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Each bound in clothelte, is. net 

First and Last Things. By H. G. WELLS, 


Humanity's Gain from Unbelief. By CHARLES BRADLAUGH. 


A Short History of the World. By H. G. WELLS. 

Autobiography of Charles Darwin. 

The Origin of Species. By CHARLES DARWIN. (6th Copyright edition ) 

Twelve Years in a Monastery. By JOSEPH MCCABE. 

History of Modern Philosophy. By A. W. BFNN. 

Gibbon on Christianity. Being Chapters XV and XVI of Edward 

Gibbon's Decline and Fall of the Roman Empire. With Introduction 

by the Rt. Hon J. M. ROBERTSON. 
The Descent of Man. Part I and the concluding Chapter of Part III. 


History of Civilization in England. By H. T. BUCKLE. Vol. I. 
Anthropology. An Introduction to the Study of Man and Civilization. 

By SIR EDWARD B, TYLOR. Vols. I and II. 
Iphigenia. Two plays by EURIPIDES. English version by C. 1 . 

BONNER, M.A. (Trinity College, Cambridge). 
Lectures and Essays. By THOMAS HENRY HUXLEY. 
The Evolution of the Idea of God. By GRANT ALLEN. 
An Agnostic's Apology. By SIR LESLIE STEPHEN, K.C.B. 
The Churches and Modern Thought. By VIVIAN PHELIPS. 
Penguin Island. By ANATOLE FRANCE 
The Pathetic Fallacy. By LLEWELYN POWYS. 
Historical Trials (a Selection). By SIR JOHN MACDONELL. 
A Short History of Christianity. Byithe RT. HON. J. M. ROBERTSON. 
The Martyrdom of Man. By WINWOOD READE. 
Head-Hunters : Black, White, and Brown. By A. C. HAD DON. 
The Evidence for the Supernatural. By IVOR LL. TUCKETT. 
The City of Dreadful Night, and Other Poems. By JAMES THOMSON 

("B. V."). 
In the Beginning. The Origin of Civilisation. By PROF. G. ELLIOT 

Adonis : A Study in the History of Oriental Religion. By SIR JAMES G. 


Our New Religion. By the RT. HON. H. A. L. FISHER. 
On Compromise, By JOHN VISCOUNT MORLEY, O.M., P,C. 
History of the Taxes on Knowledge. By COLLET DOBSON COLLET. 
The Existence of God. By JOSEPH MCCABE. 
The Story of the Bible. By MACLEOD YEARSLEY, F.R.C.S., etc. 
Savage Survivals. By J. HOWARD MOORE. 
The Outcast. By WINWOOD READE. 
The Revolt o! the Angels. By ANATOLE FRANCE. 
Penalties Upon Opinion ; or Some Records of the Laws o! Heresy and 

Blasphemy. Brought together by HYPATIA BRADLAUGH BONNER. 
Oath, Curse, and Blessing. By E. CRAWLEY. 
Fireside Science. By SIR E. RAY LANKESTER, F.R.S. Prepared by 


TJie Thinker's Library, No. 3 










First pitblidcd in the Thinker's Library, February, 
Second Impression, March, 1931, 
'Ihird Impression, March, 1934. 

Printed and Published in Groat Britain for the Rationalist Press 

Association Limited by C. A, Watts & Co, 1 united, 5 & 6 Johnson's 

Court, Meet Street, London, E,l\4, 






II OUR BODILY FRAME . . , . , 18 














XV GOD AND THE WORLD , , , , , 225 






INDEX 313 



THE present study of the Monistic Philosophy is in- 
tended for thoughtful readers of every condition who are 
engaged in an honest search for the truth. The steady 
increase of this effort of man to attain a knowledge of the 
truth is one of the most salient features of the nineteenth 
century. The fact is easily explained by the history of 
humanity; by the open contradiction that has developed 
during the century between science and the traditional 
"Revelation"; and, finally, by the inevitable extension 
and deepening of the rational demand for an elucidation 
of the innumerable facts that have been brought to light, 
and for a fuller knowledge of their causes. 

Unfortunately, this vast progress of empirical know- 
ledge in our " Century of Science " has not been accom- 
panied by a corresponding advancement in theoretical 
interpretation in that higher knowledge of the causal 
nexus of individual phenomena which we call philosophy. 
We find, on the contrary, that the abstract and almost 
wholly metaphysical science which has been taught in our 
universities for the last hundred years under the name of 
" philosophy " is far from assimilating our hard-earned 
treasures of experimental research. On the other hand, 
we have to admit, with equal regret, that most of the 
representatives of what is called "exact science" are 
content with the special care of their own narrow branches 
of observation and experiment, and deem superfluous th* 


deeper study of the universal connection of the pheno- 
mena they observe that is, philosophy. While the pure 
empiricists "do not see the wood for the trees," the 
metaphysicians, on the other hand, are satisfied with the 
general picture of the wood, and trouble not about its 
individual trees. The idea of a "philosophy of nature," 
to which both methods of research, the empirical and the 
speculative, naturally converge, is even yet contemptu- 
ously rejected by large numbers of representatives of both 

This unnatural and fatal opposition between Science and 
Philosophy, between the results of experience and of 
thought, is undoubtedly becoming more and more painful 
to thoughtful people. That is easily proved by the in- 
creasing spread of the course of the last half -century. 
It is seen, too, in the welcome fact that, in spite of the 
mutual aversion of the scientific observer and the specula- 
tive philosopher, nevertheless eminent thinkers from both 
camps are making a united effort to attain the solution of 
that highest object of inquiry which we briefly denominate 
the "world-riddles." The studies of these "world- 
riddles " which I offer in the present work cannot reason- 
ably claim to give a perfect solution of them : they merely 
offer to a wide circle of readers a critical inquiry into the 
problem, and seek to answer the question as to how 
nearly we have approached the solution at the present 
day. What stage in the attainment of truth have we 
actually arrived at in this closing year of the nineteenth 
century? What progress have we really made during its 
course towards that immeasurably distant goal? 

The answer which I give to these great questions must, 
naturally, be merely subjective and only partly correct; 
for my knowledge of nature and my ability to interpret 
it are limited, as are those of every man. The one point 


that I can claim, and which, indeed, I must ask of my 
strongest opponents, is that my Monistic Philosophy is 
sincere from beginning to end it is the complete expres- 
sion of the conviction that has come to be, after many 
years of ardent research into Nature and unceasing re- 
flection on the true basis of its phenomena. For fully 
half a century has my mind's work proceeded, and I now, 
in my sixty-sixth year, may venture to claim that it is 
mature ; I am fully convinced that this " ripe fruit " of 
the tree of knowledge will receive no important addition 
and suffer no substantial modification during the brief 
spell of life that remains to me. 

The present work is the continuation, confirmation, and 
integration of the views which I have urged for a genera- 
tion. It marks the close of my studies of the Monistic 
conception of the universe. The earlier plan, which I 
projected many years ago, of constructing a complete 
" System of Monistic Philosophy " on the basis of evolu- 
tion, will never be carried into effect now. My strength 
is no longer equal to the task, and many warnings of 
approaching age urge me to desist. Indeed, I am wholly 
a child of the nineteenth century, and with its close I 
draw the line under my life's work. 

The vast extension of human knowledge which has 
taken place during the present century, owing to a happy 
division of labour, makes it impossible to-day to range 
over ail its branches with equal thoroughness, and to show 
their essential unity and connection. Even the genius of 
the highest type, having an equal command of every 
branch of science, and largely endowed with the artistic 
faculty of comprehensive presentation, would be incapable 
of setting forth a complete view of the cosmos in the 
space of a moderate volume. My own command of the 
various branches of science is uneven and defective, so 


that I can attempt no more than to sketch the general 
plan of such a world-picture, and point out the pervading 
unity of its parts, however imperfect be the execution. 
Thus it is that this work on the world-enigma has some- 
thing of the character of a sketch-book, in which studies 
of unequal value are associated. As the material of the 
book was partly written many years ago^ and partly pro- 
duced for the first time during the last few years, the 
composition is, unfortunately, uneven at times; repeti- 
tions, too, have proved unavoidable. I trust those defects 
will be overlooked. 

In taking leave of my readers, I venture the hope that, 
through my sincere and conscientious work in spite of 
its faults, of which I am not unconscious I have con- 
tributed a little towards the solution of the great enigma. 
Amid the clash of theories, I trust that I have indicated 
to many a reader who is absorbed in the zealous pursuit 
of purely rational knowledge that path which, in my firm 
conviction, alone leads to truth the path of empirical 
investigation and of the Monistic Philosophy which is 
based upon it. 


Jena, Germany, j8<ft< 




The condition of civilisation and of thought at the close of the 
nineteenth century. Progress of our knowledge of nature of the 
organic and inorganic sciences. The Law of Substance and the 
Law of Evolution. Progress of technical science and of applied 
chemistry. Stagnancy in other departments of life: legal and 
political administration., education and the Chuich. Conflict of 
reason and dogma. Anthropism, Cosmological perspective. 
Cosmological theorems. Refutation of the delusion of man's 
importance. Number of "world -riddles," Criticism of the 
M seven " enigmas. The way to solve them. Function of the 
senses and of the brain. Induction and deduction. Reason, 
sentiment, and revelation, Philosophy and science. Experience 
and speculation. Dualism and monism. 

THE close of the nineteenth century offers one of the 
most remarkable spectacles to the thoughtful observer. 
All educated people are agreed that it has in many respects 
immeasurably outstripped its predecessors, and has 
achieved tasks that were deemed impracticable at its com- 
mencement. An entirely new character has been given to 
the whole of our modern civilisation, not only by our 
astounding theoretical progress in sound knowledge of 
nature, but also by the remarkably fertile practical applica- 
tion of that knowledge in technical science, industry, com- 
merce, and so forth. On the other hand, however, we 
have made little or no progress in moral and social life, 
in comparison with earlier centuries; at times there ha* 



been serious reaction. And from this obvious conflict 
there have arisen, not only an uneasy sense of dismember- 
ment and falseness, but even the danger of grave cata- 
strophes In the political and social world. It is, then, not 
merely the right, but the sacred duty, of every right- 
minded and humanitarian thinker to devote himself con- 
scientiously to the settlement of that conflict, and to 
warding off the dangers that it brings in its train. In 
our conviction this can only be done by a courageous 
effort to attain the truth, and by the formation of a clear 
view of the world a view that shall be based on truth 
and conformity to reality. 

If we recall to mind the imperfect condition of science 
at the beginning of the century, and compare this with 
the magnificent structure of its closing years, we are com- 
pelled to admit that marvellous progress has been made 
during its course. Every single branch can boast that it 
has, especially during the latter half of the century, made 
numerous acquisitions of the utmost value. Both in our 
microscopic knowledge of the little and in our telescopic 
investigation of the great, we have attained an invaluable 
insight that seemed inconceivable a hundred years ago. 
Improved methods of microscopic and biological research 
have not only revealed to us an invisible world of living 
things in the kingdom of the protists, full of an infinite 
wealth of forms, but they have taught us to recognise in 
the tiny cell the all-pervading " elementary organism " of 
whose social communities the tissues the body of every 
muiticellular plant ' and animal, even that of man, is 
composed. This anatomical knowledge is of extreme 
importance; and it is supplemented by the embryological 
discovery that each of the higher muiticellular organisms is 
developed out of one simple cell, the impregnated ovum. 
The " Cellular theory," which has been founded on that 
discovery, has given us the first true indication of the 
physical, chemical, and even the psychological, processes 
of life those mysterious phenomena for whose explanation 
it had been customary to postulate a supernatural "vital 
force " or "immortal soul." Moreover, the true character 
of disease has been made clear and intelligible to the 


physician for the first time by the cognate science of 
Cellular Pathology. 

The discoveries of the nineteenth century in the 
inorganic world are no less important. Physics has made 
astounding progress in every section of its province in 
optics and acoustics, in magnetism and electricity, in 
mechanics and thermo-dynamics ; and, what is still more 
important, it has proved the unity of the forces of the 
entire universe. The mechanical theory of heat has shown 
how intimately they are connected, and how each can, in 
certain conditions, transform itself directly into another. 
Spectrum analysis has taught us that the same matter 
which enters into the composition of all bodies on earth, 
including its living inhabitants, builds up the rest of the 
planets, the sun, and the most distant stars. Astro-physics 
has considerably enlarged our cosmic perspective in reveal- 
ing to us, in the immeasurable depths of space, millions 
of circling spheres, larger than our earth, and, like it, in 
endless transformation, in an eternal rhythm of life and 
death. Chemistry has introduced us to a multitude of 
new substances, ail of which arise from the combination 
of a few (about seventy) elements that are incapable of 
further analysis ; some of them play a most important part 
in every branch of life. It has been shown that one of 
these elements carbon is the remarkable substance that 
effects the endless variety of organic syntheses, and thus 
may be considered "the chemical basis of life." How- 
ever, all the particular advances of physics and chemistry 
yield in theoretical importance to the discovery of the 
great law which brings them to one common focus, the 
"Law of Substance." As this fundamental cosmic law 
establishes the eternal persistence of matter and force, 
their unvarying constancy throughout the entire universe, 
it has become the pole-star that guides our Monistic 
Philosophy through the mighty labyrinth to a solution of 
the world-problem. 

Since we intend to make a general survey of the actual 
condition of our knowledge of nature and its progress 
during the present century in the following chapters, we 
shall delay no longer with the review of its particular 


branches. We would only mention one important advance, 
which was contemporary with the discovery of the law 
of substance, and which supplements it the establishment 
of the theory of evolution. It is true that there were 
philosophers who spoke of the evolution of things a 
thousand years ago; but the recognition that such a law 
dominates the entire universe, and that the world is 
nothing else than an eternal "evolution of substance," is 
a fruit of the nineteenth century. It was not until the 
second half of this century that it attained to perfect 
clearness and a universal application. The immortal merit 
of establishing the doctrine on an empirical basis, and 
pointing out its world-wide application, belongs to the 
great scientist Charles Darwin; he it was who, in 1859, 
supplied a solid foundation for the theory of descent, which 
the able French naturalist Jean Lamarck had already 
sketched in its broad outlines in 1809, and the fundamental 
idea of which had been almost prophetically enunciated 
in 1799 by Germany's greatest poet and thinker, Wolfgang 
Goethe. In that theory we have the key to " the question 
of all questions," to the great enigma of "the place of 
man in nature," and of his natural development. If we 
are in a position to-day to recognise the sovereignty of the 
law of evolution and, indeed, of a monistic evolution in 
every province of nature, and to use it, in conjunction with 
the law of substance, for giving a simple interpretation of 
all natural phenomena, we owe this chiefly to those three 
distinguished naturalists ; they shine as three stars of the 
first magnitude amid ail the great men of the century. 

This marvellous progress in a theoretical knowledge of 
nature has been followed by a manifold practical applica- 
tion in every branch of civilised life. If we are to-day in 
the "age of commerce," if international trade and com- 
munication have attained dimensions beyond the concep- 
tion of any previous age, if we have transcended the limits 
of space and time by our telegraph and telephone, we owe 
it, in the first place, to the technical advancement of 
physics, especially in the application of steam and elec- 
tricity. If, in photography, we can, with the utmost 
ease, compel the sunbeam to create for us in a moment's 


time a correct picture of any object we like ; if we have 
made enormous progress in agriculture, and in a variety 
of other pursuits; if, in surgery, we have brought an 
infinite relief to human pain by our chloroform and 
morphia, our antiseptics and serous therapeutics, we owe 
it all to applied chemistry. But it is so well known how 
much we have surpassed all earlier centuries through 
these and other scientific discoveries that we need linger 
over the question no longer. 

While we look back with a just pride on the immense 
progress of the nineteenth century in a knowledge of 
nature and in its practical application, we find, unfortun- 
ately, a very different and far from agreeable picture when 
we turn to another and not less important province of 
modern life. To our great regret we must endorse the 
words of Alfred Wallace : ** Compared with our astounding 
progress in physical science and its practical application, 
our system of government, of administrative justice, and 
of national education, and our entire social and moral 
organisation, remain in a state of barbarism.'* To con- 
vince ourselves of the truth of this grave indictment we 
need only cast an unprejudiced glance at our public life, 
or look into the mirror that is daily offered to us by the 
press, the organ of public sentiment. 

We begin our review with justice, the fundamentum 
regnorum. No one can maintain that its condition to-day 
is in harmony with our advanced knowledge of man and 
the world. Not a week passes in which we do not read 
of judicial decisions over which every thoughtful man 
shakes his head in despair ; many of the decisions of our 
higher and lower courts are simply unintelligible. We 
are not referring in the treatment of this particular 
" world-problem " to the fact that many modern States, 
in spite of their paper constitution, are really governed 
with absolute despotism, and that many who occupy the 
bench give judgment less in accordance with their sincere 
conviction than with wishes expressed in higher quarters. 
We readily admit that the majority of judges and counsel 
decide conscientiously, and err simply from human frailty. 
Most of their errors, indeed, are due to defective prepara- 


tion. It is popularly supposed that these are just the men 
of highest education, and that on that very account they 
have the preference in nominations to different offices. 
However, this famed " legal education " is for the most 
part rather of a formal and technical character. They 
have but a superficial acquaintance with that chief and 
peculiar object of their activity, the human organism, and 
its most important function, the mind. That is evident 
from the curious views as to the liberty of the will, 
responsibility, etc., which we encounter daily. I once 
told an eminent jurist that the tiny spherical ovum from 
which every man is developed is as truly endowed with 
life as the embryo of two, or seven, or even nine months. 
He laughed incredulously. Most of our students of juris- 
prudence have no acquaintance with anthropology, psycho- 
logy, and the doctrine of evolution the very first requi- 
sites for a correct estimate of human nature. They have 
" no time " for it ; their time is already too largely be- 
spoken for lighter pursuits and purposes. Their scanty 
hours of study are required for the purpose of learning 
some hundreds of paragraphs of law books, a knowledge 
of which is supposed to qualify the jurist for any position 
whatever in our modern civilised community. 

We shall touch but lightly on the unfortunate province 
of politics, for the unsatisfactory condition of the modern 
political world is only too familiar. In a great measure 
its evils are due to the fact that most of our officials are 
men without an acquaintance with those social relations of 
which we find the earliest types in comparative zoology 
and the theory of evolution, in the cellular theory and 
study of the protists. We can only arrive at a correct 
knowledge of the structure and life of the social body, the 
State, through a scientific knowledge of the structure and 
life of the individuals who compose it, and the cells of 
which they are in turn composed. If our political rulers 
and our " representatives of the people " possessed this 
invaluable biological and anthropological knowledge, we 
should not find our journals so full of the sociological 
blunders and political nonsense which at present disfigure 
our Parliamentary reports, and even many of our official 


documents. Worst of all is it when the modern State 
flings itself into the arms of the reactionary Church, and 
when the narrow-minded self-interest of parties and the 
infatuation of short-sighted party-leaders lend their sup- 
port to the hierarchy. Then are witnessed such sad scenes 
as the German Reichstag put before our eyes even at the 
close of the nineteenth century. We have the spectacle 
of the educated German people in the power of the ultra- 
montane Centre, under the rule of the Roman papacy, 
which is its bitterest and most dangerous enemy. Then 
superstition and stupidity reign instead of right and 
reason. Never will our Government improve until it casts 
off the fetters of the Church and raises the views of the 
citizens on man and the world to a higher level by a 
general scientific education. That does not raise the ques- 
tion of any special form of constitution. Whether a 
Monarchy or a Republic be preferable, whether the con- 
stitution should be aristocratic or democratic, are subordi- 
nate questions in comparison with the supreme question : 
Shall the modern civilised State be ecclesiastical or secular? 
Shall it be theocratic ruled by the irrational formulae of 
faith and by clerical despotism or nomocratic under the 
sovereignty of rational laws and civic right? The first 
task is to kindle a rational interest in our youth, and to 
uplift our citizens and free them from superstition. That 
can only be achieved by a timely reform of our schools. 

Our education of the young is no more in harmony with 
modern scientific progress than our legal and political 
world. Physical science, which is so much more im- 
portant than all other sciences, and which, properly under- 
stood, really embraces the so-called moral sciences, is still 
regarded as a mere accessory in our schools, if not treated 
as the Cinderella of the curriculum. Most of our teachers 
still give the most prominent place to that dead learning 
which has come down from the cloistral schools of the 
Middle Ages. In the front rank we have grammatical 
gymnastics and an immense waste of time over a 
" thorough knowledge " of classics and of the history of 
foreign nations. Ethics, the most important object of 
practical philosophy, is entirely neglected, and its place 


is usurped by the ecclesiastical creed. Faith must take 
precedence over knowledge not the scientific faith which 
leads to a monistic religion, but the irrational superstition 
that lays the foundation of a perverted Christianity. The 
valuable teaching of modern cosmology and anthropology, 
of biology and evolution, is most inadequately imparted, 
if not entirely unknown, in our higher schools ; while the 
memory is burdened with a mass of philological and his- 
torical facts which are utterly useless, either from the 
point of view of theoretical education or for the practical 
purposes of life. Moreover, the antiquated arrangements 
and the distribution of faculties in the universities are just 
as little in harmony with the point we have reached in 
monistic science as the curriculum of the primary and 
secondary schools. 

The climax of the opposition to modern education and 
its foundation, advanced natural philosophy, is reached, 
of course, in the Church. We are not speaking here of 
Ultramontane Papistry, nor of the orthodox sects which 
do not fall far short of it in ignorance and in the crass 
superstition of their dogmas. We are imagining our- 
selves for the moment to be in the church of a liberal 
Protestant minister, who has a good average education, 
and who finds room for "the rights of reason " by the 
side of his faith. There, besides excellent moral teach- 
ing, which is in perfect harmony with our own monistic 
ethics, and humanitarian sentiments of which we cordially 
approve, we hear ideas on the nature of God, of the world, 
of man, and of life, which are directly opposed to all 
scientific experience. It is no wonder that physicists and 
chemists, doctors and philosophers, who have made a 
thorough study of nature, refuse a hearing to such 
preachers. Our theologians and our politicians are just 
as ignorant as our philosophers and our jurists of that 
elementary knowledge of nature which is based on the 
monistic theory of evolution, and which is already far 
transcended in the triumph of our modern learning. 

From thig opposition, which we can only briefly point 
out at present, there arise grave conflicts in our modern 
life, which urgently demand a settlement. Our modern 


education, the outcome of our great advance in knowledge, 
has a claim upon every department of public and private 
life; it would see humanity raised, by the instrumentality 
of reason, to that higher grade of culture, and, conse- 
quently, to that better path towards happiness, which 
has been opened out to us by the progress of modern 
science. That aim, however, is vigorously opposed by the 
influential parties who would detain the mind in the 
exploded views of the Middle Ages, with regard to the 
most important problems of life ; they linger in the fold 
of traditional dogma, and would have reason prostrate 
itself before their *' higher revelation." That is the con- 
dition of things, to a very large extent, in theology and 
philosophy, in sociology and jurisprudence. It is not that 
the motives of the latter are to be attributed, as a rule, 
to pure self-interest ; they spring partly from ignorance of 
the facts and partly from an indolent acquiescence in tra- 
dition. The most dangerous of the three great enemies 
of reason and knowledge is not malice, but ignorance, or, 
perhaps, indolence. The gods themselves still strive in 
vain against these two latter influences when they have 
happily vanquished the first. 

One of the main supports of that reactionary system 
is still what we may call ''anthropism." I designate by 
this term "that powerful and world-wide group of 
erroneous opinions which opposes the human organism 
to the whole of the rest of nature, and represents it to be 
the preordained end of the organic creation, an entity 
essentially distinct from it, a god-like being. " Closer 
examination of this group of ideas shows it to be made 
up of three different dogmas, which we may distinguish 
as the anthropocentric 9 the anthropomorphic, and the 
anthropolatrou* . l 

I. The anthropocentric dogma culminates in the idea 
that man is the preordained centre and aim of all terres- 
trial life or, in a wider sense, of the whole universe. As 
this error is extremely conducive to man's interest, and as 
it is intimately connected with the creation-myth of the 
three great Mediterranean religions, and with the dogmas 

1 Anthropolatry mean* : " A divine worship of human nature." 


of the Mosaic, Christian, and Mohammedan theologies, it 
still dominates the greater part of the civilised world. 

II. The anthropomorphic dogma is likewise connected 
with the creation-myth of the three aforesaid religions, and 
of many others. It likens the creation and control of the 
world by God to the artificial creation of a skilful engineer 
or mechanic, and to the administration of a wise ruler. 
God, as creator, sustainer, and ruler of the world, is thus 
represented after a purely human fashion in his thought 
and work. Hence it follows, in turn, that man is god- 
like. " God made man to his own image and likeness." 
The older, naive mythology is pure " homotheism," attri- 
buting human shape, flesh, and blood to the gods. It is 
more intelligible than the modern mystic theosophy that 
adores a personal god as an invisible properly speaking, 
gaseous being, yet makes him think, speak, and act in 
human fashion ; it gives us the paradoxical picture of a 
"gaseous vertebrate." 

III. The anthropolatric dogma naturally results from 
this comparison of the activity of God and man ; it ends in 
the apotheosis of the human organism. A further result 
is the belief in the personal immortality of the soul, and 
the dualistic dogma of the twofold nature of man, whose 
" immortal soul " is conceived as but the temporary in- 
habitant of the mortal frame. Thus these three anthrop- 
istic dogmas, variously adapted to the respective profes- 
sions of the different religions, came at length to be vested 
with an extraordinary importance, and proved the source 
of the most dangerous errors. The anthropistic view of 
the world which springs from them is in irreconcilable 
opposition to our monistic system ; indeed, it is at once 
disproved by our new cosmological perspective. 

Not only the three anthropistic dogmas, but many other 
notions of the dualistic philosophy and orthodox religion 
are found to be untenable as soon as we regard them 
critically from the cosmological perspective of our monistic 
system. We understand by that the comprehensive view 
of the universe which we obtain from the highest point of 
our monistic interpretation of nature. From that stand- 
point we see the truth of the following "cosmological 


theorems," most of which, in our opinion, have already 
been amply demonstrated : 

(1) The universe, or the cosmos, is eternal, infinite, and 
illimitable. (2) Its substance, with its two attributes 
(matter and energy), fills infinite space, and is in eternal 
motion. (3) This motion runs on through infinite time 
as an unbroken development, with a periodic change from 
life to death, from evolution to devolution. (4) The in- 
numerable bodies which are scattered about the space- 
filling ether all obey the same "law of substance "; while 
the rotating masses slowly move towards their destruction 
and dissolution in one part of space, others are springing 
into new life and development in other quarters of the 
universe. (5) Our sun is one of these unnumbered perish- 
able bodies, and our earth is one of the countless transitory 
planets that encircle them. (6) Our earth has gone 
through a long process of cooling, before water, in liquid 
form (the first condition of organic life), could settle 
thereon. (7) The ensuing biogenetic process, the slow 
development and transformation of countless organic 
forms, must have taken many millions of years consider- 
ably over a hundred. 1 (8) Among the different kinds of 
animals which arose in the later stages of the biogenetic 
process on earth the vertebrates have far outstripped all 
other competitors in the evolutionary race. (9) The most 
important branch of the vertebrates, the mammals, were 
developed later (during the Triassic period) from the lower 
amphibia and the reptiiia. (10) The most perfect and 
most highly-developed branch of the class mammalia is the 
order of primates, which first put in an appearance, by 
development from the lowest prochoriata, at the beginning 
of the Tertiary period at least three million years ago. 
(11) The youngest and most perfect twig of the branch 
primates is man, who sprang from a series of man-like 
apes towards the end of the Tertiary period. (12) Con- 
sequently, the so-called " history of the world "that is, 
the brief period of a few thousand years which measures 
the duration of civilisation is an evanescently short 

1 Of. my Cambridge lecture, The Last Link, " Geological Time and 


episode in the long course of organic evolution, just as 
this, in turn, is merely a small portion of the history of 
our planetary system ; and as our mother earth is a mere 
speck in the sunbeam in the illimitable universe, so man 
himself is but a tiny grain of protoplasm in the perishable 
framework of organic nature. 

Nothing seems to me better adapted than this magnifi- 
cent cosmological perspective to give us the proper 
standard and the broad outlook which we need in the 
solution of the vast enigmas that surround us. It not 
only clearly indicates the true place of man in nature, but 
it dissipates the prevalent illusion of man's supreme im- 
portance, and the arrogance with which he sets himself 
apart from the illimitable universe, and exalts himself to 
the position of its most valuable element. This boundless 
presumption of conceited man has misled him into making 
himself "the image of God," claiming an "eternal life " 
for his ephemeral personality, and imagining that he 
possesses unlimited "freedom of will." The ridiculous 
imperial folly of Caligula is but a special form of man's 
arrogant assumption of divinity. Only when we have 
abandoned this untenable illusion, and taken up the correct 
cosmological perspective, can we hope to reach the solution 
of the "riddles of the universe." 

The uneducated member of a civilised community is 
surrounded with countless enigmas at every step, just as 
truly as the savage. Their number, however, decreases 
with every stride of civilisation and of science ; and the 
monistic philosophy is ultimately confronted with but one 
simple and comprehensive enigma the " problem of sub- 
stance." Still, we may find it useful to include a certain 
number of problems under that title. In the famous 
speech which Emil du Bois-Reymond delivered in 1880, 
in the Liebnitz session of the Berlin Academy of Sciences, 
he distinguished seven world -enigmas, which he enumer- 
ated as follows: (1) The nature of matter and force. 
(2) The origin of motion. (3) The origin of life. (4) 
The (apparently preordained) orderly arrangement of 
nature. (5) The origin of simple sensation and con- 
sciousness. (6) Rational thought, and the origin of the 


cognate faculty, speech. (7) The question of the freedom 
of the will. Three of these seven enigmas are considered 
by the orator of the Berlin Academy to be entirely trans- 
cendental and insoluble they are the first, second, and 
fifth; three others (the third, fourth, and sixth) he con- 
siders to be capable of solution, though extremely difficult ; 
as to the seventh and last "world-enigma," the freedom 
of the will, which is one of the greatest practical import- 
ance, he remains undecided. 

As my monism differs materially from that of the 
Berlin orator, and as his idea of the " seven great 
enigmas " has been very widely accepted, it may be useful 
to indicate their true position at once. In my opinion the 
three transcendental problems (1, 2, and 5) are settled by 
our conception of substance (vide chap, xii.) ; the three 
which he considers difficult, though soluble (3, 4, and 6), 
are decisively answered by our modern theory of evolu- 
tion ; the seventh and last, the freedom of the will, is not 
an object for critical, scientific inquiry at all, for it is a 
pure dogma, based on an illusion, and has no real 

The means and methods we have chosen for attaining 
the solution of the great enigma do not differ, on the 
whole, from those of all purely scientific investigation 
firstly, experience ; secondly, inference. Scientific experi- 
ence comes to us by observation and experiment, which 
involve the activity of our sense-organs in the first place, 
and, secondly, of the inner sense-centres in the cortex of 
the brain. The microscopic elementary organs of the 
former are the sense-cells ; of the latter, groups of gan- 
glkmic cells. The experiences which we derive from the 
outer world by these invaluable instruments of our mental 
life are then moulded into ideas by other parts of the 
brain, and these, in their turn, are united in a chain of 
reasoning by association. The construction of this chain 
may take place in two different ways, which are, in my 
opinion, equally valuable and indispensable : induction and 
deduction. The higher cerebral operations, the construc- 
tion of complicated chains of reasoning, abstraction, the 
formation of concepts, the completion of the perceptive 


faculty by the plastic faculty of the imagination in a 
word, consciousness, thought, and speculation are func- 
tions of the ganglionic cells of the cortex of the brain, just 
like the preceding simpler mental functions. We unite 
them all in the supreme concept of reason. 1 

By reason only can we attain to a correct knowledge 
of the world and a solution of its great problems. Reason 
is man's highest gift, the only prerogative that essentially 
distinguishes him from the lower animals. Nevertheless, 
it has only reached this high position by the progress of 
culture and education, by the development of knowledge. 
The uneducated man and the savage are just as little (or 
just as much) "rational " as our nearest relatives among 
the mammals (apes, dogs, elephants, etc.). Yet the 
opinion still obtains in many quarters that, besides our 
god-like reason, we have two further (and even surer!) 
methods of receiving knowledge Emotion and Revela- 
tion. We must at once dispose of this dangerous error. 
Emotion has nothing whatever to do with the attainment 
of truth. That which we prize under the name of 
" emotion" is an elaborate activity of the brain, which 
consists of feelings of like and dislike, motions of assent 
and dissent, impulses of desire and aversion. It may be 
influenced by the most diverse activities of the organism, 
by the cravings of the senses and the muscles, the 
stomach, the sexual organs, etc. The interests of truth 
are far from promoted by these conditions and vacillations 
of emotion ; on the contrary, such circumstances often 
disturb that reason which alone is adapted to the pursuit 
of truth, and frequently mar its perceptive power. No 
cosmic problem is solved, or even advanced, by the 
cerebral function we call emotion. And the same must 
be said of the so-called "revelation," and of the "truths 
of faith " which it is supposed to communicate ; they are 
based entirely on a deception, consciously or unconsciously, 
as we shall see in the sixteenth chapter. 

We must welcome as one of the most fortunate steps in 
the direction of a solution of the great cosmic problems 

1 As to induction and deduction, vide The Natural History qf 


the fact that of recent years there is a growing tendency 
to recognise the two paths which alone lead thereto 
experience and thought, or speculation to be of equal 
value, and mutually complementary. Philosophers have 
come to see that pure speculation such, for instance, as 
Plato and Hegel employed for the construction of their 
idealist systems does not lead to knowledge of reality. 
On the other hand, scientists have been convinced that 
mere experience such as Bacon and Mill, for example, 
made the basis of their realist systems is insufficient of 
itself for a complete philosophy. For these two great 
paths of knowledge, sense-experience and rational thought, 
are two distinct cerebral functions ; the one is elaborated 
by the sense-organs and the inner sense-centres, the other 
by the thought-centres, the great " centres of association 
in the cortex of the brain," which He between the sense- 
centres. (Cf. cc. vii. and x.) True knowledge is only 
acquired by combining the activity of the two. Never- 
theless, there are still many philosophers who would con- 
struct the world out of their own inner consciousness, and 
who reject our empirical science precisely because they 
have no knowledge of the real world. On the other hand, 
there are many scientists who still contend that the sole 
object of science is " the knowledge of facts, the objective 
investigation of isolated phenomena " ; that " the age of 
philosophy " is past, and science has taken its place. 1 
This one-sided over-estimation of experience is as danger- 
ous an error as the converse exaggeration of the value of 
speculation. Both channels of knowledge are mutually 
indispensable. The greatest triumphs of modern science 
the cellular theory, the dynamic theory of heat, the 
theory of evolution, and the law of substance are 
philosophic achievements ; they are not, however, the fruit 
of pure speculation, but of an antecedent experience of 
the widest and most searching character. 

At the commencement of the nineteenth century 
the great idealistic poet Schiller gave this counsel to 

1 Rudolph Virchow, Die Qr&ndung drr Berliner UniversMt, und 
der tibergang au* dem philosophischen in das ncUurwissenschaftlicfu 
ZeitalUr. (Berlin; 1893.) 


both groups of combatants, the philosophers and the 
scientists : 

Does strife divide your efforts no union bless your toil ? 
Will truth e'er be delivered if ye your forces rend ? 

Since then the situation has, happily, been profoundly 
modified; while both schools, in their different paths, 
have pressed onwards towards the same high goal, they 
have recognised their common aspiration, and they draw 
nearer to a knowledge of the truth in mutual covenant. 
At the end of the nineteenth century we have returned to 
that monistic attitude which our greatest realistic poet, 
Goethe, had recognised from its very commencement to 
be alone correct and fruitful. 

All the different philosophical tendencies may, from the 
point of view of modern science, be ranged in two 
antagonistic groups ; they represent either a dualistic or 
a monistic interpretation of the cosmos. The former is 
usually bound up with teleological and idealistic dogmas, 
the latter with mechanical and realistic theories. Dual- 
ism, in the widest sense, breaks up the universe into two 
entirely distinct substances the material world and an 
immaterial God, who is represented to be its creator, 
sustainer, and ruler. Monism, on the contrary (likewise 
taken in its widest sense), recognises one sole substance in 
the universe, which is at once " God and Nature " ; 
body and spirit (or matter and energy) it holds to be 
inseparable. The extra-mundane God of dualism leads 
necessarily to Theism ; the intra-mundane God of the 
monist leads to Pantheism. 

The different ideas of monism and materialism, and 
likewise the essentially distinct tendencies of theoretical 
and practical materialism, are still very frequently con- 
fused. As this and other similar cases of confusion of 
ideas are very prejudicial, and give rise to innumerable 
errors, we shall make the following brief observations, in 
order to prevent misunderstanding : 

I. Pure monism is identical neither with the theoreti- 
cal materialism that denies the existence of spirit, and 
dissolves the world into a heap of dead atoms, nor with 


the theoretical spiritualism (lately entitled "energetic" 
spiritualism by Ostwald) which rejects the notion oi 
matter, and considers the world to be a specially-arranged 
group of "energies," or immaterial natural forces, 
II, On the contrary, we hold, with Goethe, that 
"matter cannot eiist and be operative without spirit, nor 
spirit without matter," We adhere firmly to the pure, 
unequivocal monism of Spinoza; Matter, or infinitely- 
extended substance, and Spirit (or Energy), or sensitive 
and thinking substance, are the two fundamental attri- 
butes, or principal properties, of the all-embracing divine 
essence of the world, the universal substance, (Cf, chap. 

