physical type of ghost the * mind ' in Eccles' view is still 
too remote from cerebral activities. There is only one life by 
which the mind and brain function. The realistic explanation 
must somehow account for the real unity of life as well as for 
the apparent difference between thought and cerebral physi- 
ology. Descartes' dichotomy between spirit and matter has at 
least some grounds of intelligibility, but Eccles' dichotomy 
between a materialistic mind and neurophysiological activity 
is devoid of all intelligibility. Finally, an adequate resolution 
of the mind-body problem must allow the mind to act according 
to its non-material nature, explaining simultaneously the on- 
tological unity of the person and the diversity of thought and 
physiological changes. 

To date the only adequate solution to the mind-body problem 
is the one suggested by Aristotle and Galen, and developed 
throughout the centuries even to our own day. The solution 
can be called adequate because it does in fact explain the 
ontological unity of the living being and at the same time 
accounts for the immaterial nature of thought and the effect 
of biochemical changes on the psychological person. The Aris- 
totelian view, commonly called the hylomorphic theory, can 
easily be misunderstood. If it is misunderstood, the hylo- 
moi-phic theory offers no real solution at all; in fact, it might 
even be an obstacle to a real solution. 

First it is important to note that according to the Aristotelian 


view the soul and body are not two distinct entities, that is, 
they are not two actual wholes. Two distinct entities could 
never make up one ontological person. There would have to 
be the Cartesian dichotomy of a navigator in a ship, a driver 
in an auto, a prisoner in his cell. It was Descartes' failure to 
appreciate the potential nature of the body with respect to the 
living principle that led to the dichotomy. The converse is 
likewise true: it was Descartes' failure to appreciate the acti- 
vating nature of the soul that led him to conceive the soul as 
an isolated reality. Although the words " soul " and " body " 
suggest two distinct existents, they are not to be so understood, 
if a solution to the problem is to be reached. 

Reflection on this point can be developed in two ways. First, 
the word " body " is really not the same when applied to a 
living body and to a corpse. The living body not only functions 
differently from a corpse, but it is different; it is living. One 
might admit a remote similarity between a living body and its 
corpse; it is indeed a commonly understood manner of speaking 
to call both " bodies." But it would be absurd to identify the 
living body with the mass of matter which remains after death. 
It might be objected, however, that nothing is discoverable 
in the living body which is not also in the inert mass of the 
corpse. It is true that if a chemical analysis were made imme- 
diately after death or with some means guaranteeing preserva- 
tion from corruption, the same chemical compounds would be 
found, with the possible exception of extremely labile com- 
pounds such as adenosine triphosphate (ATP) or creatine phos- 
phate. But a physical or chemical similarity is not the same 
as biological similarity. Biologically a living organism func- 
tions; a dead one does not. This should suggest that life cannot 
be identified with chemical activity. Furthermore, even chemi- 
cal similarity will gradually diminish as the analysis is made 
further removed in time from the instant of death. This seems 
to indicate clearly that the principle of life, whatever one calls 
it, is responsible for the unity and identity of the living 


A second line of reflection leads to the relationship between 
body and the principle of life. If organic activity is possible 
only when life is present, then the principle of life is not separate 
from a living organism. In fact, it is by reason of the life- 
principle that the body is living and biologically organic. In 
other words, the life-principle activates the matter in giving 
it organic life and unity of being. In this context, the material 
mass of the body and the chemical compounds are recipients 
of activation; they are capacities, potentialities for actual life. 
When Aristotle designated this ' matter ' as a passive capacity, 
it was in relation to the activizing principle of ' form.' Just as 
human life cannot be understood except in relation to an 
organism, so an organic body cannot be understood without 
reference to the life-principle, commonly called a soul. It would 
be absurd to think that the soul is some kind of unknown 
chemical substance. Rather the soul is that by which every 
chemical compound in an organism is living. Hence it is futile 
to search for a ' soul ' through chemical analysis. 

Second, it is important to note that there are important 
differences between a human soul and a purely animal soul, 
even though both are life-principles informing a highly complex 
organism. The principle of human life performs functions, such 
as thinking, willing, idealizing and reflecting, which are not 
limited to space-time patterns. This is not to say that thinking 
and willing are activities performed outside of space and time, 
but only that they are not limited as sensations and emotions 
are. In the Aristotelian tradition this transcendence of thinking 
and willing shows the spiritual nature of mind and will. The 
non-limited behavior of mind and will is, of course, derived 
from the same life-principle which animates the human body. 
Consequently the single life-principle in man is the unique 
source of both organic life in the body and of mental life trans- 
cending the limitations of space-time patterns. There can be 
no doubt that man's soul is an extraordinary type of reality: 
it animates an organic body, yet its nature and functions are 
not entirely limited to the biochemistry of the body. 


Now, how does this relate to the mind-body problem? Simply 
that the human life-principle is the source of both cerebral 
activity and mental activity, inasmuch as none of these activ- 
ities is manifest in a corpse. Granting the essential difference 
between cerebral activity and mental activity, it would be a 
serious misconception to conceive their interaction after the 
manner of two physical beings, e. g., as two chemical com- 
pounds, or as an electromagnetic wave reacts with an appro- 
priate detector. The reciprocal influence of mind and brain is 
altogether unique and any attempt to understand its nature 
must take cognizance of this fact. 

Limiting these reflections further, we may ask, how then does 
this bear on the problem of mental health and disease? There 
is no doubt that the living body has an important role in these 
matters, since injury to the physical organ, the brain, results 
in some aberrations of mental and emotional activity of the 
living person. Obviously the brain does not and cannot func- 
tion in the absence of the life-principle. It is true that chemical 
reactions, electrical currents and enzyme activity, precisely as 
such are not living, for they can be produced outside a living 
body. However, in a living body they are concurrent, con- 
comitant with the activity of the life principle and are directed 
to the functional integrity of the whole organism. The mind 
in its operation needs the brain. Every thought not only has 
some echo in the brain tissue, but in the present condition the 
mind is dependent on the brain as on an instrument. Clearly 
if something is awry in the physical apparatus, the instrument, 
the mind is to that degree impeded in its normal function. 

The brain is not simple in its structure or function. Although 
the brain is spoken of as a single organ, and sometimes even 
thought of as having a single function in much the same way 
as the heart is said to pump blood, in actuality it is extremely 
complex.^ This complexity is due not simply to the ten thou- 
sand million or more neurons which are part of its composition, 

^ J. Papez, " Neuroanatomy," in American Handbook of Psychiatry, ed. Silvano 
Arieti (New York: Basic Books, 1959), pp. 1585-1619. 


but also to the nerve cells which happen to be arranged in 
certain groups or patterns. Anatomically these patterns are 
regions such as the cerebral cortices, the cerebellum and a 
number of sub-cortical structures. Refined observation reveals 
that the neurons are often grouped in smaller functional areas, 
or units called " nuclei," Chemical studies of the brain reveal 
regional differences both qualitative and quantitative that may 
be reflective of functional heterogeneity. 

Even if direct experimental evidence were not available, one 
could conclude on other grounds that the brain displays some 
localization of function. The functions of the brain are nu- 
merous, as evidenced by the sensory functions of the mind; 
and a multiplicity of simultaneous functions requires a mul- 
tiplicity of parts. Increasing complexity of activity requires a 
corresponding increase of material parts, though not necessarily 
in a one-to-one relationship of part to function. Now, since 
there is a multiplicity of organic parts, these parts must occupy 
different places in the brain. In other words, there must be a 
spatial organization of parts, not haphazardly disposed, but 
according to the operational dependence obtaining among them. 
It follows, then that a nmltiplicity of functions, requiring a 
plurality of parts, will require a localization of these functions. 
By this is meant that particular functions will be associated 
with certain anatomical areas and perhaps even with bio- 
chemical topography. Nevertheless, there is at times consider- 
able overlapping. 

Over the years, our knowledge of localization of functions 
has become more precise.'' (Yet this is not to deny that in 
certain activities the whole brain apparently is involved.) The 
mass of material which has accumulated has been authorita- 
tively and comprehensively reviewed in three volumes of a 
recent publication.^ The various projection areas for motor or 

* R. W. Gerard, " Neurophysiology, Brain and Behavior," in S. Arieti, op. cit., 
pp. 1620-38. 

^ J. Field, Handbook of Physiology, Sect. I, Neurophysiology (Washington: Am. 
Physiological Soc, 1959-60) . 


sensory activities have been known for some time. But the cor- 
responding secondary areas are a more recent discovery. Much 
of our earlier knowledge regarding localization of brain function 
was derived from accidental injuries to the human brain. 
Thus, for example, cerebral vascular accidents (" strokes ") may 
lead to paralysis of limb or speech. Recent experimentation 
with animals has sought to determine functional centers in 
the brain by electrodes. These are permanently implanted in 
specific areas of the brain, mild electrical stimulation is applied, 
and the behavior pattern of the animal is observed.^ An alterna- 
tive procedure is to allow the animal to determine whether or 
not it is to be so electrically stimulated.® From such experi- 
ments it has been concluded that certain areas are " rewarding 
centers " since the animal would repeatedly stimulate itself in a 
seeming orgy of " pleasure " until it became physically ex- 
hausted several hours later. Similarly in the same general areas 
but at different specific points there have been discovered 
centers which mediated punishing effects since the animal would 
refrain from restimulation.^° Other studies involving experi- 
mental destruction of specific nuclei of the hypothalamus 
revealed centers which were apparently concerned with hunger, 
anger and the sex drive.^^ These and other data have now 
established the existence of functional centers in the brain for 
drives and emotions as well as for motor and sensory activities. 
Electrical stimulation of exposed temporal lobes of conscious 
human subjects during neurological procedures has contributed 

* W. R. Hess, Diencephalon: Autonomic and Extrapyramidal Functions (New 
York: Grune & Stratton, 1954). This work is a comprehensive EngHsh resume of 
his original contributions which were reported in detail in Das Zwischenhim (Basel: 
Schwabe, 1949) and in Die junktionelle organization des vegetativen N ervemysteme 
(Basel: Schwabe, 1948). 

* J. Olds and P. Milner, " Positive Reinforcement Produced by Electrical Stimu- 
lation of Septal Area and Other Regions of the Rat Brain," Journal of Comparative 
and Physiological Psychology, XLVII (1954), 419; J. Olds, " Self-Stimulation of the 
Brain," Science, CXXVII (1958), 315-324. 

^^ J. Olds, op. cit., pp. 317-324. 

^^ W. R. Hess, Hypothalamus und Thalamus (Stuttgart: Thieme, 1956) ; W. R. 
Ingram, "The Hypothalamus," Clinical Symposia, VHI (1956), 117-56. 


greatly to our knowledge of such centers/' We know that 
definite areas of the temporal cortex when stimulated by a mild 
electrical current has evoked in certain subjects a detailed 
record of some past experience. Under certain conditions even 
present experience can somehow be evaluated in the light of a 
related past experience. It is possible, too, to evoke an emotion, 
most frequently fear, but sometimes loneliness or sorrow. The 
exact significance of these observations must still be determined 
before further light can be shed on normal and abnormal 

The philosophical vocabulary of Aristotle and Aquinas has 
no term corresponding to the modern expression " behavior." 
Indeed even in current usage the precise meaning of the term 
must often be determined from the context. In reference to 
human behavior it is ordinarily conceived as including those 
operations or actions of men which are considered to proceed 
from the whole organism or individual. Thus the term is 
applied not only to deliberate, consciously motivated actions, 
which may be considered rational acts, but also to those which 
follow on emotions, or are influenced by infra-conscious factors. 
Normal behavior, then, is that which fits into a system of public 
logic and is presumably in contact with the real world. 
Abnormal behavior, in this context, in some ways offends public 
logic, although the private logic of the individual may be 
rigorously observed. As a consequence, the individual, at one 
or more points, fails to contact the real world. 

The term behavior in the present context, consequently, does 
not directly connote such isolated phenomena of the autonomic 
nervous system as heart rate, blood pressure, respiratory rate, 
perspiration, and so forth. Nevertheless, behavior has physi- 
ological and biochemical correlates of which any one parameter 
may precede, accompany, or follow the individual's total res- 
ponse to a particular environmental situation. A person's 

^' W. Penfield, " The Interpretative Cortex," Science, CXXIX (1959) , 1719-25; 
W. Penfield and L. Roberts, Speech and Brain Mechanisms (Princeton: Univ. Press, 


behavior may be influenced by his internal miHeu, but it is 
not fully determined by it. For example, ingestion of various 
drugs can accelerate or decrease reactions of the autonomic 
nervous system even to the extent of inducing intense emo- 
tional activity. The individual's behavior is clearly influenced, 
but the ultimate determination of this behavior depends upon 
intellect and will, unless the activity of these immaterial facul- 
ties is completely inhibited. The dependence of rational ac- 
tivities on the sensory functions imposes a kind of limitation 
upon the intellect and will. If the operation of the pertinent 
sensory faculties is impeded, then to some degree the function 
of the intellect and will is also impaired. It is difficult to 
determine the exact point at which the activities of intellect 
and will may be completely inhibited. 

The biochemical substrata of the emotions have, of late, 
received considerable experimental attention." Although emo- 
tion, like sensation, is itself non-chemical, there are numerous 
physiological and biochemical changes associated with an emo- 
tion, just as there are numerous changes associated with cog- 
nitive sensation. The physiological component of vision, for 
example, includes a variety of biochemical changes. Light 
impinging on the rods and cones in the retina is absorbed by 
the photosensitive pigment and produces a series of trans- 
formations leading to nervous excitation." The nerve impulses 
sent along the optic tract are dependent on biochemical activi- 
ties for their propagation inasmuch as restoration of the ion 
gradient, for example, requires energy. Additional biochemical 
changes are further associated with whatever neuronal activity 
takes place at the central receptors after receiving the nerve 
impulses. Finally, in the formation of the integrated sensory 
image associations are made with past experience, and all of 

^^ H. F. Harlow and C. M. Wollsey, ed., Biological and Biochemical Basis of 
Behavior (Madison: Univ. of Wis., 1958); L. J. West and M. Greenblatt, Explora- 
tions in the Physiology of Emotions: Psychiatric Research Reports, 12 (January) , 

^* G. Wald, " The Photoreceptor Process in Vision," in Handbook of Physiology, 
fd. cit.. Sect. I, vol. I, pp. 671-92. 


this involves considerable biochemical activity. At this point 
the cogitative sense (or the intellect) may apprehend the object 
or event perceived as good or harmful to the individual. 

The judgment estimating the perception to be good or 
harmful evokes an emotional response toward or away from 
the object. Hand in hand with this affective, or emotional 
response, there is a purely physiological and biochemical res- 
ponse which may involve a host of chemical changes in the 
body. Norepinephrine and epinephrine, for example, are lib- 
erated from nerve endings and from adrenal medulla in various 
proportions, depending on whether fear and anxiety, or anger 
and daring are the primary emotional components. Concerning 
human subjects, it has been reliably reported that normal 
urinary excretion of norepinephrine with increased secretion of 
epinephrine is associated with anxious and passive emotional 
reactions. ^^ Active and aggressive emotional displays were 
found to be associated with an increased secretion of norepine- 
phrine. Other investigators have suggested that anxiety is 
mediated by epinephrine, and anger by norepinephrine.^*^ Much 
research still needs to be done before any definite associations 
can be made with various emotions. One item, however, does 
stand out: the biochemical changes can sometimes be induced 
without thereby producing the true emotion. It has been 
noticed, for example, that continuous infusion of epinephrine 
can produce subjective feelings very similar to those found 
during anxiety, and yet it would not be sufficient to produce 
the emotional anxiety state .^' On the other hand, norepine- 
phrine cannot produce comparable subjective experiences so 
as to be related to the emotion of anger.^^ All of these inves- 

^^ F. Elmadjian, " Excretion and Metabolism of Epinephrine and Norepinephrine 
in Man," in F. A. Gibbs, ed., Molecules and Mental Health (Philadelphia: Lippin- 
cott, 1959) , pp. 77-99. 

^* D. H. Funkenstein, S. H. King and M. E. Drolette, Mastery of Stress (Cam- 
bridge: Harvard, 1957), pp. 19-25. 

" D. R. Hawkins, J. T. Monroe, M. G. Sandifer and C. R. Vernon, " Psychological 
and Physiological Responses to the Continuous Epinephrine Infusion — An Approach 
to the Study of the Affect, Anxiety," m West and Greenblatt, op. cit., pp. 40-52. 

^» Ibid., p. 48. 


ligations confirm the traditional view of the emotions as im- 
manent activities consequent upon an estimative judgment, 
distinct from biochemical changes, yet associated with them. 

Another factor which tends to modify the operation of the 
mind and will is temperament. In the absence of any extensive 
analysis of this area, it might be said that a considerable 
component of temperament is physiological in origin." This 
in turn may reflect a genetic influence on the biochemical 
constitution of the individual. The four basic temperaments 
furnished by classic authors classify men according to the kind 
of response made to a given stimuli: the quick and slow, the 
lasting and ephemeral. Each of the basic temperaments is char- 
acterized by the possible pairs made up from one in each set. 
This suggests an actual connection with the central nervous 
system geared to respond in a certain manner to stimuli. 
Differences in temperament are apparently associated with 
differences in the responsiveness of the nervous system. What- 
ever an individual's temperament might be, it must be taken 
into consideration when evaluating normal and abnormal be- 
havior. At present too little is known about the correlation of 
temperament and abnormal behavior to draw any conclusions. 

The endocrine pattern of an individual, however, is clearly 
associated in some way with temperament. It is tempting to 
suggest that the hormonal factors may actually constitute the 
primary biochemical substratum of temperament. It is well 
known now that the hypothalamus influences the activity of 
the pituitary gland, probably through the release of neuro- 
hormones.-" The pituitary gland, in turn, governs the activity 
of several other glands, the adrenals, thyroid and gonads, whose 
products influence the activity of other organs in the body and 
the brain itself. While the sexual behavior of animals is pri- 
marily determined by the hormones liberated by the gonads, 
there are other influences in man which modify the basic 

L. M. Bond, The Effect of Bodily Temperament on Psychical Characteristics 
(River Forest: Aquinas Library, 1948) . 

'° W. S. Fields, ed., Hypothalamic-Hypophysial Interrelationships (Springfield: 
Thomas, 1956) . 


gonadal effect. Nevertheless the great influence of various 
hormones on human behavior cannot be overlooked. Adminis- 
tration of thyroxin to a hypothyroid individual can convert 
a sluggish, perpetually tired individual to a bright, active 
person. Out of such observations has grown the entirely new 
field of psychoendocrinology.-^ 

Biochemical Disturbances and Abnormal Behavior 

In classifying biochemical disturbances and abnormal be- 
havior, it is best to begin with the class of congenital mental 
deficiencies which result from what is frequently called a 
" metabolic error." In its essential form this concept was first 
proposed by Sir Archibald Garrod when he suggested that 
certain diseases, e. g., alkaptonuria and albinism, could be 
explained by the absence of certain specific enzymes.'" How- 
ever, it has not yet been directly established that a particular 
enzyme is absent. All that one can conclude is that the enzyme 
in question is not junctioning properly. The failure of an 
enzyme to function normally can be due to at least one of 
several causes: (1) the enzyme may truly be absent, (2) it 
may have a relatively slight structural abnormality, or (3) 
though normal, it may not be able to function because of some 
obstructive alteration in the cell or organism.-^ Furthermore, 
in some instances the enzyme defect can be further traced to 
the apparent absence or failure of a particular gene.^* The 
resulting condition can involve a variety of physiological dis- 
turbances, some of greater consequence than others. In some 
cases the full development of the illness can be forestalled by 
eliminating from the diet those substances which cannot be 
metabolized because of the enzyme defect. 