M \ 




Fundamental importance of anatomy. Human anatomy. Hippo- 
crates, Aristotle, Galen, Vesaliua. Comparative anatomy, 
Georges Cuvier, Johannes Mttller. Carl Gegenbaur, Histology, 
The cellular theory. Schleiden and Schwann. Kolliker. 
Virchow. Man a vertebrate a tetrapod a mammal a placental 
a primate. Prosimia; and simiae. T-he catarrh in. Papiomor- 
phic arid anthropomorphic apes. Essential likeness of man and 
the ape in corporal structure. 

ALL biological research, all investigation into the forms 
and vital activities of organisms, must first deal with the 
visible body, in which the morphological and physiological 
phenomena are observed. This fundamental rule holds 
good for man just as much as for all other living things, 
Moreover, the inquiry must not confine itself to mere 
observation of the outer form ; it must penetrate to the 
interior, and study both the general plan and the minute 
details of the structure. The science which pursues this 
fundamental investigation in the broadest sense is 
anatoim . 

The first stimulus to an inquiry into the human frame 
arose, naturally, in medicine. As it was usually practised 
by the priests in the older civilisations, we may assume 
that these highest representatives of the education of the 
time had already acquired a certain amount of anatomical 
knowledge two thousand years before Christ, or even 
earlier. We do not, however, find more exact observa- 
tions, founded on the dissection of mammals, and applied, 
by analogy, to the human frame, until we come to the 
Greek scientists of the sixth and fifth centuries before 
Christ Empedocles (of Agrigentum) and Democritus (of 



Abdera), and especially the most famous physician of 
classic antiquity, Hippocrates (of Cos). It was from these 
and other sources that the great Aristotle, the renowned 
"father of natural history," equally comprehensive as 
investigator and philosopher, derived his first knowledge. 
After him only one anatomist of any consequence is found 
in antiquity, the Greek physician Claudius Galenus (of 
Pergamus), who developed a wealthy practice in Rome in 
the second century after Christ, under the Emperor 
Marcus Aurelius. All these ancient anatomists acquired 
their knowledge, as a rule, not by the dissection of the 
human body itself which was then sternly forbidden 
but by a study of the bodies of the animals which most 
closely resembled man, especially the apes; they were all, 
indeed, comparative anatomists. 

The triumph of Christianity and its mystic theories 
meant retrogression to anatomy, as it did to all the other 
sciences. The popes were resolved above all things to 
detain humanity in ignorance; they rightly deemed a 
knowledge of the human organism to be a dangerous 
source of enlightenment as to our true nature. During 
the long period of thirteen centuries the writings of Galen 
were almost the only source of human anatomy, just as 
the works of Aristotle were for the whole of natural 
history. It was not until the sixteenth century, when the 
spiritual tyranny of the Papacy was broken by the Refor- 
mation, and the geocentric theory, so intimately connected 
with Papal doctrine, was destroyed by the new cosmic 
system of Copernicus, that the knowledge of the human 
frame entered upon a new period of progress. The great 
anatomists Vesalius (of Brussels), and Eustachius and Fal- 
iopius (of Modena), advanced the knowledge of our bodily 
structure so much by their own thorough investigations 
that little remained for their numerous followers to do, 
with regard to the more obvious phenomena, except the 
substantiation of details. Andreas Vesalius, as courageous 
as he was talented and indefatigable, was the pioneer of 
the movement; he completed in his twenty-eighth year 
(1543) that great and systematic work, De humani cor- 
porit fabrica; he gave to the whole of human anatomy a 


new and independent scope, and a more solid foundation. 
On that account he was, at a later date, at Madrid where 
he was physician to Charles V. and Philip II. condemned 
to death by the Inquisition as a magician. He only 
escaped by undertaking a pilgrimage to Jerusalem; in 
returning he suffered shipwreck on the Isle of Zante, and 
died there in misery and destitution. 

The great merit of the nineteenth century, as far as our 
knowledge of the human frame is concerned, lies in the 
founding of two new lines of research of immense import- 
ance comparative anatomy and histology, or microscopic 
anatomy. The former was intimately associated with 
human anatomy from the very beginning ; indeed, it had 
to supply the place of the latter so long because the dis- 
section of human corpses was a crime visited with capital 
punishment that was the case even in the fifteenth 
century I But the many anatomists of the next three 
centuries devoted themselves mainly to a more accurate 
study of the human organism. The elaborate science 
which we now call comparative anatomy was born in the 
year 1803, when the great French zoologist Georges 
Cuvier (a native of Mompelgard, in Alsace) published his 
profound Lemons sur V anatomic compose, and endeavoured 
to formulate, for the first time, definite laws as to the 
organism of man and the beasts. While his predecessors 
among whom was Goethe in 1790 had mainly con- 
tented themselves with comparing the skeleton of man 
with those of other animals, Cuvier's broader vision took 
in the whole of the animal organisation. He distinguished 
therein four great and mutually independent types : 
Vertebrata, Articulata, Mollusca, and Radiata. This 
advance was of extreme consequence for our " question of 
all questions," since it clearly brought out the fact that 
man belonged to the vertebral type, and differed funda- 
mentally from all the other types. It is true that the 
keen-sighted Linne* had already, In his Systema Naturae, 
made a great step in advance by assigning man a definite 
place in the class of mammals ; he had even drawn up the 
three groups of half-apes, apes, and men (Lemur, simia, 
and homo) in the order of primates. But his keen, sy- 


tematic mind was not furnished with that profound em- 
pirical foundation supplied by comparative anatomy, which 
Cuvier was the first to attain. Further developments 
were added by the great comparative anatomists of our 
own century Friedrich Meckel (Halle), Johannes 
Muller (Berlin), Richard Owen, T. Huxley, and Carl 
Gegenbaur (Jena, subsequently Heidelberg). The last- 
named, in applying to comparative anatomy the evolu- 
tionary theory which Darwin had just established, raised 
his science to the front rank of biological studies. The 
numerous comparative-anatomical works of Gegenbaur are, 
like his well-known Manual of Human Anatomy, equally 
distinguished by a thorough empirical acquaintance with 
their immense multitudes of facts, and by a comprehensive 
control of his material, and its philosophic appreciation 
in the evolutionary sense. His recent Comparative Ana- 
tomy of the Vertebrata establishes the solid foundation 
on which our conviction of the vertebral character of man 
in every aspect is chiefly based. 

Microscopic anatomy has been developed, in the course 
of the present century, in a different fashion from com- 
parative anatomy. At the beginning of the century (1802) 
a French physician, Bichat, made an attempt to dissect 
the organs of the human body into their finer constituents 
by the aid of the microscope, and to show the connection 
of these various tissuei (hista, or tela). This first attempt 
led to little result, because the scientist was ignorant of 
the one common element of all the different tissues. This 
wag first discovered (1838) in the shape of the cell, in the 
plant-world, by Matthias Schleiden,and immediately after- 
wards proved to be the same in the animal world by 
Theodore Schwann, the pupil and assistant of Johannes 
Muller at Berlin. Two other distinguished pupils of this 
great master, who are still living, Albert Kolliker and 
Rudolph Virchow, took up the cellular theory, and the 
theory of tissues which is founded on it, in the 'sixties, 
and applied them to the human organism in all its details, 
both in health and disease; they proved that, in man and 
ail other animals, every tissue is made up of the same 
microscopic particles, the cellt, and these " elementary 


organisms " are the real, self -active citizens which, in 
combinations of millions, constitute the "cellular state," 
our body. All these cells spring from one simple cell 
the cytula, or impregnated ovum by continuous sub- 
divisions. The general structure and combination of the 
tissues are the same in man as in the other vertebrates. 
Among these the mammals, the youngest and most highly- 
developed class, take precedence in virtue of certain 
special features which were acquired late. Such are, 
for instance, the microscopic texture of the hair, of 
the glands of the skin, and of the breasts, and the cor- 
puscles of the blood, which are quite peculiar to mam- 
mals, and different from those of the other vertebrates ; 
man, even in these finest histological respects, is a true 

The microscopic researches of Albert Kolliker and Franz 
Leydig (at Wiirzburg) not only enlarged our knowledge 
of the finer structure of man and the beasts in every 
direction, but they were especially important in the light 
of their connection with the evolution of the cell and the 
tissue ; they confirmed the great theory of Carl Theodor 
Siebold (1845) that the lowest animals, the Infusoria and 
the Rhizopods, are unicellular organisms. 

Our whole frame, both in its general plan and its 
detailed structure, presents the characteristic type of the 
vertebrates. This most important and most highly- 
developed group in the animal world was first recognised 
in its natural unity in 1801 by the great Lamarck ; he em- 
braced under that title the four higher animal groups of 
Linne* mammals, birds, amphibia, and fishes. To these 
he opposed the two lower classes, insects and worms, as 
invertebrates. Cuvier (1812) established the unity of the 
vertebrate type on a firmer basis by his comparative ana- 
tomy. It is quite true that all the vertebrates, from the 
fish up to man, agree in every essential feature; they all 
have a firm internal skeleton, a framework of cartilage and 
bone, consisting principally of a vertebral column and a 
skull ; the advanced construction of the latter presents 
many variations, but, on the whole, all may be reduced to 
the same fundamental type. Further, in all the verte- 


brates the "organ of the mind," the central nervous 
system, in the shape of a spinal cord and a brain, lies at 
the back of this axial skeleton. Moreover, what we said 
of its bony environment, the skull, is also true of the 
brain the instrument of consciousness and all the higher 
functions of the mind ; its construction and size present 
very many variations in detail, but its general character- 
istic structure remains always the same. 

We meet the same phenomena when we compare the 
rest of our organs with those of the other vertebrates; 
everywhere, in virtue of heredity, the original plan and 
the relative distribution of the organs remain the same, 
although, through adaptation to different environments, 
the size and the structure of particular sections offer con- 
siderable variation. Thus we find that in all cases the 
blood circulates in two main blood-vessels, of which one 
the aorta passes over the intestine, and the other the 
principal vein passes underneath, and that by the broad- 
ening out of the latter in a very definite spot a heart has 
arisen; this "ventral heart" is just as characteristic of 
all vertebrates as the "dorsal heart " is of the articulata 
and mollusca. Equally characteristic of all vertebrates is 
the early division of the intestinal tube into a " head -gut " 
(or gill-gut), which serves in respiration, and a " body- 
gut " (or liver-gut), which co-operates with the liver in 
digestion ; so are, likewise, the ramification of the mus- 
cular system, the peculiar structure of the urinary and 
sexual organs, and so forth. In all these anatomical 
relations man is a true vertebrate. 

Aristotle gave the name of four-footed, or tetrapoda, 
to all the higher warm-blooded animals which are distin- 
guished by the possession of two pairs of legs. The cate- 
gory was enlarged subsequently, and its title changed into 
the Latin "quadrupeda," when Cuvier proved that even 
" two-legged " birds and men are really "four-footed " : 
he showed that the internal skeleton of the four legs in 
all the higher land- vertebrates, from the amphibia up to 
man, was originally constructed after the same pattern out 
of a definite number of members. The " arm " of man 
and the " wing " of bats and birds have the same typical 


skeleton as the foreleg of the animals which are conspicu- 
ously "four-footed." 

The anatomical unity of the fully-developed skeleton in 
the four limbs of all tetrapods is very important. In 
order to appreciate it fully one has only to compare care- 
fully the skeleton of a salamander or a frog with that of a 
monkey or a man. One perceives at once that the humeral 
zone in front and the pelvic zone behind are made up of 
the same principal parts as in the rest of the quadrupeds. 
We find in all cases that the first section of the leg proper 
consists of one strong marrow-bone (the hurnerus, in the 
forelimb ; the femur, behind) ; the second part, on the 
contrary, originally always consists of two bones (the ulna 
and radius, in front ; the fibula and tibia, behind). When 
we further compare the developed structure of the foot 
proper we are surprised to find that the small bones of 
which it is made up are also similarly arranged and dis- 
tributed in every case : in the front limb the three groups 
of bones of the fore-foot (or " hand ") correspond in all 
classes of the tetrapoda : (1) the carpus 9 (2) the meta- 
carpus , (3) the five fingers (digiti anterior cs) ; in the rear 
limb, similarly, we have always the same three osseous 
groups of the hind-foot : (l) the tarsus, (2) the metatarsus, 
and (S) the five toes (digiti posteriores). It was a very 
difficult task to reduce all these bttle bones to one primi- 
tive type, and to establish the equivalence (or homology) 
of the separate parts in all cases ; they present extreme 
variations of form and construction in detail, sometimes 
bring partly fused together and losing their individuality. 
This great task was first successfully achieved by the most 
eminent comparative anatomist of our time, Carl Gegen- 
baur. He pointed out, in his Researches into the Com- 
parative Anatomy of the Vertebrata (1864), how this char- 
acteristic " five-toed leg " of the land-tetrapods originally 
(not before the Carboniferous period) arose out of the 
radiating fin (the breast-fin, or the belly-fin) of the ancient 
fishes. He had also, in his famous Researches into the 
Skull of the Vertebrata (1872), deduced the younger skull 
of the tetrapods from the oldest cranial form among the 
fishes, that of the shark. 


It is especially remarkable that the original number of 
the toes (five) on each o the four feet, which first ap- 
peared in the old amphibia of the Carboniferous period, 
has, in virtue of a strict heredity, been preserved even to 
the present day in man. Also, naturally and harmoni- 
ously, the typical construction of the joints, ligaments, 
muscles, and nerves of the two pairs of legs has, in the 
main, remained the same as in the rest of the ''four- 
footed." In all these important relations man is a true 

The mammals are the youngest and most advanced 
class of the vertebrates. It is true they are derived from 
the older class of amphibia, like birds and reptiles; yet 
they are distinguished from all the other tetrapods by a 
number of very striking anatomical features. Externally, 
there is the clothing of the skin with hair, and the pos- 
session of two kinds of skin-glands the sweat glands and 
the sebaceous glands. A local development of these 
glands on the abdominal skin gave rise (probably during 
the Triassic period) to the organ which is especially char- 
acteristic of the class, and from which it derives its name 
the mammanum. This important instrument of lacta- 
tion is made up of milk-glands (mammfr} and the 
" mammar-pouches " (folds of the abdominal skin); in its 
development the teats appear, through which the young 
mammal sucks its mother's milk. In internal structure 
the most remarkable feature is the possession of a complete 
diaphragm, a muscular wall which, in all mammals and 
only in mammals separates the thoracic from the abdo- 
minal cavity; in all other vertebrates there is no such 
separation. The skull of mammals is distinguished by a 
number of remarkable formations, especially in the 
maxillary apparatus (the upper arid lower jaws, mid the 
temporal bones). Moreover, the brain, the olfactory 
organ, the heart, the lungs, the internal and external 
sexual organs, the kidneys, and other parts of the body, 
present special peculiarities, both in general and detailed 
structure, in the mammals; all these, taken collectively, 
point unequivocally to an early derivation (if the mammali 
jfrom the older groups of the reptiles and amphibia, which 


must have taken place, at the latest, in the Triassic period 
at least 12,000,000 years ago! In all these important 
characteristics man is a ti*ue mammal. 

The numerous orders (12-33) which modern systematic 
zoology distinguishes in the class of mammals had been 
arranged in 1816 (by Blainville) in three natural groups, 
which still hold good as sub-classes: (1) the monotrema, 
(2) the marsupialia, and (3) the placentalia. These three 
sub-classes not only differ in the important respect of 
bodily structure and development, but they correspond, 
also, to three different historical stages in the formation of 
the class, as we shall s<*e later on. The monotremes of 
the Triassic period were followed by the marsupials of the 
Jurassic, and these by the placentals of the Cretaceous. 
Man belongs to this, the youngest, sub-class ; for he 
presents in his organisation all the features which distin- 
guish the placentals from the marsupials, and the still 
older monotremes. First of all there is the peculiar organ 
which gives a name to the placentals the placenta. It 
serves the purpose of nourishing the young mammal 
embryo for a long time during its enclosure in the 
mother's womb; it consists of blood-bearing tufts which 
grow out of the chorion surrounding the embryo, and 
penetrate corresponding cavities in the mucous membrane 
of the maternal uterus ; the delicate skin between the two 
structures is so attenuated in this spot that the nutriment 
in the mother's blood can pass directly into the blood of 
the child. This excellent contrivance for nourishing the 
embryo, which makes its first appearance at a somewhat 
late date, gives the fcetus the opportunity of a longer 
maintenance and a higher development in the protecting 
womb ; it is wanting in the implaccritaUa, the two older 
Bub-classes of the marsupials and the monotremes. There 
are, likewise, other anatomical features, particularly the 
higher development of the brain and the absence of the 
marsupial bone, which raise the placentals above all their 
implaoentai ancestors. In all these important particulars 
man is a true placental. 

The very varied sub-class of the placentals has been 
recently subdivided into a great number of orders ; they 


arc usually put at from ten to sixteen, but when we include 
the important extinct forms which have been recently dis- 
covered the number runs up to from twenty to twenty-six. 
In order to facilitate the study of these numerous orders, 
and to obtain a deeper insight into their kindred construc- 
tion, it is very useful to form them into great natural 
groups, which I have called "legions." In my latest 
attempt l to arrange the advanced system of placentals in 
phylogenetic order I have substituted eight of these legions 
for the twenty-six orders, and shown that these may be 
reduced to four main groups. These, in turn, are trace- 
able to one common ancestral group of all the placentals, 
their fossil ancestors, the brochoriata of the Cretaceous 
period. These are directly connected with the marsupial 
ancestors of the Jurassic period. We will only specify 
here, as the most important living representatives of these 
four main groups, the rodentia, the ungulata, the car- 
nivora, and the primates. To the legion of the primates 
belong the prosimiae (half-apes), the simiae (real apes), and 
man. All the members of these three orders agree in 
many important features, and are at the same time dis- 
tinguished by these features from the other twenty-three 
orders of placentals. They are especially conspicuous for 
the length of their bones, which were originally adapted 
to their arboreal manner of life. Their hands and feet 
are five-fingered, and the long fingers are excellently 
suited for grasping and embracing the branches of trees ; 
they are provided, either partially or completely, with 
nails, but have no claws. The dentition is complete, con- 
taining all four classes incisors, canine, premolars, and 
molars. Primates are also distinguished from ail the 
other placentals by important features in the special con- 
struction of the skull and the brain ; and these are the 
more striking in proportion to their development and the 
lateness of their appearance in the history of the earth. 
In all these important anatomical features our human 
organism agrees with that of all the other primates : man 
is a true primate. 

1 Systcmatiache Phylogenie, 1898, part Hi., pp. 490, 494, and 496. 


An impartial and thorough comparison of the bodily 
structure of the primates forces us to distinguish two 
orders in this most advanced legion of the mammalia 
half-apes (prosimiss or hemipitheci) and apes (simiss or 
pithed). The former seem in every respect to be the 
lower and older, the latter to be the higher and younger 
order. The womb of the half -ape is still double or two- 
horned, as it is in all the other mammals. In the true 
ape, on the contrary, the right and left wombs have com- 
pletely amalgamated ; they blend into a pear-shaped 
womb, which the human mother possesses besides the 
ape. In the skull of the apes, just as in that of man, the 
orbits of the eyes are completely separated from the 
temporal cavities by an osseous partition ; in the pro- 
simim this is either entirely wanting or very imperfect. 
Finally, the cerebrum of the prosimia is either quite 
smooth or very slightly furrowed, and proportionately 
small ; that of the, true ape is much larger, und the grey 
bed especially, the organ of higher psychic activity, is 
much more developed; the characteristic convolutions and 
furrows appear on its surface exactly in proportion as the 
ape approaches to man. In these and other important 
respects, particularly in the construction of the face and 
the hands, man presents all the anatomical marks of a 
true ape. 

The extensive order of apes was divided by Geoff roi, in 
1812, into two sub-orders, which are still universally 
accepted in systematic zoology New World and Old 
World monkeys, according to the hemisphere they respect- 
ively inhabit. The American " New World " monkeys 
are called Platyrrhinse. (flat-nosed) ; their nose is flat, and 
the nostrils divergent, with a broad partition. The " Old 
World " monkeys, on the contrary, are called collectively 
Catarrhinx (narrow-nosed); their nostrils point down- 
wards, like man's, and the dividing cartilage is narrow. 
A further difference between the two groups is that the 
tympanum is superficial in the platyrrhinse, but lies 
deeper, inside the petrous bone, in the catarrhinse ; in the 
latter a long and narrow bony passage has been formed, 
while in the former it is still short and wide, or even alto- 


gether wanting. Finally, we have a much more important 
and decisive difference between the two groups in the 
circumstance that all the Old World monkeys have the 
same teeth as man i. e., twenty deciduous and thirty- 
two permanent teeth (two incisors, one canine, two pre- 
rnolars, and three molars in each half of the jaw). The 
New World monkeys, on the other hand, have an addi- 
tional premolar in each half -jaw, or thirty -six teeth alto- 
gether. The fact that these anatomical differences of the 
two simian groups are universal and conspicuous, and that 
they harmonise with their geographical distribution in the 
two hemispheres, fully authorises a sharp systematic divi- 
sion of the two, as well as the phylogenetic conclusion that 
for a very long period (for more than a million years) the 
two sub-orders have been developing quite independently 
of each other in the western arid eastern hemispheres. 
That is a most important point in view of the genealogy 
of our race ; for man bears ail the marks of a true catarr- 
hina ; he has descended from some extinct member of this 
sub-order ID the Old World. 

The numerous types of caturrhinie which still survive In 
Asia and Africa have been formed into two sections for 
gome time the tailed, dog-like apes (the cynopitfn'd) 
and the tailless man-like apes (the anthropomorpha). The 
latter are much nearer to man than the former, not only 
in the absence of a tail and in the general build of the 
body (especially of the head), but also on account of cer- 
tain features which are unimportant in themselves, but 
very significant in their constancy. The sacrum of the 
anthropoid ape, like that of man, is made up by the fusion 
of five vertebne ; that of the cynopithecus consists of three 
(more rarely four) sacral vertebrae. The premolar teeth 
of the cynopilheci are greater in length than breadth ; 
those of the anthropomorpha are broader than they are 
long ; and the first molar has four protuberances in the 
former, five in the latter. Furthermore, the outer incisor 
of the lower jaw is broader than the inner one in the man- 
like apes and man ; in the dog-like ape it Is the smaller. 
Finally, there is a special significance in the fact, estab- 
lished by Selenka in 1890, that the anthropoid apes share 


with man the peculiar structure of the discoid placenta , 
the decidua reflexa, and the pedicle of the allantois. In 
fact, even a superficial comparison of the bodily structure 
of the anthropomorpha which still survive makes it clear 
that both the Asiatic (the orang-outang and the gibbous 
ape) and the African (the gorilla and chimpanzee) repre- 
sentatives of this group are nearer to man in build than 
any of the cynopitheci. Under the latter group we in- 
clude the dog-faced papiomorpha, the baboon, and the 
long-tailed monkey, at a very low stage. The anatomical 
difference between these low papiomorpha and the most 
highly-developed anthropoid apes is greater in every 
respect, whatever organ we take for comparison, than the 
difference between the latter and man. This instructive 
fact was established with great penetration by the 
anatomist Robert Hartmann, in his work on The Anthro- 
poid Apes; l he proposed to divide the order of Simise in 
a new way namely, into the two great groups of primaria 
(man and the anthropoid ape) and the simise proper, or 
pithed (the rest of the catarrhin?c and all the platyrrhinae). 
In any case, we have a clear proof of the close affinity of 
man and the anthropoid ape. 

Thus comparative anatomy proves to the satisfaction of 
every unprejudiced and critical student the significant fact 
that the body of man and that of the anthropoid ape are 
not only peculiarly similar, but that they are practically 
one and the same in every important respect. The same 
200 bones, in the same order and structure, make up our 
inner skeleton ; the same SOO muscles effect our move- 
ments ; the same hair clothes our skin ; the same groups 
of ganglionic ceils build up the marvellous structure of 
our brain; the same four-chambered heart is the central 
pulsometer in our circulation; the same thirty -two teeth 
are set in the same order in our jaws ; the same salivary, 
hepatic, and gastric glands compass our digestive process ; 
the same reproductive organs ensure the maintenance of 
our race. 

It is true that we find, on close examination, certain 
minor differences In point of size and shape in most of the 
1 Translated in the International Science Series, 1872. 


organs of man and the ape; but we discover the same, or 
similar, differences between the higher and lower races of 
men, when we make a careful comparison-even, in fact, 
in a minute comparison of the various individuals of our 
own race, We find no two persons who have exactly the 
same size and form of nose, ears, eyes, and so forth, One 
has only to compare attentively these special features in 
many different persons in any large company to convince 
one's self of the astonishing diversity of their construction 
and the infinite variability of specific forms, Not infre- 
quently even two sisters are so much unlike as to make 
their origin from the same parents almost incredible. Yet 
all these individual variations do not weaken the signifi- 
cance of the fundamental similarity of structure; they are 
traceable to certain minute differences in the growth of 


the individual features, 



De?elopment of physiology in antiquity and the Middle Ages. Galen, 
Experiment and vivisection. Discovery of the circulation of the 
blood by Harvey. Vitalism : Haller, Teleological and vitalistio 
conception of life. Mechanical and monistic view of th physio- 
logic-al processes, Comparative physiology in the nineteenth 
century: Johannes Muller. Cellular physiology; Virchow. 
Mammal physiology. Similarity of all vital energy in man and 
the ape. 

IT is only in the nineteenth century that our knowledge of 
human life has attained the dignity of a genuine, inde- 
pendent science; during the course of the century it has 
developed into one of the highest, most interesting* and 
most important branches of knowledge. This "science 
of the vital functions," physiology, had, it is true, been 
regarded at a much earlier date as a desirable, if not neces- 
gary, condition of success in medical treatment, and had 
been constantly associated with anatomy, the science of 
the structure of the body. But it was only much later, 
and much more slowly, than the latter that it could be 
thoroughly studied, as it had to contend with much more 
serious difficulties. 

The idea of life, as the opposite of death, naturally 
became the subject of speculation at a very early age. 
In the living man, just as in other living animals, there 
were certain peculiar changes, especially movements, 
which were wanting in lifeless nature : spontaneous loco- 
motion, the beat of the heart, the drawing of the breath, 
speech, and so forth. But the discrimination of such 
"organic movements" from similar phenomena in inor- 
ganic bodies was by no means easy, and was frequently 



impossible; the flowing stream, the flickering flame, the 
rushing wind, the falling rock, seemed to man to exhibit 
the same movements. It was quite natural that primitive 
man should attribute an independent life to these "dead " 
bodies. He knew no more of the real sources of move- 
ment in the one case than in the other. 

We find the earliest scientific observations on the nature 
of man's vital functions (as well as on his structure) in 
the Greek natural philosophers and physicians in the sixth 
and fifth centuries before Christ. The best collection of 
the physiological facts which were known at that time is 
to be found in the Natural History of Aristotle; a great 
number of his assertions were probably taken from Demo- 
critus and Hippocrates. The school of the latter had 
already made attempts to explain the mystery ; it postu- 
lated as the ultimate source of life in man and the beasts 
a volatile k * spirit of life" (pneuma) ; and Erasistratus 
(280 B.C.) already drew a distinction between the lower 
and the higher " spirit of life," the pneuma zoticon in 
the heart and the pneuma psychicon in the brain. 

The credit of gathering these scattered truths into 
unity, and of making the first attempt at a systematic 
physiology, belongs to the great Greek physician Galen; 
we have already recognised in him the first great anatomist 
of antiquity (cf. p. 19). In his researches into the organs 
of the body he never lost sight of the question of their 
vital activity, their functions ; and even in this direction 
he proceeded by the same comparative method, taking for 
his principal study the animals which approach nearest to 
man. Whatever he learned from these he applied directly 
to man. He recognised the value of physiological experi- 
ment; in his vivisection of apes, dogs, and swine he made 
a number of interesting experiments. Vivisection has 
been made the object of a violent attack in recent years, 
not only by the ignorant and narrow-minded, but by 
theological enemies of knowledge and by perfervid senti- 
mentalists ; it is, however, one of the indispensable 
methods of research into the nature of life, and has given 
us invaluable information on the most important questions. 
This was recognised by Galen 1700 years ago. 


Galen reduces all the different functions of the body to 
three groups, which correspond to the three forms of the 
pneuma, or vital spirit. The pneuma psychicon the soul 
which resides in the brain and nerves, is the cause of 
thought, sensation, and will (voluntary movement); the 
pneuma zoticon the heart is responsible for the beat of 
the heart, the pulse, and the temperature ; the pneuma 
physicon, seated in the liver, is the source of the so-called 
vegetative functions, digestion and assimilation, growth 
and reproduction. He especially emphasised the renewal 
of the blood in the lungs, and expressed a hope that we 
should some day succeed in isolating the permanent 
element in the atmosphere the pneuma, as he calls it 
which is taken into the blood in respiration. More than 
fifteen centuries elapsed before this pneuma oxygen 
was discovered by Lavoisier. 

In human physiology, as well as in anatomy, the great 
system of Galen was for thirteen centuries the Codex 
aureus, the inviolable source of all knowledge. The influ- 
ence of Christianity, so fatal to scientific culture, raised 
the same insuperable obstacles in this as in every other 
branch of secular knowledge. Not a single scientist 
appeared from the third to the sixteenth century who 
dared make independent research into man's vital activity, 
arid transcend the limits of the Galenic system. It was 
not until the sixteenth century that experiments were 
made in that direction by a number of distinguished physi- 
cians and anatomists (Paracelsus, Servetus, Vesalius, and 
others). In 1628 Harvey published his great discovery of 
the circulation of the blood, and showed that the heart is 
a pump, which drives the red stream unceasingly through 
the connected system of arteries and veins by a rhythmic, 
unconscious contraction of its muscles. Not less important 
were Harvey's researches into the procreation of animals, 
as a result of which he formulated the well-known law : 
" Every living thing comes from an egg " (omne vivum 
ex ovo). 

The powerful impetus which Harvey gave to physio- 
logical observation and experiment led to a great number 
of discoveries in the seventeenth and eighteenth centuries. 


These were co-ordinated for the first time by the learned 
Albrecht Haller about the middle of the last century; in 
his great work, Elementa Physiologies, he established the 
inherent importance of the science, independently of its 
relation to practical medicine. In postulating, however, a 
special " sensitive force or sensibility " for neural action, 
and a special "irritability " for muscular movement, 
Haller gave strong support to the erroneous idea of a 
specific " vital force " (vis vitalis). 

For more than a century afterwards, from the middle 
of the eighteenth until the middle of the nineteenth 
century, medicine and (especially) physiology were domin- 
ated by the old idea that a certain number of the vital 
processes may be traced to physical and chemical causes, 
but that others are the outcome of a special vital force 
which is independent of physical agencies. However 
much scientists differed in their conceptions of its nature 
and its relation to the "soul," they were all agreed as 
to its independence of, and essential distinction from, the 
chemico-physical forces of ordinary "matter "; it was a 
self-contained force (archtvus), unknown in inorganic 
nature, which compelled ordinary forces into its service. 
Not only the distinctly physical activity, the sensibility of 
the nerves and irritability of the muscles, but even the 
phenomena of sense-activity, of reproduction, and of 
development, seemed so wonderful and so mysterious in 
their sources that it was impossible to attribute them to 
simple physical and chemical processes. As the free 
activity of the vital force was purposive and conscious, it 
led, in philosophy, to a complete teleology ; especially did 
this seem indisputable when even the " critical " philo- 
sopher Kant had acknowledged, in his famous critique of 
the teleological position, that, though the mind's authority 
to give a mechanical interpretation of all phenomena is 
theoretically unlimited, yet its actual capacity for such 
interpretation does not extend to the phenomena of 
organic life ; here we are compelled to have recourse to a 
purposive therefore supernatural principle. This diver- 
gence of the vital phenomena from the mechanical pro- 
cesses of life became, naturally, more conspicuous as 


science advanced in the chemical and physical explanation 
of the latter. The circulation of the blood and a number 
of other phenomena could be traced to mechanical 
agencies ; respiration and digestion were attributable to 
chemical processes like those we find in inorganic nature. 
On the other hand, it seemed impossible to do this with 
the wonderful performances of the nerves and muscles, 
and with the characteristic life of the mind ; the co- 
ordination of all the different forces in the life of the 
individual seemed also beyond such a mechanical inter- 
pretation. Hence there arose a complete physiological 
dualism an essential distinction was drawn between in- 
organic and organic nature, between mechanical and vital 
processes, between material force and life-force, between 
the body and the soul. At the beginning of the nine- 
teenth century this vitalism was firmly established in 
France by Louis Dumas, and in Germany by Rcil. 
Alexander H'imboldt had already published a poetical 
presentation of it in 1795, in his narrative of the Legend 
of Rhodes ; it is repeated, with critical notes, in his Views 
of Nature. 

In the first half of the seventeenth century the famous 
philosopher Descartes, starting from Harvey's discovery 
of the circulation of the blood, put forward the idea that 
the body of man, like that of other animals, is merely an 
intricate machine, and that its movements take place 
under the same mechanical laws as the movements of an 
automaton of human construction. It is true that 
Descartes, at the same time, claimed for man the exclusive 
possession of a perfectly independent immaterial soul, and 
held that its subjective experience, thought, was the only 
thing in the world of which we have direct and certain 
cognisance ("Cogito, er/ro sum"). Yet this dualism 
did not prevent him from doing much to advance our 
knowledge of the mechanical life-processes in detail. 
Borelli followed (1660) with a reduction of the move- 
ments of the animal body to purely physical laws, and 
Sylvius endeavoured, about the same time, to give a 
purely chemical explanation of the phenomena of digestion 
and respiration ; the former founded the iatrornechanical, 


the latter the iatro chemical, school of medicine. How- 
ever, these rational tendencies towards a natural, mechan- 
ical explanation of the phenomena of life did not attain 
to a universal acceptance and application ; in the course of 
the eighteenth century they fell entirely away before the 
advance of teleological vitalism. The final disproof of the 
latter and a return to mechanism only became possible 
with the happy growth of the new science of comparative 
physiology in the 'forties of the present century. 

Our knowledge of the vital functions, like our know- 
ledge of the structure, of the human body was originally 
obtained, for the most part, not by direct observation of 
the human organism itself, but by a study of the more 
closely-related animals among the vertebrates, especially 
the mammals. In this sense the very earliest beginning 
of human anatomy and physiology was ''comparative." 
But the distinct science of "comparative physiology," 
which embraces the whole sphere of life-phenomena, from 
the lowest animal up to man, is a triumph of the nine- 
teenth century. Its famous creator was Johannes Mailer, 
of Berlin (born, the son of a shoemaker, at Coblentz, in 
1801). For fully twenty-five years from 1833 to 1858 
this most versatile and most comprehensive biologist of 
our age evinced an activity at the Berlin University, as 
professor and investigator, which is only comparable with 
the associated work of Hailer and Cuvier. Nearly every 
one of the great biologists who have taught and worked 
in Germany for the last sixty years was, directly or in- 
directly, a pupil of Johannes Muller. Starting from the 
anatomy and physiology of man, he soon gathered all the 
chief groups of the higher and lower animals within his 
sphere of comparison. As, moreover, he compared the 
structure of extinct animals with the living, and the 
healthy organism with the diseased, aiming at a philoso- 
phic grouping of all the phenomena of life, he attained a 
biological knowledge far in advance of his predecessors. 

The most valuable fruit of these comprehensive studies 
of Johannes Muller was his Manual of Human Physiology. 
This classical work contains much more than the title indi- 
cates ; it is the sketch of a comprehensive "comparative 


biology." It Is still unsurpassed in respect of its con- 
tents and range of investigation. In particular, we find 
the methods of observation and experiment applied in it as 
masterfully as the philosophic processes of induction and 
deduction. Miiller was originally a vitalist, like all the 
physiologists of his time. Nevertheless, the current idea 
of a vital force took a novel form in his speculations, and 
gradually transformed itself into the very opposite. For 
he attempted to explain the phenomena of life mechanic- 
ally in every department of physiology. His "trans- 
figured " vital force was not above the physical and 
chemical laws of the rest of nature, but entirely bound up 
with them. It was, in a word, nothing more than life 
itself that is, the sum of all the movements which we 
perceive in the living organism. He sought especially to 
give them the same mechanical interpretation in the life 
of the senses and of the mind as in the working of the 
muscles ; the same in the phenomena of circulation, 
respiration, and digestion as in generation and develop- 
ment. M tiller's success was chiefly due to the fact that he 
always began with the simplest life-phenomena of the 
lowest animals, and followed them step by step in their 
gradual development up to the very highest, to man. In 
this his method of critical comparison proved its value both 
from the physiological and from the anatomical point of 
view. Johannes Miiller is, moreover, the only great 
scientist who has equally cultivated these two branches of 
research, and combined them with equal brilliancy. Im- 
mediately after his death his vast scientific kingdom fell 
into four distinct provinces, which are now nearly always 
represented by four or more chairs human and compara- 
tive anatomy, pathological anatomy, physiology, and the 
history of evolution. This division of Muller's immense 
realm of learning in 1858 has been compared to the 
rending of the empire which Alexander the Great had 
consolidated and ruled. 