^^ M. Reiss, " Psychoendocrinology," in M. Reiss, ed., Psychoendocrinology (New 
York: Grune & Stratton, 1958) , pp. 1-40. 

^^ D. Y-y. Hsia, Inborn Errors of Metabolism (Chicago: Year Book, 1959), p. 105. 

" Ibid. 

-* R. W. Lippman, T. L. Perry and S. W. Wright, " The Biochemical Basis of 
Mental Dysfunction. II: Mental Deficiency (Amentia)," Metabolism, VII (1958), 
274. Cf. L. S. Penrose, The Biology of Mental Defect (New York: Grune and 
Stratton, 1949). 


One type of congenital mental deficiency is exemplified by 
the condition known as phenylpyruvic oligophrenia or as 
phenylketonuria."^' The first term emphasizes the impairment 
of the brain or mental function; the second refers to the rela- 
tively high concentration of phenylpyruvic acid found in the 
urine of the affected individual. Careful study of many cases 
has revealed that it is an hereditary disorder of protein meta- 
bolism mediated by a non-sex-linked recessive gene."'' As a 
result of this genetic defect, there is a defect of the enzyme 
system, phenylalanine hydroxylase. Without the proper func- 
tioning of phenylalanine hydroxylase, there is an excessive 
accumulation of phenylalanine in the blood and cerebrospinal 
fluid. The precise manner in which the deleterious effect is 
brought about is not known. Apparently it is the excess of 
phenylalanine (or one of its products) which interferes with 
the proper development of the central nervous system and 
leads to a consequent mental retardation. If this condition is 
discovered very early in the infant's life, the development of 
mental deficiency can be largely prevented by administering 
a diet free of the offending amino acid."^ 

Another type of mental deficiency resulting from a congenital 
metabolic defect is cretinism,"^ It should be noted, however, that 
a primary deficiency in the synthesis of the thyroid hormone is 
not the only cause of cretinism. It can also arise from other 
causes of thyroid hypofunction, e. g., from abnormal embryonic 
development of the thyroid gland or from deficient dietary 

^^ For a general review of this disease see the following: G. A. Jervis, " Phenyl- 
pyruvic Oligophrenia," in Genetics and the Inheritance of Integrated Neurological 
and Psychiatric Patterns (Baltimore: Williams & Wilkins, 1954), 259-282; W. E. 
Knox and D. Y-y. Hsia, " Pathogenic Problems in Phenylketonuria," American 
Journal of Medicine, XXII (1957) , 687 ff. 

^^ Lippman, op. cit., p. 276; C. Mitoma, R. M. Auld and S. Uudenfriend, " The 
Enzymatic Defect in Phenylpyruvic Oliogophrenia," Proceedings of the Society for 
Experimental Biology and Medicine, XCIV (1957), 634. 

^' M. D. Armstrong and F. H. Tyler, " Studies on Phenylketonuria. I: Restricted 
Phenylalanine Intake in Phenylketonuria," Journal of Clinical Investigation, XXXIV 
(1955), 565. 

^* Cf. J. B. Stanbury and E. M. McGirr, " Sporadic or Non-Endemic Familial 
Cretinism with Goiter," American Journal of Medicine, XXlI (1957), 712. 


iodine. A few weeks after birth the characteristic physical 
stigmata appear, accompanied by signs of involvement of the 
central nervous system."" Decreased acuity of the special senses 
is evident; speech and socialization are retarded; muscular 
coordination is impeded, and unless the condition is treated 
the mental status of the individual is no more than that of an 

The second large class of biochemical disturbances giving rise 
to abnormal behavior consists of acquired metabolic malfunc- 
tions. This class can be broken down into diseases arising from 
some nutritional deficiency and those arising from a toxic 
substance either exogenous or presumptively endogenous. The 
latter type, indeed, may be due in whole or part to a congenital 
defect, but in the present state of our knowledge it remains an 
open question. Diseases arising from nutritional deficiency are 
of many types, but only one need be mentioned because of its 
striking mental involvement: pellagra. 

Pellagra has a variety of symptoms which, in the more 
advanced stages, include a considerable mental dysfunction 
characterized by a clouding of consciousness, hallucinations 
and confusion, frequently terminating in a psychosis if adequate 
treatment is not instituted.^" It has been determined that this 
condition is due to the absence of one of the B vitamins, nico- 
tinic acid (or its amide) , or its precursor, tryptophan. ^^. In 
1937 it was discovered that pellagra could be relieved by 
administering nicotinic acid (not to be confused with the 
alkaloid nicotine) .^- The importance of this vitamin is that 
it is an integi-al part of one of the coenzymes, known as diphos- 

-® H. P. Rome and D. B. Robinson, " Psychiatric Conditions Associated with 
Metabolic, Endocrine and Nutritional Disorders," in American Handbook of Psy- 
chiatry, ed. cit., II, p. 1274. 

'°R. L. Cecil and R. F. Loeb, ed., A Textbook of Medicine (Philadelphia: 
Saunders, 1959) , p. 547. 

'^ J. Gregory, " The Role of Nicotinic Acid (Niacin) in Mental Health and Dis- 
ease," Journal of Mental Science, CI (1955), 85. 

''''D. T. Smith, J. M. Ruffin and S. G. Smith, "Pellagra Successfully Treated 
with Nicotinic Acid: A Case Report," Journal of the American Medical Association, 
CIX (1937), 2054. 


phopyridine nucleotide (DPN) . It is essential to the meta- 
bolism of carbohydrates, and its absence can seriously impair 
energy production. Since almost the sole source of energy for 
the brain is glucose, it is obvious that anything which interferes 
with the proper metabolism of this carbohydrate will also 
reduce brain function considerably. 

The most interesting group of acquired biochemical dis- 
turbances causing abnormal mental behavior is that arising 
from the ingestion of a toxic substance. Obviously a great 
variety of chemical substances can produce toxic symptoms 
when taken in excessive quantities or by an individual with an 
idiosyncrasy for a particular compound. Among the inorganic 
substances must be listed lead,^^ manganese,^* mercury ^^ and 
bromides.^*' Of these, the bromides are perhaps the best under- 
stood.^^ For example, an excess of bromide ion in the blood, 
generally resulting from an excessive use of bromide salts to 
" quiet the nerves," replaces an equivalent amount of chloride 
ion in the body fluids. When the concentration of bromide ion 
reaches 150 mg. per cent,^^ toxic symptoms are likely to appear. 
These symptoms may range from simple sluggishness and for- 
ge tfulness to delirium and hallucinations. In certain predis- 
posed cases, a pattern of transitory schizophrenia has been 
known to appear.^^ 

Among organic compounds known to produce behavioral 
abnormalities are such items as amphetamine, cortisone, ACTH 

** W. T. Haverfield, P. C. Bucy and A. S. Elonen, " The Surgical Treatment of 
Lead Encephalopathy," Journal of the American Medical Association, CXIV (1940) , 
2432; R. K. Byers and E. E. Lord, "Late Effects of Lead Poisoning on Mental 
Development," American Journal of Diseases of Children, LXVI (1943), 329. 

** G. C. Cotzias, " Manganese in Health and Disease," Physiological Reviews, 
XXXVin (1958), 503-531. 

*^ L. T. FairhaJl, " Inorganic Industrial Hazards," Physiological Reviews, XXV 
(1945), 182. 

^' M. Levin, " Bromide Psychoses: Four Varieties," American Journal of Psy- 
chiatry, CIV (1948) , 798. 

^■^ M. Levin, " Toxic Psychoses," in S. Arieti, op. cit., p. 1222 ff. 

^^ Ibid., p. 1224. 