Among the many pupils of Johannes Miiller who, either 
during his lifetime or after his death, laboured hard for 
the advancement of the various branches of biology, one 
of the most fortunate if not the most important was 


Theodor Schwann. When the able botanist Schleiden, 
in 1838, indicated the cell as the common elementary 
organ of all plants, and proved that all the different tissues 
of the plant are merely combinations of cells, Johannes 
Muller recognised at once the extraordinary possibilities 
of this important discovery. He himself sought to point 
out the same composition in the various tissues of the 
animal body for instance, in the spinal cord of verte- 
brates and thus led his pupil, Schwann, to extend the 
discovery to all the animal tissues. This difficult task 
was accomplished by Schwann in his Microscopic Re- 
$earches into the Accordance in the Structure and Growth 
of Plants and Animal* (1839). Thus was the foundation 
laid of the "cellular theory," the profound importance of 
which, both in physiology and anatomy, has become 
clearer and more widely recognised in each subsequent 
year. Moreover, it was shown by two other pupils of 
Johannes Muller the able physiologist Ernst Brucke, of 
Vienna, and the distinguished histologist Albert Koliiker, 
of Wurzburg that the activity of all organisms is, in the 
ultimate analysis, the activity of the components of their 
tissues, the microscopic cells. Brucke correctly denomi- 
nated the cells the " elementary organisms,*' and showed 
that, in the body of man and of all other animals, they 
are the only actual, independent factors of the life-process. 
Koliiker earned special distinction, not only in the con- 
struction of the whole science of histology, but particularly 
by showing that the animal ovum and its products are 
simple cells. 

Still, however widely the immense importance of the 
cellular theory for all biological research was acknow- 
ledged, the " cellular physiology " which is based on it 
only began an independent development very recently. 
In this Max Verworn (of Jena) earned a twofold distinc- 
tion. In his Psycho-physiological Studies of the Protistx 
(1889) he showed, as a result of an ingenious series of 
experimental researches, that the " theory of a cell-soul " 
which I put forward In 1866 l is completely established 

1 Zell-seelen und Seeltn-zellen. Ernst HaeokeL GesanwutU pop*- 
L H0. 1878. 


by an accurate study of the unicellular protozoa, and that 
"the psychic phenomena of the protistae form the bridge 
which unites the chemical processes of inorganic nature 
with the mental life of the highest animals." Verworn 
has further developed these views, and based them on the 
modern theory of evolution, in his General Physiology. 
This distinguished work returns to the comprehensive 
point of view of Johannes Miiller, in opposition to the 
one-sided and narrow methods of those modern physiolo- 
gists who think to discover the nature of the vital pheno- 
mena by the exclusive aid of chemical and physical 
experiments. Verworn showed that it is only by Mailer's 
comparative method and by a profound study of the 
physiology of the cell that we can reach the. higher stand- 
point which will give us a comprehensive survey of the 
wonderful realm of the phenomena of life. Only thus 
do we become convinced that the vital processes in man 
are subject to the same physical and chemical laws as 
those of all other animals. 

The fundamental importance of the cellular theory for 
all branches of biology was made clear in the second half 
of the nineteenth eenlury, not only by the rapid progress 
of morphology and physiology, but also by the entire 
reform of that biological science which has always been 
deemed most important on account of its relation to 
practical medicine pathology, or the science of disease. 
Many even of the older physicians were convinced that 
human diseases were natural phenomena like all other 
manifestations of life, and should be studied scientifically 
like other vital functions. Particular schools of medicine, 
the latrnphysical and the latrochemical, had already in 
the seventeenth century attempted to trace the sources of 
disease to certain physical and chemical changes. How- 
ever, the imperfect condition of science at that period 
precluded any lasting result of these efforts. Many of 
the older theories, which sought the nature of disease in 
supernatural and mystical causes, were almost universally 
accepted down to the middle of the nineteenth century. 

It was then that Rudolph Virchow, another pupil of 
Mftller, conceived the happy idea of transferring the 


cellular theory from the healthy to the diseased organ- 
ism ; he sought in the more minute metamorphoses of the 
diseased cells and the tissues they composed the true 
sources of those larger changes which, in the form of 
disease, threaten the living organism with peril and death. 
Especially during the seven years of his professorship at 
Wurzburg (1849-56) Virchow pursued his great task with 
such brilliant results that his Cellular Pathology (pub- 
lished in 1858) turned, at one stroke, the whole of patho- 
logy and the dependent science of practical medicine into 
new and eminently fruitful paths. This reform of medi- 
cine is significant for our present purpose in that it led 
to a monistic arid purely scientific conception of disease. 
In sickness, no less than in health, man is subject to the 
same "eternal iron laws" of physics and chemistry as all 
the rest of the organic world. 

Among the numerous classes of animals which modern 
zoology distinguishes, the mammals occupy a pre-eminent 
position, not only on morphological grounds, but also for 
physiological reasons. As man belongs to the class of 
mammals (see p. 25) by every portion of his frame, we 
must expect him to share his characteristic functions with 
the rest of the mammals. Such we find to be the case. 
The circulation of the blood and respiration are accom- 
plished in man under precisely the same laws and in the 
same manner as in all the other mammals and in these, 
alone; they are determined by the peculiar structure of 
their heart and lungs. In mammals only is all the arterial 
blood conducted from the left ventricle of the heart to 
the body by one, the left, branch of the aorta, while in 
birds it passes along the right branch, and in reptiles 
along both branches. The blood of the mammal is distin- 
guished from that of any other vertebrate by the circum- 
stances that its red cells have lost their nucleus (by 
reversion). The respiratory movements are effected 
largely by the diaphragm in this class of animals alone, 
because only in them does it form a complete partition 
between the pectoral and abdominal cavities. Special 
importance, however, in this highest class of animals, 
attache* to the production of milk in the breasts (mam- 


mae), and to the peculiar method of the rearing of the 
young, which entails the supplying of the offspring with 
the mother's milk. As this nutritive process reacts most 
powerfully on the other vital functions, and the maternal 
affection of mammals must have arisen from this intimate 
form of rearing, the name of the class justly reminds us 
of its great importance. In millions of pictures, most of 
them produced by painters of the highest rank, the 
"madonna with the child " is revered as the purest and 
noblest type of maternal love the instinct which is 
found in its extreme form in the exaggerated tenderness 
of the mother-ape. 

As the apes approach nearest to man of all the mammals 
In point of structure, we shall expect to hear the same 
of their vital functions; and that we find to be the case. 
Everybody knows how closely the habits, the movements, 
the sense-activity, the mental life, and the parental cus- 
toms of apes resemble those of man. Scientific physiology 
proves the same significant resemblance in other less 
familiar processes, particularly in the working of the 
heart, the division of the breasts, and the sexual life. 
In the latter connection it is especially noteworthy that 
the mature females of many kinds of apes suffer a period- 
ical discharge of blood from the womb, which corresponds 
to the menstruation of the human female. The secretion 
of the milk in the glands and the suctorial process also 
take place in the female ape in precisely the same fashion 
as in women. 

Finally, it is of especial interest that the speech of apes 
seems on physiological comparison to be a stage in the 
formation of articulate human speech. Among living 
apes there is an Indian species which is musical; the 
hyobatet tyndactylut sings a full octave in perfectly pure, 
harmonious half-tones. No impartial philologist can hesi- 
tate any longer to admit that our elaborate rational 
language has been slowly and gradually developed out of 
the imperfect speech of our Pliocene simian ancestors. 



The older embryology. The theory of preformation. The theory of 
scatulation. Haller and Leibnitz, The theory of epigenesis. 
C. F. Wolff. The theory of germinal layers. Carl Ernest Baer. 
Discovery of the human ovurn. Remak, Kblliker. Theegg-cll 
and the sperm-cell. The theory of the gastraea. Protozoa 
and metazoa. The ova and the spermatozoa. Oscar Hertwig. 
Conception. Embryonic development in man. Uniformity of 
the vertebrate embryo. The germinal membranes in man. The 
amnion, the seroleinma, arid the allantois. The formation of the 
placenta and the ''afterbirth." The deeiduaxnti. the funiculu* 
umbilicalis. The discoid placenta of man and the ape. 

COMPARATIVE ontogeny, or the science of the development 
of the individual animal, is a child of tiie nineteenth 
century in even a truer sense than comparative anatomy 
and physiology. How is the child formed in the mother's 
womb? How do animals evolve from ova? How does 
the plant come forth from the seed? These pregnant 
questions have occupied the thoughtful mind for thousands 
of years. Yet it is only seventy years since the ernhryo- 
logist Baer pointed out the correct means and methods 
for penetrating into the mysteries of embryonic life; it 
is only forty years since Darwin, by his reform of the 
theory of descent, gave us the key which should open 
the long-closed door, and lead to a knowledge of embry- 
onic agencies. As I have endeavoured to give a complete, 
popular presentation of this very interesting but difficult 
study in the first section of my Anthropogeny, I shall 
confine myself here to a brief survey and discussion of the 
most important phenomena. Let ur> first cast an his- 



torical glance at the older ontogeny, 1 and the theory of 
preformation which is connected with it. 

The classical works of Aristotle, the many-sided "father 
of science," are the oldest known scientific sources of 
embryology, as we found them to be for comparative 
anatomy. Not only in his great Natural History, but 
also in a small special work, Five Books on the Generation 
and Development of Animals, the great philosopher gives 
us a host of interesting facts, adding many observations 
on their significance; it was not until our own days that 
many of them were fully appreciated, and, indeed, we 
may say, discovered afresh. Naturally, many fables and 
errors are mixed up with them ; it was all that was known 
at that time of the hidden growth of the human germ. 
Yet during the long space of the next two thousand years 
the slumbering science made no further progress. It was 
not until the commencement of the seventeenth century 
that there was a renewal of activity. In 1600 the Italian 
anatomist Fabricius ab Aquapendente published at Padua 
the first pictures and descriptions of the embryos of man 
ad some of the higher animals; in 1687 the famous 
Marcello Malpighi of Bologna, a distinguished pioneer 
alike in zoology and botany, published the first consistent 
exposition of the growth of the chick in the hatched egg. 

All these older scientists were possessed with the idea 
that the complete body, with all its parts, was already 
contained in the ovum of animals, only it was so minute 
and transparent that it could not be detected; that, there- 
fore, the whole development was nothing more than a 
growth, or an "unfolding " of the parts that were already 
" in-folded " (involute)* This erroneous notion, almost 
universally accepted until the beginning of the present 
century, is called the " performation theory "; sometimes 
it is called the "evolution theory " (in the literal sense of 
" unfolding ") ; but the latter title is accepted by modern 
scientists for the very different theory of "transformation." 

Closely connecter] with the preformation theory, and 

describes the formation of the individual ; phytogeny the 
genesis of n *pecie or larger group ; biogcny the development of life in 
either sense. 


as a logical consequence of it, there arose in the last 
century a further theory which keenly interested all 
thoughtful biologists the curious " theory of scatula- 
tion." L As it was thought that the outline of the entire 
organism, with all its parts, was present in the egg, the 
ovary of the embryo had to be supposed to contain the 
ova of the following generation ; these, again, the ova of 
the next, and so on in infinitum I On that basis the dis- 
tinguished physiologist Haller calculated that God had 
created together, 6000 years ago on the sixth day of his 
creatorial labours the germs of 200,000,000,000 men, 
and ingeniously packed them all in the ovary of our 
venerable mother Eve. Even the gifted philosopher Leib- 
nitz fully accepted this conclusion, and embodied it in 
his monadist theory ; and as, on his theory, soul and body 
are in eternal, inseparable companionship, the consequence 
had to be accepted for the soul; " the souls of men 
have existed in organised bodies in their ancestors from 
Adam downwards that is, from the very beginning of 

In the month of November, 1759, a young doctor of 
twenty-six years, Caspar Friedrich Wolff (son of a Berlin 
tailor), published his dissertation for the degree at Halle, 
under the title Theoria Gcneratiotiis. Supported by a 
series of most laborious and painstaking observations, he 
proved the entire falsity of the dominant theories of pre- 
formation and scatulation. In the hatched egg there is 
at first no trace of the coming chick and its organs ; 
instead of it we find on top of the yolk a small, circular, 
white disk. This thin " germinal-disk " becomes gradu- 
ally round, and then breaks up into four folds, lying 
upon each other ; these are the rudiments of the four 
chief systems of organs the nervous system above, the 
muscular system underneath, the vascular system (with 
the heart), and, finally, the alimentary canal. Thus, as 
Wolff justly remarked, the embryonic development does 
not consist in an unfolding of pre-formed organs, but in 
a series of new constructions ; it is a true epigenesis. One 

1 Literally " boxing-up " or "packing"; the force of the term 
appears in the next sentence. 


part arises after another, and all make their appearance 
in a simple form, which is very different from the later 
structure. This only appears after a series of most re- 
markable formations. Although this great discovery one 
of the most important of the eighteenth century could 
be directly proved by a verification of the facts Wolff had 
observed, and although the "theory of generation " which 
was founded on it was in reality not a theory at all, but 
a simple fact, it met with no sympathy whatever for half 
a century. It was particularly retarded by the high 
authority of Haller, who fought it strenuously with the 
dogmatic assertion that " there is no such thing as 
development : no part of the animal body is formed before 
another; all were created together." Wolff, who had to 
go to St. Petersburg, was long in his grave before the 
forgotten facts he had observed were discovered afresh 
by Oken at Jena in 1806. 

After Wolff's " epigenesis theory " had been established 
by Oken and Neckel (whose important work on the 
development of the alimentary canal was translated from 
Latin into German), a number of young German scientists 
devoted themselves eagerly to more accurate embryological 
research. The most important and successful of these 
was Carl Ernst Baer. His principal work appeared in 
1828, with the title, History of the Development of 
Animals : Observations and Reflections. Not only are the 
phenomena of the formation of the germ clearly illustrated 
and fully described in it, but it adds a number of very 
pregnant speculations. In particular, the form of the 
embryo of man and the mammals is correctly presented, 
and the vastly different development of the lower inverte- 
brate animals is also considered. The two leaf -like layers 
which appear in the round germ-disk of the higher verte- 
brates first divide, according to Baer, into two further 
layers, and these four germinal layers are transformed 
into four tubes, which represent the fundamental organs 
the skin-layer, the muscular-layer, the vascular-layer, and 
the mucous-layer. Then, by very complicated evolution- 
ary processes, the later organs arise in substantially the 
tame manner In man and all the other vertebrates. The 


three chief groups of invertebrates, which, in their turn, 
differ widely from each other, have a very different 

One of the most important of Baer's many discoveries 
was the finding of the human ovum. Up to that time 
the little vesicles which are found in great numbers in 
the human ovary and in that of all other mammals had 
been taken for the ova. Baer was the first to prove, in 
1827, that the real ova are enclosed in these vesicles the 
" Graafian follicles " and much smaller, being tiny 
spheres one- 120th of an inch in diameter, visible to the 
naked eye as minute specks under favourable conditions. 
He discovered likewise that from this tiny ovum of the 
mammal there developes first a characteristic germ-globule, 
a hollow sphere with liquid contents, the wall of which 
forms the slender germinal membrane, or blastoderm. 

Ten years after Baer had given a firm foundation to 
embryological science by his theory of germ-layers a new 
task confronted it on the establishment of the cellular 
theory in 1838. What is the relation of the ovum and 
the layers which arise from it to the tissues and cells 
which compose the fully-developed organism? The cor- 
rect answer to this difficult question was given about the 
middle of this century by two distinguished pupils of 
Johannes Miiller Robert Remak, of Berlin, and Albert 
Kolliker, of Wurzburg. They showed that the ovum is 
at first one simple cell, and that the many germinal 
globules, or granules, which arise from it by repeated 
segmentation are also simple cells. From this mulberry- 
like group of cells are constructed first the germinal 
layers, and subsequently by differentiation, or division of 
labour, all the different organs. Kolliker has the further 
merit of showing that the seminal fluid of male animals 
is also a mass of microscopic cells. The active pin-shaped 
"seed-animalcules," or spermatozoa, in it are merely 
ciliated cells, as I first proved in the case of the seed- 
filaments of the sponge in 1866. Thus it was shown that 
both the materials of generation, the male sperm and the 
female ova, fell in with the cellular theory. That was a 
discovery of which the great philosophic significance was 


not appreciated until a much later date, on a close study 
of the phenomena of conception in 1875. 

All the older studies in embryonic development con- 
cern man and the higher vertebrates, especially the em- 
bryonic bird, since hens' eggs are the largest and most 
convenient objects for investigation, and are plentiful 
enough to facilitate experiment; we can hatch them in 
the incubator, as well as by the natural function of the 
hen, and so observe from hour to hour, during the space 
of three weeks, the whole series of formations, from the 
simple germ-cell to the complete organism. Even Baer 
had only been able to gather from such observations the 
fact that the different classes of vertebrates agreed in the 
characteristic form of the germ-layers and the growth of 
particular organs, hi the innumerable classes of inverte- 
brates, on the othrr hand that is, in the great majority 
of animals the embryonic development seemed to run 
quite a different course, and most of them seemed to be 
altogether without true germinal layers. It was not until 
about the middle of the century that such layers were 
found in some of the Invertebrates. Huxley, for instance, 
found them in the medusur in 1849, and Koliiker in the 
cephalopoda in 1844. Particularly important was the dis- 
covery by Kowalewsky (1886) that the lowest vertebrate 
the lanceiet, or amphioxus is developed in just the 
same manner (and a very original fashion it is) as an 
invertebrate, apparently quite remote, tunicate the sea- 
squirt, or ascidian. Even in some of the worms, the 
radiata and the articuiata, a similar formation of the 
germinal layers was pointed out by the same observer. 
I myself was then (since 1886) occupied with the em- 
bryology of the sponges, corals, medusse, and siphono- 
phora and, as I found the same formation of two 
primary germ-layers everywhere in these lowest classes of 
multicelluiar animals, I came to the conclusion that this 
important embryonic feature is common to the entire 
animal world. The circumstance that in the sponges and 
the cnidaria (polyps, medusae, etc.) the body consists for 
a long time, sometimes throughout life, merely of two 
simple layers of cells, seemed to me especially significant. 


Huxley had already (1849) compared these, in the case 
of the medusae, with the two primary germinal layers of 
the vertebrates. On the ground of these observations and 
comparisons I then, in 1872, in my Philosophy of the 
Calcispongisc, published the "theory of the gastrsea," of 
which the following are the essential points : 

I. The whole animal world falls into two essentially 
different groups, the unicellular primitive animals (Pro- 
tozoa) and the multicellular animals with complex tissues 
(Metazoa). The entire organism of the protozoon (the 
rhizopods or the infusoria) remains throughout life a 
single simple cell (or occasionally a loose colony of cells 
without the formation of tissue, a coeno6tu?n). The organ- 
ism of the metazoon, on the contrary, is only unicellular 
at the commencement, and is subsequently built up of a 
uumber of cells, which form tissues. 

II. Hence the method of reproduction and develop- 
ment is very different in each of these great categories of 
animals. The protozoa usually multiply by non-sexual 
means, by fission, gemmation, or spores ; they have no 
real ova and no sperm. The metazoa, on the contrary, 
are divided into male and female sexes, and generally 
propagate sexually, by means of true ova, which are 
fertilised by the male sperm. 

III. Hence, further, true germinal layers, and the 
tissues which are formed from them, are found in the 
metazoa ; they are entirely wanting in the protozoa. 

IV. In all the metazoa only two primary layers appear 
at first, and these have always the same essential signifi- 
cance ; from the outer layer the external skin and the 
nervous system are developed ; from the inner layer are 
formed the alimentary canal and all the other organs. 

V. I called the germ, which always arises first from 
the impregnated ovum, and which consists of these two 
primary layers, the "gut-larva " or the gastrula: its cup- 
shaped body with the two layers encloses originally a 
simple digestive cavity, the primitive gut (the progaster 
or archenleron), and its simple opening is the primitive 
mouth (the prottoma or blastopoms). These are the earli- 
est organs of the multicellular body, and the two cell- 


layers of Its enclosing wall, which are simple epiihelia, 
are its earliest tissues ; all the other organs and tissues are 
a later and secondary growth from these. 

VI. From this similarity, or homology, of the gastrula 
in all classes of compound animals I drew the conclusion, 
In virtue of the biogenetic law (p. G6), that all the metazoa 
come originally from one simple ancestral form, the 
gastrsea, and that this ancient (Laurentian), long-extinct 
form had the structure and composition of the actual 
gastrula, in which it is preserved by heredity. 

VII. This phylogenetic conclusion, based on the com- 
parison of ontogenetic facts, is confirmed by the circum- 
stance that there. are several of these gastnrades still in 
existence (gastrsemaria, cyemaria, phy&emaria, etc.), and 
also some ancient forms of other animal groups whose 
organisation is very little higher (the olynthus of the 
sponges, the hydra, or common fresh-water polyp, of the 
cnidaria, the convoluta and other cryptoca^la, or worms 
of the simplest type, of the platodes). 

VIII. In the further development of the various tissue- 
forming animals from the gastrula we have to distinguish 
two principal groups. The earlier and lower types (the 
ccelenteria or acoelomia) have no body cavity (no vent, 
and no blood ; such is the case with the gastryeacles, 
sponges, cnidaria, and platodes. The later and higher 
types (the c&lomaria or bilateria), on the other hand, 
have a true body cavity, and generally blood and a vent ; 
to these we must refer the worms and the higher types 
of animals which were evolved from these later on, the 
echinodermata, mollusca, articulata, tunicata, and verte- 

Those are the main points of my "gastnea theory " ; I 
have since enlarged the first sketch of it (given in 1872), 
and have endeavoured to substantiate it in a series of 
"Studies of the gastraea theory" (1878-84). Although 
it was almost universally rejected at first, and fiercely 
combated for ten years by many authorities, it is now 
(and has been for the last fifteen years) accepted by nearly 
all my colleagues. Let us now see what far-reaching 
consequences follow from it, and from the evolution of 


the germ, especially with regard to our great question, 
"the place of man in nature." 

The human ovum, like that of all other animals, is a 
single ceil, and this tiny globular egg-cell (about the 
120th of an inch in diameter) has just the same char- 
acteristic appearances as that of all other viviparous organ- 
isms. The little ball of protoplasm is surrounded by a 
thick, transparent, finely reticulated membrane, called 
the zona pelhicida ; even the little globular germinal 
vesicle (the cell-nucleus), which is enclosed in the proto- 
plasm (the cell-body), is of the same size and the same 
qualities as in the rest of the mammals. The same applies 
to the active spermatozoa of the male, the minute, thread- 
like, ciliated cells of which millions are found in every 
drop of the seminal fluid ; on account of their life-like 
movements they were previously taken to be forms of 
life, as the name indicates (spermatozoa = sperm-animals). 
Moreover, the origin of both these important sexual cells 
in their respective organs is the same in man as in the 
other mammals ; both the ova in the ovary of the female 
and the spermatozoa in the spermarium of the male arise 
in the game fashion they always come from cells, which 
are originally derived from the coelous epithelium, the 
layer of cells which clothes the cavity of the body. 

The most important moment in the life of every man, 
as in that of all other complex animals, is the moment in 
which he begins his individual existence; it is the moment 
when the sexual cells of both parents meet and coalesce 
for the formation of a single simple cell. This new cell, 
the impregnated egg-cell, is the individual stem-cell (the 
cytula), the continued segmentation of which produces 
the cells of the germinal layers and the gastrula. With 
the formation of this cytula, hence in the process of con- 
ception itself, the existence of the personality, the in- 
dependent individual, commences. This ontogenetic fact 
is supremely important, for the most far-reaching con- 
clusions may be drawn from it. In the first place, we 
have a clear perception that man, like all the other com- 
plex animals, inherits all his personal characteristics, 
bodily and mental, from his parents; and, further, we 


come to the momentous conclusion that the new person- 
ality which arises thus can lay no claim to " immortality." 

Hence the minute processes of conception and sexual 
generation are of the first importance. We are, however, 
only familiar with their details since 1875, when Oscar 
Hertwig, my pupil and fellow-traveller at that time, began 
his researches into the impregnation of the eg of the sea- 
urchin at Ajaccio, in Corsica. The beautiful capital of 
the island in which Napoleon I. was born in 1768 was also 
the spot in which the mysteries of animal conception were 
carefully studied for the first time in their most important 
aspects. Hertwig found that the one essential element in 
conception is the coalescence of the two sexual cells and 
their nuclei. Only one out of the millions of male ciliated 
cells which press round the ovum penetrates to its nucleus. 
The nuclei of both cells, of the spermatozoon and of the 
ovurn, drawn together by a mysterious force, which we 
take to be a chemical sense-activity, related to smell, 
approach each other and rnelt into one-. Thus, by the 
sensitive perception of the sexual nuclei, following upon 
* kind of "erotic chemicotropism," a new cell is formed, 
which unites in itself the inherited qualities of both 
parents ; the nucleus of the spermatozoon conveys the 
paternal features, the nucleus of the ovum those of the 
mother, to the stem-cell, from which the child is to be 
developed. That applies both to the bodily and to the 
mental characteristics. 

The formation of the germinal layers by the repeated 
division of the stem-cell, the growth of the gastrula and 
of the later germ-structures which succeed it, take place 
In man in just the same manner as in the other higher 
mammals, under the peculiar conditions which differen- 
tiate this group from the lower vertebrates. In the earlier 
stages of development these special characters of the 
placentaiia are not to be detected. The significant em- 
bryonic or larval form of the chordula, which succeeds 
the gastrida, has substantially the same structure in all 
vertebrates; a simple straight rod, the dorsal cord, lies 
lengthways along the main axis of the shield-shaped bodv 
the " embryonic shield " ; above the cord the spinal 


marrow developes out of the outer germinal layer, while 
the gut makes its appearance underneath. Then, on both 
sides, to the right and left of the axial rod, appear the 
segments of the "pro-vertebrae " and the outlines of the 
muscular plates, with which the formation of the members 
of the vertebrate body begins. The gill-clefts appear on 
either side of the fore-gut; they are the openings of the 
gullet, through which, in our primitive fish-ancestors, the 
water which had entered at the mouth for breathing pur- 
poses made its exit at the sides of the head. By a 
tenacious heredity these gill-clefts, which have no mean- 
ing except for our fish-like aquatic ancestors, are still 
preserved in the embryo of man and all the other verte- 
brates. They disappear after a time. Even after the 
five vesicles of the embryonic brain appear in the head, 
and the rudiments of the eyes and ears at the sides, and 
after the legs sprout out at the base of the fish-like 
embryo, in the form of two roundish, flat buds, the f<etus 
is still so like that of other vertebrates that it is indis- 
tinguishable from them. 

The substantial similarity in outer form and inner 
structure which characterises the embryo of man and 
other vertebrates in this early stage of development is an 
embryological fact of the first importance ; from it, by the 
fundamental law of biogeny, we may draw the most 
momentous conclusions. There is but one explanation of 
it heredity from a common parent form. When we see 
that, at a certain stage, the embryos of man and the ape, 
the dog and the rabbit, the pig and the sheep, although 
recognisable as higher vertebrates, cannot be distinguished 
from each other, the fact can only be elucidated by 
assuming a common parentage. And this explanation is 
strengthened when we follow the subsequent divergence 
of these embryonic forms. The nearer two animals are 
in their bodily structure, and, therefore, in the scheme 
of nature, so much the longer do we find their embryos 
retain this resemblance, and so much the nearer do they 
approach each other in the ancestral tree of their respec- 
tive group, so much the closer is their genetic relationship. 
Hence it is that the embryos of man and the anthropoid 


ape retain the resemblance much later, at an advanced 
stage of development, when their distinction from the 
embryos of other mammals can be seen at a glance. I 
have illustrated this significant fact by a juxtaposition of 
corresponding stages in the development of a number of 
different vertebrates in my Natural History of Creation 
and in my Anthropogeny. 

The great phylogenetic significance of the resemblance 
we have described is seen, not only in the comparison of 
the embryos of vertebrates, but also in the comparison 
of their protective membranes. All vertebrates of the 
three higher classes reptiles, birds, and mammals are 
distinguished from the lower classes by the possession of 
certain special foetal membranes, the amnion and the 
serolemma. The embryo is enclosed in these membranes, 
or bags, which are full of water, and is thus protected 
from pressure or shock. This provident arrangement 
probably arose during the Permian period, when the oldest 
reptiles, the proreptilia, the common ancestors of all the 
amniotes (animals with an arm* km), completely adapted 
themselves to a life on land. Their direct ancestors, the 
amphibia, and the fishes are devoid of these foetal mem- 
branes ; they would have been superfluous to these in- 
habitants of the water. With the inheritance of these 
protective coverings are closely connected two other 
changes in the amniotes : firstly, the entire disappearance 
of the gills (while the gill arches and clefts continue to 
be inherited as "rudimentary organs"); secondly, the 
construction of the allantois. This vesicular bag, filled 
with water, grows out of the hind-gut in the embryo of 
all the amniotes, and is nothing else than an enlargement 
of the bladder of their amphibious ancestors. From its 
innermost and inferior section is formed subsequently the 
permanent bladder of the amniotes, while the larger outer 
part shrivels up. Usually this has an important part to 
play for a long time as the respiratory organ of the 
embryo, a number of large blood vessels spreading out 
over its inner surface. The formation of the membranes, 
the amnion, and the serolemma, and of the allantois, is 
just the same, and is effected by the same complicated 


process of growth, in man as in all the other anmiotes; 
man it a true arnniote. 

The nourishment of the foetus in the maternal womb it 
effected, as is well known, by a peculiar organ, richly 
supplied with blood at its surface, called the placenta. 
This important nutritive organ is a spongy round disk, 
from six to eight inches in diameter, about an inch thick, 
and one or two pounds in weight; it is separated after 
the birth of the child, and issues as the "afterbirth." 
The placenta consists of two very different parts, the foetal 
and the maternal part. The latter contains highly- 
developed sinuses, which retain the blood conveyed to 
them by the arteries of the mother. On the other hand, 
the foetal placenta is formed by innumerable branching 
tufts or villi, which grow out of the outer surface of the 
allantois, and derive their blood from the umbilical 
vessels. The hollow, blood-filled villi of the foetal placenta 
protrude into the sinuses of the maternal placenta, and 
the slender membrane between the two is so attenuated 
that it offers no impediment to the direct interchange of 
material through the nutritive blood-stream (by osmosis). 

In the older and lower groups of the placentals the 
entire surface of the chorion is covered with a number of 
short villi; these " chorion-villi " take the form of pit-like 
depressions of the mucous membrance of the mother, and 
are easily detached at birth. That happens in most of the 
ungulata (the sow, camel, mare, etc.), the cetacea, and 
the prosimict; ; these " malloplacentalia " (animals with a 
diffuse placenta) have been denominated the indeciduata. 
The same formation is present in man and the other 
placentals in the beginning. It is soon modified, however, 
as the villi on one part of the chorion are withdrawn ; 
while on the other part they grow proportionately 
stronger, and unite intimately with the mucous membrane 
of the womb. It is in consequence of this intimate 
blending that a portion of the uterus is detached at birth, 
and carried away with loss of blood. This detachable 
membrane the decidua is a characteristic of the higher 
placentalia, which have, consequently, been grouped 
under the title of deciduata; to that category belong the 


carnassia, rodentia, sirniae, and man. In the caruassia and 
some of the ungulata (the elephant, for instance) the 
placenta takes the form of a girdle, hence they are known 
as the zonoplacentalia ; in the rodentia, the insectivora 
(the mole and the hedgehog), the apes and man, it takes 
the form of a disk. 

Even ten years ago the majority of embryologists 
thought that man was distinguished by certain peculiar- 
ities in the form of the placenta namely, by the pos- 
session of what is called the decidua reflexa, and by a 
special formation of the umbilical cord which unites the 
decidua to the foetus. It was supposed that the rest of 
the placentals, including the apes, were without these 
special embryonic structures. The funiculus umbilicalis 
is a smooth, cylindrical cord, from sixteen to twenty- 
three inches long, and as thick as the little finger. It 
forms the connecting link between the foetus and the 
maternal placenta, since it conducts the nutritive vessels 
from the body of the foetus to the placenta ; it comprises, 
besides, the pedicle of the allantois and the yelk-sac. 
The yelk-sac in the human case forms the greater portion 
of the germinal vesicle during the third week of gestation ; 
but it shrivels up afterwards, so that it was formerly 
entirely missed in the mature fostus. Yet it remains all 
the time in a rudimentary condition, and may be detected 
even after birth as the little umbilical vesicle. Moreover, 
even the vesicular structure of the allantois disappears at 
an early stage in the human case ; with a deflection of the 
ainnion, it gives rise to the pedicle. We cannot enter here 
into a discussion of the complicated anatomical and em- 
bryological relations of these structures. I have described 
and illustrated them in my Anthropogeny (twenty-third 

The opponents of evolution still appealed to these 
" special features " of human embryology, which were 
supposed to distinguish man from all the other mammals, 
even so late as ten years ago. But in 1890 Emil Selenka 
proved that the same features are found in the anthropoid 
apes, especially in the orang (satyrus), while the lower 
apes are without them. Thus Huxley's pitbecometra 


thesis was substantiated once more: "The differences be- 
tween man and the great apes are not so great as are those 
between the man-like apes and the lower monkeys." The 
supposed "evidences flffoiwt the near blood-relationship 
of man and the apes " proved, on a closer examination of 
the real circumstances, to be strong reasons in favour of it, 
Every scientist who penetrates with open eyes into thu 
dark but profoundly interesting labyrinth of our embryonic 
development, and who is competent to compare it critically 
with that of the rest of the mammals, will find in it a 
most important aid towards the elucidation of the descent 
of our species. For the various stages of our embryonic 
development, in the character of paKngenettc 1 phenomena 
of heredity, cast a brilliant light on the corresponding 
stages of our ancestral tree, in accordance with the great 
law of biogeny. But even the cenogenetic phenomena of 
adaptation, the formation of the temporary foetal organs 
the characteristic foetal membranes, and especially the 
placenta give us sufficiently definite indications of our 
cloie genetic relationship with the primates. 

1 Beep, 117, 



Origin of man. Mythical history of creation. Moses and Linne, 
The creation of permanent species. The catastrophic theory : 
Ouvier. Transformiam : Goethe. Theory of descent : Lamarck. 
Theory of selection : Darwin. Evolution (phylogeny), Ancestral 
trees. General morphology. Natural history of creation. 
Systematic phylogeny. Fundamental law of biogeny. Anthro- 
pogeny, Descent of man from the ape. Pithecoid theory, The 
fossil pithecanthropus of Dubois. 

THE youngest of the great branches of the living tree of 
biology is the science we call biological evolution or 
phylogeny. It came into existence much later, and under 
much more difficult circumstances, than its natural sister, 
embryonic evolution or ontogeny. The object of the latter 
was to attain a knowledge of the mysterious processes by 
which the individual organism, plant or animal, developed 
from the egg. Phylogeny has to answer the much more 
obscure and difficult question : " What is the origin of the 
different organic species of plants and animals? " 

Ontogeny (embryology and metamorphism) could follow 
the empirical method of direct observation in the solution 
of its not remote problem ; it needed but to follow, day 
by day and hour by hour, the visible changes which the 
foetus experiences during a brief period in the course of its 
development from the ovum. Much more difficult was 
the remote problem of phylogeny ; for the slow processes 
of gradual construction, which effect the rise of new 
species of animals and plants, go on imperceptibly during 
thousands and even millions of years. Their direct observa- 
tion is possible only within very narrow limits; the vast 
majority of these historical processes can only be known 
by indirect inference by critical reflection, and by 



a comparative use of empirical sciences which belong to 
very different fields of thought, palaeontology, ontogeny, 
and morphology. To this we must add the immense 
opposition which was everywhere made to biological evolu- 
tion on account of the close connection between questions 
of organic creation and supernatural myths and religious 
dogmas. For these reasons it can easily be understood 
how it is that the scientific existence of a true theory of 
origins was only secured, amidst fierce controversy, in the 
course of the last forty years. 

Every serious attempt that was made, before the be- 
ginning of the nineteenth century, to solve the problem 
of the origin of species lost its way in the mythological 
labyrinth of the supernatural stories of creation. The 
efforts of a few distinguished thinkers to emancipate them- 
selves from this tyranny and attain to a naturalistic inter- 
pretation proved unavailing. A great variety of creation- 
myths arose in connection with their religion in all the 
ancient civilised nations. During the Middle Ages 
triumphant Christendom naturally arrogated to itself the 
ole right of pronouncing on the question ; and, the Bible 
being the basis of the structure of the Christian religion, 
the whole story of creation was taken from the book of 
Genesis. Even Carl Linne, the famous Swedish scientist, 
started from that basis when, in 1735, in his classical 
Systema Naturas, he made the first attempt at a systematic 
arrangement, nomenclature, and classification of the in- 
numerable objects in nature. As the best practical aid 
in that attempt, he introduced the well-known double or 
binary nomenclature; to each kind of animals and plants 
he gave a particular specific name, and added to it the 
wider-reaching name of the genus. A gchut served to 
unite the nearest related specie* ; thus, for instance, Linne* 
grouped under the genus "dog" (cants), as different 
species, the house-dog (cant* /amtJtara), the jackal (cant* 
aureui), the wolf (cant* lupus), the fox (cant* vulpet), etc. 
This binary nomenclature immediately proved of such 
great practical assistance that it was universally accepted, 
and is still always followed in zoological and botanical 


But the theoretical dogma which Linne* himself con- 
nected with his practical idea of species was fraught with 
the gravest peril to science. The first question which 
forced itself on the mind of the thoughtful scientist was 
the question as to the nature of the concept of species, its 
contents, and its range. And the creator of the idea 
answered this fundamental question by a naive appeal to 
the dominant Mosaic legend of creation : ** Species tot 
tunt divert ae, quot diversas formas ab initio creavit infi- 
nitum en* " (There are just so many distinct species as 
there were distinct types created in the beginning by the 
Infinite). This theosophic dogma cut short ail attempt at 
m natural explanation of the origin of species. Linne* was 
acquainted only with the plant and animal worlds that exist 
to-day ; he had no suspicion of the much more numerous 
extinct species which had peopled the earth with their 
varying forms in the earlier period of its development. 

It was not until the beginning of the nineteenth cen- 
tury that we were introduced to these fossil animals by 
Cuvier. In his famous work on the fossil bones of the 
four-footed vertebrates he gave (1812) the first correct 
description and true interpretation of many of these fossil 
remains. He showed, too, that a series of very different 
animal populations have succeeded each other in the 
various stages of the earth's history. Since Cuvier held 
firmly to Linne's idea of the absolute permanency of 
species, he thought their origin could only be explained 
by the supposition that a series of great cataclysms and 
new creations had marked the history of the globe; he 
imagined that all living creatures were destroyed at the 
commencement of each of these terrestrial revolutions, 
and an entirely new population was created at its close. 
Although this " catastrophic theory " of Cuvier's led to 
the most absurd consequences, and was nothing more than 
a bald faith in miracles, it obtained almost universal 
recognition, and reigned triumphant until the coming of 

It is easy to understand that these prevalent ideas of 
the absolute unchangeably and supernatural creation of 


organic species could not satisfy the more penetrating 
thinkers. We find several eminent minds, already, in the 
second half of the last century, busy with the attempt to 
find a natural explanation of the "problem of creation." 
Pre-eminent among them was the great German poet and 
philosopher Wolf&ang Goethe, who, by his long and 
assiduous study of morphology, obtained, more than a 
hundred years ago, a clear insight into the intimate con- 
nection of all organic forms, and a firm conviction of a 
common natural origin. In his famed Metamorphoti* of 
Plant* (1790) he derived all the different species of plants 
from one primitive type, and all their different organs 
from one primitive organ the leaf. In his vertebral 
theory of the skull he endeavoured to prove that the skulls 
of the vertebrates including man were all alike made 
up of certain groups of bones, arranged in a definite 
structure, and that these bones are nothing else than 
transformed vertebra;. Jt was his penetrating study of 
comparative osteology that led Goethe to a firm eon vie- 
tion of the unity of the animal organisation ; he had 
recognised that the human skeleton is framed on the same 
fundamental type as that of all other vertebrates "built 
on a primitive plan that only deviates more or less to one 
side or other in its very constant features, and still deve- 
lopes and refashions itself daily." This remodelling, or 
transformation , is brought about, according to Goethe, by 
the constant interaction of two powerful constructive 
forces a centripetal force within the organism, the "ten- 
dency to specification," and a centrifugal force without, 
the tendency to variation, or the "idea of metamor- 
phosis " ; the former corresponds to what we now call 
heredity, the latter to the modern idea of adaptation. 
How deeply Goethe had penetrated into their character by 
these philosophic studies of the "construction and recon- 
struction of organic natures," and how far, therefore, he 
must be considered the most important precursor of 
Darwin and Lamarck, may be gathered from the interest- 
ing passages from his works which I have collected in the 
fourth chapter of my Natural Hiftory of Creation. These 


evolutionary ideas of Goethe, however, like analogous ideas 
of Kant, Owen, Treviranus, and other philosophers of the 
commencement of the century (which are quoted in the 
above work), did not amount to more than certain general 
conclusions. They had not that great lever which the 
"natural history of creation " needed fdr its firm founda- 
tion on a criticism of the dogma of fixed species ; this lever 
was first supplied by Lamarck. 

The first thorough attempt at a scientific establishment 
of transformism was made at the beginning of the nine- 
teenth century by the great French scientist Jean 
Lamarck, the chief opponent of his colleague Cuvier, at 
Paris. He had already in 1802, in his Observations on 
Living Organisms, expressed the new ideas as to the 
mutability and formation of species which he thoroughly 
established in 1809 in the two volumes of his profound 
work, Philosophic Zoologique* In this work he first gave 
expression to the correct idea, in opposition to the preva- 
lent dogma of fixed species, that the organic " species " is 
an artificial abstraction, a concept of only relative value, 
like the wider-ranging concepts of genus, family, order, 
and class. lie went on to affirm that all species are 
changeable, and have arisen from older species in the 
course of very long periods of time. The common parent 
forms from which they have descended were originally 
very simple and lowly organisms. The first and oldest of 
them arose by abiogenesis. While the type is preserved 
by heredity in the succession of generations, adaptation, 
on the other hand, effects a constant modification of the 
species by change of habits and the exercise of the various 
organs. Even our human organism has arisen in the same 
natural manner, by gradual transformation, from a group 
of pithecoid mammals. For all these phenomena indeed, 
for all phenomena both in nature and in the mind 
Lamarck takes exclusively mechanical, physical, and 
chemical activities to be the true efficient causes. His 
magnificent Philosophic Zoologique contains all the 
elements of a purely monistic system of nature on the 
basis of evolution. I have fully treated these achieve- 
ments of Lamarck in the fourth chapter of my Anthro- 


pogeny, and in the fourth chapter of the Natural History 
of Creation. 

Science had now to wait until this great effort to give a 
scientific foundation to the theory of evolution should 
shatter the dominant myth of a " specific creation, and 
open out the path of natural " development. In this 
respect Lamarck was not more successful in resisting the 
conservative authority of his great opponent, Cuvier, than 
was his colleague and sympathiser GeofFroy St. Ililaire, 
twenty years later. The famous controversies which he 
had with Cuvier in the Parisian Academy in 1830 ended 
with the complete triumph of the latter. I have elsewhere 
fully described these conflicts, in which Goethe took so 
lively an interest. The great expansion which the study 
of biology experienced at that time, the abundance of 
interesting discoveries in comparative anatomy and physio- 
logy, the establishment of the cellular theory, and the 
progress of ontogeny, gave zoologists and botanists so 
overwhelming a flood of welcome material to deal with 
that the difficult and obscure question of the origin of 
species was easily forgotten for a time. People rested 
content with the old dogma of creation. Even when 
Charles Lyell refuted Cuvier's extraordinary "catastro- 
phic theory " in his Principle* of Geology, in 1880, and 
vindicated a natural, continuous evolution for the inor- 
ganic structure of our planet, his simple principle of 
continuity found no one to apply it to the organic world. 
The rudiments of a natural phylogeny which were buried 
in Lamarck's works were as completely forgotten as the 
germ of a natural ontogeny which Caspar Friedrich Wolff 
had given fifty years earlier in his Theory of Generation. 
In both cases a full half-century elapsed before the great 
idea of a natural development won a fitting recognition. 
Only when Darwin (in 1859) approached the solution of 
the problem from a different side altogether, and made 
a happy use of the rich treasures of empirical knowledge 
which had accumulated in the meantime, did men begin 
to think once more of Lamarck as his great precursor. 

The unparalleled success of Charles Darwin is well 
known. It shows him to-day, at the close of the century, 


to have been, if not the greatest, at least the most 
effective, of its distinguished scientists. No other of the 
many great thinkers of our time has achieved so magnifi- 
cent, so thorough, and so far-reaching a success with a 
single classical work as Darwin did in 1859 with his 
famous Origin of Specie*. It is true that the reform of 
comparative anatomy and physiology by Johannes Miiller 
had inaugurated a new and fertile epoch for the whole of 
biology ; that the establishment of the cellular theory by 
Sehleiden and Schwann, the reform of ontogeny by Baer, 
and the formulation of the law of substance by Robert 
Mayer and Helmholtz, were scientific facts of the first 
importance ; but no one of them has had so profound an 
influence on the whole structure of human knowledge as 
Darwin's theory of the natural origin of species. For it 
at once gave us the solution of the mystic *' problem of 
creation," the great " question of all questions" the 
problem of the true character and origin of man himself. 

If we compare the two great founders of transformism, 
we find in Lamarck a preponderant inclination to deduc- 
tion, and to forming a complete monistic scheme of 
nature ; in Darwin we have a predominant application of 
induction, and a prudent concern to establish the different 
parts of the theory of selection as firmly as possible on a 
basis of observation and experiment. While the French 
scientist far outran the then limits of empirical knowledge, 
and rather sketched the programme of future investiga- 
tion, the English empiricist was mainly preoccupied about 
securing a unifying principle of interpretation for a mass 
of empirical knowledge which had hitherto accumulated 
without being understood. We can thus understand how 
It was that the success of Darwin was just as overwhelm- 
ing as that of Lamarck was evanescent. Darwin, how- 
ever, had not only the signal merit of bringing all the 
results of the various biological sciences to a common 
focus in the principle of descent, and thus giving them a 
harmonious interpretation, but he also discovered, in the 
principle of selection, that direct cause of transformism 
which Lamarck had missed. In applying, as a practical 
breeder, the experience of artificial selection to organisms 


in a state of nature, and in recognising in the "struggle 
for life "the selective principle of natural selection, Dar- 
win created his momentous "theory of selection," which 
is what we properly call Darwinism. 

One of the most pressing of the many important tasks 
which Darwin proposed to modern biology was the reform 
of the zoological and botanical system. Since the in- 
numerable species of animals and plants were not created 
by a supernatural miracle, but evolved by natural pro- 
cesses, their ancestral tree is their ''natural system." 
The first attempt to frame a system in this sense was 
made by myself in 1866, in my General Morphology of 
Organisms. The first volume of this work (''General 
Anatomy ") dealt with the "mechanical science of the 
developed forms " ; the second volume (" General Evolu- 
tion ") was occupied with the science of the "developing 
forms." The systematic introduction to the latter formed 
a "genealogical survey of the natural system of organ- 
isms." Until that time the term "evolution " had been 
taken to mean exclusively, both in zoology and botany, 
the development of individual organisms embryology, or 
metamorphic science. I established the opposite view, 
that this history of the embryo (ontogeny) must be com- 
pleted by a second, equally valuable, and closely-connected 
branch of thought the history of the race (phylogeny). 
Both these branches of evolutionary science are, in my 
opinion, in the closest causal connection ; this arises from 
the reciprocal action of the laws of heredity and adapta- 
tion ; it has a precise and comprehensive expression in my 
"fundamental law of biogeny." 

As the new views I had put forward in my General 
Morphology met with very little notice, and still less 
acceptance, from my scientific colleagues, in spite of their 
severely scientific setting, I thought I would make the 
most important of them accessible to a wider circle of 
informed readers by a smaller work, written in a more 
popular style. This was done in 1868, in The Natural 
History of Creation (a series of popular scientific lectures 
on evolution in general, and the systems of Darwin, 
Goethe, and Lamarck in particular). If the success of 


my General Morphology was far below my reasonable 
anticipation, that of The Natural History of Creation went 
far beyond it. In a period of thirty years nine editions 
and twelve different translations of it have appeared. In 
spite of its great defects, the book has contributed much 
to the popularisation of the main ideas of modern evolu- 
tion. Still, I could only give the barest outlines in it of 
my chief object, the phylogenetic construction of a natural 
system. I have, therefore, given the complete proof, 
which is wanting in the earlier work, of the phylogenetic 
system in a subsequent larger work, my Systematic Phyto- 
geny (outlines of a natural system of organisms on the 
basis of their specific development). The first volume of 
it deals with the protists and plants (1894), the second 
with the invertebrate animals (1806), and the third with 
the vertebrates (1895). The ancestral tree of both the 
smaller and the larger groups is carried on in this work 
as far as rny knowledge of the three great "ancestral 
documents " palaeontology, ontogeny, and morphology 
qualified me to extend it. 

I had already, in my General Morphology (at the end of 
the fifth book), described the close causative connection 
which exists, in my opinion, between the two branches of 
organic evolution as one of the most important ideas of 
transformism, and I had framed a precise formula for it 
in a number of *' theses on the causal nexus of biontic 
and phyletic development "; " Ontogenesis is a brief and 
rapid recapitulation of phylogenesis, determined by the 
physiological functions of heredity (generation) and 
adaptation (maintenance)." Darwin himself had empha- 
sised the great significance of his theory for the elucida- 
tion of embryology in 1859, and Fritz Miiller had en- 
deavoured to prove it as regards the Crustacea in the able 
little work, Fact* and Arguments for Darwin (1864). My 
own task has been to prove the universal application and 
the fundamental importance of the biogenetic law in a 
series of works, especially in the Biology of the Calci- 
$pongi(c (1872), and in Studies of the Gastrtea Theory 
(1873-84). The theory of the homology of the germinal 
Uv r ers and of the relations of palingenesis to ccno gene sis 


which I have exposed in them has been confirmed subse- 
quently by a number of works of other zoologists. That 
theory makes it possible to follow nature's law of unity in 
the innumerable variations of animal embryology ; it gives 
us for their ancestral history a common derivation from 
a simple primitive stem-form. 

The far-seeing founder of the theory of descent, 
Lamarck, clearly recognised in 1809 that it was of uni- 
versal application ; that even man himself, the most highly- 
developed of the mammals, is derived from the same stem 
as all the other mammals ; and that this in its turn belongs 
to the same older branch of the ancestral tree as the rest 
of the vertebrates. He had even indicated the agencies 
by which it might be possible to explain man's descent 
from the apes as the nearest related mammals. Darwin, 
who was, naturally, of the same conviction, purposely 
avoided this least acceptable consequence of his theory in 
his chief work in 1859, and put it forward for the first 
time in his Descent of Man in 1871. In the meantime 
(1863) Huxley had very ably discussed this most important 
consequence of evolution in his famous Man'* Place in 
Nature. With the aid of comparative anatomy and onto- 
geny, and the support of the facts of palaeontology, 
Huxley proved that the "descent of man from the ape " 
is a necessary consequence of Darwinism, and that no other 
scientific explanation of the origin of the human race is 
possible. Of the same opinion was Carl Gegenbaur, the 
most distinguished representative of comparative anatomy, 
who lifted his science to a higher level by a consistent 
and ingenious application of the theory of descent. 

As a further consequence of the " pithecoid theory " 
(the theory of the descent of man from the ape), there 
now arose the difficult task of investigating, not only the 
nearest related mammal ancestors of man in the Tertiary 
epoch, but also the long series of the older animal ancestors 
which had lived in earlier periods of the earth's history 
and been developed in the course of countless millions of 
years. I had made a start with the hypothetical solution 
of this great historic problem in my General Morphology ; 
a further development of It appeared In 1874 in my 


Anthropogeny (first section, Origin of the Individual; 
second section, Origin of the Race). The fourth, en- 
larged, edition of this work (1891) contains that theory 
of the development of man which approaches nearest, in 
my own opinion, to the still remote truth, in the light of 
our present knowledge of the documentary evidence. I 
was especially preoccupied in its composition to use the 
three empirical "documents " palaeontology, ontogeny, 
and morphology (or comparative anatomy) as evenly and 
harmoniously as possible. It is true that my hypotheses 
were in many cases supplemented and corrected in detail by 
later phylogenetic research; yet I am convinced that the 
ancestral tree of human origin which I have sketched 
therein is substantially correct. For the historical suc- 
cession of vertebrate fossils corresponds completely with 
the morphological evolutionary scale which is revealed to 
us by comparative anatomy and ontogeny. After the 
Silurian fishes come the dipnoi of the Devonian period, the 
Carboniferous amphibia, the Permian reptilia, and the 
Mesozoic mammals. Of these, again, the lowest forms, 
the monotremes, appear first in the Triassic period, the 
marsupials in the Jurassic, and then the oldest placentals 
in the Cretaceous. Of the placentals, in turn, the first 
to appear in the oldest Tertiary period (the Eocene) are 
the lowest primates, the prosimise, which are followed 
by the simiae in the Miocene. Of the catarrhinie, the 
cynopitheci precede the anthropomorpha ; from one branch 
of the latter, during the Pliocene period, arises the ape- 
man without speech (the pithecanthroput alalut); and 
from him descends, finally, speaking man. 

The chain of our earlier invertebrate ancestors is much 
more difficult to investigate and much less safe than this 
tree of our vertebrate predecessors ; we have no fossilised 
relics of their soft, boneless structures, so palaeontology 
can give us no assistance in this case. The evidence of 
comparative anatomy and ontogeny, therefore, becomes 
all the more important. Since the human embryo passes 
through the same cJiordula-stage as the germs of all other 
vertebrates, since it evolves, similarly, out of two ger- 
minal layers of a gattrula, we infer, in virtue of the bio- 


genetic law, the early existence of corresponding ancestral 
forms vormalia, gastraeada, etc. Most important of all 
is the fact that the human embryo, like that of ail other 
animals, arises originally from a single cell ; for this 
"stem-cell" (cytula) the impregnated egg-cell points 
indubitably to a corresponding unicellular ancestor, a 
primitive Laurentian protozoon. 

For the purpose of our monistic philosophy, however, 
It is a matter of comparative indifference how the suc- 
cession of our animal predecessors may be confirmed in 
detail. Sufficient for us, as an incontestable historical 
fact, is the important thesis that man descends imme- 
diately from the ape, and secondarily from a long series 
of lower vertebrates. I have laid stress on the logical 
proof of this " pithecometra-tliesis " in the seventh book 
of the General Morphology: "The thesis that man has 
been evolved from lower vertebrates, and immediately 
from the ftmue, is a special inference which results with 
absolute necessity from the general inductive law of the 
theory of descent." 

For the definitive proof and establishment of this 
fundamental pithecometra-thesis the palaeontological dis- 
coveries of the last thirty years are of the greatest im- 
portance ; in particular, the astonishing discoveries of a 
number of extinct mammals of the Tertiary period have 
enabled us to draw up clearly in its main outlines the 
evolutionary history of this most important class of 
animals, from the lowest oviparous monotremes up to man. 
The four chief groups of the placentals, the heterogeneous 
legions of the carnassia, the rodentia, the unguiata, and 
the primates, seem to be separated by profound gulfs 
when we confine our attention to their representatives of 
to-day. But these gulfs are completely bridged, and the 
sharp distinctions of the four legions are entirely lost, 
when we compare their extinct predecessors of the Tertiary 
period, and when we go back into the Eocene twilight of 
history in the oldest part of the Tertiary period at least 
5,000,000 years ago. There we find the great sub-class 
of the placentals, which to-day comprises more than 2500 
species, represented by only a small number of little, 


insignificant " pro-placentals " ; and in these prochoriata 
the characters of the four divergent legions are so inter- 
mingled and toned down that we cannot in reason do 
other than consider them as the precursors of those fea- 
tures. The oldest carnassia (the ictopsales), the oldest 
rodentia (the etthonyc hales), the oldest ungulata (the 
condylarthrales), and the oldest primates (the lemura- 
vales), ail have the same fundamental skeletal structure, 
and the same typical dentition of the primitive placentals, 
consisting of forty-four teeth (three incisors, one canine, 
four premolars, and three molars in each half of the jaw) ; 
all are characterised by the small si/e and the imperfect 
structure of the brain (especially of its chief part, the 
cortex, which does not become a true "organ of thought " 
until later on in the Miocene and Pliocene representatives) ; 
they have all short legs and five-toed, flat-soled feet 
(plantigrada). In many cases among these oldest pla- 
centals of the Eocene period it was very difficult to say 
at first whether they should be classed with the carnassia, 
rodentia, ungulata, or primates ; so very closely, even to 
confusion, do these four groups of the placentals, which 
diverge so widely afterwards, approach each other at that 
time. Their common origin from a single ancestral group 
follows incontestably. These prochoriata lived in the pre- 
ceding Cretaceous period (more than 8,000,000 years ago), 
and were probably developed in the Jurassic period from 
a group of insectivorous marsupials (amphitheria) by the 
formation of a primitive placenta diffusa, n placenta of the 
simplest type. 

But the most important of all the recent pabrontological 
discoveries which have served to elucidate the origin of the 
placentals relate to our own stem, the legion of primates. 
Formerly fossil remains of the primates were very scarce. 
Even Cuvier, the great founder of palaeontology, main- 
tained until his last day (1882) that there were no fossil- 
ised primates; he had himself, it is true, described the 
skull of an Eocene prosima (adapts), but he had wrongly 
classed it with the ungulata. However, during the last 
twenty years a fair number of well-preserved fossilised 
skeletons of prosimiae and simine have been discovered ; in 


them we find all the chief Intermediate members, which 
complete the connecting chain of ancestors from the oldest 
prosimiae to man. 

The most famous and most interesting of these dis- 
coveries is the fossil ape-man of Java, the much-talked-of 
pithecanihropui erectus, found by a Dutch military doctor, 
Eugen Dubois, in 1894. It is in truth the much-sought 
" missing link," supposed to be wanting in the chain of 
primates, which stretches unbroken from the lowest 
catarrhinae to the highest-developed man. I have dealt 
exhaustively with the significance of this discovery in the 
paper which I read on August 2Gth, 1898, at the Fourth 
International Zoological Congress at Cambridge. 1 The 
paleontologist, who knows the conditions of the forma- 
tion and preservation of fossils, will think the discovery 
of this pithecanthropus an unusually lucky accident, The 
apes, being arboreal, seldom came into the circumstance 
(unless they happened to fall into the water) which would 
secure the preservation and petrifaction of their skeleton. 
Thus, by the discovery of this fossil man-monkey of Java 
the descent of man from the ape has become just as clear 
and certain from the palnsontologieal side as it was pre- 
viously from the evidence of comparative anatomy and 
ontogeny. We now have all the principal documents 
which tell the history of our race. 

1 Vide the translation of Dr, Hans Gadow ; The Last Link. (A, 
andC. Black.) 



Fundamental importance of psychology. Its definition and methods. 
Divergence of views thereon. Dualistio and monistic psychology. 
Relation to the law of substance. Confusion of ideas. Psycho- 
logical metamorphoses : Kant, Virchow, Du Boia-Reymond. 
Methods of research of psychic science. Introspective method (self- 
observation), Exact method (psycho-physics). Comparative 
method (animal psychology ). Psychological change of principles : 
Wundt, Folk-psychology and ethnography: Baatian, Onto- 
' genetic psychology : Prayer. Phylogenetic psychology : Darwin, 

THE phenomena which are comprised under the title of 
the "life of the soul," or the psychic activity, are on the 
one hand the most important and interesting, on the 
other the most intricate and problematical, of all the 
phenomena we are acquainted with. As the knowledge of 
nature, the object of the present philosophic study, is 
itself a part of the life of the soul, and as anthropology, 
and even cosmology, presuppose a correct knowledge of 
the 4< psyche," we may regard psychology, the scientific 
study of the soul, both as the foundation and the postulate 
of all other sciences. From another point of view it is 
itself a part of philosophy, or of physiology, or of 

The great difficulty of establishing it on a naturalistic 
basis arises from the fact that psychology, in turn, pre- 
supposes a correct acquaintance with the human organism, 
especially the brain, the chief organ of psychic activity. 
The great majority of " psychologists " have little or no 
acquaintance with these anatomical foundations of the 
soul, and thus it happens that in no other science do we 
find such contradictions and untenable notions as to its 



proper meaning and its essential object as are current in 
psychology. This confusion has become more and more 
palpable during the last thirty years, in proportion as the 
immense progress of anatomy and physiology has in- 
creased our knowledge of the structure and the function! 
of the chief psychic organ. 

What we call the soul is, in my opinion, a natural phe- 
nomenon; 1 therefore consider psychology to be a branch 
of natural science a section of physiology. Conse- 
quently, I must emphatically assert from the commence- 
ment that we have no different methods of research for 
that science than for any of the others; we have in the 
first place observation and experiment, in the second place 
the theory of evolution, and in the third place meta- 
physical speculation, which seek to penetrate as far aa 
possible into the cryptic nature of the phenomena by 
inductive and deductive reasoning. However, with a 
view to a thorough appreciation of the question, we must 
first of all put clearly before the reader the antithesis of 
the dualistic and the monistic theories. 

The prevailing conception of the psychic activity, which 
we contest, considers soul and body to be two distinct 
entities. These two entities can exist independently of 
each other; there is no intrinsic necessity for their union. 
The organised body is a mortal, material nature, chemically 
composed of living protoplasm and its compounds (plasma- 
products). The soul, on the other hand, is an immortal, 
immaterial being, a spiritual agent, whose mysterious 
activity is entirely incomprehensible to us. This trivial 
conception is, by its very terms, spiritualistic, and its con- 
tradictory is, in a certain sense, materialistic. It is, at 
the same time, supernatural and transcendental, since it 
affirms the existence of forces which can exist and operate 
without a material basis; it rests on the assumption that 
outside of and beyond nature there is a "spiritual," 
immaterial world, of which we have no experience, and of 
which we can learn nothing by natural means. 

This hypothetical " spirit world, " which is supposed to be 
entirely independent of the material universe, and on the 
assumption of which the whole artificial structure of the 


dualistic system is based, is purely a product of poetic 
imagination ; the same must be said of the parallel belief 
in the " immortality of the soul," the scientific impossi- 
bility of which we must prove more fully later on (chap. 
ii.). If the beliefs which prevail in these credulous 
circles had a sound foundation, the phenomena they relate 
to could not be subject to the "law of substance"; 
moreover, this single exception to the highest law of the 
cosmos must have appeared very late in the history of 
the organic world, since it only concerns the " soul " of 
man and of the higher animals. The dogma of "free 
will," another essential element of the dualistic psycho- 
logy, is similarly irreconcilable with the universal law of 

Our own naturalistic conception of the psychic activity 
teea in it a group of vital phenomena which are dependent 
on a definite material substratum, like ail other pheno- 
mena. We shall give to this material basis of all psychic 
activity, without which it is inconceivable, the provisional 
name of "psychoplasm "; and for tins good reason that 
chemical analysis proves it to be a body of the group 
we call protoplasmic bodies, the albuminoid carbon-com- 
binations which are at the root of all vital processes. In 
the higher animals, which have a nervous system and 
tense-organs, "ueuroplasm," the nerve-material, has been 
differentiated out of psychoplasm. Our conception is, in 
this sense, materialistic. It is at the same time empirical 
mid naturalistic, for our scientific experience has never yet 
taught us the existence of forces that can dispense with 
A material substratum, or of a spiritual world over and 
aliove the realm of nature. 

Like all other natural phenomena, the psychic processes 
re subject to the supreme, all-ruling law of substance; 
not even in this province is there a single exception to 
this highest cosmological law (compare chap. xii.). The 
phenomena of the lowly psychic life of the unicellular 
protist and the plant, and of the lowest animal forms 
their irritability, their reflex movements, their sensitive- 
ness and instinct of self-preservation are directly deter- 
mined by physiological action in the protoplasm of their 


cells that is, by physical and chemical changes which 
are partly due to heredity and partly to adaptation. And 
we must say just the same of the higher psychic activity 
of the higher animals and man, of the formation of ideas 
and concepts, of the marvellous phenomena of reason and 
consciousness; for the latter have been phylogenetically 
evolved from the former, and it is merely a higher degree 
of integration or centralisation, of association or combina- 
tion of functions which were formerly isolated, that has 
elevated them in this manner. 

The first task of every science is the clear definition of 
the object it has to investigate. In no science, however, 
is this preliminary task so difficult as in psychology ; and 
this circumstance is the more remarkable since logic, the 
science of defining, is itself a part of psychology. When 
we compare all that has been said by the most distin- 
guished philosophers and scientists of all ages on the 
fundamental idea of psychology, we find ourselves in a 
perfect chaos of contradictory notions. What, really, Is 
the "soul"? What is its relation to the "mind"? 
What is the inner meaning of "consciousness"? What 
Is the difference between "sensation " and "sentiment "? 
What is "instinct"? What is the meaning of "free 
will " ? What is " presentation " ? What is the difference 
between "intellect" and "reason"? What is the true 
nature of "emotion "? What is the relation between all 
these "psychic phenomena" and the "body"? The 
answers to these and many other cognate questions are 
infinitely varied ; not only are the views of the most 
eminent thinkers on these questions widely divergent, but 
even the same scientific authority has often completely 
changed his views in the course of his psychological de- 
velopment. Indeed, this "psychological metamorphosis " 
of so many thinkers has contributed not a little to the 
colossal confusion of idea* which prevails in psychology 
more than in any other branch of knowledge. 

The most interesting example of such an entire change 
of objective and subjective psychological opinions is found 
In the case of the most influential leader of German philo- 
sophy, Immanuel Kant. The young, severely critical 


Kant came to the conclusion that the three great buttresses 
of mysticism " God, freedom, and immortality " were 
untenable in the light of " pure reason " ; the older, 
dogmatic Kant found that these three great hallucinations 
were postulates of " practical reason," and were, as such, 
indispensable. The more the distinguished modern school 
of '* NeoKantians " urges a " return to Kant " as the 
only possible salvation from the frightful jumble of 
modern metaphysics, the more clearly do we perceive the 
undeniable and fatal contradiction between the funda- 
mental opinions of the young and the older Kant. We 
hail return to this point later on. 

Other interesting examples of this change of views are 
found in two of the most famous living scientists, R. 
Virchow and E. du Bois-Reymond; the metamorphoses 
of their fundamental views on psychology cannot be over- 
looked, as both these Berlin biologists have played, a most 
important part at Germany's greatest university for more 
than forty years, and have, therefore, directly and in- 
directly, had a most profound influence on the modern 
mind. Rudolph Virchow, the eminent founder of cellular 
pathology, was a pure monist in the best days of his 
scientific activity, about the middle of the century; he 
passed at that time as one of the most distinguished 
representatives of the newly-awakened materialitm, which 
appeared in 1855, especially through two famous works, 
almost contemporaneous in appearance Ludwig Buchner's 
Force and Matter and Carl Vogt's Superstition and 
Science. Virchow published his general biological views 
on the vital processes in man which he took to be purely 
mechanical natural phenomena in a series of distin- 
guished papers in the first volumes of the Archiv fUr 
patkologiscke Anatomic, which he founded. The most 
important of these articles, and the one in which he most 
clearly expresses his monistic views of that period, is that 
on "The Tendencies towards Unity in Scientific Medi- 
cine " (1849). It was certainly not without careful 
thought, and a conviction of its philosophic value, that 
Virchow put this "medical confession of faith" at the 
head of hia Collected Es$ay$ on Scientific Medicine in 


1850. He defended in it, clearly and definitely, the 
fundamental principles of monism, which I am presenting 
here with a view to the solution of the world-problem ; 
he vindicated the exclusive value of empirical science, of 
which the only reliable sources are sense and brain 
activity ; he vigorously attacked anthropological dualism, 
the alleged "revelation,** and the transcendental philo- 
sophy, with their two methods " faith and anthropo- 
morphism." Above all, he emphasised the monistic 
character 'of anthropology, the inseparable connection of 
spirit and body, of force and matter. **I am convinced," 
he exclaims, at the end of his preface, " that I shall never 
find myself compelled to deny the thesis of t/ie unity of 
human nature." Unhappily, this ''conviction " proved to 
be a grave error. Twenty-eight years afterwards Virchow 
represented the diametrically opposite view : it is to be 
found in the famous speech on "The Liberty of Science 
in Modern States," which he delivered at the Scientific 
Congress at Munich in 1877, and which contains attacks 
that I have repelled in my Free Science and Free Teach- 
ing (1878). 

In Emil du Bois-Reymond we find similar contradic- 
tions with regard to the most important and fundamental 
theses of philosophy. The more completely the distin- 
guished orator of the Berlin Academy had defended the 
main principles of the monistic philosophy, the more he 
had contributed to the refutation of vitalism and the 
transcendental view of life, so much the louder was the 
triumphant cry of our opponents when in 1872, in his 
famous Ignorabimus speech, he spoke of consciousness as 
an insoluble problem, and opposed _jtJtflULlie^other 
tions of the brain as a superjj ^ 

return to the point in the 

The peculiar character 
mena, especially of cons 
modifications of our ord/ 
have, for instance, to 
jVcti, external observa^ 
the $ubjectivt, internal 
own personality in the 


majority of psychologists have started from this "cer- 
tainty of the ego": " Coffito, ergo turn," as Descartes 
said "I think, therefore I am." Let us first cast a 
glance at tills way of inquiry, and then deal with the 
second, complementary method. 

By far the greater part of the theories of the soul which 
have been put forward during the last 2000 years or more 
are based on introspective inquiry that is, on "self- 
observation," and on the conclusions which we draw from 
the association and criticism of these subjective experi- 
ences. Introspection is the only possible method of in- 
quiry for an important section of psychology, especially 
for the study uf consciousness. Hence this cerebral 
function occupies a special position, and has been a more 
prolific source of philosophic error than any of the others 
(cf. chap. x.). Il is, however, most unsatisfactory, and 
it leads to entirely false or incomplete notions, to take 
this self -observation of the mind to be the chief, or 
especially to be the only, source of mental science, as has 
happened in the case of many and distinguished philo- 
sophers. A great number of the principal psychic pheno- 
mena, particularly the activity of the senses and speech, 
can only be studied in the same way as every other vital 
function of the organism that is, firstly by a thorough 
anatomical study of their organs, and secondly by an 
exact physiological analysis of the functions which depend 
on them. In order, however, to complete this external 
study of the mental life and to supplement the results of 
internal observation, one needs a thorough knowledge of 
human anatomy, histology, ontogeny, and physiology. 
Most of our so-called ** psychologists " have little or no 
knowledge of these indispensable foundations of anthro- 
pology ; they are, therefore, incompetent to pronounce on 
the character even of their own "soul." It must be 
remembered, too, that the distinguished personality of 
one of these psychologists usually offers a specimen of an 
educated mind of one of the highest civilised races ; it is 
the last link of a long ancestral chain, and the innumerable 
older and inferior links are indispensable for its proper 
understanding. Hence it is that most of the psycho- 


logical literature of the day is so much waste paper. The 
introspective method is certainly extremely valuable and 
indispensable ; still it needs the constant co-operation and 
assistance of the other methods. 

In proportion as the various branches of the human tree 
of knowledge have Developed during the century and the 
methods of the different sciences have been perfected, the 
desire has grown to make them exec* ; that is, to make 
the study of phenomena as purely empirical as possible, 
and to formulate the resultant laws as clearly as the cir- 
cumstances permit if possible, mathematically. The 
latter is, however, only feasible in a small province of 
human knowledge, especially in those sciences in which 
there is a question of measurable quantities ; in mathe- 
matics, in the first place, and to a greater or less extent 
in astronomy, mechanics, and a great part of physics 
and chemistry. Hence these studies are called "exact 
sciences " in the narrower sense. It is, however, pro- 
ductive only of error to call all the physical sciences exact, 
and oppose them to the historical, mental, and moral 
sciences. The greater part of physical science can no more 
be treated as an exact science than history can ; this is 
especially true of biology and of its subsidiary branch, 
psychology. As psychology is a part of physiology, it 
must, as a general rule, follow the chief methods of that 
science. It must establish the facts of psychic activity 
by empirical methods as much as possible, by observation 
and experiment, and it must then gather the laws of the 
mind by inductive and deductive inferences from its 
observations, and formulate them with the utmost dis- 
tinctness. But, for obvious reasons, it is rarely possible 
to formulate them mathematically. Such a procedure is 
only profitable in one section of the physiology of the 
senses ; it is not practicable in the greater part of cerebral 

One small section of physiology, which seems amenable 
to the "exact" method of investigation, has been care- 
fully studied for the last twenty years and raised to the 
position of a separate science under the title of p*t/cJio- 
phyiict. Its founders, the physiologists Theodor Fechner 


and Ernst Heinrich Weber, first of all closely investigated 
the dependence of sensations on the external stimuli that 
act on the organs of sense, and particularly the quantita- 
tive relation between the strength of the stimulus arid the 
intensity of the sensacion. They found that a certain 
minimum strength ot stimulus is requisite for the excite- 
ment of a sensation, and that a given stimulus must be 
varied to a definite amount before there is any perceptible 
change in the sensation. For the highest sensations (of 
sight, hearing, and pressure) the law holds good that 
their variations are proportionate to the changes in the 
strength of the stimulus From this empirical "law of 
Weber " Fechner inferred, by mathematical operations, 
his *' fundamental law of psycho-physics," according to 
which the intensity of a sensation increases in arithmetical 
progression, the strength of the stimulus in geometrical 
progression. However, Fechner's law and other psycho- 
physical laws are frequently contested, and their " exact- 
ness " is called into question. In any case modern psycho- 
physics has fallen far short of the great hopes with which 
it was greeted twenty years ago; the field of its applica- 
bility is extremely limited. One important result of its 
work is that it has proved the application of physical laws 
in one, if only a small, branch of the life of the "soul " 
an application which was long ago postulated on prin- 
ciple by the materialist psychology for the whole province 
of mental life. In this, as in many other branches of 
physiology, the " exact " method has proved inadequate 
and of little service. It is the ideal to aim at everywhere ; 
but it is unattainable In most cases. Much more profitable 
are the comparative and genetic methods. 

The striking resemblance of man's psychic activity to 
that of the higher animals especially our nearest rela- 
tives among the mammals is a familiar fact. Most 
uncivilised races still make no material distinction between, 
the two sets of mental processes, as is proved by the 
well-known animal fables, the old legends, and the idea 
of the transmigration of souls. Even most of the philo- 
sophers of classical antiquity shared the same conviction, 
and discovered no essential qualitative difference, but 


merely a quantitative one, between the soul of man and 
that of the brute. Plato himself, who was the first to 
draw a fundamental distinction between soul and body, 
made one and the same soul (or "idea ") pass through a 
number of animal and human bodies in his theory of 
metempsychosis. It was Christianity, intimately con- 
necting faith in immortality with faith in God, that 
emphasised the essential difference of the immortal soul 
of man from the mortal soul of the brute. In the du alls tic 
philosophy the idea prevailed principally through the in- 
fluence of Descartes (164S); he contended that man alone 
had a true "soul," and, consequently, sensation and free 
will, and that the animals were mere automata, or 
machines, without will or sensibility. Ever since the 
majority of psychologists including even Kant have 
entirely neglected the mental life of the brute, and re- 
stricted psychological research to man : human psycho- 
logy, mainly introspective, dispensed with the fruitful 
comparative method, and so remained at that lower point 
of view which human morphology took before Cuvier 
raised it to the position of a "philosophic science" by 
the foundation of comparative anatomy. 