^* M. Levin, " Transitory Schizophrenias Produced by Bromide Intoxication," 
American Journal of Psychiatry, CIII (1946), 229-237. 


and barbiturates." Ethyl alcohol, as everyone knows, affects 
normal behavior in varying degrees. In extreme alcoholism, as 
for example in delirium tremens and acute alcohol hallucinosis, 
optic and auditory hallucinations, respectively, are common.*^ 

A very interesting group recently brought to the attention 
of the psychiatric profession is known as psychomimetic drugs. 
A descriptive definition of these drugs presented a few years 
ago is still adequate: " Psychomimetic agents are substances 
that produce changes in thought, perception, mood, and, some- 
times, in posture, occurring alone or in concert, without causing 
either major disturbances of the autonomic nervous system or 
addictive craving, and, although with overdosage, disorienta- 
tion, memory disturbance, stupor and even narcosis may occur, 
these reactions are not characteristic." *' In some respects the 
behavioral changes brought about by these drugs resemble the 
mental and emotional symptoms associated with one or other 
of the psychoses. Most of these drugs in current experimental 
use are naturally occurring compounds, or compounds obtained 
from them by slight chemical change. Among the better known 
of these interesting drugs are lysergic acid diethylamide (LSD- 
25) , mescaline (from the Peyote cactus) , and psilocybin (from 
the mushroom, Psilocybe mexicana Heim) . 

The first of these drugs, LSD-25, is apparently unique in the 
truly minute amount which will produce the typical mental 
changes. These changes usually begin in an half hour and reach 
a peak at one and one-half hours. Among the outstanding 
symptoms are visual hallucinations, often fantastic in structure. 
While auditory hallucinations are rare, taste disturbances are 
quite frequent. Consciousness itself, however, is never markedly 
affected, and orientation in place remains intact, but there is 
rather a profound change in the perception of time. After about 

*" M. Levin, " Toxic Psychoses," ed. cit., p. 1225 ff. 

*^ G. N. Thompson, "Acute and Chronic Alcoholic Conditions," in S. Arieti, op. 
cit., pp. 1208-1210. 

** H. Osmond, "A Review of the Clinical Effects of Psychomimetic Agents," 
Annals of the New York Acadeviy of Science, LXVI (1957), 418. 


eight hours the symptoms ordinarily disappear.*^ No claim is 
made here that a true psychosis can be duplicated by the 
use of this drug. In fact, schizophrenic patients who have 
taken LSD state that the experiences induced by the drug 
are different from their own schizophrenia. To date, many 
experimental attempts have been made to isolate particular 
biochemical changes which induce the observed effects. How- 
ever, no certain conclusion has yet been reached.** 

The third and final category of metabolic disorders leading 
to abnormal behavior is a miscellany. In the other classes, the 
disorder was traced either (1) to a congenital defect involving 
an absence or a malfunction of an enzyme or hormone, or (2) 
to what was called, for want of a better term, " an acquired 
mteabolic disorder " resulting from a nutritional deficiency or 
from ingestion of a chemical substance. Although these first 
two classes can account for some of the emotional and mental 
diseases, they cannot, at present, account for the psycho- 
pathological conditions known as " functional psychoses." It 
has been suggested in the past and again more recently that 
schizophrenia, for example, is the result of an abnormal meta- 
bolism producing a toxic (neuro- or psychotoxic) substance.*'^ 
Presumably in such an explanation, the symptomology of the 
disease would be traced to the action of the endogenous toxic 
compound, whereas the metabolic error producing the " psycho- 
poison " would be the disease itself. 

** A. Wikler, The Relation of Psychiaty to Pharmacology (Baltimore: Williams 
& Wilkins, 1957) , pp. 69-70. 

** H. Hoagland, "A Review of Biochemical Changes Induced In Vivo by Lysergic 
Acid Diethylamide and Similar Drugs," Annals of the Neio York Academy of 
Science, LXVI (1957) , 445-458; J. A. Bain, "A Review of the Biochemical Effects 
In Vitro of Certain Psychomimetic Agents," Annals of the New York Academy of 
Sciences, LXVI (1957) , 459-467. 

*^ H. Osmond, " Chemical Concepts of Psychosis (Historical Contributions) ," in 
M. Rinkel and H. C. B. Denber, ed., Chemical Concepts of Psychosis (New York: 
McDowell & Obolensky, 1958), pp. 3-26; R. G. Heath, "Physiological and Bio- 
chemical Studies in Schizophrenia with Particular Emphasis on Mind-Brain Rela- 
tionships," in C. C. Pfeiffer and J. R. Smythies, International Review of Neuro- 
biology (New York: Academic Press, 1959), I, 299-331. 


Probably the most extensive biochemical study of mental 
illness has been of that large amorphous gi'oup, the schizo- 
phrenias. A recently published review of the field makes it clear 
that biochemists are still very far from giving a biochemical 
account of schizophrenia,*'' The more thorough biochemical 
approach to the problem has been to explore biochemical para- 
meters of the whole body, rather than to restrict investigations 
to the chemistry of the brain. *^ 

First of all with regard to schizophrenia, there is little doubt 
that no single factor will account for it. Schizophrenia, after 
all, is a generic name and not a specific disease. Further, 
it is most probable that there are predisposing factors as 
well as " triggering " events which must be considered. While 
there is suggestive evidence for some genetic factor in the 
development of schizophrenia, this is not certain. A further 
difficulty is that too little is known of the brain's biochemical 
topology. There is a real probability that the biochemical 
changes in question take place in very restricted areas of the 
brain. It is even possible that chemical systems operative in 
these areas are unknown in others. Consequently, any abnor- 
mality in such unique systems would be extremely difficult to 
detect, since the existence and nature of the system itself would 
hardly be suspected. One attractive hypothesis, though as yet 
unproved, is the possibility of an abnormal metabolism of 
commonly occurring substances, such as epinephrine yielding 
adrenochrome, adrenolutin or similar compounds.*^ 

The isolation of serotonin (5-hydroxytryptamine) , a sub- 
stance found in the brain in relatively high concentrations 
(although also present in other tissues of the body) , has raised 
the hopes of some that this substance might be implicated in 

"S. S. Kety, "Biochemical Theories of Schizophrenia," Science, CXXIX (1959), 
1528-1532 and 1590-1596. 

*''' D. Richter, " Biochemical Aspects of Schizophrenia," in Derek Richter, ed., 
Schizophrenia: Soinatic Aspects (New York: MacMillan, 1957) , pp. 53-75. 

** A. Hoffer, "Adrenaline Metabolites and Schizophrenia," Diseases of the Nervous 
System, Monograph Supplement, XXI (1960), No. 2, pp. 1-8. 


the etiology of schizophrenia.*'"' It has been suggested that a 
metaboHc disorder which alters the concentration of serotonin 
in the brain would result in a psychosis.^" Notwithstanding the 
amount of evidence to show that serotonin as well as several 
other compounds (e. g., norepinephrine, acetylcholine, gamma 
aminobutyric acid) have important roles in the proper func- 
tioning of the brain, no definite conclusion can yet be drawn 
with regard to their causality in mental illness. Another sub- 
stance which has been suggested as a causative agent in schizo- 
phrenia is taraxein.^^ This compound, isolated from the blood 
of schizophrenic patients, has been known to produce bizarre 
behavior in animals and in volunteer human subjects." The 
chemical nature of taraxein has not yet been determined pre- 
cisely. Unfortunately, not all the evidence supports the view 
that taraxein is a psychotoxic substance produced by schizo- 
phrenic patients. ^^ Consequently, no single substance has yet 
been found which conclusively induces this particular mental 

■3t * * 

There remains the task of correlating relevant material 
already discussed with certain observations. First, too little is 
known at present for an adequate biochemical specification of 
the exact nature of mental health; it is not even possible to 
associate a particular disease with a specific biochemical change 
or with a pattern of changes (with the possible exception of 

*' Kety, op. cit., pp. 1592-3. 

^"D. W. Wooley and E. Shaw, Science, CXIX (1954), 587; J. H. Gaddum, 
" Drugs Antagonistic to 5-Hydroxytryptamine," in CIBA Foundation Symposium 
on Hypertension (Boston: Little, Brown and Co., 1954) , pp. 75-77. 

" R. G. Heath, S. Marten, B. E. Leach, M. Cohen and C. Angels, " Effect on 
Behavior in Humans with the Administration of Taraxein," American Journal oj 
Psychiatry, CXIV (1957) , 14-24. 

'^^ R. G. Heath, S. Marten, B. E. Leach, M. Cohen and C. A. Feigley, " Behavioral 
Changes in Nonpsychotic Volunteers Following the Administration of Taraxein, The 
Substance Obtained from Serum of Schizophrenic Patients," American Journal oj 
Psychiatry, CXIV (1958) , 917-20; R. G. Heath, B. E. Leach and M. Cohen, "Mode 
of Action of Taraxein: Follow up Studies," in Gibbs, op. cit., pp. 17-43. 

"Kety, op. cit., pp. 1590-91. 


certain mental deficiencies as mentioned above) . Further, it is 
extremely hazardous at present to say whether the observed 
biochemical abnormality is the cause or the effect of a mental 
illness. They might even be concomitant, the result of a 
common cause. While the tendency in research at present has 
been to search for a gross and manifest biochemical abnor- 
mality, it is entirely possible that small changes in one ana- 
tomical area may be accumulative with similar small changes 
in other areas. Further, the deviation from the normal range 
in the activity of one biochemical system, though relatively 
insignificant in itself, may be highly important when coupled 
with changes in other chemical systems that serve the same ulti- 
mate behavioral expression. Notwithstanding certain reversals 
met with in current research, we may say summarily that the 
experimental determination of some kind of disturbance in the 
biochemistry of the central nervous system, at least, is con- 
fidently expected. It might further be noted that mental health 
might be dependent, in the chemical order, on the proper con- 
centrations of certain compounds and on activities of particular 
enzymes in specific areas of the brain, whereas mental illness 
may result from an imbalance of these very same substances.^* 
The fact that chemical compounds, e. g., LSD, mescaline, 
amphetamine, can bring about symptoms of mental illness 
suggests the brain's chemistry has been disturbed. 