Scientific interest in the psychic activity of the brute 
was revived in the second half of the last century, in 
connection with the advance of systematic zoology and 
physiology. A strong impulse was given to it by the 
work of Iteimarus : General Observations on the Instinctt 
of Animal* (Hamburg, 1760). At the same time a 
deeper scientific investigation hacf been facilitated by the 
thorough reform of physiology, by Johannes Miiller. 
This distinguished biologist, having a comprehensive 
knowledge of the whole field of organic nature, of 
morphology and of physiology, introduced the "exact 
methods " of observation and experiment into the whole 
province of physiology, and, with consummate skill, com- 
bined them with the comparative methods. He applied 
them not only to mental life in the broader sense (to 
speech, senses, and brain-action), but to all the other 
phenomena of life. The sixth book of hia Manual of 
Human Phyiiology treats especially of the life of the 


soul, and contains eighty pages of important psychological 

During the last forty years a great number of works 
on comparative animal psychology have appeared, prin- 
cipally occasioned by the great impulse which Darwin gave 
in 1859 by his work on The Origin of Speciet, and by 
the application of the idea of evolution to the province of 
psychology. The more important of these works we owe 
to Romanes and Sir J. Lubbock in England, to W. 
Wundt, L. Buchner, G. Schneider, Fritz Schulze, and 
Karl Groos in Germany; to Alfred Espinas and E. Jour- 
dan in France; and to Tito Vignoli in Italy. 

In Germany, Wilheliu Wundt of Leipzig is considered 
to be the ablest living psychologist; he has the inestim- 
able advantage over most other philosophers of a thorough 
zoological, anatomical, and physiological education. 
Formerly assistant and pupil of Helmholtz, Wundt had 
early accustomed himself to follow the application of the 
laws of physics and chemistry through the whole field of 
physiology, and, consequently, in the sense of Johannes 
Miiller, in psychology, as a sub-section of the latter. 
Starting from this point of view, Wundt published his 
valuable " Lectures on human and animal psychology " in 
1863. He proved, as he himself tells us in the preface, 
that the theatre of the most important psychic processes 
is in the ** unconscious soul," and he affords us "a view 
of the mechanism which, in the unconscious background 
of the soul, manipulates the impressions which arise from 
the external stimuli." What seems to me, however, of 
special importance and value in Wundt's work is that 
he " extends the law of the persistence of force for the 
first time to the psychic world, and makes use of a 
series of facts of electro-physiology by way of demonstra- 

Thirty years afterwards (1892) Wundt published a 
second, much abridged, and entirely modified edition of 
his work. The important principles of the first edition 
re entirely abandoned in the second, and the monistic is 
exchanged for a purely dualistic standpoint. Wundt him- 
self says in the preface to the second edition that he has 


emancipated himself from tiie fundamental errors of the 
first, and that he ** learned many years ago to consider 
the work a sin ,of his youth " ; it " weighed on him as a 
kind of crime, from which he longed to free himself as 
soon as possible." In fact, the most important systems 
of psychology are completely opposed to each other in 
the two editions of Wundt's famous Observation*. In 
the first edition he is purely monistic and materialistic, in 
the second edition purely dualistic and spirit u ah' stic. In 
the one psychology is treated as a physical science, on the 
same laws as the whole of physiology, of which it is only 
a part; thirty years afterwards he finds psychology to be 
a spiritual science, with principles and objects entirely 
different from those of physical science. This conversion 
is most clearly expressed in his principle of psycho- 
physical parallelism, according to which " every psychic 
event has a corresponding physical change " ; but the two 
are completely independent, and are not in any natural 
causal connection. This complete dualism of body and 
soul, of nature and mind, naturally gave the liveliest 
satisfaction to the prevailing school-philosophy, and was 
acclaimed by it as an important advance, especially seeing 
that it came from *a distinguished scientist who had pre- 
viously adhered to the opposite system of monism. As I 
myself continue, after more than forty years' study, in 
this "narrow " position, and have not been able to free 
myself from it in spite of all my efforts, I must naturally 
consider the " youthful sin" of the young physiologist 
Wundt to be a correct knowledge of nature, and energetic- 
ally defend it against the antagonistic view of the old 
philosopher Wundt. 

This entire change of philosophical principles, which 
we find in Wundt, as we found t in Kant, Virchow, Du 
Bois-Reymond, Carl Ernst Baer, and others, is very inter- 
esting. In their youth these able and talented scientists 
embrace the whole field of biological research in a broad 
survey, and make strenuous efforts to find a unifying 
natural basis for their knowledge; in their later years 
they have found that this is not completely attainable, and 
so they entirely abandon the idea. In extenuation of 


these psychological metamorphoses they can, naturally, 
plead that in their youth they overlooked the difficulties 
of the great task, and misconceived the true goal ; with 
the maturer judgment of age and the accumulation of 
experience they were convinced of their errcyrs, and dis- 
covered the true path to the source of truth. On the 
other hand, it is possible to think that great scientists 
approach their task with less prejudice and more energy 
in their earlier years that their vision is clearer and 
their judgment purer ; the experiences of later years 
tfomethues have the effect, not of enriching, but of dis- 
turbing, tlie mind, and with old age there comes a 
gradual decay of the brain, just as happens in all other 
organs. In any case, this change of views is in itself an 
instructive psychological fact; because, like many other 
forms of change of opinion, it shows that the highest 
psychic functions are subject to profound individual 
changes in the course of life, like all the other vital 

For the profitable construction of comparative psycho- 
logy it is extremely important not to confine the critical 
comparison to man and the brute in general, but to put 
side by side the innumerable gradations of their mental 
activity. Only thus can we attain a clear knowledge of 
the long scale of psychic development which runs un- 
broken from the lowest, unicellular forms of life up to the 
mammals, and to man at their head. But even within the 
limits of our own race such gradations are very noticeable, 
and the ramifications of the ''psychic ancestral tree " are 
very numerous. The psychic difference between the 
crudest savage of the lowest grade and the most perfect 
specimen of the highest civilisation is colossal much 
greater than is commonly supposed. By the due apprecia- 
tion of this fact, especially in the latter half of the cen- 
tury, the "anthropology of the uncivilised races" has 
received a strong support, and comparative ethnography 
has come to be considered extremely important for psycho- 
logical purposes. Unfortunately, the enormous quantity 
of raw material of this science has not yet br.n treated in 
& satisfactory critical manner. What confused and mystic 


ideas still prevail in this department may be seen, for 
instance, in the Volkergedanke of the famous traveller, 
Adolf Bastian, who, though a prolific writer, merely turns 
out a hopeless mass of uncritical compilation and confused 

The most neglected of all psychological methods, even 
up to the present day, is the evolution of the soul; yet 
this little-frequented path is precisely the one that leads 
us most quickly *nd securely through the gloomy primeval 
forest of psychological prejudices, dogmas, and errors, U> 
a clear insight into many of the chief psychic problems. 
As I did in the other branch of organic evolution, I again 
put before the reader the two great branches of the science 
which I differentiated in 1SG6 ontogeny and phylogeny. 
The ontogeny, or embryonic development of the soul, in- 
dividual or biontic psychogeny, investigates tlie gradual 
and hierarchic development of the soul iu the individual, 
and seeks to learn the laws by which it is controlled. For 
a great part of the life of iiie mind a good deal has been 
done in this direction for centuries ; rational pedagogy 
must have at an early date set itself the task of the theo- 
retical study of gradual development arid formative 
capacity of the young mind that was committed to it for 
education and formation. Most pedagogues, however, 
were idealistic or dualistic philosophers, arid so they went 
to work with ail the prejudices of the spiritualistic psycho- 
logy. It is only in the last few decades that this dog- 
matic tendency has been largely superseded even in the 
school by scientific methods; we now find a greater con 
cern to apply the chief laws of evolution even in the 
discussion of the soul of the child. The raw material of 
the child's soul is already qualitatively determined by 
heredity from parents and ancestors; education has the 
noble task of bringing it to a perfect maturity by intellec- 
tual instruction and moral training that is, by adaptation. 
Wilhelm Preyer was the first to lay the foundation of our 
knowledge of the early psychic development in his in- 
teresting work on The Mind of the Child. Much is still 
to be done in the study of the later stages and metamor- 
phoses of the individual soul, and once more the correct, 


critical application of the biogenetic law is proving a 
guiding star to the scientific mind. 

A new and fertile epoch of higher development dawned 
for psychology and all other biological sciences when 
Charles Darwin applied the principles of evolution to them 
forty years ago. The seventh chapter of his epoch-making 
work on The Origin of Spect'ei is devoted to instinct. It 
contains the valuable proof that the instincts of animals 
are subject, like ail other vital processes, to the general 
laws of historic development. The special instincts of 
particular species were formed by acfa;>(atto?i, and the 
modifications thus acquired were handed on to posterity 
by heredity ; in their formation and preservation natural 
selection plays the same part as in the transformation of 
every other physiological function. Darwin afterwards 
developed this fundamental thought in a number of works, 
showing that the same laws of "mental evolution " hold 
good throughout the entire organic world, not less in man 
than in the brute, and even in the plant. Hence the 
unity of the organic world, which is revealed by the com- 
mon origin of its members, applies also to the entire 
province of psychic life, from the simplest unicellular 
organism up to man. 

To George Romanes \vp owe the further development of 
Darwin's psychology and its special application to the 
different sections of psychic activity. The-two volumes of 
his work on evolutionary psychology which were com- 
pleted are among the most valuable productions of psycho- 
logical literature. For, conformably to the principles of 
our modern monistic research, his first care was to collect 
and arrange all the important facts which have been 
empirically established in the field of comparative psycho- 
logy in the course of centuries ; in the second place, these 
facts are tested with an objective criticism, and systematic- 
ally distributed ; finally, such rational conclusions are 
drawn from them on the chief general questions of 
psychology as are in harmony with the fundamental prin- 
ciples of modern monism. The first volume of Romanes's 
work bears the title of Mental Evolution in the Animal 
World; it presents, in natural connection, the entire 


length of the chain of psychic evolution in the animal 
world, from the simplest sensations and instincts of the 
lowest animals to the elaborate phenomena of conscious- 
ness and reason in the highest. It contains also a num- 
ber of extracts from a manuscript which Darwin left " on 
instinct," and a complete collection of all that he wrote 
in the province of psychology. 

The second and more important volume of Romanes's 
work treats of " Mental evolution in man and the origin 
of human faculties." The distinguished psychologist 
gives a convincing proof in it " that the psychological 
barrier between man and the brute has been overcome." 
Man's power of conceptual thought and of abstraction has 
been gradually evolved from the non-conceptual stages of 
thought and ideation in the nearest related mammals. 
Man's highest mental powers reason, speech, and con- 
science have arisen from the lower stages of the same 
faculties in our primate ancestors (the simiae and pro- 
Simla;). Man has no single mental faculty which is his 
exclusive prerogative. His whole psychic life differs from 
that of the nearest related mammals only in degree, and 
not in kind ; quantitatively, not qualitatively. 

I recommend those of my readers who are interested in 
these momentous questions of psychology to study the 
profound work of Romanes. I am completely at one with 
him and Darwin in almost all their views and convictions. 
Wherever an apparent discrepancy is found between these 
authors and my earlier productions, it is either a case of 
imperfect expression on my part or an unimportant differ- 
ence in application of principle. For the rest, it if 
characteristic of this "science of ideas" that the most 
eminent philosophers hold entirely antagonistic views on 
its fundamental notions. 



Psychological unity of organic nature. Material basis of the soul : 
psycnoplasm. Scale of sensation. Scale of movement. Scale of 
redei action. Simple and compound reflex action. Reflex action 
and consciousness, fccale of perception. Unconscious and con- 
scious perception. Scale of memory , Unconscious and conscious 
memory. Association of perceptions, Instinct. Primary and 
secondary instincts. Scale of reason. Language. Emotion and 
passion. The will. Freedom of the will. 

THK great progress which psychology has made, with the 
assistance of evolution, in the latter half of the century 
culminates in the recognition of the psychological unity of 
the organic world. Comparative psychology, in co-opera- 
tion with the ontogeny and phylogeny of the psyche, has 
enforced the conviction that organic life in all its stages, 
from the simplest unicellular protozoon up to man, springs 
from the same elementary forces of nature, from the 
physiological functions of sensation and movement. The 
future task of scientific psychology, therefore, is not, as 
it once was, the exclusively subjective and introspective 
analysis of the highly-developed mind of a philosopher, 
but the objective, comparative study of the long gradation 
by which man has slowly arisen through a vast series of 
lower animal conditions. This great task of separating 
the different steps in the psychological ladder, and proving 
their unbroken phylogenetic connection, has only been 
seriously attempted during the last ten years, especially 
in the splendid work of Romanes. We must confine our- 
selves here to a brief discussion of a few of the genera) 
questions which that gradation has suggested. 

All the phenomena of the psychic life are, without 
exception, bound up with certain material changes in tl 
living substance of the body, the protoplasm. We have 



given to that part of the protoplasm which seems to be 
the indispensable substratum of psychic life the name of 
ptychoplasm (the "soul-substance," in the monistic sense); 
in other words, we do not attribute any peculiar " essence " 
to it, but we consider the psyche to be merely a collective 
idea of all the psychic function* of protoplasm. In this 
sense the "soul" is merely a physiological abstraction 
like "assimilation" or "generation." In man and the 
higher animals, in accordance with the division of labour 
of the organs and tissues, the psychoplasm is a differen- 
tiated part of the nervous system, the neuroplasm of the 
ganglionic cells and their fibres. In the lower animals, 
however, which have no special nerves and organs of 
sense, and in the plants, the psychoplasm has not yet 
reached an independent differentiation. Finally, in the 
unicellular protists, the psychoplasm is identified either 
with the whole of the living protoplasm of the simple cell 
or with a portion of it. In all cases, in the lowest as well 
as the highest stages of the psychological hierarchy, a cer- 
tain chemical composition and a certain physical activity 
of the psychoplasm are indispensable before the "soul" 
can function or act. That is equally true of the elemen- 
tary psychic function of the plasmatic sensation and move- 
ment of the protozoa, and of the complex functions of the 
sense-organs and the brain in the higher animals and man. 
The activity of the psychoplasm, which we call the 
"soul," is always connected with metabolism. 

All living organisms, without exception, are sensitive ; 
they are influenced by the condition of their environment, 
and react thereon by certain modifications in their own 
structure. Light and heat, gravity and electricity, me- 
chanical processes and chemical action in the environment, 
act as stimuli on the sensitive psychoplasm, and effect 
changes in its molecular composition. We may distin- 
guish the following five chief stages of this sensibility : 

I. At the lowest stage of organisation the whole 
ptychoplasm, as such, is sensitive, and reacts on the 
stimuli from without ; that is the case with the lowest 
protists, with many plants, and with some of the most 
rudimentary animals. 


II. At the second stage very simple and undiscriminat- 
ing sense-organs begin to appear on the surface of the 
organism, in the form of protoplasmic filaments and pig- 
ment spots, the forerunners of the nerves of touch and the 
eyes ; these are found in some of the higher protists, and 
in many of the lower animals and plants. 

III. At the third stage specific organs of sense, each 
with a peculiar adaptation, have arisen by differentiation 
out of these rudimentary processes : there are the chemical 
instruments of smell and taste, and the physical organs 
of touch, temperature, hearing, and sight. The "specific 
energy " of these sense-organs is not an original inherent 
property, but has been gained by functional adaptation 
and progressive heredity. 

IV. : The fourth stage is characterised by the central- 
isation or integration of the nervous system, and, conse- 
quently, of sensation ; by the association of the previously 
Isolated or localised sensations presentations arise, though 
they still remain unconscious. That is the condition of 
many both of the lower and the higher animals. 

V. Finally, at the fifth stage, the highest psychic 
function, conscious perception, is developed by the mirror- 
ing of the sensations in a central part of the nervous 
ystera, as we find in man and the higher vertebrates, and 
probably in some of the higher invertebrates, notably the 

All living organisms without exception have the faculty 
of spontaneous movement, in contradistinction to the 
rigidity and inertia of unorganised substances (e. #., 
crystals) ; in other words, certain changes of place of the 
particles occur in the living psychoplasm from internal 
causes, which have their source in its own chemical com- 
position. These active vital movements are partly dis- 
covered by direct observation and partly only known in- 
directly, by inference from their effects. We may distin- 
guish five stages of them. 

I. At the lowest stage of organic life, in the chro- 
macea, and many protophyta and lower metaphyta, we 
perceive only those movements of growth which are com- 
mon to all organisms. They are usually go glow that they 


cannot be directly observed ; they have to be inferred 
from their results from the change in size and form of 
the growing organism. 

! II. Many protists, particularly unicellular algae of the 
groups of diatomacea and desmidiacea, accomplish a kind 
of creeping or swimming motion by excretion, or by 
ejecting a slimy substance at one side. 

III. Other organisms which float in water for in- 
stance, many of the radiolaria, siphonophora, ktenophora, 
and others ascend and descend by altering their specific 
gravity, sometimes by osmosis, sometimes by the separa- 
tion or squeezing-out of air. 

IV. Many plants, especially the sensitive plant! 
(mimosa) and other papilionacea, effect movements of their 
leaves or other organs by change of pressure that is, they 
alter the strain of the protoplasm, and, consequently, its 
pressure on the enclosing elastic walls of the cells. 

V. The most important of all organic movements are 
the phenomena of contraction t. e. t changes of form at 
the surface of the organism, which are dependent on a 
twofold displacement of their elements; they always in- 
volve two different conditions or phases of motion con- 
traction and expansion. Four different forms of this 
plasmatic contraction may be enumerated : 

(o) Amoeboid movement (in rhizopods, blood-cells, pig- 
ment-cells, etc.). 

(6) A similar flow of protoplasm within enclosed cells. 

(c) Vibratory motion (ciliary movements) in infusoria, 
spermatozoa, ciliated epithelial cells. 

(d) Muscular movement (in most animals). 

The elementary psychic activity that arises from the 
combination of sensation and movement is called reflex (in 
the widest sense), reflective function, or reflex action. 
The movement no matter what kind it is seems in this 
case to be the immediate result of the stimulus which 
evoked the sensation ; it has, on that account, been called 
stimulated motion in its simplest form (in the protists). 
All living protoplasm has this feature of irritability. Any 
physical or chemical change in the environment may, in 
certain circumstances, act as a stimulus on the psycho- 


plasm, and elicit or "release " a movement. We shall see 
later on how this important physical concept of "releas- 
ing " directly connects the simplest organic reflex actions 
with similar mechanical phenomena of movement in the 
inorganic world (for instance, in the explosion of powder 
by a spark, or of dynamite by a blow). We may distin- 
guish the following seven stages in the scale of reflex 
action : 

I. At the lowest stage of organisation, in the lowest 
protists, the stimuli of the outer world (heat, light, elec- 
tricity, etc.) cause in the indifferent protoplasm only those 
indispensable movements of growth and nutrition which 
are common to all organisms, and are absolutely necessary 
for their preservation. That is also the case in most of 
the plants. 

II. In the case of many freely-moving protists (espe- 
cially the amoeba, the heliozoon, and the rhizopod) the 
stimuli from without produce on every spot of the un- 
protected surface of the unicellular organism external 
movements which take the form of changes of shape, and 
sometimes changes of place (amoeboid movement, pseudo- 
pod formation, the extension and withdrawal of what look 
like feet) ; these indefinite, variable processes of the pro- 
toplasm are not yet permanent organs. In the same way, 
general organic irritability takes the form of indetermi- 
nate reflex action in the sensitive plants and the lowest 
oietazoa ; in many multicellular organisms the stimuli may 
be conducted from one cell to another, as all the cells are 
connected by fine fibres. 

III. Many protists, especially the more highly -deve- 
loped protozoa, produce on their unicellular body two Little 
organs of the simplest character an organ of touch and 
an organ of movement. Both these instruments are direct 
external projections of protoplasm ; the stimulus, which 
alights on the first, is immediately conducted to the other 
by the psychoplasm of the unicellular body, and causes it 
to contract. This phenomenon is particularly easy to 
observe, and even produce experimentally, in many of the 
tationary infusoria (for instance, the poteriodendron 
among the flagellate, and the rorticella among the ciliata). 


The faintest stimulus that touches the extremely sensitive 
hairs, or cilia, at the free end of the cells, immediately 
causes a contraction of a thread-like stalk at the other, 
fixed end. This phenomenon is known as a " simple reflex 

IV. These phenomena of the unicellular organism of 
the infusoria lead on to the interesting mechanism of the 
neuro-muscular cells, which we find in the multicellular 
body of many of the lower metazoa, especially in the 
cnidaria (polyps and corals). Each single neuro-muscular 
cell is a u unicellular reflex organ "; it has on its surface 
a sensitive spot, and a motor muscular fibre inside at the 
opposite end ; the latter contracts as soon as the former 
is stimulated. 

V. In other cnidaria, notably in the free swimming 
medusae which are closely related to the stationary 
polyps the simple neuro-muscular cell becomes two 
different cells, connected by a filament : an external sense- 
cell (in the outer skin) and an internal muscular cell 
(under the skin). In this bicelltilar reflex organ the one 
cell ts the rudimentary organ of sensation, the other of 
movement; the connecting bridge of the psychoplasmic 
filament conducts the stimulus from one to the other. 

VI. The most important step in the gradual con- 
struction of the reflex mechanism is the division into 
three cells : in the place of the simple connecting bridge 
we spoke of there appears a third independent cell, the 
soul-cell , or gangl ionic cell ; with it appears also a new 
psychic function, unconscious presentation, which lias its 
seat in this cell. The stimulus is first conducted from 
the sensitive cell to this intermediate presentative or 
psychic cell, and then issued from this to the motor 
muscular cell as a mandate of movement. These tri- 
cellular reflex organs are preponderantly developed in the 
great majority of the invertebrates. 

VII. Instead of this arrangement we find in most of 
the vertebrates a quadricellular reflex organ, two distinct 
"soul-cells," instead of one, being inserted between the 
sensitive cell and the motor cell. The external stimulus, 
In this case, Is first conducted centripetally to the sen si- 


tive ceil (the sensible psychic cell), from this to the 
will-cell (the motor psychic cell), and from this, finally, 
to the contractile muscular cell. When many such reflex 
organs combine and new psychic cells are interposed we 
have the intricate reflex mechanism of man and the higher 

The important distinction which we make, in mor- 
phology and physiology, between unicellular and multi- 
cellular organisms holds good for their elementary psychic 
activity, reflex action. In the unicellular protists (both 
the plasmodomous primitive plants, or protophyta, and 
the plasmophagous primitive animals, or protozoa) the 
whole physical process of reflex action takes place in the 
protoplasm of one single cell; their "cell-soul " seems to 
be a unifying function of the psychoplasrn of which the 
various phases only begin to be seen separately when the 
differentiation of special organs sets in. 

The second stage of psychic activity, compound reflex 
action, begins with the cenobitic protists (e. g. the volvox 
and the carchesium). The innumerable social cells which 
make up this cell-community or coenobiuin are always 
more or less connected, often directly connected by fila- 
mentous bridges of protoplasm. A stimulus that alights 
on one or more cells of the community is communicated 
to the rest by means of the connecting fibres, and may 
produce a general contraction. This connection is found, 
also, in the tissues of the multicellular animals and plants. 
It was erroneously believed at one time that the cells of 
vegetal tissue were completely isolated from each other, 
but we have now discovered fine filaments of protoplasm 
throughout, which penetrate the thick membranes of the 
cells, and maintain a material and psychological com- 
munication between their living plasmic contents. That 
is the explanation of the mimosa : when the tread of the 
passer-by shakes the root of the plant, the stimulus is 
immediately conveyed to all the cells, and causes a 
general contraction of its tender leaves and a drooping of 
the stems. 

An important and universal feature of all reflex pheno- 
mena is thft absence of consciousness. For reasons which 


we shall give in the tenth chapter we only admit the 
presence of consciousness in man and the higher animals, 
not in plants, the lower animals, and the protists ; con- 
sequently all stimulated movements in the latter must be 
regarded as reflex that is, all movements which are not 
spontaneous, not the outcome of internal causes (impul- 
sive and automatic movements). 1 It is different with the 
higher animals, which have developed a centralised ner- 
vous system and elaborate sense-organs. In these cases 
consciousness has been gradually evolved from the psychic 
reflex activity, and now conscious, voluntary action 
appears, in opposition to the still continuing reflex action 
below. However, we must distinguish two different pro- 
cesses, as we did in the question of instinct primary and 
secondary reflex action. Primary reflex actions are those 
which have never reached the stage of consciousness in 
phyletic development, and thus preserve the primitive 
character (by heredity from lower animal forms). Second- 
ary reflex actions are those which were conscious, volun- 
tary actions in our ancestors, but which afterwards became 
unconscious from habit or the lapse of consciousness. It 
is impossible to draw a hard-and-fast line in such cases 
between conscious arid unconscious psychic function. 

Older psychologists (Herbart, for instance) considered 
*' presentation " to be the fundamental psychic pheno- 
menon, from which all the others are derived. Modern 
comparative psychology endorses this view in so far as it 
relates to the idea of unconscious presentation ; but it 
considers conscious presentation to be a secondary pheno- 
menon of mental life, entirely wanting in plants and the 
lower animals, and only developed in the higher animals. 
Among the many contradictory definitions which psycho- 
logists have given of "presentation," we think the best 
is that which makes it consist in an internal picture of the 
external object which IB given us in sensation an " idea " 
in the broader sense. We may distinguish the following 
four stages in the rising scale of presentative function : 

I. Cellular presentation. At the lowest stages we find 

1 Of. Max Yerworn, Ptychophysiologisch* ProtisUn-Studitn, pp. 
185, 140. 


presentation to be a general physiological property of 
psychoplasm ; even in the simplest unicellular protist sen- 
sations may leave a permanent trace in the psychoplasm, 
and these may be reproduced by memory. In more than 
four thousand kinds of radiolaria, which I have described, 
every single species is distinguished by a special, here- 
ditary skeleton structure. The construction of this 
specific, and often highly elaborate, skeleton by a cell of 
the simplest description (generally globular) is only in- 
telligible when we attribute the faculty of presentation, 
and, indeed, of a special reproduction of the plastic "feel- 
ing of distance," to the constructive protoplasm as I 
have pointed out in my Psychology of the Radiolaria. 1 

II. Histionic presentation. In the coenobia or cell- 
colonies of the social protists, and still better in the 
tissues fin the Greek, technical term, his ta ; hence the 
name his Atonic] of plants and lower, nerveless animals 
(sponges, polyps, etc.), we find the second stage of uncon- 
scious presentation which consists of the common psychic 
activity of a number of closely connected cells. If a 
single stimulus may, instead of simply spending itself in 
the reflex movement of aa organ (the leaf of a plant, for 
instance, or the arm of a polyp), leave a permanent im- 
pression, which can be spontaneously reproduced later on, 
we are bound to assume, in explaining the phenomenon, a 
hist ionic presentation, dependent on the psychoplasm of 
the associated tissue-cells. 

III. Unconscious presentation in the ganglionic cells. 
This third and higher stage of presentation is the common- 
est form the function takes in the animal world ; it seems 
to be a localisation of presentation in definite "soul-cells." 
In its simplest form it appears at the sixth stage of 
reflex action, when the tricellular reflex organ arises : the 
eat of presentation is then the intermediate psychic cell, 
which is interposed between the sensitive cell and the 
muscular cell. With the increasing development of the 
animal nervous system and its progressive differentiation 
and integration, this unconscious presentation also rises 
to higher stages. 

1 . Haeckel, General Natural History of the Radiolaria ; 1887. 


IV. Conscious presentation in the cerebral cell*. With 
the highest stage of development of the animal organisa- 
tion consciousness arises, as a special function of a certain 
central organ of the nervous system. As the presentations 
are conscious, and as special parts of the brain arise for 
the association of these conscious presentations, the organ- 
ism is qualified for those highest psychic functions which 
we call thought and reflection, intellect and reason. 
Although the tracing of the phyletic barrier between the 
older, unconscious and the younger, conscious presentation 
is extremely difficult, we can affirm, with some degree of 
probability, that the evolution of the latter from the 
former was polyphyletic [that is to say, took place along 
a number of independent lines] ; because we find conscious 
and rational thought, not only in the highest forms of 
the vertebrate stem (man, mammals, birds, and a part 
of the lower vertebrates), but also in the most highly 
developed representatives of other animal groups (ants 
and other insects, spiders and the higher crabs among the 
articulata, cephalopods among the mollusca). 

The evolutionary scale of memory is closely connected 
with that of presentation ; this extremely important 
function of the psychoplasm the condition of all further 
psychic development consists essentially in the repro- 
duction of presentations. The impressions in the bio- 
plasm which the stimulus produced as sensations, and 
which became presentations in remaining, are revived by 
memory; they pass from potentiality to actuality. The 
latent potential energy of the psychoplasm is trans- 
formed into kinetic, energy. We may distinguish four 
stages in the upward development of memory, corre- 
sponding to the four stages of presentation. 

I. Cellular memory. Thirty years ago Ewald Hering, 
in a thoughtful work, showed "memory to be a general 
property of organised matter," and indicated the great 
significance of this function, "to which we owe almost 
all that we are and have." Six years later, in my work 
on The Perigenesis of the Plastidule, or the Undulatory 
Origin of the Parts of Life, I developed these ideas, and 
endeavoured to base them on the principles of evolution. 


I have attempted to show in that work that unconscious 
memory is a universal and very important function of ail 
plastidules ; that is, of those hypothetical molecules, or 
groups of molecules, which Naegeli has called Micellue, 
others bioplasts, and so forth. Only living plastidules, as 
individual molecules of the active protoplasm, are reproduc- 
tive, and so gifted with memory ; that is the chief difference 
between the organic and inorganic worlds. It might be 
stated thus: " Heredity is the memory of the plastidule, 
while variability is its comprehension. " The elementary 
memory of the unicellular protist is made up of the 
molecular memory of the plastidules or micellx, of which 
its living cell-body is constructed. As regards the extra- 
ordinary performances of unconscious memory in these 
unicellular protists, nothing could be more instructive 
than the infinitely varied and regular formation of their 
defensive apparatus, their shells and skeletons ; in par- 
ticular, the diatomes and cosmaria among the protophytes, 
and the radiolaria and thalamophora among the protozoa, 
afford an abundance of most interesting illustrations. In 
many thousand species of these protists the specific form 
which is inherited is relatively constant, and proves the 
fidelity of their unconscious cellular memory. 

II. Histionic memory. Equally interesting examples 
of the second stage of memory, the unconscious memory 
of tissues, are found in the heredity of the individual 
organs of plants and the lower, nerveless animals (sponges, 
etc.). This second stage seems to be a reproduction of 
the histionic presentations, that association of cellular 
presentations which sets in with the formation of co;nobia 
in the social protists. 

III. In the same way we must regard the third stage, 
the unconscious memory of those animals which have a 
nervous system, as a reproduction of the corresponding 
44 unconscious presentations" which are stored up in cer- 
tain ganglionic cells. In most of the lower animals all 
memory is unconscious. Moreover, even in man and the 
higher animals, to whom we must ascribe consciousness, 
the daily acts of unconscious memory are much more 
numerous and varied than those of the conscious faculty ; 


we shall easily convince ourselves of that if we make an 
impartial study of a thousand unconscious acts we per- 
form daily out of habit, and without thinking of them, 
in walking, speaking, writing, eating, and so forth. 

IV. Conscious memory, which is the work of certain 
brain-cells in man and the higher animals, is an " internal 
mirroring " of very late development, the highest out- 
come of the same psychic reproduction of presentations 
which were mere unconscious processes in the ganglionic 
cells of our lower animal ancestors. 

The concatenation of presentations usually called the 
"association of ideas" also runs through a long scale, 
from the lowest to the highest stages. This, too, is 
originally and predominantly unconscious ( t4 instinct ") ; 
only in the higher classes of animals does it gradually 
become conscious ("reason")- The psychic results of 
this "association of ideas " are extremely varied; still, a 
very long, unbroken line of gradual development connects 
the simplest unconscious association of the lowest protist 
with the elaborate conscious chain of ideas of the civilised 
man. The unity of consciousness in man is given as its 
highest outcome (Hume, Condillar). All higher mental 
activity becomes more perfect in proportion as the normal 
association extends to more numerous presentations, and 
in proportion to the order which is imposed on them by 
the ** criticism of pure reason." In dreams, where this 
criticism is absent, the association of the reproduced 
impressions often takes the wildest forms. Even in the 
work of the poetic imagination, which constructs new 
groups of images by varying the association of the impres- 
sions received, and in hallucinations, etc., they are often 
most unnaturally arranged, and seem to the prosaic ob- 
server to be perfectly irrational. This is especially true 
of supernatural "forms of belief," the apparitions of 
spiritism, and the fantastic notions of the transcendental 
dualist philosophy ; though it is precisely these abnormal 
associations of "faith" and of "revelation" that have 
often been deemed the greatest treasures of the human 
mind (cf. chap. xvi.). 

The antiquated psychology of the Middle Ages (which, 


however, still numbers many adherents) considered the 
mental life of man and that of the brute to be two entirely 
different phenomena; the one it attributed to "reason," 
the other to "instinct." In harmony with the traditional 
story of creation, it was assumed that each animal species 
had received a definite, unconscious psychic force from 
the Creator at its formation, and that this instinct of each 
species was just as unchangeable as its bodily structure. 
Lamarck proved the untenableness of this error in 1809 
by establishing the theory of descent, and Darwin com- 
pletely demolished it in 1859. With the aid of his theory 
of selection he proved the following important theses : 

1. The instincts of species show Individual differences, 
and are just as subject to modification under the law of 
adaptation as the morphological features of their bodily 

2. These modifications (generally arising from a change 
of habits) are partly transmitted to offspring by heredity, 
and thus accumulate and are accentuated in the course of 

8. Selection 9 both artificial and natural, singles out 
certain of these inherited modifications of the psychic 
activity ; it preserves the most useful and rejects the least 

4. The divergence of psychic character which thus 
arises leads, in the course of generations, to the formation 
of new instincts, just as the divergence of morphological 
character gives rise to new species. 

Darwin's theory of instinct is now accepted by most 
biologists ; Romanes has treated it so ably, and so greatly 
expanded it, in his distinguished work on Mental Evolu- 
tion in the Animal World, that I need merely refer to 
it here. I will only venture the brief statement that, in 
my opinion, there are instincts in all organisms in all 
the protists and plants as well as in all the animals and 
in man ; though in the latter they tend to disappear in 
proportion as reason makes progress at their expense. 

The two chief classes of instincts to be differentiated 
are the primary and the secondary. Primary instincts are 
the common lower impulses which are unconscious and 


inherent in the psychoplasm from the commencement of 
organic life; especially the impulses to self-preservation 
(by defence and maintenance) and to the preservation of 
the species (by generation and the care of the young). 
Both these fundamental instincts of organic life, hunger 
and love, sprang up originally in perfect unconsciousness, 
without any co-operation of the intellect or reason. It 
is otherwise with the secondary instincts. These were 
due originally to an intelligent adaptation, to rational 
thought and resolution, and to purposive conscious action. 
Gradually, however, they became so automatic that this 
"other nature" acted unconsciously, and, even through 
the action of heredity, seemed to be "innate" in sub- 
sequent generations. The consciousness and deliberation 
which originally accompanied these particular instincts of 
the higher animals and man have died away in the course 
of the life of the plastidules (as in "abridged heredity "). 
The unconscious purposive actions of the higher animals 
(for instance, their mechanical instincts) thus come to 
appear in the light of innate impulses. We have to 
explain in the same way the origin of the " a priori ideas " 
of man ; they were originally formed empirically by his 
predecessors. 1 

In the superficial psychological treatises which ignore 
the mental activity of animals and attribute to man only a 
"true soul," we find him credited also with the exclusive 
possession of reason and consciousness. This is another 
trivial error (still to be found in many a manual, never- 
theless) which the comparative psychology of the last 
forty years has entirely dissipated. The higher verte- 
brates (especially those mammals which are most nearly 
related to man) have just as good a title to "reason " as 
man himself, and within the limits of the animal world 
there is the same long chain of the gradual development 
of reason as in the case of humanity. The difference be- 
tween the reason of a Goethe, a Kant, a Lamarck, or a 
Darwin, and that of the lowest savage, a Veddah, an 
Akka, a native Australian, or a Patagonian, is much 
greater than the graduated difference between the reason 
1 ride The Natural History of Creation. 


of the latter and that of the most " rational " mammals, 
the anthropoid apes, or even the papiomorpha, the dog, 
or the elephant. This important thesis has been con- 
vincingly proved by the thoroughly critical comparative 
work of Romanes and others. We shall not, therefore, 
attempt to cover that ground here, nor to enlarge on the 
distinction between the reason and the intellect ; as to the 
meaning and limits of these concepts philosophic experts 
give the most contradictory definitions, as they do on so 
many other fundamental questions of psychology. In 
general it may be said that the process of the formation 
of concepts, which is common to both these cerebral 
functions, is confined to the narrower circle of concrete 
proximate associations in the intellect, but reaches out 
to the wider circle of abstract and more comprehensive 
groups of associations in the work of reason. In the long 
gradation which connects the reflex actions and the in- 
stincts of the lower animals with the reason of the highest, 
intellect precedes the latter. And there is the fact, of 
great importance to our whole psychological treatise, that 
even these highest of our mental faculties are just as 
much subject to the laws of heredity and adaptation as 
are their respective organs; Flechsig pointed out in 1894 
that the *' organs of thought," in man and the higher 
mammals, are those parts of the cortex of the brain which 
lie bet wen the four inner sense-centres (cf. chapters x. 
and xi.). 