On the other hand, it is possible that mental health and 
disease involve the chemistry of the entire body and not merely 
that of the brain. It is generally recognized that the body 
under stress responds with a change in the endocrine balance.^^ 
The basic hormonal and biochemical patterns of the body, 
which may represent the physiological component of tempera- 
ment, could act as a dispositive cause for certain behavioral 

54 ■ 

L. G. Abood, " Some Chemical Concepts of Mental Health and Disease," in 
The Effect of Pharmacologic Agents on the Nervous System (Baltimore: Williams & 
Wilkins, 1959), p. 393. 

^^ J. S. L. Browne, " The Interplay Between Endocrine Disturbance and Psy- 
chological Aberrations," CIBA Foundation Colloquia on Endocrinology, vol. Ill, 
Hormones, Psychology and Behavior (Philadelphia: Blakiston, 1952), pp. 112-19. 


disturbances, whereas the actual disturbance itself might have 
as its proximate biochemical cause the altered chemistry of the 

Nevertheless, there is no basis for the claim put forward by 
some, that all mental illnesses will some day prove to have 
their origin in such chemical changes. It is well known that 
a persistent emotional reaction with its attendant chemical 
changes can bring about changes of a more permanent kind, 
which in turn produce the variety of pathological behavior. 
Even a moral stress can be the primary factor in the etiology 
of an individual's mental aberrations. Some moral stresses 
could conceivably be successfully countered in the shelter of 
the mind for a time. But sooner or later such stresses would 
bring in their wake emotional involvements with the conse- 
quent alteration in the normal biochemistry of the individual. 
More commonly, moral problems arise from patterns of activity 
and emotional behavior at variance with a person's moral code. 
Consequently, a daily involvement in such biochemical storms 
could rightly be expected to result in more permanent chemical 
changes. These changes would then be the molecular roots for 
the abnormal mental symptoms. 

How then can a mental disease be reversed by psychotherapy, 
if biochemical changes are the substrata of the disease.? One 
likely answer is that psychotherapy removes, gradually per- 
haps, the state of moral or emotional stress. Once these stresses 
have been removed, the attendant biochemical changes should 
reverse, unless relatively irreversible structural changes have 
taken place, and general homeostatic mechanisms will tend to 
restore normal biochemical functioning. 

It should be remembered that pharmacological treatment of 
mental illness is more symptomatic than curative, unless the 
primary cause of the illness happened to be a truly biochemical 
disturbance. In this case a compound which will restore the 
normal biochemical pattern will also remove the psychological 
symptoms due to the abnormal chemistry. The use of phar- 
macological agents in the immediate treatment of abnormal 


behavior has been almost purely empirical. Yet, not only have 
such agents alleviated the disturbing symptoms, but they have 
often permitted other means of therapy to be more effective. 
Patients, otherwise unapproachable, can be made amenable to 
psychotherapy in this way. Then, too, a number of drugs are 
extremely useful in exploring the chemical foundations of nor- 
mal and abnormal behavior.^® Once again the sensitivity of 
man's emotional and mental makeup to his chemical environ- 
ment is clearly indicated. 

Fear has been expressed by some that the elucidation of the 
biochemical factors of behavior might compromise man's free- 
dom and his moral responsibility. This would be true if his 
mind were no more than the functioning brain. In the last 
analysis man's freedom and moral responsibility are guaranteed 
by the spiritual, the immaterial nature of his mind. The mind 
does indeed depend upon the brain for the raw material of 
its thought, and the will is influenced by emotions and feelings. 
But the mind and will, transcending neurons, chemical and all 
matter, function with a certain independence from material 
limitations, and consequently cannot be forced by anything 
material. Only the hylomorphic interpretation of man's pecu- 
liar nature can explain satisfactorily his existential unity and 
his dependence upon as well as his transcendence over bio- 
chemical composition. 

Albert S. Moraczewski, O. P. 

Houston State Psychiatric Institute, 
Texas Medical Center, 
Houston, Texas. 

^"M. Sidman, "Behavioral Pharmacology," Psychopliarmacologia, I (1959), 1-19; 
R. M. Featherstone and A. Simon, A Pharmacologic Apjrroach to the Study of the 
Mind (Springfield: Thomas, 1959) . 



THEOLOGIANS and philosophers have rightly stigma- 
tized Freud's concept of moral conscience as a carica- 
ture of the real thing. The psychological phenomenon 
which Freud called the superego, and which he equivalated 
with the traditional notion of conscience, in fact lacks the 
essential note of conscience. Nevertheless, since Freud was a 
gifted investigator, the presumption is that the superego is a 
reality and, since Freud credited it with a significant note in 
human activity, it would seem to be something important. 
The following paper attempts to analyze Freud's conception 
of the superego in terms of Thomistic thought, comparing it 
with more valid notions of conscience, and defining the area 
in human activity, especially in moral activity, into which the 
functioning of the superego enters as something significant. 

I. The Notion of the Superego 

(1) The Fundaments of Human Nature According to Freud. 

Speaking broadly, the superego is the part in a man which 
tells him that he ought to do something or ought not to do it. 
In Freud's conception, a mature human personality comprises 
three basic structures: the id, the ego and the superego. If a 
rough description is permissible at the beginning, the id may 
be called the pool of instinctual drives, repressed complexes 
images and thoughts — a wholly unconscious area of the mind. 
The ego is the agency of all sense perceptions and conscious 
thought, and the initiator of deliberate activities. The super- 
ego is the source of moral incitement and constraint, and is 
largely unconscious. 

Of these three, the primitive part and only native part is 
the id. In the id, instinctual impulses arise, and indeed arise 
by a natural and uncontrollable necessity, welling up con- 



tinuously, as it were, as the psychological manifestations of 
more basic vital processes. When an impulse — the raw material 
of psychological life — arises, it is credited with creating a 
psychological tension; when it is discharged through some 
appropriate motor activity (as, for example, the infantile 
impulse to suck may be satisfied by the breast) , the tension 
is dissolved. This relief of tension is pleasure; the law of the 
id is to seek it. Once an instinct has found an appropriate 
means of satisfaction, it becomes attached to the activity, and 
to the images and ideas of that activity, and henceforth is 
oriented towards obtaining satisfaction continuously through 
the same activity. 

It happens, however, in the course of his development, that 
a child finds certain satisfactions prohibited, restricted, or pre- 
vented — he is not allowed to take the breast, or not allowed 
to keep it as long as he likes. He becomes more aware then 
of the impingement of the outside world; he is forced to take 
reality into account. Thus the ego begins to develop. The ego 
comprises the perceptions of the outer world, the coherent 
central processes of the individual, and the processes by which 
conscious motor activities are carried out. The principle that 
rules in the ego is reality; it relates man to the self he finds 
himself to be and to his environment. Fundamentally, of 
course, the ego is at the service of the id. Although it is attuned 
to reality, its main function even in this regard is to locate 
in reality the most appropriate means of satisfying instinctual 
impulses for the id, while avoiding the disagreeable results 
this satisfaction might sometimes entail. 

To obtain its proper results, the ego must ' censor ' the 
instinctual movements of the id, that is, when the id demands 
some satisfaction which the ego has learned is actually pro- 
ductive of disagreeable results — pain, punishment, parental 
disapproval — the ego must negate the id's demands. A con- 
flict ensues when the ego refuses to execute the action sought 
by the id. Eventually the ego refuses even to allow the idea 
to remain in consciousness; it suppresses the idea. But the 


idea with its instinctual drive does not die; it vanishes into the 
unconsiousness of the id, where it remains, still dynamic, still 
restless, still seeking some new outlet. How it can get past 
the censorship of the ego, and accomplish its purpose is a long 
and involved story; it is sufficient here to note that sometimes 
the instinctual drives successfully accomplish their aim; some- 
times they are deflected from a minor object without severe 
psychological injury resulting; sometimes they are deflected at 
some cost to psychological balance.^ 

Within the ego, the superego is formed. Freud's earliest 
works did not mention this mental agency, but after long 
investigation, he found himself constrained to postulate some 
institution in the mind distinct from the ego and the id." 
He found that much of the censoring process — the ' do this ' 
and ' do not do that,' in the sense of moral obligation — was 
accomplished not consciously, as the ego works, but uncon- 
sciously; and not on the basis of reality as the ego perceives 
it and consciously evaluates it, but on some other basis more 

^ Cf. Freud, " Neurosis and Psychosis," Coll. Papers, Vol. 2, pp. 250 seq. (Hogarth 
Press, London, 1956) 

' Perhaps it would be useful here to note two of Freud's methodological canons, 
as an aid to following his reasoning on these subjects. First of all, he tried always 
to proceed on a strictly empirical basis. He would examine the psychological mani- 
festations — thoughts, images, feelings, urges — as they were conscious or latent or 
dreamed, whether they seemed meaningful or not, whether they were competent or 
apparently disorganized and defective — and from the material gathered proceed to 
the postulation of the mental structures to explain them. This is, of course, the 
classic mode of procedure in establishing a faculty psychology; Freud, however, 
totally disavowed faculty psychology. To distinguish faculties by their acts and 
objects, and, more to the point, from their activities and objects, seemed to him a 
display of sterile theorizing. He was content in determining manifest activities in 
their concrete complexity, and the hidden activities, especially buried complexes, 
they seemed to postulate, but he did not attempt to define a structure of faculties 
which might underlie the variety of activities. His result would most resemble, in 
Thomistic terms, a description of actual habits or dispositions. Secondly, Freud tried 
to conceive the elements of his psychological structure in mechanistic and physical 
terms, in consonance with a basically anti-vitalist and materialist outlook. For this 
reason, many of his conceptions and the terms he uses to express them, seem mere 
metaphors, and not particularly apt metaphors, for the world of machines does not 
do justice to the subtleties of the mind. Once however these biases are taken into 
account, the real meaning of the things he is discussing is more apparent. 


or less divorced from reality; and that this mysterious censor- 
ship's function was often effected with a psychological force 
considerably greater than that which usually accompanies 
reality-oriented activities. He formulated therefore the notion 
of the superego. The superego is a largely acquired but uncon- 
scious agency of censorship, formed within the ego, which 
forbids and commands and punishes disobedience by generating 
painful feelings of guilt.^ 

(2) Arguments for the existence of the superego. 