The higher grade of development of ideas, of intellect 
and reason, which raises man so much above the brute, is 
intimately connected with the rise of language. Still, 
here also we have to recognise a long chain of evolution 
which stretches unbroken from the lowest to the highest 
stages. Speech is no more an exclusive prerogative of 
man than reason. In the wider sense, it is a common 
feature of all the higher gregarious animals, at least of 
all the articulata and the vertebrates, which live in com- 
munities or herds; they need it for the purpose of under- 
standing each other and communicating their impressions. 
This is effected either by touch, or by signs, or by sounds 
having a definite meaning. The song of the bird or of 


the anthropoid ape (hylobatet), the bark of the dog, the 
neigh of the horse, the chirp of the cricket, the cry of the 
cicada, are all specimens of animal speech. Only in man, 
however, has that articulate conceptual speech developed 
which has enabled his reason to attain such high achieve- 
ments. Comparative philology, one of the most interest- 
ing sciences that has arisen during the century, has shown 
that the numerous elaborate languages of the different 
nations have been slowly and gradually evolved from a 
few simple primitive tongues (Wilhelm Humboldt, Bopp, 
Schleicher, Steinthal, and others). August Schleicher of 
Jena, in particular, has proved that the historical develop- 
ment of language takes place under the same phylogenetic 
laws as the evolution of other physiological faculties and 
their organs. Romanes (1893) has expanded this proof, 
and amply demonstrated that human speech, also, differs 
from that of the brute only in degree of development, not 
in essence and kind. 

The important group of psychic activities which we 
embrace under the name of " emotion " plays a conspicuous 
part both in theoretical and practical psychology. From 
our point of view they have a peculiar importance, from 
the fact that we clearly see in them the direct connection 
of cerebral functions with other physiological functions 
(the beat of the heart, sense-action, muscular movement, 
etc.) ; they, therefore, prove the unnatural and untenable 
character of the philosophy which would essentially dis- 
sociate psychology from physiology. All the external 
expressions of emotional life which we find in man are 
also present in the higher animals (especially in the anthro- 
poid ape and the dog) ; however varied their development 
may be, they are all derived from the two elementary 
functions of the psyche, sensation and motion, and from 
their combination in reflex action 'and presentation. To 
the province of sensation, in a wide sense, we must 
attribute the feeling of like and dislike which determines 
the emotion ; while the corresponding desire and aversion 
(love and hatred), the effort to attain what is liked and 
avoid what is disliked, belong to the category of movr- 
ment. " Attraction " and " repulsion " seem to be the 


sources of will, that momentous element of the soul which 
determines the character of the individual. The passions, 
which play so important a part in the psychic life of man, 
are but intensifications of emotion. Romanes has recently 
shown that these also are common to man and the brute. 
Even at the lowest stage of organic life we find in all the 
protists those elementary feelings of like and dislike, re- 
vealing themselves in what are called their tropisms, in the 
striving after light or darkness, heat or cold, and in their 
different relations to positive and negative electricity. On 
the other hand, we find at the highest stage of psychic life, 
In civilised man, those finer shades of emotion, of delight 
and disgust, of love and hatred, which are the mainsprings 
of civilisation and the inexhaustible sources of poetry. 
Yet a connecting chain of all conceivable gradations unites 
the most primitive elements of feeling in the psychoplasm 
of the unicellular protist with the highest forms of passion 
that rule in the ganglionic cells of the cortex of the human 
brain. That the latter are absolutely amenable to physical 
laws was proved long ago by the great Spinoza in his 
famous Statics of Emotion. 

The notion of will has as many different meanings and 
definitions as most other psychological notions presenta- 
tion, soul, mind, and so forth. Sometimes will is taken 
in the widest sense as a cosmic attribute, as in the World 
at Will and Presentation of Schopenhauer; sometimes it 
is taken in its narrowest sense as an anthropological attri- 
bute, the exclusive prerogative of man as Descartes 
taught, for instance, who considered the brute to be a 
mere machine, without will or sensation. In the ordinary 
use of the term, wUl is derived from the phenomena of 
voluntary movement, and is thus regarded as a psychic 
attribute of most animals. But when we examine the 
will in the light of comparative physiology and evolution 
we find as we do in the case of sensation that it is a 
universal property of living psychoplasm. The automatic 
and the reflex movements which we observe everywhere, 
even in the unicellular protists, seem to be the outcome of 
inclinations which are inseparably connected with the very 
idea of life. Even in the plants and lowest animals these 


inclinations, or tr op isms, seem to be the joint outcome of 
the inclinations of all the combined individual cells. 

But when the " tricellular reflex organ " arises (page 
93), and a third independent cell the "psychic," or 
" ganglionic, " cell is interposed between the sense-cell 
and the motor-cell, we have an independnt elementary 
organ of will. In the lower animals, however, this will 
remains unconscious. It is only when consciousness arises 
in the higher animals, as the subjective mirror of the 
objective, though internal, processes in the neuroplasm 
of the psychic cells, that the will reaches that highest stage 
which likens it in character to the human will, and which, 
in the case of man, assumes in common parlance the predi- 
cate of "liberty. 11 Its free dominion and action become 
more and more deceptive as the muscular system and the 
sense-organs develop with a free and rapid locomotion, 
entailing a correlative evolution of the brain and the 
organs of thought. 

The question of the liberty of the will is the one which 
has more than any other cosmic problem occupied the time 
of thoughtful humanity, the more so that in this case 
the great philosophic interest of the question was enhanced 
by the association of most momentous consequences for 
practical philosophy for ethics, education, law, and go 
forth. Emil du Bois-Reymond, who treats it as the 
seventh and last of his "seven cosmic problems," rightly 
says of the question: "Affecting everybody, apparently 
accessible to everybody, intimately involved in the funda- 
mental conditions of human society, vitally connected with 
religious belief, this question has been of immeasurable 
importance in the history of civilisation. There is prob- 
ably no other object of thought on which the modern 
library contains so many dusty folios that will never again 
be opened." The importance of the question is also seen 
in the fact that Kant put it in the same category with the 
questions of the immortality of the soul and belief in 
God. He called these three great questions the indis- 
pensable "postulates of practical reason," though he had 
already clearly shown them to have no reality whatever 
in the light of pure reason. 


The most remarkable fact in connection with this fierce 
and confused struggle over the freedom of the will is, 
perhaps, that It has been theoretically rejected, not only 
by the greatest critical philosophers, but even by their 
extreme opponents, and yet it is still affirmed to be self- 
evident by the majority of the people. Some of the first 
teachers of the Christian Churches such as St. Augustine 
and Calvin rejected the freedom of the will as decisively 
14.1 the famous leaders of pure materialism, Hoi bach in the 
eighteenth and Buchner in the nineteenth century. 
Christian theologians deny It because it is irreconcilable 
with their belief In the omnipotence of God and in pre- 
destination. God, omnipotent and omniscient, saw and 
willed ail things from eternity he must, consequently, 
have predetermined the conduct of man. If man, with his 
free will, were to act otherwise than God had ordained, 
God would not be almighty and all-knowing. In the same 
>ense Leibnitz, too, was an unconditional determinist. 
The monistic scientists of the last century, especially 
Laplace, defended determinism as a consequence of their 
mechanical view of life. 

The great struggle between the determinist and the 
indetermlnist, between the opponent and the sustainer of 
the freedom of the will, has ended to-day, after more 
than 2000 years, completely in favour of the determinist. 
The human will has no more freedom than that of the 
higher animals, from which it differs only in degree, not 
in kind. In the last century the dogma of liberty was 
fought with general philosophic and cosmological argu- 
ments. The nineteenth century has given us very dif- 
ferent weapons for its definitive destruction the powerful 
weapons which we find in the arsenal of comparative 
physiology and evolution. We now know that each act 
of the will is as fatally determined by the organisation of 
the individual and as dependent on the momentary con- 
dition of his environment as every other psychic activity. 
The character of the inclination was determined long a#o 
by heredity from parents and ancestors ; the determination 
to each particular act is an instance of adaptation to the 
circumstances of the moment wherein the strongest motive 

ii uvv/viuiug w uit IpQ lullC 

1 I 1l .1 I I 





1 4 1 ill 



Importance of ontogeny to psychology. Development of the child- 
soul Commencement of existence of the individual soul. The 
storing of the soul. Mythology of the origin of the soul. 
Physiology of the origin of the soul Elementary processes in 
conception. Coalescence of the ovum and the spermatozoon. 
Cell-love. Heredity of the soul from parents and ancestors. Its 
physiological nature as the mechanics of the protoplasm. Blend- 
ing of souls (psychio amphigony). Reversion, psychological 
atavism. The biogenetic law in psychology. Palingenetic repeti- 
tion and cenogenetic modification. Embryonic and post-embryonic 

THE human soul whatever we may hold as to its nature 
undergoes a continual development throughout the life of 
the individual. This ontogenetic fact is of fundamental 
importance in our monistic psychology, though the " pro- 
fessional " psychologists pay little or no attention to it. 
Since the embryology of the individual is, on Baer's 
principle and in accordance with the universal belief of 
modern biologists the " true torch-bearer for all research 
into the organic body," it will afford us a reliable light on 
the momentous problems of the psychic activity. 

Although, however, this " embryology of the soul" is 
so important and interesting, it has hitherto met with 
the consideration it deserves only within a very narrow 
circle. Until recently teachers were almost the only ones 
to occupy themselves with a part of the problem; since 
their avocation compelled them to assist and supervise 
the formation of the psychic activity in the child, they 
were bound to take a theoretical interest, also, in the 
psychogenetic facts that came under their notice. How- 
ever, these teachers, for the most part, both in recent 
and in earlier times, were dominated by the current 



dualistic psychology in so far as they reflected at all ; 
and they were totally ignorant of the important facts of 
comparative psychology, and unacquainted with the struc- 
ture and function of the brain. Moreover, their observa- 
tions only extended to children in their school-days, or in 
the years immediately preceding. The remarkable phe- 
nomena which the individual psychogeny of the child 
offers in its earliest years, and which are the joy and 
admiration of all thoughtful parents, were scarcely ever 
made the subject of serious scientific research. Wilhelm 
Preyer was the pioneer of this study in his interesting 
work on The Mind of the Child (1881). To obtain a 
perfectly clear knowledge of the matter, however, we must 
go further back still ; we must commence at the first 
appearance of the soul in the impregnated ovum. 

The origin of the human individual body and soul 
was still wrapped in complete mystery at the beginning 
of the nineteenth century. Caspar Friedrich Wolff had, 
it is true, discovered the true character of embryonic 
development in 1759, in his Theoria Generationis, and 
proved with the confidence of a critical observer that there 
is a true epigenesi* t. 6., a series of very remarkable 
formative processes in the evolution of the foetus from 
the simple ovum. But the physiologists of the time, with 
the famous Albert Haller at their head, flatly refused to 
entertain these empirical truths, which may be directly 
proved by microscopic observation, and clung to the old 
dogma of "preformation." This theory assumed that in 
the human ovum and in the egg of all other animals 
the organism was already present, or "preformed," in all 
its parts ; the " evolution " of the embryo consisted liter- 
ally in an " unfolding " (evolutio) of the folded organs. 
One curious consequence of this error was the theory of 
scatulation, which we have mentioned on p. 45 ; since the 
ovary had to be admitted to be present in the embryo of 
the woman, it was also necessary to suppose that the germs 
of the next generation were already formed in it, and so 
on in infinitum. Opposed to this dogma of the "Ovul- 
ists " was the equally erroneous notion of the " Animal- 
cu lists " ; the latter held that the ererm was not really in 


the female ovum, but in the paternal element, and that 
the store of succeeding generations was to be sought in 
the spermatozoa. 

Leibnitz consistently applied this theory of scatulation, 
or "boxing-up," to the human soul; he denied that either 
soul or body had a real development (eptgenesu), and said 
in his Theodicy : " Thus I consider that the souls which 
are destined one day to become human exist in the seed, 
like those of other species; that they have existed in our 
ancestors as far back as Adam that is, since the beginning 
of the world in the forms of organised bodies/' Similar 
notions prevailed in biology and philosophy until the third 
decade of the present century, when the reform of embryo- 
logy by Baer gave them their death-blow. In the province 
of psychology, however, they still find many adherents; 
they form one group of the many curious mystical ideas 
which give us a living illustration of the ontogeny of the 

The more accurate knowledge which we have recently 
obtained, through comparative ethnology, of the various 
forms of myths of ancient and modern uncivilised races 
is also of great interest in psychogeny. Still, it would 
take us too far from our purpose if we were to enter into 
it with any fulness here; we must refer the reader to 
Adalbert Svoboda's excellent work on Forms of Faith 
(1897). In respect of their scientific and poetical contents, 
we may arrange all pertinent psychogcnetic myths in the 
following five groups : 

I. The myth of transmigration. The soul lived for- 
merly in the body of another animal, and passed from this 
into a human body. The Egyptian priests, for instance, 
taught that the human soul wandered through all the 
species of animals after the death of the body, returning 
to a human frame after 3000 years of transmigration. 

II. The myth of the in-planting of the soul. The soul 
existed independently in another place a psychogenetic 
store, as it were (in a kind of embryonic slumber or latent 
life); it was taken out by a bird (sometimes represented 
as an eagle, generally as a white stork), and implanted in 
the human body. 


III. The myth of the creation of the soul. God creates 
the souls, and keeps them stored sometimes in a pond 
(living in the form of plankton), according to other myths 
in a tree (where they are conceived as the fruit of a 
phanerogam) ; the Creator takes them from the pond or 
tree, and inserts them in the human germ during the act 
of conception. 

IV. The myth of the scatulation of the soul (the theory 
of I^eibnitz, which we have given above). 

V. The myth of the division of the soul (the theory of 
Rudolph Wagner [1855] and of other physiologists). 
In the act of procreation a portion is detached from both 
the (immaterial) souls of the parents ; the maternal con- 
tribution passes in the ovum, the paternal in the spermato- 
zoa; when these two germinal cells coalesce, the two 
psychic fragments that accompany them also combine to 
form a new (immaterial) soul. 

Although the poetic fancies we have mentioned as to 
the origin of the individual human soul are still widely 
accepted, their purely mythological character is now firmly 
established. The deeply interesting and remarkable re- 
search which has been made in the course of the last 
twenty-five years into the more minute processes of the 
impregnation and germination of the ovum has made it 
clear that these mysterious phenomena belong entirely to 
the province of cellular physiology (cf. p. 39). Both the 
female element, the ovum, and the male fertilising body, 
the sperma or spermatozoa, are simple cellt. These living 
cells possess a certain sum of physiological properties to 
which we give the title of the "cell-soul," just as we do 
in the permanently unicellular protist (see p. 39). Both 
germinal cells have the faculty of movement and sensation. 
The young ovum, or egg-cell, moves after the manner of 
an amoeba ; the minute spermatozoa, of which there are 
millions in every drop of the seminal fluid, are ciliated 
cells, and swim about as freely in the sperm, by means of 
their lashes or cilia, as the ordinary ciliated infusoria (the 

When the two cells meet as a result of copulation, or 
when they are brought into contact through artificial 


fertilisation (in the fishes, for instance), they attract each 
other and become firmly attached. The main cause of this 
cellular attraction is a chemical sensitive action of the 
protoplasm, allied to smell or taste, which we call "erotic 
chemicotropism " ; it may also be correctly (both in the 
chemical and the romantic sense) termed " cellular 
affinity/' or "sexual cell-love." 1 A number of the ciliated 
cells in the sperm swim rapidly towards the stationary egg- 
cell and seek to penetrate into it. As Hertwig showed in 
1875, as a rule only one of the suitors is fortunate enough 
to reach the desired goal. As soon as this favoured sper- 
matozoon has pierced into the body of the ovum with its 
head (the nucleus of the cell), a thin mucous layer is 
detached from the ovum which prevents the further 
entrance of spermatozoa. The formation of this protective 
membrane was only prevented when Hertwig kept the 
ovum stiff with cold by lowering the temperature, or 
benumbed it with narcotics (chloroform, morphia, nico- 
tine, etc.) ; then there was " super-impregnation " or " poiy- 
spermy " a number of sperm-threads pierced into the 
body of the unconscious ovum. This remarkable fact 
proved that there is a low degree of "cellular instinct " 
(or, at least, of specific, lively sensation) in the sexual 
cells just as effectively as do the important phenomena 
that immediately follow in their interior. Both nuclei 
that of the ovum and that of the spermatozoon attract 
each other, approach, and, on contact, completely fuse 
together. Thus from the impregnated ovum arises the 
important new cell which we call the "stem-cell" 
(cyttila), from the repeated segmentation of which the 
whole polycellular organism is evolved. 

The psychological information which is afforded by 
these remarkable facts of impregnation, which have only 
been properly observed during the last twenty-five years, 
is supremely important; its vast significance has hitherto 
been very far from appreciated. We shall condense the 
main conclusions of research in the following five theses : 

I. Each human individual, like every other higher 
animal, is a single simple cell at the commencement of 
his existence. 


II. This "stem-cell " (cytula) is formed in the same 
manner in all cases that is, by the blending or copulation 
of two separate cells of diverse origin, the female ovum 
and the male spermatozoon. 

III. Each of these sexual cells has its own "cell-soul " 
that is, each is distinguished by a peculiar form of sensa- 
tion and movement. 

IV. At the moment of conception or impregnation, 
not only the protoplasm and the nuclei of the two sexual 
cells coalesce, but also their " cell-souls " ; in other words, 
the potential energies which are latent in both, and in- 
separable from the matter of the protoplasm, unite for the 
formation of a new potential energy, the "germ-soul " of 
the newly-constructed stem-cell. 

V. Consequently, each personality owes his bodily and 
spiritual qualities to both parents ; by heredity the nucleus 
of the ovum contributes a portion of the maternal features, 
while the nucleus of the spermatozoon brings a part of the 
father's characteristics. 

By these empirical facts of conception, moreover, the 
further fact of extreme importance is established that 
every man, like every other animal, has a beginning of 
existence ; the complete copulation of the two sexual cell- 
nuclei marks the precise moment when not only the body, 
but also the "soul,** of the new stem-cell makes its 
appearance. This fact suffices of itself to destroy the myth 
of the immortality of the soul, to which we shall return 
later on. It suffices, too, for the destruction of the still 
prevalent superstition that man owes his personal existence 
to the favour of God. Its origin is rather to be attributed 
solely to the " eroa " of his parents, to that powerful 
impulse that is common to all polycellular animals and 
plants, and leads to their nuptial union. But the essential 
point in this physiological process is not the " embrace, *' 
as was formerly supposed, or the amorousness connected 
therewith ; it is simply the introduction of the spermato- 
zoa into the vagina. This is the sole means, in the land- 
dwelling animals, by which the fertilising element can 
reach the released ova (which usually takes place in the 
uterus in man). In the case of the lower aquatic animals 


(fishes, mussels, medusae, etc.) the mature sexual elements 
on both sides are simply discharged into the water, and 
their union is left to chance ; they have no real copulation, 
and so they show none of those higher psychic " erotic " 
functions which play so conspicuous a part in the life of 
the higher animals. Hence it is, also, that ali the lower 
non-copulating animals are wanting in those interesting 
organs which Darwin has called ** secondary sexual char- 
acters," and which are the outcome of sexual selection : 
such are the beard of man, the antlers of the stag, the 
beautiful plumage of the bird of paradise and of so many 
other birds, together with other distinctions of the male, 
which are absent in the female. 

Among the above theses as to the physiology of con- 
ception, the inheritance of the psychic qualities of the two 
parents is of particular importance for psychological pur- 
poses. It is well known that every child inherits from 
both his parents peculiarities of character, temperament, 
talent, acuteness of sense, and strength of will. It is 
equally well known that even psychic qualities are often 
(if not always) transmitted from grandparents by heredity 
often, in fact, a man resembles his grandparents more 
than his parents in certain respects ; and that is true both 
of bodily and mental features. All the chief laws of 
heredity which I first formulated In my General Morpho- 
logy 9 and then popularised in my Natural History of 
Creation , are just as valid and universal in their application 
to psychic phenomena as to bodily structure in fact, they 
are frequently more striking and conspicuous in the former 
than in the latter. 

However, the great province of heredity, to the In- 
estimable Importance of which Darwin first opened our 
eyes in 1859, is thickly beset with obscure problems and 
physiological difficulties. We dare not claim, even after 
forty years of research, that all its aspects are clear to us. 
Yet we have done so much that we can confidently speak 
of heredity as physiological function of the organism, 
which is directly connected with the faculty of generation ; 
and we must reduce it, like all other vita! phenomena, to 
exclusively physical and chemical processes, to the me- 


chanics of the protoplasm. We now know accurately 
enough the process of impregnation itself; we know that 
in it the nucleus of the spermatozoon contributes the quali- 
ties of the male parent, and the nucleus of the ovum gives 
the qualities of the mother, to the newly-born stem-cell. 
The blending of the two nuclei is the "physiological 
moment " of heredity ; by it the personal features of both 
body and soul are transmitted to the new individual. 
These facts of ontogeny are beyond the explanation of the 
dualistic and mystic psychology which still prevails in the 
schools; whereas they find a perfectly simple interpreta- 
tion in our monistic philosophy. 

The physiological fact which is most material for a 
correct appreciation of individual psychogeny is the con- 
tinuity of the psyche through the rise and fall of genera- 
tions. A new individual comes into existence at the 
moment of conception ; yet it is not an independent entity, 
either in respect of its mental or its bodily features, but 
merely the product of the blending of the two parental 
factors, the maternal egg-cell and the paternal sperm-ceil. 
The cell-souls of these two sexual cells combine in the act 
of conception for the formation of a new cell-soul, just as 
truly as the two cell-nuclei, which are the material vehicles 
of this psychic potential energy, unite to form a new 
nucleus. As we now see that the individuals of one and 
the same species even sisters born of the same parents 
always show certain differences, however slight, we must 
assume that these variations were already present in the 
chemical plasmatic constitution of the generative cells 
themselves. 1 

These facts alone would suffice to explain the infinite 
variety of individual features, of soul and of bodily form, 
that we find in the organic world. As an extreme, but 
one-sided, consequence of them, there is the theory of 
Weismann, which considers the amphimixis, or the blend- 
ing of the germ-plasm in sexual generation, to be the 
universal and the sole cause of individual variability. This 
exclusive theory* which is connected with his theory of 
the continuity of the germ-plasm, is, in my opinion, an 

1 Law of individual variation. Vide Natural History of Creation. 


exaggeration. I am convinced, on the contrary, that the 
great laws of progressive heredity and of the correlative 
functional adaptation apply to the soul as well as to the 
body. The new characteristics which the individual has 
acquired during life may react to some extent on the 
molecular texture of the germ-plasm In the egg-cell and 
sperm-cell, and may thus be transferred to the next 
generation by heredity in certain conditions (naturally, 
only in the form of latent energy). 

Although in the soul-blending at the moment of concep- 
tion only the latent forces of the two parent souls are 
transmitted by the coalescence of the erotic cell-nuclei, 
till it is possible that the hereditary psychic influence of 
earlier, and sometimes very much older, generations may 
be communicated at the same time. For the laws of 
latent heredity or atavism apply to the soul just as validly 
as to the anatomical organisation. We find these remark- 
able phenomena of reversion in a very simple and 
instructive form in the alternation of generations of the 
polyps and medusae. Here we see two very different 
generations alternate so regularly that the first resembles 
the third, fifth, and so on ; while the second (very different 
from the preceding) is like the fourth, sixth, etc. (Natural 
History of Creation). We do not find such alternation 
of generations in man and the higher animals and plants, 
in which, owing to continuous heredity, each generation 
resembles the next; nevertheless, even in these cases we 
often meet with phenomena of reversion, which must be 
reduced to the same law of latent heredity. 

Eminent men often take more after their grandparents 
than their parents, even in the finer shades of psychic 
activity ia th possession of certain artistic talents or 
inclinations, in force of character, and in warmth of tem- 
perament; not infrequently there is a striking feature 
which neither parents nor grandparents possessed, but 
which may be traced a long way back to an older branch 
of the family. Even in- these remarkable cases of atavism 
the same laws of heredity apply to the psyche and to the 
physiognomy, to the personal quality of the sense-organs, 
muscles, skeleton, and other parts of the body. We can 


trace them most clearly in reigning dynasties and in old 
families of the nobility, whose conspicuous share in the 
life of the State has given occasion to a more careful 
historical picture of the individuals in the chain of genera- 
tions for instance, in the Hohenzollerns, the princes of 
Orange, the Bourbons, etc., and in the Roman Caesars. 

The causal nexus of biontic (individual) and phylctic 
(historical) evolution, which I gave in my Genera/ Mor- 
phology as the supreme law at the root of all biogenetic 
research, has a universal application to psychology no less 
than to morphology. I have fully treated the special 
importance which it has with regard to man, in both 
respects, in the first chapter of my Anthropogeny. In 
man, as in all other organisms, " the embryonic develop- 
ment is an epitome of the historical development of the 
species. This condensed and abbreviated recapitulation is 
the more complete in proportion as the original epitomised 
development (palingenesis) is preserved by a constant 
heredity ; on the other hand, it falls off from completeness 
La proportion as the later disturbing development (ceno- 
genesis) is accentuated by varying adaptation." 

While we apply this law to the evolution of the foul, 
we must lay special stress on the injunction to keep both 
sides of it critically before us. For, in the case of man. 
just as in all the higher animals and plants, such appreci- 
able perturbations of type (or cenogencses) have taken 
place during the millions of years of development that the 
original simple idea of palingenesis, or "epitome of 
history," has been greatly disturbed and altered. While, 
on the one side, the palinge-nettc 
by the laws of like-time and 
subject to an essential ceno genetic 
hand, by the laws of abbreviated^ 
That is clearly seen in the < 
psychic organs, the nervous sj 
a< nse-organs. But it applies 
tie psychic functions, which 
the normal construction of the 
U subject to great cenogenetic 
other viviparous animals, pre 


development of the embryo occupies a longer time within 
the body of the mother. But we have to distinguish two 
periods of individual psychogeny : (1) the embryonic, and 
(2) the post-embryonic development of the soul. 

1. Embryonic psychogeny. The human foetus, or 
embryo, normally takes nine months (or 270 days) to 
develop in the uterus. During this time it is entirely cut 
off from the outer world, and protected, not only by the 
thick muscular wall of the womb, but also by the special 
foetal membranes (embryolemmata) which are common to 
all the three higher classes of vertebrates reptiles, birds, 
and mammals. In all the classes of amniotes these mem- 
branes (the amnion and the terolemma) develop in just the 
same fashion. They represent the protective arrange- 
ments which were acquired by the earliest reptiles (pro- 
reptilia), the common parents of all the amniotes, in the 
Permian period (towards the end of the palaeozoic age), 
when these higher vertebrates accustomed themselves to 
live on land and breathe the atmosphere. Their ancestors, 
the amphibia of the Carboniferous period, still lived and 
breathed in the water, like their earlier predecessors, the 

In the case of these older and lower vertebrates that 
lived in the water, the embryonic development had the 
palingenetic character in a still higher degree, as is the 
case in most of the fishes and amphibia of the present day. 
The familiar tadpole and the larva of the salamander or 
the frog still preserve the structure of their fish-ancestors 
in the first part of their life in the water; they resemble 
them, likewise, in their habits of life, in breathing by 
gills, in the action of their sense-organs, and in other 
'psychic organs. Then, when the interesting metamor- 
phosis of the swimming tadpole takes place, and when it 
adapts itself to a land-life, the fish-like body changes Into 
that of a four-footed, crivding amphibian; instead of the 
gill breathing in the water comes an exclusive breathing 
of the atmosphere by , nieans of lungs, and, with the 
changed habits of life, even the psychic apparatus, the 
nervous system, nd the sense-organs reach a higher 
degree of cons truet win. / If we could completely follow the 


psychogeny of the tadpole from beginning to end, we 
should be able to apply the biogenetic law in many ways 
to its psychic evolution. For it developes in direct com- 
munication with the changing conditions of the outer 
world, and so must quickly adapt its sensation and move- 
ment to these. The swimming tadpole has not only the 
structure, but the habits of life, of a fish, and only acquires 
those of a frog in its metamorphosis. 

It is different with man and ail the other amniotes; 
their embryo is entirely withdrawn from the direct in- 
fluence of the outer world, and cut off from any reciprocal 
action therewith, by enclosure in its protective mem- 
branes. Besides, the special care of the young on the part 
of the amniotes gives their embryo much more favourable 
conditions for the cenogenetic abbreviation of the palin- 
genetic evolution. There is, in the first place, the excellent 
arrangement for the nourishment of the embryo ; in the 
reptiles, birds, and monotremes (the oviparous mammals) 
it is effected by the great yellow nutritive yelk, which is 
associated with the ejrg ; in the rest of the mammals (the 
marsupials and placentals) it is effected by the mother's 
blood, which is conducted to the foetus by the blood vessels 
of the yelk-sac and the allantois. In the case of the most 
highly developed placentals this elaborate nutritive 
arrangement has reached the highest degree of perfection 
by the construction of a placenta; hence in these classes 
the embryo is fully developed before birth. But its soul 
remains during all this time in a state of embryonic slum- 
ber, a state of repose which Preyer has justly compared to 
the hibernation of animals. We have a similar long sleep 
in the chrysalis stage of those insects which undergo a 
complete metamorphosis butterflies, bees, flies, beetles, 
and so forth. This sleep of the pupa, during which the 
most important formations of organs and tissues take 
place, is the more interesting from the fart that the pre- 
ceding condition of the free larva (caterpillar, grub, or 
maggot) included a highly developed psychic activity, and 
that this is, significantly, lower than the stage which is 
seen afterwards (when the chrysalis sleep is over) in the 
perfect, winged, sexually mature insect. 


its special province to solve for us the great enigma of 
the nature and origin of the human soul. 

The methods and paths which will lead us to the remote 
goal of a complete phylogenetic psychology a goal that 
is still buried in the mists of the future, and almost im- 
perceptible to many do not differ from those of other 
brandies of evolutionary research. Comparative anatomy, 
physiology, and ontogeny are of the first importance. 
Much support is given also by palaeontology, for the order 
In which the fossil remains of the various classes of verte- 
brates succeed each other in the course of organic evolution 
reveals to us, to some extent, the gradual growth of their 
psychic power as well as their phyietic connection. We 
must admit that we are here, aa we are in every branch of 
phylogenetic research, driven to the construction of a 
number of hypotheses in order to fill up the considerable 
lacunae of empirical phylogeny. Yet these hypotheses cast 
so clear and significant a light on the chief stages of his- 
torical development that we are afforded a most gratifying 
insight into their entire course. 

The comparative psychology of man and the higher 
animals enables us to learn from the highest group of the 
placentals, the primates, the long strides by which the 
human soul has advanced beyond the psyche of the anthro- 
poid ape. The phylogeny of the mammals and of the 
lower vertebrates acquaints us with the long series of the 
earlier ancestors of the primates which have arisen within 
this stem since the Silurian age. All these vertebrates 
agree in the structure and development of their character- 
istic psychic organ the spinal cord. We learn from the 
comparative anatomy of the verraalia that this spinal cord 
has been evolved from a dorsal aero ganglion, or vertical 
brain, of an invertebrate ancestor. We learn, further, 
from comparative ontogeny that this simple psychic organ 
has been evolved from the stratum of cells in the outer 
germinal layer, the ectoderm, of the platodes. In these 
earliest flat-worms, which have no specialised nervous 
system, the outer skin-covering serves as a general sensi- 
tive and psychic organ. Finally, comparative embryology 
teaches us that these timple tnetnzoa have arisen by gas- 


trulation from blastfeades, from hollow spheres, the wall of 
which is merely one simple layer of cells, the blastoderm ; 
and the same science, with the aid of the biogenetic law, 
explains how these protozoic coenobia originally sprang 
from the simplest unicellular organisms. 

On a critical study of these different embryonic forma- 
tions, the evolution of which from each other we can 
directly observe under the microscope, we arrive, by means 
of the great law of biogcny, at a series of most important 
conclusions as to the chief stages in the development of 
our psychic life. We may distinguish eight of these, to 
begin with : 

I. Unicellular protozoa with a simple cell-soul : the 
infusoria. l 

II. Multicellular protozoa with a communal soul : the 

III. The earliest metazoa with an epithelial soul : the 

IV. Invertebrate ancestors with a simple vertical 
brain : the vermalia. 

V. Vertebrates without skull or brain, with a simple 
spinal cord : the acrania. 

VI. Animals with skull and brain (of five vesicles) : the 

VII. Mammals with predominant development of the 
cortex of the brain : the placentals. 

VIII. The higher anthropoid apes and man, with 
organs of thought (in the cerebrum) : the anthropomorpha. 

Among these eight stages in the development of the 
human soul we may further distinguish more or less 
clearly a number of subordinate stages. Naturally, how- 
ever, in reconstructing them we have to fall back on the 
same defective evidence of empirical psychology which the 
comparative anatomy and physiology of the actual fauna 
affords us. As the craniote animals of the sixth stage 
and these are true fishes are already found fossilised in 
the Silurian system, we are forced to assume that the five 
preceding series of ancestors (which were incapable of 
fossilisation) were evolved in an earlier, p re-Silurian age. 

I. The cell-$oul (or cytoptyche) : first stage of phyletic 


psychogenesis. The earliest ancestors of man and all 
other animals were unicellular protozoa. This fundamental 
hypothesis of rational phylogeiiy is based, in virtue of the 
phylogenetic law, on the familiar embryological fact that 
every man, like every other metazoon (i. e. every multi- 
cellular organism with tissues), begins his personal exist- 
ence as a simple cell, the stem-cell (cytula), or the impreg- 
nated egg-cell (see p. 51). As this cell has a "soul " from 
the commencement, so had also the corresponding uni- 
cellular ancestral /orms, which were represented in the 
oldest series of man's ancestors by a number of different 

We learn the character of the psychic activity of these 
unicellular organisms from the comparative physiology of 
the protists of to-day. Close observation and careful ex- 
periment have opened out to us in this respect, in the 
second half of the nineteenth century, a new world of the 
most interesting phenomena. The best description of 
them was given by Max Verworn in his thoughtful work, 
based on original research, Psycho-physiological Studiet of 
the Protisti. The work includes, also, the few earlier 
observations of the "psychic life of the protist." Ver- 
worn came to the firm conclusion that the psychic processes 
are unconscious in all the protists, that the phenomena of 
sensation and movement coincide with the molecular vital 
processes in their protoplasm, and that their ultimate 
causes are to be sought In the properties of the proto- 
plasmic molecules (the plastidules). "Hence the psychic 
phenomena of the pro lists form a bridge that connects the 
chemical processes of the inorganic world with the psychic 
life of the highest animals ; they represent the germ of the 
highest psychic phenomena of the metazoa and of man." 

The careful observations and many experiments of Ver- 
worn, together with those of Wilhelm Engelmann, Wil- 
helm Preyer, Richard Hertwig, and other more recent 
students of the protists, afford conclusive evidence for my 
"theory of the cell-soul.** On the strength of several 
years of study of different kinds of protists, especially 
rhizopods and infusoria, I published a theory thirty-three 
years ago to the effect that every living cell has psychic 


properties, and that the psychic life of the multicellular 
animals and plants is merely the sum-total of the psychic 
functions of the cells which build up their structure. In 
the lower groups (in algae and sponges, for instance) all 
the cells of the body have an equal share in it (or with 
very slight differences) ; in the higher groups, in harmony 
with the law of the " division of labour," only a select 
portion of them are involved the "soul-cells." The 
important consequences of this "cellular psychology" 
were partly treated in my work on The Perigvnetii of the 
Plastidule (1876), and partly in my speech at Munich, in 
1877, on "Modern Evolution in Relation to the Whole of 
Science." A more popular presentation of them is to be 
found in my two Vicuna papers (1878) on "The- Origin 
and Development of the Sense-Organs " and on " Cell- 
Souls and Soul-Cells." 

Moreover, the cell-soul, even within the limits of the 
protist world, presents a long series of stages of develop- 
ment, from the most simple and primitive to a compara- 
tively elaborate activity. In the earliest and simplest 
protists the faculty of sensation and movement is equally 
distributed over the entire protoplasm of the homogeneous 
morsel; in the higher forms certain "cell-instruments," 
or organella, appear, as their physiological organs. Motor 
cell -parts of that character are found in the pseudopodis 
of the rhizopods, and the vibrating hairs, lashes, or cili 
of the infusoria. The cell-nucleus, which is wanting in 
the earlier and lower protists, is considered to be an In- 
ternal central organ of the cell-life. It is especially note- 
worthy, from a physiologico-chemical point of view, that 
the very earliest protists were plasmodomous, with plant- 
like nutrition hence protophyta, or primitive plants; 
from these came as a secondary stage, by metasitism, the 
first plasmophagi, with animal nutrition the protozoa, or 
primitive animals. 1 This metasitism, or circulation of 
nutritive matter, implies an important psychological ad- 
vance; with it began the development of those character- 
istic properties of the animal soul which are wanting in 
the plant. 

1 Of. E. Haeckel, Sytttmatie Pkylogeny, vol. i. 


We find the highest development of the animal cell-soul 
In the class of ciliata, or ciliated infusoria. When we 
compare their activity with the corresponding psychic life 
of the higher, multi cellular animals, we find scarcely any 
psychological difference ; the sensitive and motor organella 
of these protozoa seem to accomplish the same as the 
tense-organs, nerves, and muscles of the metazoa. Indeed, 
we have found in the great cell-nucleus (meganucleus) of 
the infusoria a central organ of psychic activity, which 
plays much the same part in their unicellular organism as 
the brain does in the psychic life of higher animals. 
However, it is very difficult to determine how far this 
comparison is justified ; the views of experts diverge con- 
siderably over the matter. Some take all spontaneous 
bodily movement in them to be automatic, or impulsive, 
and all stimulated movement to be reflex ; others are con- 
vinced that such movements are partly voluntary and in- 
tentional. The latter would attribute to the infusoria a 
certain degree of consciousness, and even self -conscious- 
ness; but this is rejected by the others. However that 
very difficult question may be settled, it does not alter the 
fact that these unicellular protozoa give proof of the pos- 
session of a highly-developed "cell-soul," which is of 
great interest for a correct decision as to the psyche of 
our earliest unicellular ancestors. 

II. The communal or cenobitic soul (cccnopsyckc) : 
second stage of phyletic psychogenesis. Individual de- 
velopment begins, in man and in all other multicellular 
animals, with the repeated segmentation of one simple 
cell. This stem-cell, the impregnated ovum, divides first 
into two daughter-cells, by a process of ordinary indirect 
segmentation ; as the process is repeated there arise (by 
equal division of the egg) successively four, eight, sixteen, 
thirty-two, sixty-four, such new cells, or "blastomeres." 
Usually (that is, in the case of the majority of animals) 
an irregular enlargement sooner or later takes the place of 
this original regular division of cells. But the result is 
the same in all cases the formation of a (generally 
spherical) cluster of heterogeneous (originally homo- 
geneous) cells. This stage is called the morula ("mul- 


berry/ 9 which it somewhat resembles in shape). Then, 
as a rule, a fluid gathers in the -interior of this aggregate 
of cells; it changes into a spherical vesicle; all the cells 
go to its surface, and arrange themselves in one simple 
layer the blastoderm. The hollow sphere which is thus 
formed is the important stage of the "germinal vesicle," 
the blattula, or blastosphere. 

The psychological phenomena which we directly observe 
in the formation of the bias tula are partly sensations, 
partly movements of this community of cells. The move- 
ments may be divided into two groups; (1) the inner 
movements, which are always repeated in substantially the 
same manner in the process of ordinary (indirect) seg- 
mentation of cells (formation of the axis of the nucleus, 
mitosis, karyokinesis, etc.) ; (2) the outer movements, 
which are seen in the regular change of position of the 
social cells and their grouping for the construction of the 
blastoderm. We assume that these movements are here- 
ditary and unconscious, because they are always deter- 
mined in the name fashion by heredity from the earlier 
protist ancestors. The sensations, also, fall into two 
groups: (1) the sensations of the individual cells, which 
reveal themselves in the assertion of their individual in- 
dependence and their relation to neighbouring cells (with 
which they are in contact, and partly in direct combina- 
tion, by means of protoplasmic fibres); (2) the common 
sensation of the entire community of cells which is seen in 
the individual formation of the hlastula as a hollow vesicle. 

The causal interpretation of the formation of the blastula 
is given us by the biogenetic law, which explains the 
phenomena we directly observe to be the outcome of 
heredity, and relates them to corresponding historical pro- 
cesses which took place long ago in the origin of the 
eariist protist-coenobia, the blastaeads. But we get a 
physiological and psychological insight into these import- 
ant phenomena of the earliest cell-communities by ob- 
servation and experiment on their modern representatives. 
Such permanent cell-communities or colonies are still found 
in great numbers both among the plasmodomous primitive 
plants (for instance, the paulotomacea, diatomacea, volvo- 


cinae, etc.) and the plasmophagous primitive animals (the 
infusoria and rhizopods). In all these coenobia we can 
easily distinguish two different grades of psychic activity, 
(1) the cell-soul of the individual cells (the "elementary 
organisms "), and (2) the communal sou) of the entire 

III. The tissue-soul (histopsyche): third stage of 
phyletic psychogenesis. In all multicellular, tissue-form- 
ing plants (metaphyta) and in the lowest, nerveless classes 
of tissue-forming animals (metazoa) we have to distinguish 
two different forms of psychic activity namely, (1) the 
psyche of the individual ceils which compose the tissue, 
and (2) the psyche of the tissue itself, or of the ** cell- 
state " which is made up of the tissues. This " tissue- 
soul " is the higher psychological function which gives 
physiological individuality to the compound multicellular 
organism as a true 4< cell-common wealth." It controls all 
the separate " cell-souls " of the social ceils the mutually 
dependent " citizens" which constitute the community. 
This fundamental twofold character of the psyche in the 
metaphyta and the lower, nerveless metazoa is very im- 
portant. It may be verified by unprejudiced observation 
and suitable experiment, in the first place, each single 
cell has its own sensation and movement, and, in addition, 
each tissue and each organ, composed of a number of 
homogeneous cells, has its special irritability and psychic 
unity (e. g. the pollen and stamens). 

A. The plant-soul (phytopsyche) is, in our view, the 
summary of the entire psychic activity of the tissue 
forming, multicellular plant (the metaphyton, as distinct 
from the unicellular protophyton) ; it is, however, the 
subject of the most diverse opinions even at the present 
day. It was once customary to draw an essential dis- 
tinction between the plant and the animal, OB the ground 
that th<- latter had a "soul " and the plant had none. 
However, an unprejudiced comparison of the irritability 
and movements of various higher plants and lower animals 
convinced many observers, even at the beginning of the 
century, that there must be a "soul " on both sides. At 
a later date Fechner, Leitgeb, and others, strongly con- 


tended for the plant-soul. But a profounder knowledge 
of the subject was obtained when the similarity of the 
elementary structure of the plant and of the animal was 
proved by the cellular theory, and especially when the 
similarity of conduct of the active living protoplasm in 
both was shown in the plasma-theory of Max Schultze 
(1859). Modern comparative physiology has shown that 
the physiological attitude towards various stimuli (light, 
heat, electricity, gravity, friction, chemical action, etc.) 
of the "sensitive'* portions of many plants and animals 
is exactly the same, and that the reflex movements which 
the stimuli elicit take place in precisely the same manner 
on both sides. Hence, if it was necessary to attribute 
this activity to a "soul " in the lower, nerveless inetazoa 
(sponges., polyps, etc.), it was also necessary in the case of 
many (if not all) metaphyta, at least in the very sensitive 
mimosa, the " fly-traps " (dionxa and drosera), and the 
numerous kinds of climbing plants. 

It is true that modern vegetal physiology has given a 
purely physical explanation of many of these stimulated 
movements, or tropisms, by special features of growth , 
variations of pressure, etc. Yet these mechanical causes 
are neither more nor less psycho-physical than the similar 
" reflex movements " of the sponges, polyps, and other 
nerveless metazoa, even though their mechanism is en- 
tirely different. The character of the tissue-soul reveals 
itself in the same way in both cases the cells of the 
tissue (the regular, orderly structure of cells) transmit the 
stimuli they have received in one part, and thus provoke 
movements of other parts, or of the whole organ. This 
transmission of stimuli has as much title to be called 
"psychic activity" as its more complete form in the 
higher animals with nerves ; the anatomic explanation of 
it is that the social cells of the tissue, or cell-community, 
are not isolated from each other (as was formerly suj>- 
posed), but are connected throughout by fine threads or 
bridges of protoplasm. When the sensitive mimosa closes 
its graceful leaves and droops its stalk at contact, or on 
being shaken ; when the irritable fly-trap (the dionaea) 
swiftly claps its leaves together at a touch, and captures 


the fly ; the sensation seems to be keener, the transmission 
of the stimulus more rapid, and the movement more 
energetic, than in the reflex action of the stimulated bath- 
sponge and many other sponges. 

B. The soul of the nerveless metazoa. Of very special 
interest for comparative psychology in general, and for 
the phylogeny of the animal soul in particular, is the 
psychic activity of those lower metazoa which have tissues, 
and sometimes differentiated organs, but no nerves or 
specific organs of sense. To this category belong four 
different groups of the earliest coelenterates (a) the gas- 
trrcades, (b) the platodaria, (c) the sponges, and (d) the 
hydropolyps, the lowest forms of cnidaria. 

The gastrseads (or animals with a primitive gut) form a 
small group of the lowest crelenterates, which is of great 
importance as the common ancestral group of all the 
mctazoa. The body of these little swimming animals 
looks like a tiny (generally oval) vesicle, which has a 
simple cavity with one opening the primitive gut and the 
primitive mouth. The wail of the digestive cavity is 
formed of two simple layers of cells, or epithelium, the 
inner of which the gut-layer is responsible for the 
vegetal activity of nourishment, while the outer, or skin- 
layer, discharges the animal functions of movement and 
sensation. The homogeneous sensitive cells of the skin- 
layer bear long, slender hairs or lashes (cilia) 9 by the 
vibration of which the swimming motion is effected. The 
few surviving forms of gastrseads, the gastrsemaria (tricho- 
placidse) and cyemaria (orthonectidx), are extremely inter- 
esting, from the fact that they remain throughout life at 
m stage of structure which is passed by all the other 
metazoa (from the sponge to man) at the commencement 
of their embryonic development. As I have shown in my 
Theory of the Gastrsea (1872), a very characteristic embry- 
onic form, the gastntla, is immediately developed from the 
blastula in all the tissue-animals. The germinal membrane 
(blastoderm), which represents the wall of the hollow 
vesicle, forms a depression at one side, and this soon sinks 
in so deep that the inner cavity of the vesicle disappears, 
half of the membrane which bends in is thus laid on. 


and inside, the other half; the latter forms the thin-layer 
or outer germinal layer (ectoderm or epiblast), and the 
former becomes the gut-layer, or inner germinal layer 
(cndoderm or hypoblast). The new cavity of the cup- 
shaped body is the digestive stomach-cavity (the pro- 
gaster), and its opening is the primitive mouth (or pro- 
stoma). 1 The skin-layer, or ectoderm, is the primitive 
psychic organ in the metazoa ; from it, in all the nerve- 
animals, not only the external skin and the organs of 
sense, but also the nervous system, are developed. In the 
gastreeads, which have no nerves, all the cells which com- 
pose the simple epithelium of the ectoderm are equally 
organs of sensation and of movement; we have here the 
tissue-soul in its simplest form. 

The platodaria, the earliest and simplest form of the 
platodes, seem to be of the same primitive construction. 
Some of these cryptocoela the convoluta, etc. have no 
specific nervous system, while their nearest relatives, the 
turbellaria, have already differentiated one, and even 
developed a vertical brain. 

The spongci form a peculiar group in the animal world, 
which differs widely in organisation from all the other 
metazoa. The innumerable kinds of sponges grow, as a 
rule, at the bottom of the sea. The simplest form of 
sponge, the olynthu$, is in reality nothing more than a 
gaslrsea, the body- wall of which is perforated like a sieve, 
with fine pores, in order to permit the entrance of the 
nourishing stream of water. In the majority of sponges 
even in the most familiar one, the bath-sponge the 
bulbous organism constructs a kind of stem or tree, which 
is made up of thousands of these gastrseads, and permeated 
by a nutritive system of canals. Sensation and movement 
are only developed in the faintest degree in the sponges; 
they have no nerves, muscles, or organs of sense. It was, 
therefore, quite natural that such stationary, shapeless, 
insensitive animals should have been commonly taken to 
be plants in earlier years. Their psychic life for which 
no special organs have been differentiated is far inferior 
to that of the mimosa and other sensitive plants. 
1 Of. Anthropogtny and Natural History of Creation. 


The soul of the cnidaria is of the utmost importance in 
comparative and phylogenei.ic psychology ; for in this 
numerous group of the ere lent crates the historical evolution 
of the nerve-soul out of the tissue-soul is repeated before 
our eyes. To this group belong the innumerable classes 
of stationary polyps and corals, and of swimming medusae 
and siphonophora. As the common ancestor of ail the 
cuidaria we can safely assign a very simple polyp, which 
is substantially the same in structure as the common, still- 
surviving, fresh-water polyp the hydra. Yet the hydrae, 
and the stationary, closely-related hydropolyps, have no 
nerves or higher sense-organs, although they are extremely 
sensitive. On the other hand, the free-swimming medusae, 
which are developed from them and are still connected 
with them by alternation of generations have an inde- 
pendent nervous system and specific sense-organs. Here, 
also, we may directly observe the ontogenetic evolution 
of the nerve-soul (neuropsyche) out of the tissue-soul 
(histopsyche), and thus learn its phylogenetic origin. 
This is the more interesting as such phenomena are poly- 
phyletic ; that is, they have occurred several times more 
than once, at least quite independently. As I have 
shown elsewhere, the hydromedusre have arisen from the 
hydropolyps in a different manner from that of the evolu- 
tion of the scyphornedusoe from the scyphopolyps ; the 
gemmation is terminal in the case of the latter, and lateral 
with the former. In addition, both groups have char- 
acteristic hereditary differences in the more minute struc- 
ture of their psychic organs. The class of siphonophora 
is also very interesting to the psychologist. In these 
pretty, free-swimming organisms, which come from the 
hydromedusae, we can observe a double soul : the personal 
soul of the numerous individualities which compose them, 
and the common, harmoniously -acting psyche of the entire 

IV. The nerve-soul (neuropsyche) ; fourth stage of 
phyletic psychogeny. The psychic life of all the higher 
animals is conducted, as in man, by means of a more or 
less complicated "psychic apparatus." This apparatus in 
always composed of three chief sections : the organs of 


sense are responsible for the various sensations ; the 
muscles effect the movements ; the nerves form the con- 
nection between the two by means of a special central 
organ, the brain or ganglion. The arrangement and 
action of this psychic mechanism have been frequently 
compared with those of a telegraphic system ; the nerves 
are the wires, the brain the central, and the sense-organs 
subordinate stations. The motor-nerves conduct the com- 
mands of the will centrifugally from the nerve-centre to 
the muscles, by the contraction of which they produce the 
movements : the sensitive nerves transmit the various 
sensations centripetal ly that is, from the peripheral 
sense-organs to the brain and thus render ail account of 
the impressions they receive from the outer world. The 
ganglionic cells, or "psychic cells," which compose the 
centra) nervous organ, are the most perfect of all organic 
elements; they not only conduct the commerce between 
the muscles and the organs of sense, but they also effect 
the highest performances of the animal soul, the formation 
of ideas and thoughts, and especially consciousness. 

The great progress of anatomy, physiology, histology, 
and ontogeny has recently added a wealth of interesting 
discoveries to our knowledge of the mechanism of the soul. 
If speculative philosophy assimilated only the most im- 
portant of these significant results of empirical biology, it 
would have a very different character from that it unfor- 
tunately presents. As I have not space for an exhaustive 
treatment of them here, I will confine myself to a relation 
of the chief facts. 

Each of the higher animal species ha* a characteristic 
psychic organ; the central nervous system of each ha* 
certain peculiarities of shape, position, and composition. 
The medusae, among the radiating cnidaria, have a ring 
of nervous matter at the border of the fringe, generally 
provided with four or eight ganglia. The mouth of the 
five-rayed cnidarion is girt with a nerve-ring, from which 
proceed five branches. The bi-symmetrical platodes and 
the verrnalia have a vertical brain, or acroganglion, com- 
posed of two dorsal ganglia, lying above the mouth ; from 
these " upper ganglia " two branch nerves proceed to the 


skin and the muscles. In some of the vermalia and hi 
the mollusca a pair of ventral " lower ganglia " are added, 
which are connected with the former by a ring round the 
gullet. This ring is found also in the articulata ; but in 
these it is continued on the belly side of the long body as 
a ventral medulla, a double fibre like a rope- ladder, which 
expands into a double ganglion in each member. The 
vertebrates have an entirely different formation of the 
psychic organ ; they have always a spinal medulla de- 
veloped at the back of the body ; and from an expansion 
of its fore part there arises subsequently the characteristic 
vesicular brain. 1 

Although the psychic organs of the higher species of 
animals differ very materially in position, form, and com- 
position, nevertheless comparative anatomy Is in a position 
to prove a common origin for most of them namely, from 
the vertical brain of the platodes and vermalia; they have 
all, moreover, had their origin in the outermost layer of 
the embryo, the ectoderm , or outer skin-layer. Hence 
we find the same typical structure in all varieties of the 
central nervous organ a combination of ganglionic cells, 
or " psychic cells " (the real active elementary organs of 
the soul), and of nerve fibres, which effect the connection 
and transmission of the action. 

The first fact we meet in the comparative psychology 
of the vertebrates, and which should be the empirical start- 
ing-point of all scientific human psychology, is the 
characteristic structure of the central nervous system. 
This central psychic organ has a particular position, shape, 
and texture in the vertebrate, as it has in all the higher 
species. In every case we find a spinal medulla, a strong 
cylindrical nervous cord, which runs down the middle of 
the back, In the upper part of the vertebral column (or 
the cord which represents it). In every case a number 
of nerves branch off from this medulla in regular division, 
one pair to each segment or -vertebra. In every case this 
medullary cord arises in the same way in the foetus ; a 
fine groove appears in the middle axis of the skin at the 
back; then the parallel borders of this medullary groove 
1 Cf. Natural ffistory 


are lifted up a little, bend over towards each other, and 
form into a kind of tube. 

The long dorsal cylindrical medullary tube which is 
thus formed is thoroughly characteristic of the verte- 
brates; it is always the same in the early embryonic sketch 
of the organism, and it is always the chief feature of the 
different kinds of psychic organ which evolve from it in 
time. Only one single group of invertebrates has a similar 
structure : the rare marine tunicata, the copelata, aschlia, 
and thalidiae. These animals have other important peculi- 
arities of structure (especially in the chorda and the gut) 
which show a striking divergence from the other inverte- 
brates and resemblance to the vertebrates. The inference 
we draw is that both these groups, the vertebrates and 
the tunicates, have arisen from a common ancestral group 
of the vermalia, the prochordonia. 1 Still, there is a 
great difference between the two classes in the fact that 
the body of the tunicate does not articulate, or form 
members, and has a very simple organisation (most of 
them subsequently attach themselves to the bottom of the 
gea and degenerate). The vertebrate, on the other hand, 
is characterised by an early development of internal 
members, and the formation of pro-vertebrae (vertebratio). 
This prepares the way for a much higher development of 
their organism, which finally attains perfection in man. 
This is easily seen in the finer structure of his spinal cord, 
and in the development of a number of segmental pairs 
of nerves which proceed to the various parts of the body. 

The long ancestral history of our " vertebrate soul " 
commences with the formation of the most rudimentary 
spinal cord in the earliest acrania; slowly and gradually, 
through a period of many millions of years, it conducts: 
to that marvellous structure of the human brain which 
seems to entitle the highest primate form to quite an 
exceptional position in nature. Since a clear conception 
of this slow and steady progress of our phyietic psycho- 
geny is indispensable for a true psychology, we must 
divide that vast period into a number of stages or sections : 
in each of them the perfecting of the structure of the 
1 BM ohftpt. xri. and irii. of my Anthropogeny. 


nervous centre has been accompanied by a corresponding 
evolution of its function, the psyche. I distinguish eight 
of these periods in the phytogeny of the spinal cord, 
which are characterised by eight different groups of verte- 
brates : (1) the acrania; (2) the cyclostomata ; (S) the 
fishes ; (4) the amphibia ; (5) the implacental mammals 
(monotremes and marsupials) ; (6) the earlier placental 
mammals, especially the prosimiie ; (7) the younger 
primates, the siim'a> ; and (8) the anthropoid apes and man. 

I. First stage the acrania: their only modern repre- 
sentative is the lancelet or amphioxus ; the psychic organ 
remains a simple medullary tube, and contains a regularly 
segmented spinal cord, without brain. 

II. Second stage the cyclostomata : the oldest group 
of the craniota, now only represented by the petromy- 
tontes and myxinoides .* the fore-termination of the cord 
expands into a vesicle, which then subdivides into five 
successive parts the great-brain, intermediate-brain, 
middle-brain, little-brain, and hind-brain : these five 
cerebral vesicles form the common type from which the 
brain of all craniota has evolved, from the lamprey to 

III. Third stage the primitive fishes (selachii) : similar 
to the modern shark : in these oldest fishes, from which 
ail the gnathostomata descend, the more pronounced 
division of the five cerebral vesicles sets in. 

IV. Fourth stage the amphibia. These earliest land- 
animals, making their first appearance in the Carboniferous 
period, represent the commencement of the characteristic 
itructure of the tetrapod and a corresponding development 
of the fish-brain : it advances still further in their Permian 
tuccessora, the reptiles, the earliest representatives of 
which, the tocotauria, are the common ancestors of ail the 
amniota (reptiles and birds on one side, mammals on the 

V.-VIII. Fifth to tbe eighth stages the mammals. 
I have exhaustively treated, and illustrated with a number 
of plates, in my ,4 nthropogeny, the evolution of our 
nervous system and the correlative question of the develop- 
ment of the soul. I have now, therefore, merely to refer 


the reader to that work. It only remains for me to add 
a few remarks on the last and most interesting class of 
facts pertaining to this to the evolution of the soul and 
its organs within the limits of the class mammalia. In 
doing so, I must remind the reader that the monophyletic 
origin of this class that is, the descent of ail the mammaU' 
from one common ancestral form (of the Triassic period) 
is now fully established. 

The most important consequence of the monophyletic 
origin of the mammals is the necessity of deriving the 
human soul from a long evolutionary series of other 
mammal-souls. A deep anatomical and physiological gulf 
separated the brain structure and the dependent psychic 
activity of the higher mammals from those of the lower : 
this gulf, however, is completely bridged over by a long 
series of intermediate stages. The period of at least 
fourteen (more than a hundred, on other estimatei) 
million years, which has elapsed since the commencement 
of the Triassic period, is amply sufficient to allow even 
the greatest psychological advance. The following is A 
summary of the results of investigation in this quarter, 
which has recently been very penetrating : 

I. The brain of the mammal is difFerentiated from that 
of the other vertebrates by certain features, which are 
found in all branches of the class ; especially by a prepon- 
derant development of the first and fourth vesicles, the 
cerebrum and cerebellum, while the third vesicle, the 
middle-brain, disappears altogether. 

IJ. The brain development of the lowest and earliest 
mammals (the monotremes, marsupials, and prochoriates) 
is closely allied to that of their palaeozoic ancestors, the 
Carboniferous amphibia (the ttegocephala) and the 
Permian reptiles (the tocosauria). 

III. During the Tertiary period commences the typical 
development of the cerebrum, which distinguishes the 
younger mammals so strikingly from the older. 

IV. The special development (quantitatively and quali- 
tatively) of the cerebrum which is so prominent a feature 
in man, and which is the root of his pre-eminent psychic 
achievements, is only found, outside humanity, in a small 


section of the most highly-developed mammals of the 
earlier Yertiary epoch, especially in the anthropoid apes, 

V, Tin differences of brain-structure and psychic 
faculty which separate man from the anthropoid ipe ire 
slighter than the corresponding interval between the 
Mithropoid apes and the lower primates (the earliest 
siminnd prosimis), 

VI, Consequently, the historical, gradual evolution of 
the human soul from a long chain of higher and lower 
mammal-souls must, by application of the universally 
valid ['hyletic laws of the theory of descent, be regarded 
is a /act which has been scientifically proved. 



Consciousness as a natural phenomenon. Iti definition. Difficulties 
of the problem. Ita relation to the life of the toul. Our human 
consciousness. Various theories: I. Anthropistic theory 
(Descartes). II. Neurological theory (Darwin), III. Animal 
theory (Schopenhauer), IV. Biological theory (Feohner). V. 
Cellular theory (Jfriti Hehultze). VI. Atomistic theory. Moniitio 
and du&Hstic theories. Transcendental character of consciousness, 
The Igiiorabimus rerdict of Du Bois-Reyraond, Physiology of 
consciousness. Discovery of the organs of thought by Flechsig. 
Pathology. Double and intermittent consciousness. Ontogeny 
of consciousness : modifications at different ages. Phytogeny of 
consciousness. Formation of concepts. 

No phenomenon of the life of the soul is so wonderful and 
so variously interpreted as consciousness. The most con- 
tradictory views are current to-day, as they were 2,000 
years ago, not only with regard to the nature of this 
psychic function and its relation to the body, but even as 
to its diffusion in the organic world and its origin and 
development. It Is more responsible than any other 
psychic faculty for the erroneous idea of an "immaterial 
soul " and the belief in " personal immortality " ; many 
of the gravest errors that still dominate even our modern 
civilisation may be traced to it. Hence it is that I have 
entitled consciousness "the central mystery of psycho- 
logy " : it is the strong citadel of all mystic and dualistic 
errors, before whose ramparts the best equipped efforts 
of reason threaten to miscarry. This fact would suffice 
of itself to induce us to make a special critical study of 
consciousness from our monistic point of view. We shall 
see that consciousness Is simply a natural phenomenon 
like any other psychic quality, and that It Is subject to the 
law of substance like all other natural phenomena. 



Even as to the elementary idea of consciousness, its con- 
tents and extension, the views of the most distinguished 
philosophers and scientists are widely divergent. Perhaps 
the meaning of consciousness is best conceived as an in- 
ternal perception, and compared with the action of a 
mirror. As its two chief departments we distinguish 
objective and subjective consciousness consciousness of 
the outer world, the non-ego, and of the ego. By far the 
greater part of our conscious activity, us Schopenhauer 
justly remarked, belongs to the consciousness of the world, 
or the non-ego : this world-consciousnes* embraces all pos- 
ible phenomena of the outer world which are in any sense 
accessible to our minds. Much more contracted is the 
cphere of telf-consciousnest, the internal mirror of all our 
own psychic activity, all our presentations, sensations, and 

Many distinguished thinkers, especially on the physio- 
logical side (Wundt and Ziehen, for instance), take the 
Ideas of consciousness and psychic function to be identical 
"all psychic action is conscious"; the province of 
psychic life, they say, is co-extensive with that of con- 
sciousness. In our opinion, such a definition gives an 
undue extension to the meaning of consciousness, and 
occasions many errors and misunderstandings. We share, 
rather, the view of other philosophers (Romanes, Fritz 
Schultze, and Paulsen), that even our unconscious presen- 
tations, sensations, and volitions pertain to our psychic 
life; indeed, the province of these unconscious psychic 
actions (retlex action, and so forth) is far more extensive 
than that of consciousness. Moreover, the two provinces 
arc intimately connected, and are separated by no sharp 
line of demarcation. An unconscious presentation may 
become conscious at any moment; let our attention be 
withdrawn from it by some other object, and forthwith it 
disappears from consciousness once more. 

The only source of our knowledge of consciousness is 
that faculty itself; that is the chief cause of the extra- 
ordinary difficulty of subjecting it to scientific research. 
Subject and object are one and the same in it : the per- 
ceptive subject mirrors itself In its own inner nature, 


which is to be the object of our inquiry. Thus we can 
never have a complete objective certainty of the con- 
sciousness of otiiers ; we can only proceed by a comparison 
of their psychic condition with our own. As Jong as this 
comparison is restricted to normal people we are justified 
in drawing certain conclusions as to their consciousness, 
the validity of which is unchallenged. But when we pass 
on to consider abnormal individuals (the genius, the 
eccentric, the stupid, or the insane) our conclusions from 
analogy are either unsafe or entirely erroneous. The same 
must be said with even greater truth when we attempt to 
compare human consciousness with that of the animals 
(even the higher, but especially the lower). In that case 
such grave difficulties arise that the views of physiologists 
and philosophers diverge as widely as the poles on the 
subject. We shall briefly enumerate the most important 
of these views. 

I. The anthropistic theory of contciousnen. It is 
peculiar to man. To Descartes we must trace the wide- 
spread notion that consciousness and thought are man's 
exclusive prerogative, and that he alone is blessed with an 
"immortal soul.** This famous French philosopher and 
mathematician (educated in a Jesuit college) established a 
rigid partition between the psychic activity of man and 
that of the brute. In his opinion the human soul, a think- 
ing, immaterial being, is completely distinct from the 
liody, which is extended and material. Yet it is united 
to the body at a certain point in the brain (the glandula 
pineali*) for the purpose of receiving impressions from the 
outer world and effecting muscular movements. The 
animals, not being endowed with thought, have no soul : 
they are mere automata, or cleverly-constructed machines, 
whose sensations, presentations, and volitions are purely 
mechanical, and take place according to the ordinary laws 
of physics. Hence Descartes was a dualist in human 
psychology, and a rnonist in the psychology of the brute. 
This open contradiction in so clear and acute a thinker is 
very striking; in explaining it, it is not unnatural to sup- 
pose that he concealed his real opinion, and left the 
discovery of It to independent scholar*. Ag a pupil of the 


Jesuit*, Descartes had been taught to deny the truth in 
the face of his better insight ; and perhaps he dreaded the 
power ami the fires of the Church. Besides, his sceptical 
principle, that every sincere effort to attain the truth must 
start with a doubt of the traditional dogma, had already 
drawn upon him fanatical accusations of scepticism and 
atheism. The great influence which Descartes had on sub- 
sequent philosophy was very remarkable, and entirely in 
harmony with bis "book-keeping by double entry." The 
materialists of the seventeenth and eighteenth centuries 
appealed to the Cartesian theory of the animal-soul and 
itt purely mechanical activity in support of their monistic 
psychology. The spiritualist*, on the other hand, asserted 
that their dogma of the immortality of the soul and its 
independence of the body was firmly established by 
Descartes' theory of the human soul. This view is still 
prevalent in the camp of the theologians and duaiistic 
metaphysicians. The scientific conception of nature, how- 
ever, which has been built up in the nineteenth century, 
has, with the aid of empirical progress in physiological and 
comparative psychology, completely falsified it. 

JI. Neurological theory of conscioutnes*. It is present 
only in man and those higher animals which have a 
centralised nervous system and organs of sense. The con- 
viction that a large number of animals at least the higher 
mammals are not less endowed than man with a thinking 
soul and consciousness prevails in modern zoology, exact 
physiology, and the monistic psychology. The immense 
progress we have made in the various branches of biology 
has contributed to bring about a recognition of this im- 
portant truth. We confine ourselves for the present to the 
higher vertebrates, and especially the mammals. That 
the most intelligent specimens of these highly-developed 
vertebrates af>es and dogs, in particular have a strong 
resemblance to man in their whole psychic life has been 
recognised and speculated on for thousands of years. 
Their faculty of presentation and sensation, of feeling and 
desirfe, is so like that of man that we need adduce no proof 
of our thesis. But even the higher associations! activity 
of the brain, the formation of judgment! and their con- 


aection into chains of reasoning, thought, and conscious- 
ness in the narrower sense, are developed in them after 
the same fashion as in man : they differ only in degree, 
not in kind. Moreover, we learn from comparative 
anatomy and histology that the intricate structure of the 
hrain (both in general and in detail) is substantially the 
same in the mammals as it is in man. The same lesson 
is enforced by comparative ontogeny with regard to the 
origin of these psychic organs. Comparative physiology 
teaches us that the various states of consciousness are just 
the same in these highest placentals as in man; and we 
learn by experiment that there is the same reaction to 
external stimuli. The higher animals can be narcotised 
by alcohol, chloroform, ether, etc., and may be hypnotised 
by the usual methods, just as in the case of man. 

It is, however, impossible to determine mathematically 
at what stage of animal life consciousness is to be first 
recognised as such. Some zoologists draw the line very 
high in the scale, others very low. Darwin, who most 
accurately distinguishes the various stages of consciousness, 
intelligence, and emotion in the higher animals, and 
explains them by progressive evolution, points out how 
difficult, or even impossible, it is to determine the first 
beginning of this supreme psychic faculty in the lower 
animals. Personally, out of the many contradictory 
theories, I take that to be most probable which holds the 
centralisation of the nervou* tystem to be a condition of 
consciousness ; and that is wanting in the lower classes of 
animals. The presence of a central nervous organ, of 
highly-developed sense-organs, and an elaborate associa- 
tion of groups of presentations, seems to me to be required 
before the unity of consciousness is possible. 

III. Animal theory of confctotwncsj. All animals, and 
they alone, have consciousness. This theory would draw 
* sharp distinction between the psychic life of the animal 
and of the plant. Such a distinction was urged by many 
of the older writers, and was clearly formulated by Linn 
in his celebrated Syttema Naturse : the two great king- 
doms of the organic world are, in his opinion, divided by 
the fact that animals have sensation and consciousness, and 


the plants are devoid of them. Later on Schopenhauer 
laid stress on the same distinction : " Consciousness is only 
known to us as a feature of animal nature. Even though 
it extend upwards through the whole animal kingdom, 
even to man and his reason, the unconsciousness of the 
plant, from which it started, remains as the basic feature. 
In the lowest animals we have but the dawn of it." The 
inaccuracy of this view was obvious by about the middle 
of the present century, when a deeper study was made of 
the psychic activity of the lower animal forms, especially 
the coelenterates (sponges and cnidaria) : they are un- 
doubtedly animals, yet there is no more trace of a definite 
consciousness in* them than in most of the plants. The 
distinction between the two kingdoms was still further 
obliterated when more careful research was made into their 
unicellular forms. There is no psychological difference 
between the plasmophagous protozoa arid the plasmodom- 
ous protophyta, even in respect to their consciousness. 

IV. Biological theory of consciousness. It is found In 
all organisms, animal or vegetal, but not in lifeless bodies 
(such as crystals). This opinion is usually associated with 
the idea that all organisms (as distinguished from inorganic 
substances) have souls : the three ideas life, soul, and 
consciousness are then taken to be co-extensive. Another 
modification of this view holds that, though these funda- 
mental phenomena of organic life are inseparably con- 
nected, yet consciousness is only a part of the activity of 
the soul, and of the vital activity. Fechner, in particular, 
has endeavoured to prove that the plant has a "soul," in 
the same sense as an animal is said to have one ; and many 
credit the vegetal soul with a consciousness similar to that 
of the animal soul. In truth, the remarkable stimulated 
movements of the leaves of the sensitive plants (the 
mimosa, drosera, and dionaea), the automatic movements 
of other plants (the clover and wood-sorrel and especially 
the hedysarum), the movements of the "sleeping plants " 
(particularly the papilionacea), etc., are strikingly similar 
to the movements of the lower animal forms : whoever 
ascribes consciousness to the latter cannot refuse it to such 
vegetal forms. 


V. Cellular theory of consciousness. It is a vital pro- 
perty of every cell. The application of the cellular theory 
to every branch of biology involved its extension to 
psychology. Just as we take the living cell to be the 
k * elementary organism " in anatomy and physiology, and 
derive the whole system of the multicellular animal or 
plant from it, so, with equal right, we may consider the 
u cell-soul " to be the psychological unit, and the complex 
psychic activity of the higher organism to be the result 
of the combination of the psychic activity of the cells 
which compose it. I gave the outlines of this cellular 
psychology in my General Morphology in 1866, and 
entered more fully into the subject in my paper on Cell- 
souls and Soul-cells. I was led to a deeper study of this 
4 'elementary psychology" by my protracted research into 
the unicellular forms of life. Many of these tiny (gener- 
ally microscopic) protists show similar expressions of 
sensation and will, and similar instincts and movements, 
to those of higher animals ; that is especially true of the 
very sensitive and lively Infusoria. In the relation of 
these sensitive cell-organisms to their environment, and in 
many other of their vital expressions (for instance, in the 
wonderful architecture of the rhizopods, the thalamo- 
phora, and the infusoria), we seem to have clear indica- 
tions of conscious psychic action. If, then, we accept the 
biological theory of consciousness (No. IV.), and credit 
every psychic function with a share of that faculty, we 
shall be compelled to ascribe it to each independent pro- 
tist-cell. In that case its material basis would be either 
the entire protoplasm of the cell or its nucleus, or a por- 
tion of it. In the " psychade- theory " of Fritz Schultze 
the elementary consciousness of the psychade would have 
the same relation to the individual cells as personal con- 
sciousness has to the multicellular organism of the per- 
sonality in the higher animals and man. It is impossible 
definitely to disprove this theory, which I held at one time. 
Still, I now feel compelled to agree with Max Verworn 
in his belief that none of the protists have a developed 
self-consciousness, but that their sensations and move* 
ments are of an unconscious character. 


VI. At omit tic theory of contciouinett. It it an elemen- 
tary property of all atoms. This atomistic hypothesis 
goes farthest of all the different views as to the extension 
of consciousness. It certainly escapes the difficulty which 
many philosophers and biologists experience in solving the 
problem of the first origin of consciousness. It is a pheno- 
menon of so peculiar a character that a derivation of it 
from other psychic functions seems extremely hazardous. 
It seemed, therefore, the easiest way out of the difficulty 
to conceive it as an inherent property of all matter, like 
gravitation or chemical affinity. On that hypothesis there 
would be as many forms of this original consciousness as 
there are chemical elements ; each atom of hydrogen would 
have its hydrogenic consciousness, each atom of carbon its 
carbonic consciousness, and so forth. There are philo- 
sophers, even, who ascribe consciousness to the four 
elements of Empedocles, the union of which, by " love and 
hate," produces the totality of things. 