What are the evidences for such a mental institution? First 
of all, there is the argument from the psychology of child 
development. Infants even at an early age are subject to a 
certain amount of ' training,' a matter of parental prohibitions 
or demands, reinforced with smiles and rewards or with frowns 
and punishments. In the beginning, the child must be con- 
stantly prompted to do what he has been told; the enforcing 
agency is part of the reality external to himself. Eventually, 
however, he will begin to do what he has been told even when 
his parents are absent. Evidently he has made their exhor- 
tations and prohibitions part of his own mental equipment. 
He has absorbed, not only what they have told him should be 
done or not done, but has also absorbed, or developed, the 
impulse to follow these directions. This, in a superficial way, 
is a description of the forming of the superego.* 

Another argument for the superego is drawn from a situation 
common in psychoanalysis, the occurrence of ' resistance.' 
When analyzing a patient, Freud would endeavor to have him 
relate all the thoughts and images that came to his mind by 
the process of relaxed, free association. In this way he hoped 
to uncover the more or less hidden mental complexes which 
lay at the source of the patient's troubles. But he frequently 

^ Freud, loc. cit. 

*Cf. Freud, "On Narcissism: An Introduction," Coll. Papers, vol. 4, pp. 50-53; 
Joseph Nuttin, Psychoanalysis and Personality, pp. 19-20. (Sheed and Ward, New 
York, 1953). 


found that the patient would offer ' resistance ' to the flow of 
thoughts — his memory would ' fail,' he would be unable to 
make a connection, he would dismiss a line of thought as 
meaningless and irrelevant. Often these breaks in the mental 
flow were accompanied by fairly distinct feelings of emotional 
distress. Or again, sometimes, when a sound explanation of 
some of the patient's thoughts or feelings was offered by the 
analyst, the patient would firmly or even violently reject them, 
for no manifestly good reason and with a gi'eat show of emotion. 
Freud concluded that the mental force which originally cen- 
sored and repressed certain ideas (which were generally shame- 
ful or painful or humilating or in some way highly disagreeable) 
must be still operative in the psychism, and that, moreover, 
its present activity was itself largely unconscious. Therefore, 
besides the conscious censorship of the ego function, it was 
necessary to postulate another unconscious censoring agency.^ 
Another factor which enlarged and confirmed the concept of 
the superego was the sense of moral obligation manifested by 
many neurotics. Many patients who came for psychoanalytic 
treatment exhibited an intense need to measure up to moral 
standards often impossibly high and rigid. They seemed to be 
driven to achieve perfection according to self-imposed goals, 
and unable moreover to make allowances for any personal 
weaknesses or external circumstances which might make the 
goals unattainable. Ruled by these interior compulsions, they 
were unable to find satisfaction in the reasonable goals most 
people are contented with, unable to find peace in anything 
other than the achievement of their standards. Failure was 
always attributable to some fault on their part, and failure 
was followed by an acute sense of guilt. (This was also regarded 
as a weakness to be stamped out, and failure to overcome it 
produced further guilt feelings.) The standards by which they 
lived seemed beyond their own judgment, modification and 
control — they were unquestioned and unquestionable — and in 
fact, they seemed to be largely unconscious. Such a phe- 

* Cf. Freud, The Ego and the Id, pp. 15-18. (Hogarth Press, London, 1957) 


nomenon contrary to the best interests of the patient and 
seemingly imposed by some hostile and alien, and yet internal 
agency, seemed to Freud to demand a special mental structure 
to account for it.® 

To these main arguments, Freud added others, not always 
as plausible. He seemed to think, for instance, that the presence 
of the superego was betrayed by ordinary phraseology in every- 
day speech. Thus the exprssion: " I feel inclined to do this 
but my conscience says ' no '," led him to infer the existence 
of a power in man separate and contrary to the primary 
personality, the " I." As has been pointed out, however, the 
same situation can be expressed: " I will not do this, although 
I am tempted to." Now this would indicate that the primary 
personality is separate from and contrary to the inclination. 
All, in fact, that can be deduced from such expressions is the 
presence of a duality; nothing can be concluded about the 
primacy of the factors involved.' 

But leaving aside the debatable proofs, what can be deduced 
from the admissible evidence.'* Certainly many of Freud's 
observations as cited above are psychologically meaningful. 
Before we deduce any final conclusions, however, about the 
superego, we must go into a more thorough account of its 
actual formation, and this brings up the question of the Oedipus 
complex. For Freud, the superego — this inner sense of com- 
pulsion to do or not do — is formed out of the resolution of the 
Oedipus complex, and cannot be understood on any other basis.® 

(3) The origin of the superego. 

The Oedipus complex may be described briefly as follows. 
In infancy a male child develops first of all a strong instinctual 
atti action towards his mother, based on the warmth and affec- 

* Freud, "On Narcissism: An Introduction," Coll. Papers, vol. 4, pp. 50-59. Cf. 
Karen Homey, New Ways in Psychoanalysis, pp. 207-210; Freud, " The Economic 
Problem in Masochism," Coll. Papers, vol. 2, pp. 265-66. 

'' Cf. Nuttin, Psychoanalysis and Personality, p. 178. 

* Freud, The Ego and the Id, pp. 40-46. 


tion she shows, and the satisfaction of his hunger by nursing, 
etc. At the same time he is identifying himself with his father, 
that is to say, he begins to mold himself on the pattern of his 
father.^ He does this, not only because he is like his father, 
male, but also because he wants to share in the affection his 
mother has for her husband. In a few years, as the child 
passes through the ages of four and five, the increasing inten- 
sity of affection (which Freud conceived as basically sexual) 
for the mother, puts the father more and more in the light of 
a rival and an obstacle to the exclusive enjoyment of the 
mother's favors. Jealous and hostile feelings arise toward the 
father; the wish to get rid of him and replace him in the 
mother's affections becomes more manifest. This combination 
of identifying-hostile feelings (ambivalent feelings) towards the 
father and affection for the mother constitutes what Freud 
called the simple positive Oedipus complex. If this description 
in more or less Freudian terms seems hard to accept, perhaps 
the reality underlying the description can be more readily seen 
in the formulation of another psychoanalyst: In a child, love 
is extraordinarily wholehearted and jealous.^" 

In a girl child, the normal development of the complex is 
like that of a boy, but with the roles of each parent reversed; 
her ambivalent feelings develop with regard to her mother, 
with whom she identifies and whom she wants to supplant in 
her father's affections. 

In either girl or boy, the situation can become much more 
complicated, and, according to Freud, usually does. The boy 

' The concept of identification is a key concept in depth psychology. It signifies 
a psychological reaction something like imitation but much more profound. ^Vhen 
a child identifies himself with another, he does not merely take up his patterns of 
behavior, he absorbs into himself wholeheartedly the ways of thinking, feeling, acting 
of the other person, and not only consciously but, so deep is the sense of unity with 
the other person, even consciously. The two principal motives behind identification 
are lost love and emulation. "When one who is loved must be renounced, a com- 
pensation may be made in the form of identification, or when one meets a rival, 
identification can be motivated by the desire for equality with him. See Baudouin, 
The Mind of the Child, pp. 245-46. (Dodd, Mead & Co., New York, 1933) 

^"Baudouin, op. cit., p. 51. 


may not only have ambivalent feelings towards his father and 
simple affection for his mother, but he may display an affec- 
tionate, feminine attitude towards the father, and a corre- 
sponding identification and jealousy towards his mother, for 
in Freud's opinion, each individual is basically bi-sexual. In 
this case there is a two-fold Oedipus complex, also called the 
complete complex. Its parallel, with the proper substitutions, 
can be found in girls. Generally this secondary or inverted 
complex is subordinate to the primary complex as described 
respectively for a boy or a girl; it is possible, however, that it 
be the dominant complex in the child, in which case the basic 
instinctual orientation is reversed. In actual practice, the whole 
range of possibilities is found realized, from simple positive 
complexes to complete inverted ones. 

However, in the complete Oedipus complex, there are only 
four instinctual trends to account for, regardless of their or- 
ganization. For the sake of simplicity, we will limit ourselves 
to the case of the boy: his primary affection is for his mother, 
with a sense of identification with his father and a sense of 
hostility towards him as well. Secondarily, he has affection 
for the father with identification and jealous reactions towards 
his mother. 

The next step is the dissolution of this complex. It is evident 
that the child cannot long endure the tensions aroused by the 
Oedipus complex. He cannot tolerate feelings of hostility 
towards his parents on whom he depends for all his love, 
affection, approval, protection, parents who are so much 
stronger than he is. He must suppress his hostility and its 
cause — the Oedipus complex. 

The first step in this dissolution involves giving up the 
mother as an object of affections, and principally for fear of 
the father's punishing power. But it is not easy to give up 
an object one loves — something must take its place. In this 
dilemma, the boy can respond with either of two alternatives: 
he can either identify with his mother (we can give up a love 
object if we take it into ourselves, into imagination and 


emotion, and there cherish it) or he can intensify his identifica- 
tion with his father (we can evade aggressors by identifying 
with them) .'^ This latter alternative is termed the more 
normal, for it confirms the masculinity of the boy, and allows 
him to retain a certain affection for his mother, i. e. after the 
pattern of his father's with whom he has now identified him- 
self. The relative strength of the masculine-feminine disposi- 
tions in the child determines, in Freud's early opinion, which 
identification will preponderate. 

Insofar as the boy identifies with his father, not only does 
he preserve his relationship to his mother as love object, but 
his relationship to his father as love object (the inverted 
element in the complete Oedipus complex) is dropped. Simi- 
larly, in renouncing his mother as primary object of love, and 
in overcoming his jealousy towards her, he will achieve by 
identification an affection for the father, patterned on the 
mother's. The Oedipus complex is now wholly resolved, as 
the boy is strongly identified with his father and mildly with his 
mother, and affectionate towards both, hostile towards neither.^^ 

(4) The superego is born. 

The identification with the two parents is the beginning of 
the superego, the origin of the sense of right and wrong, the 
starting point for ' morality,' religion and culture. In virtue 
of the identification of himself with his parents, into which he 
has been pressed by the need of overcomnig the Oedipus 
complex and the conflict which ensued from it, the child 
unconsciously and unreservedly makes his own the attitudes 
towards right and wrong which have been expressed by his 
parents, for his very sense of rightness and wrongness is the 
introjected image of parental approval or disapproval. Hence- 
forth he feels inwardly that he must do the things dictated 
by parental images he has absorbed, and this is the sufficient 

^^ Cf. Anna Fred, The Ego and Mechanisms of Defense, pp. 117 seq. (Hogarth 
Press, London, 1954) 

"■" Freud, The Ego and the Id, pp. 40-46. 


reason for his sense of obligation; similarly, he must avoid 
what the inwardly adopted images forbid, and if he does not, 
he feels guilty. 

For Freud, this is the sole source of moral ideas; there is 
no place in this scheme for intelligent insight into the natural 
order of things or of values as a possible principle of the sense 
of morality/^ Deliberate consideration and judgment play no 
part in morality; the moral norms for any individual are the 
parental images, with all their imaged laws, commands, power 
and authority, which first exist for the child in external reality 
and are then automatically introjected by the attempt to be 
free from the Oedipal conflict. Thus Freud terms the moral 
sense a precipitate in the ego of the parental figures, deriving 
its compelling force from the sexual urges which have been 
inhibited and re-channelled, deflected from their primal aims 
and objects precisely by means of the formation of parental 
images. By the force of these mental identifications, the child 
is determined in his sense of morality — all that he will do and 
say, think and like, is now established for him through parental 
identification/* Morality then, is essentially infantile, on a 
level with the mental development of the child absorbing it, 
and hence uncritical. It is, moreover, unconscious, perhaps 
because it was formed at an unreflective stage of life, perhaps 
because the crisis by which it was formed and with which it is 
associated was a painful crisis, and thus subject to repression; 
these points are not clear in Freud. 

^' Some of Freud's disciples hold that the sense of morality has origin in elements 
which are prior to the dissolution of the Oedipus complex (cf. Ferenczi, Melanie 
Klein, Erikson) , and others give some weight to the function of reason (the reality 
related ego) in forming the moral sense, but it seems safe to say that all orthodox 
Freudians make the effects of the dissolution of the Oedipus complex the major 
component in the production of a sense of right and wrong. In Freud's own WTitings 
there is mention of pre-oedipal elements, e. g. instinctual movements and formations, 
which presumably would have some effect in the development of a sense of 
morality, but it does not seem that Freud himself made the deduction explicit. 
See, for example, " Instincts and Their Vicissitudes," Coll. Papers, vol. 4, pp. 75-79. 

^* Freud, " The Economic Problem in Masochism," Coll. Papers, vol. 2, pp. 263- 
266; The Ego and the Id, pp. 46-51. 


In actual fact, of course, the identifications mentioned above 
may not take place so easily. If the Oedipus complex itself is 
not normal, or if it cannot be completely resolved normally, 
the stage is set for later psychological difficulties. These con- 
siderations, however, are irrelevant to our present point. Here 
we wish only to inquire further into what this mode of forma- 
tion tells us about the superego itself — what character is 
imparted to the superego from the resolution of the instinctual 
forces which comprised the Oedipus complex. 

Obviously, insofar as the superego is formed by the process 
of identification, it serves as a norm or ideal for the ego, as a 
pattern to which the child must conform. A boy wants to be 
like his father, and feels that he does wrong if in any way he 
fails to live up to this ideal. This is the simple ego-ideal aspect 
of the superego, the basis for the urge to strive for perfection. 
But along with this ideal-pattern aspect, there are certain 
prohibitions set up in the child's mind: he must not do certain 
things that his father does. This aspect — the taboo-aspect — 
is understandable when we recollect the original motive for 
forming the ego-ideal — the child wishing to escape from the 
tensions aroused by feeling rivalry for the father. He escaped 
by avoiding any further competition with his father, with 
regard to his mother's affections; he left the field to his rival 
and contented himself with emulating him. Inextricably bound 
up with the image of his father are his father's prerogatives: 
his special place in the mother's affections. The child then has 
abandoned his former role of rivalry; he is careful now not to 
trespass, he formulates a series of prohibitions whose funda- 
mental enforcement agency is, subjectively, the forbidding 
image of his father. This is the basis of the prohibitory sense 
in people. The superego then is twofold: to be like the father, 
and not to do everything he does.^^ 

To a lesser degree, in the resolution of the normal complete 
complex, the child also wants to be like his mother, and yet 
not like her, i.e. not to take her place in his father's affections. 

^^ Freud, The Ego and the Id, pp. 44-45. 


With these deep desires as their roots, all the prohibitions, 
exhortations, expressed or implied wishes, ideals, goals, opinions, 
and attitudes, etc. of his parents take on added force and 
meaning — they begin to constitute for the child the code by 
which he regulates his life; the code which, if he obeys it, 
produces a sense of contentment like the contentment he felt 
when his parents approved of him; the code which, when broken, 
gives him a sense of guilt or wrongdoing like the guilt he felt 
when he experienced a threat in his relationships with his 

The force of the superego depends on many factors. The 
stronger the original Oedipus complex, the stronger the identi- 
fications necessary to resolve it, and therefore the stronger the 
ego-ideal which results from it. The more rigid and harsh the 
parents were, the more rigid and harsh is the image developed 
from them, and the more urgent the need of resolving the 
complex — both factors producing a more exacting superego.^® 

Other factors may also account for the strength of a superego. 
In every person there is a certain narcissistic element — self- 
love — which varies inversely with the strength of his object 
loves. (It is a matter of common experience that love of self 
impedes love of others, love of others leads to a certain self- 
forgetfulness.) Now a child has an enormous narcissistic love, 
almost a megalomania. He can be pictured as thinking that the 
whole world revolves around him, that he should have every 
satisfaction, and he becomes enraged when thwarted. Freud 
asks: Where does this narcissistic love go in the adult, for 
obviously it is much diminished in normal adults. His con- 
clusion is that, since this love must be directed somewhere, it 
must have been absorbed in the love of the ego-ideal. This 
accounts for much of the force the ideal exerts on the ego, (e. g. 
it has the force of the displaced narcissistic impulse) and mani- 
festly the greater the degree of narsissistic love, the stronger 
is the resulting superego. ^^ 

^^ Freud, "The Economic Problem in Masochism," Coll. Papers , Vol. 2, pp. 


Freud. " On Narcissism: An Introduction," Coll. Papers, vol. 4, p. 50. 


In a similar fashion, the drives of other basic instinctual 
impulses are found expressing themselves through the superego. 
The masochistic element, which finds pleasure in being hurt, 
turns up in the superego as ' obedience * and submission, or as 
self-deprecatory or self-accusing impulses.^* The exhibitionist 
urge is displaced into the desire for approval. Sadistic impulses, 
which find pleasure in hurting, turn up as moral domineering, 
as contempt for others because of their * moral * inferiority. In 
general, the fundamental libidinal impulses are deflected from 
their sexual orientation to the parents (infantile objects) to 
de-sexualized social relationships, to institutions of law, religion, 
politics and all forms of public and community activity, for 
which one now has respect, love, devotion, etc., as the super- 
ego pattern dictates .^^ 

In Freud's formulation these evolutions of instinctual move- 
ments to new aims and objects must be understood as simple 
mechanical transfers of psychic energy from one mode of dis- 
charge to an alternative mode more acceptable to the ego. New 
objects were demanded by the ego when infantile objects were 
found to bring punishment; the id is satisfied as long as they 
can substitute for the primitive objects. Essentially, however, 
the id always retains its primal orientation; hence a person who 
is later loved because he resembles the parent, is loved by the 
same instinctual urge that originally found satisfaction in the 
parent. The psychic energy has been canalized to another but 
basically (psychologically) identical object.^" 

The result of this acceptation is that, for Freud, there is no 
real development of the superego after infancy, only a kind 
of re-structuralization of the primitive elements. The norms 

^® Freud, op. cit., pp. 52-55; see Dalbiez, Psychoanalytic Method and the Doctrine 
of Freud, vol. I, p. 408-409. (Longmans Green & Co., New York, 1948) . 

^* Cf. Nuttin, Psychoanalysis and Personality, pp. 44-45. 

^° Cf. Nuttin, loc. cit., quoting Ernest Jones on this point. " The shift from the 
original sexual object to a secondary social object is not only a substitution of the 
one for the other, but rather a canalization of the primitive sexual energy in a new 
direction. To state it exactly, one should speak about displacement and not about 
substitution or replacement." 


of moral conduct having once been established in early child- 
hood, do not mature thereafter. The do's and don'ts of the 
infantile period are basically the do's and don'ts of a whole 
life span. As other factors make their influence felt on the 
growing child — teachers, other members of the family, civil 
authorities — and other ideals attract him — heroes, leaders — as 
new goals and new prohibitions are incorporated into the super- 
ego, they are automatically associated with the old solely in 
virtue of their identifiability with the original and basic parental 
images. The latter, moreover, always remain the strongest and 
most decisive elements in the individual's sense of right and 

(5) The Superego after Freud. 

Psychoanalysis, following Freud, has been more or less faith- 
ful to his formulation of the notion of the superego, although 
it has assiduously worked to clarify and enrich the concept, 
Freud himself admitting that there was much yet to be ex- 
plained. Ernest Jones, an orthodox disciple, introduced a 
distinction into the superego, setting off a conscious sense of 
morality which corresponds to adult moral valuation against 
the unconscious moral norms derived from infantile reactions. 
This distinction certainly goes a long way towards aligning 
the superego with the moral sense as it is generally conceived. ^^ 

An instance of another approach, aiming at clarifying and 
stabilizing the relationship of the superego to infantile mental 
formations, shows the varieties of infantile thinking often 
manifested in superego activity. Children, for example, exhibit 
a species of magical thinking, not clearly distinguishing fact 
from fancy, and wish from deed. There is also a childish sense 
of justice — the child thinks he must be punished for wishes as 
well as deeds, and that punishment is inevitable and poetically 
proportioned to the crime. He also thinks he can propitiate an 
offended authority by ritualistic acts, by undoing in an imagi- 
native way the wrong he has done. This kind of thinking is 

" Cf. Dalbiez, op. cit., p. 409. 


apparent in adults, as part of their moral outlook, especially 
in some cases of neuroses."^ 

Since religion and morality are so closely bound together, 
some authors examine religious phenomena to detect the evi- 
dence of superego characteristics. Freud himself originally 
interpreted the role of God as an evidence of the father 
identification reaction in the formation of the superego. Others 
see in the combination of exhortation to an ideal and prohi- 
bition of evil acts found in sacred writings the reflection of the 
two fundamental aspects of the superego, ideal and taboo. "^ 

These authors, as well as many others, accept Freud's basic 
configurations, and develop and apply them, with the purpose 
of explaining all (or perhaps only some) ethical or moral 
and religious conduct on the basis of deep and early instinc- 
tual movements, and the reactions to them. Others how- 
ever pick and choose among the elements of the superego, 
accepting some and rejecting others as insufficiently proved, or 
simply erroneous. Dr. Homey, for instance, does not accept 
the superego as a special mental agency, but rather as a special 
need — as a need to be perfect and infallible, and a need which 
must be maintained by pretense wherever reality denies it. 
Like Freud, she sees the genesis of this need in parental 
authority, not, however, as the resolution of untenable sexual 
orientations. When a child has been forced to conform too 
rigidly to parental standards, he loses his own initiative, goals 
and judgments. He takes the easy way out, abandons his 
sense of self-reliance, and relies solely on the approval of others, 
becoming finally the victim of alien norms of conduct. These 
norms then do not constitute a valid moral standard for the 
individual; they are not responses to true values rightly appre- 
hended and appreciated. They are nothing but a sham of 
morality, which has taken the place of true standards and eflec- 

*' Cf. Vincent P. Mahoney, M. D., " Scrupulosity from the Psychoanalytic View- 
point," Bjilletin of the Guild of Catholic Psychiatrists, vol. V, #2. 

"^ Mortimer Ostow, " Religion and Psychiatry," American Handbook of Psychiatry, 
pp. 1789 sqq. 


lively prevents true standards from developing. In two ways 
this formulation of superego activity is a radical departure 
from Freud's. In the first place, it allows for a twofold form 
of moral standards in individuals — a true moral code based on 
verified and voluntarily adopted standards, and a false moral 
code, based on parental dominance. Freud would have all moral 
codes to be of the second type. Secondly, the latter type of 
moral codes does not necessarily have to appear in a child — 
the Oedipus complex is not universal, hence not universally 
resolved by the introjection of parental images. Hence a purely 
superego-type moral standard may not always appear, and 
even when it does appear, it may be resolved and supplanted 
by a reasonable and conscious form of morality. What is 
involved in this latter form of moral sense (and rejected in 
Freud's formulation) is an enduring capacity in the individual 
to grow morally, from infant morality to mature morality, by 
a qualitatively differentiated development of moral insights. 
Hence the effects of infantile experiences and the modes of 
infantile reaction, however profound, are not the decisive deter- 
minants of mature character.-* 

Other psychoanalysts have followed these same general paths, 
deriving many fundamental ideas from Freud, but developing 
them less mechanistically, and with more appreciation of the 
intelligent and free aspects of human psychology, and more 
optimism about its plasticity in response to these more human 
influences. Fr. Joseph Nuttin accepts the notion of the deep 
influence of parental authority on the mind of children, but 
insists on the positive and creative elements in the child's 
reaction. For him, identification is not merely a passive adop- 
tion of alien standards consequent on the repression of sexual 
urges, but more a drive towards self-realization, which in the 
child is admittedly in the direction of being like his father, 
but even here is not wholly devoid of some kind of appreciation 
of the values adopted. And as the child grows older, there is 
more and more the aspect of reasonable discernment and willing 

** Karen Horney, Neio Ways in Psychoanalysis, Chap. XII. 


cooperation in the discovery and acceptance of ideals and pro- 
hibitions, which, so long as they are objectively valid, serve 
not to stultify the character but to enlarge and enrich it. 
There is moral growth through widening awareness and revision 
of old standards in the light of new ones. This is not to say 
that such a conscious drive towards self-realization operates 
equally well in everyone, or entirely in anyone, but it is in 
evidence frequently enough to demand some explanation be- 
yond Freud's. Nuttin therefore rejects the idea that the original 
identification of a child is purely the result of the failure of 
sexual possession, and that subsequent identifications are really 
the infantile identifications repeated in new instances, and 
finally that real moral development is arrested at the infantile 
stage. Finally he rejects the ubiquity of the Oedipus complex, 
and, consequently, the doctrine that the resolution of this 
complex results in the formation of what is man's sole agency 
of normative or moral conduct, a superego.-^ This also seems 
to be the position taken by Roland Dalbiez in his critique of 
Freudian doctrine.-^ 

(b) Conclusions about the superego. 

What therefore can be concluded? Certainly it can be granted 
that there is an internal but acquired norm for judging right 
and wrong, and that in its formation it is closely connected 
with parental training, deriving indeed much of its efficacy 
from the deep emotional ties with parents, which in infants 
constitute almost the whole of affective life. The first and 
natural impulses of a child would be to be like his parents. 
It can also be seen that excessive harshness in discipline can 
cause excessive rigor in the norms adopted by children, and 
excessive sensitiveness to the demands of these norms, and that 
obedience to the norms can generate a sense of satisfaction, 
disobedience a painful sense of guilt, quite dissociated from real 

^^ Joseph Nuttin, Psychoanalysis and Personality, pp. 63, 178-183. 
"'Roland Dalbiez, Psychoanalytic Method and the Doctrine of Freud, vol. I, 
pp. 407 seq.; vol. II, pp. 280-327. 


right and wrong. These norms could, moreover, be so restrictive 
that they would prevent or inhibit normal growth to moral and 
emotional maturity. They could operate practically uncon- 
sciously in virtue of their early and unquestioned acceptance; 
they constitute the way to do things, the way things have 
always been done, and the factor of unconscious influence could 
be increased if the norms themselves form parts of painful 
emotional complexes. These norms can become involved with 
elements of self-love, of self-deprecation, of childish dependence 
on others, of aggressive or spiteful attitudes. Their character 
can invade and color all the moral and religious life of an 
individual, and, no doubt, of a society too. 

That moral codes are formed simply and universally as the 
result of the repression and resolution of some sexually oriented 
instinctual complex directed towards the parents is an unwar- 
ranted generalization, however useful the concept might be in 
understanding particular cases of abnormal mental develop- 
ment. That a moral norm is nothing but an engulfed parental 
image, unsusceptible of real growth and qualitative develop- 
ment is also untenable, along with its corollary, that there is 
no objective validity to moral, social and religious standards. 

But leaving aside these exaggerations, it must be admitted 
that the concept of the superego has deepened our insight into 
the actual workings of the human psychism, and has proved its 
value in the solution of some difficult psychological problems. 

II. The Notion of Conscience 

Our purpose now, however, is to try to apply some of the 
conclusions taken from the study of the