Personally, I have never subscribed to this hypothesis 
of atomic consciousness. I emphasise the point because 
Emil du Bois-Heymond has attributed it to me. In the 
controversy I had with him (1880) he violently attacked 
my *' pernicious and false philosophy," and contended that 
I had, in my paper on The Perigeneti* of the Plastidule, 
" laid it down as a metaphysical axiom that every atom 
has its individual consciousness." On the contrary, I 
explicitly stated that I conceive the elementary psychic 
qualities of sensation and will, which may be attributed 
to atoms, to be unconiciou* just as unconscious as the 
elementary memory which I, in company with that dis- 
tinguished physiologist Ewald Hering, consider to be "a 
common function of all organised matter " or, more 
correctly, "living substance." Du Bois-Reymond curi- 
ously confuses "foul" and "consciousness": whether 
from oversight or not I cannot say. Since he considers 
consciousness to be a transcendental phenomenon (as we 
shall see presently), while denying that character to other 
psychic functions the action of the senses, for example 
I must infer that he recognises the difference of the two 
ideas. Other parts of his eloquent speeches contain quite 


the opposite view, for the famous orator not infrequently 
contradicts himself on important questions of principle. 
However, 1 repeat that, in my opinion, consciousness is 
only part of the psychic phenomena which we find in man 
and the higher animals; the great majority of them are 

However divergent are the different views as to the 
nature and origin of consciousness, they may, nevertheless, 
on a clear and logical examination, all be reduced to two 
fundamental theories the transcendental (or dualistic) and 
the physiological (or monistic). I have myself always 
held the latter view, in the light of my evolutionary prin- 
ciples, and it is now shared by a great number of distin- 
guished scientists, though it is by no means generally 
accepted. The transcendental theory is the older and 
much more common ; it has recently come once more into 
prominence, principally through Du Bois-Reymond, and 
it has acquired a great importance in modern discussions 
of cosmic problems through his famous " Ignorabimus 
speech." On account of the extreme importance of this 
fundamental question we must touch briefly on its main 

In the celebrated discourse on "The Limits of Natural 
Science " which E. du Bois-Reymond gave on August 
14th, 1872, at the Scientific Congress at Leipzig, he spoke 
of two "absolute limits " to our possible knowledge of 
nature which the human mind will never transcend in its 
most advanced science never, as the oft-quoted termina- 
tion of the address, "Ignorabiinus," emphatically pro- 
nounces. The first absolutely insoluble " world-enigma " 
is the "connection of matter and force," and the distinc- 
tive character of these fundamental natural phenomena ; 
we shall go more fully into this " problem of substance " 
in the twelfth chapter. The second insuperable difficulty 
of philosophy is given as the problem of consciousness 
the question how our mental activity is to be explained by 
material conditions, especially movements, how '* substance 
[the substance which underlies matter and force] conies, 
under certain conditions, to feel, to desire, and to think." 

For brevity, and in order to give a characteristic name 


orients of psychic activity that produce thought and con- 
sciousness. In front we have the frontal brain or centre 
of association; behind, on top there is the vertical brain, 
or parietal centre of association, and underneath the prin- 
cipal brain, or "the great occipito-temjjoral centre of 
association " (the most important of all) ; lower down, 
Had internally, the insular brain or the insula of Reii, the 
insular centre of association. These four " thought- 
centres," distinguished from the intermediate "sense- 
centres M by a peculiar and elaborate nerve-structure, are 
the true and sole organs of thought and consciousness. 
Flechsig has recently pointed out that in the case of man 
very specific structures are found in one part of them ; 
these structures are wanting in the other mammals, arid 
they, therefore, afford an explanation of the superiority of 
man's mental powers. 

The momentous announcement of modern physiology, 
that the cerebrum is the organ of consciousness and mental 
action in man and the higher mammals, is illustrated and 
confirmed by the pathological study of its diseases. When 
parts of the cortex are destroyed by disease their respec- 
tive functions are affected, and thus we are enabled, to 
some extent, to localise the activities of the brain ; when 
certain parts of the area are diseased, that portion of 
thought and consciousness disappears which depends on 
those particular sections. Pathological experiment yields 
the same result ; the decay of some known area (for 
instance, the centre of speech) extinguishes its function 
(speech). In fact, there is proof enough in the most 
familiar phenomena of consciousness of their complete 
dependence on chemical changes in the substance of the 
brain. Many beverages (such as coffee and tea) stimulate 
our powers of thought ; others (such as wine and beer) 
intensify feeling; musk and camphor reanimate the faint* 
tng consciousness ; ether and chloroform deaden it, and so 
forth. How would that be possible if consciousness were 
an immaterial entity, independent of these anatomical 
organs? And what becomes of the consciousness of the 
14 immortal soul " when it no longer has the use of these 
organs ? 


These and other familiar facts prove that man's con- 
sciousness and that of the nearest mammals is change- 
able, and that its activity is always open to modification 
from inner (alimentation, circulation, etc.) and outer 
causes (lesion of the brain, stimulation, etc.)- Very in- 
structive, too, are the facts of double and intermittent 
consciousness, which remind us of "alternate generation* 
of presentations." The same individual has an entirely 
different consciousness on different days, with a change of 
circumstances ; he does not know to-day what he did 
yesterday : yesterday lie could say, " I am I " ; to-day he 
must say, *' I am another being." Such iiitermittence of 
eonsciousness may last not only days, but months, and 
even years ; the change may even become permanent. 

As everybody knows, the new-born infant has no con- 
sciousness. Preyer has shown that it is only developed 
ttf ler the child has begun to speak ; for a long time it 
speaks of itself in the third person. In the important 
moment when it first pronounces the word "I," when the 
feeling of self becomes clear, we have the beginning of 
self-consciousness, and of the antithesis to the non-ego. 
The rapid and solid progress in knowledge which the 
child makes in its first ten years, under the care of 
parents and teachers, and the slower progress of the 
second decade, until it reaches complete maturity of mind, 
are intimately connected with a great advancement in the 
growth and development of consciousness and of its organ, 
the brain. But even when the pupil has got his *' certifi- 
cate of maturity " his consciousness is still far from 
mature ; it is then that his " world-consciousness ?l first 
begins to develop, in his manifold relations with the outer 
world. Then, in the third decade, we have the full 
maturity of rational thought and consciousness, which, in 
cases of normal development, yield their ripe fruits during 
the next three decades. The slow, gradual degeneration 
of the higher mental powers, which characterises senility, 
usually sets in at the commencement of the seventh 
decade sometimes earlier, sometimes later. Memory, 
receptiveness, and interest in particular objects gradually 
decay ; though productivity, mature consciousness, and 


philosophic interest in general truths often remain for 
many years longer. 

The individual development of consciousness of earlier 
youth proves the universal validity of the biogenetic law ; 
and, indeed, it is still recognisable in many ways during 
the later years. In any case, the ontogenesis of conscious- 
ness makes it perfectly clear that it is not an " immaterial 
entity," but a physiological function of the brain, and 
that it is, consequently, no exception to the general law 
of substance. 

From the fact that consciousness, like all other psychic 
functions, is dependent on the normal development of 
certain organs, and that it gradually unfolds in the child 
in proportion to the development of those orgattJ, we may 
already conclude that it has arisen in the animal kingdom 
by a gradual historical development. Still, however cer- 
tain we are of the fact of this natural evolution of con- 
sciousness, we are, unfortunately, not yet in a position to 
enter more deeply into the question and construct special 
hypotheses in elucidation of it. Palaeontology, it is true, 
gives us a few facts which are not without significance. 
For instance, the quantitative and qualitative development 
of the brain of the placental mammals during the Tertiary 
period is very remarkable. The cavity of many of the 
fossil skulls of the period has been carefully examined, 
and has given us a good deal of reliable information as 
to the size, and, to some extent, as to the structure, of the 
brain they enclosed. We find, within the limits of one 
and the same group (the ungulates, the rodents, or the 
primates), a marked advance in the later miocene and 
pliocene specimens as compared with the earlier eocene and 
oligocene representatives of the same stem : in the former 
the brain (in proportion to the size of the organism) is 
0-8 times as large as in the latter. 

Moreover, that highest stage of consciousness which is 
reached by man alone has been evolved step by step 
even by the very progress of civilisation from a lower 
condition, as we find illustrated to-day in the case of 
uncivilised races. That is easily proved by a comparison 
of their languages, which is closely connected with the 


it is to detect 
of deli, ind eniWj 

J / 


, tie nt 

no i iiic 
dcepei doy an coiiou 



The citadel of superstition. Athanatism and thanatisra. ID dividual 
character of death. Immortality of the unicellular organisms 
(protista). Cosmic and personal immortality. Primary thanalism 
(of uncivilised peoples). Secondary thanatism (of ancient and 
recent philosophers). Athanatism and religion. Origin of the 
belief in immortality. Christian athanatism. Eternal life. The 
day of judgment Metaphysical athanatism. Substance of the 
soul. Ether souls and air souls ; fluid souls and solid souls, 
Immortality of the animal soul. Arguments for and against 
ithaiiatism. Athanatist illusions. 

WHEN we turn from the genetic study of the soul to the 
great question of its immortality, we come to that highest 
point of superstition which is regarded as the impregnable 
citadel of all mystical and dualistic notions. For in this 
crucial question, more than in any other problem, philo- 
sophic thought is complicated by the selfish interest of the 
human personality, who is determined to have a guarantee 
of his existence beyond the grave at any price. This 
"higher necessity of feeling " is so powerful that it 
sweeps aside all the logical arguments of critical reason. 
Consciously or unconsciously, most men are influenced in 
all their general views, and, therefore, in their theory of 
life, by the dogma of personal immortality; and to this 
theoretical error must be added practical consequences of 
the most far-reaching character. It is our task, therefore, 
to submit every aspect of this important dogma to a 
critical examination, and to prove its untenability in the 
light of the empirical data of modern biology. 

In order to have a short and convenient expression for 
the two opposed opinions on the question, we shall call 
the belief in man's personal immortality " athanttism " 



(from athanet or thanatot immortal. On the other 
hand, we give the name of " thanatism " (from thanatot** 
death) to the opinion which holds that at a man's death 
not only all the other physiological functions are arrested, 
but his k * soul " also disappears that is, that sum of 
cerebral functions which psychic dualism regards as a 
peculiar entity, independent of the other vital processes 
in the living body. 

In approaching this physiological problem of death we 
must point out the individual character of this organic 
phenomenon. By death we understand simply the definite 
cessation of the vital activity of the individual organism, 
no matter to which category or stage of individuality the 
organism in question belongs. Man is dead when his own 
personality ceases to exist, whether he has left offspring 
that may continue to propagate for many generations or 
not. In a certain sense we often say that the minds of 
great men (in a dynasty of eminent rulers, for instance, 
or a family of talented artists) live for many generations ; 
and in the same way we speak of the "soul " of a noble 
woman living in her children and children's children. But 
in these cases we are dealing with intricate phenomena of 
heredity, in which a microscopic cell (the sperm-cell of 
the father or the egg-cell of the mother) transmits certain 
features to offspring. The particular personalities which 
produce those sexual cells in thousands are mortal beings, 
and at their death their personal psychic activity is extin- 
guished like every other physiological function. 

A number of eminent zoologists Weismann being par- 
ticularly prominent have recently defended the opinion 
that only the lowest unicellular organisms, the protists, 
are immortal, In contradistinction to the multicellular 
plants and animals, whose bodies are formed of tissues. 
This curious theory is especially based on the fact that 
most of the protists multiply without sexual means, by 
division or the formation of spores. In such processes 
the whole body of the unicellular organism breaks up into 
two or more equal parts (daughter-cells), and each of 
these portions completes itself by further growth until it 
has the size and form of the mother-cell. However, by 


the very process of division the individuality of the uni- 
cellular creature has been destroyed; both its physio- 
logical and its morphological unity have gone. The view 
of Weismanu is logically inconsistent with the very notion 
of individual an "indivisible" entity; for it implies a 
unity which cannot be divided without destroying its 
nature. In this sense the unicellular protophyta and pro- 
tozoa are throughout life physiological individuals, just 
as much as the muiticellular tissue-plants and animals. 
Asexual propagation by simple division is found in many 
of the multicellular species (for instance, in many cnidaria, 
corals, medusae, etc.); the mother-animal, the division of 
which gives birth to the two daughter-animals, ceases to 
exist with the segmentation. "The protozoa," says 
Weisrnann, " have no individuals and no generations in the 
metazoic sense." I must entirely dissent from his thesis. 
As I was the first to introduce the title of metazoa, and 
oppose these multicellular, tissue-forming animals to the 
unicellular protozoa (infusoria, rhizopods, etc.)j and as I 
was the first to point out the essential difference in the 
development of the two (the former from germinal layers, 
and the latter not), I must protest that I consider the 
protozoa to be just as mortal in the physiological (and 
psychological) sense as the metazoa ; neither body nor 
soul is immortal in either group. The other erroneous 
consequences of Weismann's notion have been refuted by 
Moebius (1884), who justly remarks that "every event in 
the world is periodic," and that " there is no source from 
which immortal organic individuals might have sprung." 
When we take the idea of immortality in the widest 
tense, and extend it to the totality of the knowable 
universe, it has a scientific significance; it is then not 
merely acceptable, but self-evident, to the monistic philo- 
sopher. In that sense the thesis of the indestructibility 
and eternal duration of all that exists is equivalent to our 
lupreme law of nature, the law of tubstancc (see chap, 
zii.). As we intend to discuss this immortality of the 
cosmos fully later on, in establishing the theory of the 
persistence of matter and force, we shall not dilate on it 
at present. We pass oil immediately to the criticism of 


that belief in immortality which is the only sense usually 
attached to the word, the immortality of the individual 
soul. We shall first inquire into the extent and the origin 
of this mystic and dualistic notion, and point out, in 
particular, the wide acceptance of the contradictory thesis, 
our monistic, empirically-established thanatism. I must 
distinguish two essentially different forms of thanatism 
primary and secondary; primary thanatism is the original 
absence of the dogma of immortality (in the primitive 
uncivilised races); secondary thanatism is the later out- 
come of a rational knowledge of nature in the civilised 

We still find it asserted in philosophic, and specially in 
theological, works that belief in the personal immortality 
of the human soul was originally shared by all men or, 
at least, by all " rational" men. That is not the case. 
This dogma is not an original idea of the human mind, nor 
has it ever found universal acceptance. It has been abso- 
lutely proved by modern comparative ethnology that many 
uncivilised races of the earliest and most primitive stage 
had no notion either of immortality or of God. That is 
true, for instance, of the Veddahs of Ceylon, those primi- 
tive pygmies whom, on the authority of the able studies 
of the Sarasins, we consider to be a relic of the earliest 
inhabitants of India; 1 it is also the case in several of the 
earliest groups of the nearly related Dravidas, the Indian 
Seelorigs, and some native Australian races. Similarly, 
several of the primitive branches of the American race, 
in the interior of Brazil, on the upper Amazon, etc., have 
no knowledge either of gods or immortality. This primary 
absence of belief in immortality and deity is an extremely 
important fact ; it is, obviously, easy to distinguish from 
the tecondary absence of such belief, which has come 
about in the highest civilised racei as the result of 
laborious criti co-philosophical study. 

Differently from the primary thanatism which originally 

characterised primitive man, and has always been widely 

spread, the tecondary absence of belief in immortality is 

only found at a late stage of history : it is the ripe fruit 

* E. Haeckei, A Vitit to Otyltm. 


of profound reflection on life and death, the outcome of 
bold and independent philosophical speculation. We first 
meet it in some of the Ionic philosophers of the sixth 
century B.C., then in the founders of the old materialistic 
philosophy, Democritus and Empedocles, and also in 
Simonides and Epicurus, Seneca and Plinius, and in an 
elaborate form in Lucretius Carus. With the spread of 
Christianity at the decay of classical antiquity, athanat- 
isin, one of its chief articles of faith, dominated the 
world, and so, amid other forms of superstition, the myth 
of personal immortality came to be investigated with a 
high importance. 

Naturally, through the long night of the Dark Ages it 
was rarely that a brave freethinker ventured to express 
an opinion to the contrary : the examples of Galileo, 
Giordano Bruno, and other independent philosophers, 
effectually destroyed all freedom of utterance. Heresy 
only became possible when the Reformation and the 
Renaissance had broken the power of the papacy. The 
history of modern philosophy tells of the manifold methods 
by which the matured mind of man sought to rid itself of 
the superstition of immortality. Still, the intimate con- 
nection of the belief with the Christian dogma invested it 
with such power, even in the more emancipated sphere of 
Protestantism, that the majority of convinced freethinkers 
kept their sentiments to themselves. From time to time 
some distinguished scholar ventured to make a frank 
declaration of his belief in the ini possibility of the con- 
tinued life of the soul after death. This was done in 
France in the second half of the eighteenth century by 
Danton, Mirabeau, and others, and by the leaders of the 
materialistic school of those days, Holbach, Lamettrie, etc. 
The same opinion was defended by the able friend of the 
Materialists, the greatest of the Hohenzollerns, the 
monistic "philosopher of Sans-souci." What would Fred- 
erick the great, the " crowned thanatist and atheist," say, 
could he compare his monistic views with those of his 
successor of to-day? 

Among thoughtful physicians the conviction that the 
existence of the soul came to an end at death has been 


common for centuries : generally, however, they refrained 
from giving it expression. Moreover, the empirical 
science of the brain remained so imperfect during the last 
century that the soul could continue to be regarded as its 
mysterious inhabitant. It was the gigantic progress of 
biology in the present century, and especially in the 
latter half of the century, that finally destroyed the 
myth. The establishment of the theory of descent and 
the cellular theory, the astounding discoveries of ontogeny 
and experimental physiology above all, the marvellous 
progress of the microscopic anatomy of the brain 
gradually deprived athanatism of every basis ; now, indeed, 
it is rarely that an informed and honourable biologist ii 
found to defend the immortality of the soul. All the 
monistic philosophers of the century (Strauss, Feuerbach, 
Biichner, Spencer, etc.) are thanatists. 

The dogma of personal immortality owes its great 
popularity and its high importance to its intimate con- 
nection with the teaching of Christianity. This circum- 
stance gave rise to the erroneous and still prevalent belief 
that the myth is a fundamental element of all the higher 
religions. That is by no means the case. The higher 
oriental religions include no belief whatever in the immor- 
tality of the soul ; it is not found in Buddhism, the 
religion that dominates thirty per cent, of the entire 
human race ; it is not found in the ancient popular religion 
of the Chinese, nor in the reformed religion of Confucius 
which succeeded it; and, what is still more significant, it 
is not found in the earlier and purer religion of the Jews. 
Neither in the " five Mosaic books,*' nor in any of the 
writings of the Old Testament which were written before 
the Babylonian Exile, is there any trace of the notion of 
individual persistence after death. 

The mystic notion that the human soul will live for 
ever after death has had a polyphyletic origin. It was 
unknown to the earliest speaking man (the hypothetical 
homo primigeniui of Asia), to his predecessors, of course, 
the pithecanthropi*! and prothylobatet, and to the least 
developed of his modern successors, the Veddahs of 
Ceylon, the Seelongs of India, and other distant races. 


With the development of reason and deeper reflection on 
life and death, sleep and dreams, mystic ideas of a dualistic 
composition of our nature were evolved independently 
of each other in a number of the earlier races. Very 
different influences were at work in these polyphyletic 
creations worship of ancestors, love of relatives, love of 
life and desire of its prolongation, hope of better con- 
ditions of life beyond the grave, hope of the reward of 
good and punishment of evil deeds, and so forth. Com- 
parative psychology has recently brought to our knowledge 
a great variety of myths and legends of that character ; 
they are, for the most part, closely associated with the 
oldest forms of theistic and religious belief. In most of 
the modern religions athanatism is intimately connected 
with theism ; the majority of believers transfer their 
materialistic idea of a "personal God " to their "immortal 
soul." That is particularly true of the dominant religion 
of modern civilised states, Christianity. 

As everybody knows, the dogma of the immortality of 
the soul has long since assumed in the Christian religion 
that rigid form which it has in the articles of faith : " I 
believe in the resurrection of the body and in an eternal 
life." Man will arise on "the last day," as Christ is 
alleged to have done on Easter morn, and receive a reward 
according to the tenour of his earthly life. This typically 
Christian idea is thoroughly materialistic and anthropo- 
morphic ; it is very little superior to the corresponding 
crude legends of uncivilised peoples. The impossibility 
of " the resurrection of the body " is clear to every man 
who has some knowledge of anatomy and physiology. 
The resurrection of Christ, which is celebrated every 
Easter by millions of Christians, is as purely mythical as 
"the awakening of the dead," which he is alleged to 
have taught. These mystic articles of faith are just as 
untenable in the light of pure reason as the cognate 
hypothesis of "eternal life." 

The fantastic notions which the Christian Church dis- 
semi nates as to the eternal life of the immortal soul after 
the dissolution of the body are just as materialistic as the 
dogma of "the resurrection of the body." In his inter- 


eating work on Religion in the Light of the Darwinian 
Theory, Savage justly remarks : " It is one of the standing 
charges of the Church against science that it is material- 
istic. I must say, in passing, that the whole ecclesiastical 
doctrine of a future life has always been, and still is, 
materialism of the purest type. It teaches that the 
material body shall rise, and dwell in a material heaven." 
To prove this one has only to read impartially some of the 
sermons and ornate discourses in which the glory of the 
future life is extolled as the highest good of the Chris- 
tian, and belief in it is laid down to be the foundation of 
morality. According to them, all the joys of the most 
advanced modern civilisation await the pious believer in 
Paradise, while the " All-loving Father " reserves his 
eternal fires for the godless materialist 

In opposition to the materialist athanatism which is 
dominant in the Christian and Mohammedan Churches, 
we have, apparently, a purer and higher form of faith in 
metaphysical athanatism, as taught by most of our dualist 
and spiritualist philosophers. Plato must be considered 
its chief creator : in the fourth century before Christ he 
taught that complete dualism of body and soul which 
afterwards became one of the most important, theoretically, 
and one of the most influential, practically, of the Chris- 
tian articles of faith. The body is mortal, material, 
physical; the soul is immortal, immaterial, metaphysical. 
They are only temporarily associated, for the course of 
the individual life. As Plato postulated an eternal life 
before aa well as after this temporary association, he must 
be classed as an adherent of "metempsychosis," or tram- 
migration of souls; the soul existed as such, or as an 
"eternal idea," before it entered into a human body. 
When it quits one body, it seeks such other as is most 
suited to its character for its habitation. The souls of 
bloody tyrants pass into the bodies of wolves and vul- 
tures, those of virtuous toilers migrate into the bodies of 
bees and ants, and so forth. The childish naivete* of this 
Platonic morality is obvious; on closer examination hii 
views are found to be absolutely incompatible with the 
scientific truth which we owe to modern anatomy, physio- 


logy, histology, and ontogeny ; we mention them only 
because, in spite of their absurdity, they have had a pro- 
found influence on thought and culture. On the one 
hand, the mysticism of the Neo-Platonists, which pene- 
trated into Christianity, attached itself to the psychology 
of Plato; on the other hand, it became subsequently one 
of the chief supports of spiritualistic and idealistic philo- 
sophy. The Platonic "idea" gave way in time to the 
notion of psychic " substance "; this is just as incompre- 
hensible and metaphysical, though it often assumed a 
physical appearance. 

The conception of the soul as a " substance " is far from 
clear in many psychologists ; sometimes it is regarded as 
an " immaterial " entity of a peculiar character in an 
abstract and idealistic sense, sometimes in a concrete and 
realistic sense, and sometimes in a confused tertium quid 
between the two. If we adhere to the monistic idea of 
substance, which we develop in chap, xii., and which 
takes it to be the simplest element of our whole world- 
system, we find energy and matter inseparably associated 
in it. We must, therefore, distinguish in the "substance 
of the soul " the characteristic psychic energy which is 
all we perceive (sensation, presentation, volition, etc.), 
and the psychic matter, which is the indispensable basis 
of its activity that is, the living protoplasm. Thus, in 
the higher animals the "matter" of the soul is a part 
of the nervous system ; in the lower nerveless animals and 
plants it is a part of their multicellular protoplasmic body ; 
and in the unicellular protists it is a part of their proto- 
plasmic cell-body. In this way we are brought once more 
to the psychic organs, and to an appreciation of the fact 
that these material organs are indispensable for the action 
of the soul ; but the soul itself is actual it is the sum-total 
of their physiological functions. 

However, the idea of a specific " soul-substance " 
found in the dualistic philosophers who admit such a 
thing is very different from this. They conceive the 
Immortal soul to be material, yet invisible, and essentially 
different from the visible body which it inhabits* Thus 
iffutttbfltty comes to be regarded as a most important 


attribute of the soul. Some, in fact, compare the soul 
with ether, and regard it, like ether, as an extremely 
subtle, light, and highly elastic material, an imponderable 
agency, that fills the intervals between the ponderable 
particles of the living organism. Others compare the soul 
with the wind, and so give it a gaseous nature; and it is 
this simile which first found favour with primitive peoples, 
and led in time to the familiar dualistic conception. 
When a man died, the body remained as a lifeless corpse, 
but the immortal soul " flew out of it with the last 

The comparison of the human soul with physical ether 
as a qualitatively similar idea has assumed a more concrete 
shape in recent times through the great progress of 
optics and electricity (especially in the last decade); for 
these sciences have taught us a good deal about the energy 
of ether, and enabled us to formulate certain conclusions 
as to the material character of this all-pervading agency. 
As I intend to describe these important discoveries later 
on (in chap, xii.), I shall do no more at present than 
briefly point out that they render the notion of an " etheric 
soul " absolutely untenable. Such an etheric soul that 
is, a psychic substance which is similar to physical ether, 
and which, like ether, passes between the ponderable 
elements of the living protoplasm or the molecules of the 
brain, cannot possibly account for the individual life of the 
soul. Neither the mystic notions of that kind which were 
warmly discussed about the middle of the century, nor 
the attempts of modern " Neovitalists " to put their 
mystical " vital force " on a line with physical ether, 
call for refutation any longer. 

Much more widespread, and still much respected, is 
the view which ascribes a gaseous nature to the substance 
of the soul. The comparison of human breath with the 
wind is a very old one ; they were originally considered 
to be identical, and were both given the same name. 
The anemot and psyche of the Greeks, and the anima and 
spiritut of the Romans, were originally ail names for "a 
breath of wind " ; they were transferred from this to the 
breath of man. After a time this "living breath " was 


identified with the "vital force," and finally it came to 
be regarded AS the soul itself, or, in a narrower sense, as 
its highest manifestation, the "spirit." From that the 
imagination went on to derive the mystic notion of indi- 
vidual "spirits"; these, also, are stUl usually conceived 
as "aeriform beings" though they are credited with 
the physiological functions of an organism, and they have 
been photographed in certain well-known spiritist circles. 

Experimental physics has succeeded, during the last 
decade of the century, in reducing all gaseous bodies to 
a liquid most of them, also, to a solid condition. 
Nothing more is needed than special apparatus which 
exerts a violent pressure on the gases at a very low tem- 
perature. By this process not only the atmospheric 
elements, oxygen, hydrogen, and nitrogen, but even 
compound gases (such as carbonic acid gas) and gaseous (like the atmosphere), have been changed from 
gaseous to liquid form. In this way the "invisible" 
substances have become "visible " to all, and in a certain 
sense "tangible." With this transformation the mystic 
nimbus which formerly veiled the character of the gas in 
popular estimation as an invisible body that wrought 
visible effects has entirely disappeared. If, then, the 
substance of the soul were really gaseous, it should be 
possible to liquefy it by the application of a high pressure 
at a low temperature. We could then catch the soul as it 
is " breathed out " at the moment of death, condense it, 
and exhibit it in a bottle as " immortal fluid " (Fluidum 
animse immorlale). By a further lowering of temperature 
and increase of pressure it might be possible to solidify 
it to produce "soul-snow." The experiment has not 
jnet succeeded. 

If athanatism were true, if indeed the human soul were 
to Hve for all eternity, we should have to grant the same 
privilege to the souls of the higher animals, at least to 
those of the nearest related mammals (apes, dogs, etc.). 
For man is not distinguished from them by a special kind 
of soul, or by any peculiar and exclusive psychic function, 
but only by a higher degree of psychic activity, a superior 
tage of development. In particular, consciousness the 


function of the association of ideas, thought, and reason 
has reached a higher level in many men (by no means in 
ail) than in most of the animals. Yet this difference is 
far from being so great as is popularly supposed ; and it is 
much slighter in every respect than the corresponding 
difference between the higher and the lower animal souls, 
or even the difference between the highest and the lowest 
stages of the human soul itself. If we ascribe " personal 
immortality " to man, we are bound to grant it also to 
the higher animals. 

It is, therefore, quite natural that we should find this 
belief in the immortality of the animal soul among many 
ancient and modern peoples ; we even meet it sometimes 
to-day in many thoughtful men who postulate an "im- 
mortal life " for themselves, and have, at the same time, 
a thorough empirical knowledge of the psychic life of the 
animals. I once knew an old head-forester, who, being 
left a widower and without children at an early age, had 
lived alone for more than thirty years in a noble forest of 
East Prussia. His only companions were one or two 
servants, with whom he exchanged merely a few necessary 
words, and a great pack of different kinds of dogs, with 
which he lived in perfect psychic communion. Through 
many years of training this keen observer and friend of 
nature had penetrated deep into the individual souls of 
his dogs, and he was as convinced of their personal immor- 
tality as he was of his own. Some of his most intelligent 
dogs were, in his impartial and objective estimation, at 
a higher stage of psychic development than his old, 
tupid maid and the rough, wrinkled manservant. Any 
unprejudiced observer who will study the conscious and 
intelligent psychic activity of a fine dog for a jrear, 
and follow attentively the physiological processes of 
its thought, judgment, and reason, will have to admit 
that it has just as valid a claim to immortality as man 

The proofs of the immortality of the soul, which have 
been adduced for the last two thousand years, and are, 
indeed, still credited with tome validity, have their origin, 
for the most part, not in an effort to discover the truth, 


but in an alleged " necessity of emotion " that is, in 
imagination and poetic conceit. As Kant puts it, the 
immortality of the soul is not an object of pure reason, 
but a "postulate of practical reason." But we must set 
"practical reason " entirely aside, together with all the 
"exigencies of emotion, or of moral education," etc., 
when we enter upon an honest and impartial pursuit 
of truth ; for we shall only attain it by the work of 
pure reason, starting from empirical data and capable 
of logical analysis. We have to say the same of 
athanatism as of theism ; both are creations of poetic 
mysticism and of transcendental "faith," not of rational 

When we come to analyse all the different proofs that 
have been urged for the immortality of the soul, we find 
that not a single one of them is of a scientific character ; 
not a single one is consistent with the truths we have 
learnt in the last few decades from physiological psycho- 
logy and the theory of descent. The theological proof 
that a personal creator has breathed an immortal soul 
(generally regarded as a portion of the divine soul) into 
man is a pure myth. The cosmological proof that the 
"moral order of the world " demands the eternal duration 
of the human soul is a baseless dogma. The Ideological 
proof that the " higher destiny " of man involves the 
perfecting of his defective, earthly soul beyond the grave 
rests on a false anthropism. The moral proof that the 
defects and the unsatisfied desires of earthly existence 
must be fulfilled by " compensative justice " on the other 
side of eternity is nothing more than a pious wish. The 
ethnological proof that the belief in immortality, like the 
belief in God, is an innate truth, common to all humanity 
is an error in fact. The ontological proof that the 
soul, being a "simple, immaterial, and indivisible entity, " 
cannot be involved in the corruption of death is based 
on an entirely erroneous view of the psychic phenomena ; 
it is a spiritualistic fallacy. All these and similar " proofs 
of athanatism " are in a parlous condition ; they are defi- 
nitely annulled by the scientific criticism of the last few 


The extreme importance of the subject leads us to oppose 
to these untenable " proofs of immortality " a brief exposi- 
tion of the sound scientific arguments against it. The 
physiological argument shows that the human soul is not 
an independent, immaterial substance, but, like the soul of 
all the higher animals, merely a collective title for the 
sum-total of man's cerebral functions ; and these are just 
as much determined by physical and chemical processes as 
any of the other vital functions, and just as amenable to 
the law of substance. The histological argument is based 
on the extremely complicated microscopic structure of the 
brain; it shows us the true "elementary organs of the 
soul " in the ganglionic cells. The experimental argu- 
ment proves that the various functions of the soul are 
bound up with certain special parts of the brain, and 
cannot be exercised unless these are in a normal condition ; 
if the areas are destroyed, their function is extinguished ; 
and this is especially applicable to the "organs of 
thought," the four central instruments of mental activity. 
The pathological argument is the complement of the 
physiological ; when certain parts of the brain (the centres 
of speech, sight, hearing, etc.) are destroyed by sickness, 
their activity (speech, vision, hearing, etc.) disappears ; in 
this way Nature herself makes the decisive physiological 
experiment. The onto genetic argument puts before us 
the facts of the development of the soul in the individual ; 
we see how the child-soul gradually unfolds its various 
powers ; the youth presents them in full bloom, the mature 
man shows their ripe fruit ; in old age we see the gradual 
decay of the psychic powers, corresponding to the senile 
degeneration of the brain. The phylo genetic argument 
derives its strength from palaeontology, and the com- 
parative anatomy and physiology of the brain ; co-operating 
with and completing each other, these sciences prove to 
the hilt that the human brain (and, consequently, its 
function the soul) has been evolved step by step from 
that of the mammal, and, still further back, from that of 
the lower vertebrate. 

These inquiries, which might be supplemented by many 
other results of modern science, prove the old dogma of 


the immortality of the soul to be absolutely untenable; 
In the twentieth century it will not be regarded as a subject 
of serious scientific research, but will be left wholly to 
transcendental "faith." The "critique of pure reason " 
shows this treasured faith to be a mere tuperstition, like 
the belief in a personal God which generally accompanies 
it. Yet even to-day millions of " believers " not only 
of the lower, uneducated masses, but even of the most 
cultured classes look on this superstition as their dearest 
possession and their most "priceless treasure." It is, 
therefore, necessary to enter more deeply into the subject, 
and assuming it to be true to make a critical Inquiry 
into its practical value. It soon becomes apparent to the 
impartial critic that this value rests, for the most part, 
on fancy, on the want of clear judgment and consecutive 
thought. It is my firm and honest conviction that a 
definite abandonment of these " athanatist illusions " 
would involve no painful loss, but an inestimable positive 
gain for humanity. 

Man's "emotional craving " clings to the belief in im- 
mortality for two main reasons : firstly, in the hope of 
securing better conditions of life beyond the grave; and, 
secondly, in the hope of seeing once more the dear and 
loved ones whom death has torn from us. As for the first 
hope, it corresponds to a natural feeling of the justice of 
compensation, which is quite correct subjectively, but has 
no objective validity whatever. We make our claim for 
an indemnity for the unnumbered defects and sorrows of 
our earthly existence, without the slightest real prospect 
or guarantee of receiving it. We long for an eternal life 
in which we shall meet no sadness and no pain, but an 
unbounded peace and joy. The pictures that most men 
form of this 'blissful existence are extremely curious; the 
immaterial soul is placed in the midst of grossly material 
pleasures. The imagination of each believer painti the 
enduring splendour according to his personal taste. The 
American Indian, whose athanatism Schiller has so well 
depicted, trusts to find in his Paradise the finest hunting- 
grounds, with innumerable hordes of buffaloes and bears; 
the Eskimo looks forward to sun-tipped icebergs with an 


inexhaustible supply of bears, seals, and other polar 
animals; the effeminate Cingalese frames his Paradise on 
the wonderful island-paradise of Ceylon, with its noble 
gardens and forests adding that there will be unlimited 
supplies of rice and curry, of cocoa-nuts and other fruit, 
always at hand ; the Mohammedan Arab believes it will be 
a place of shady gardens of flowers, watered by cool 
springs, and filled with lovely maidens ; the Catholic 
fisherman of Sicily looks forward to a daily superabund- 
ance of the most valuable fishes and the finest maccaroni, 
and eternal absolution from all his sins, which he can 
go on committing in his eternal home; the evangelical of 
North Europe longs for an immense Gothic cathedral, in 
which he can chant the praises of the Lord of Hosts for 
all eternity. In a word, each believer really expects his 
eternal life to be a direct continuation of his individual 
life on earth, only in a "much improved and enlarged 

We must lay special stress on the thoroughly material- 
istic character of Christian athanatism, which is closely 
connected with the absurd dogma of the "resurrection of 
the body." As thousands of paintings of famous masters 
inform us, the bodies that have risen again, with the souls 
that have been born again, walk about in heaven just as 
they did on this vale of tears ; they see God with their 
eyes, they hear his voice with their ears, they sing hymns 
to his praise with their larynx, and so forth. In fine, the 
modern inhabitants of the Christian Paradise have the 
same dual character of body and soul, the same organs of 
an earthly body, as our ancient ancestors had in Odin's 
Hail in Walhalla, as the "immortal " Turks and Arabs 
have in Mohammed's lovely gardens, as the old Greek 
denii-gods and heroes had in the enjoyment of nectar 
and ambrosia at the table of Zeus. 

But, however gloriously we may depict this eternal life 
in Paradise, it remains endlen in duration. Do we realise 
what "eternity " means? the uninterrupted continuance 
of our individual life for ever! The profound legend of 
the "wandering Jew," the fruitless search for rest of the 
unhappy Ahasuerui, should teach at to appreciate such 


an "eternal life" at its true value. The best we can 
desire after a courageous life, spent in doing good accord- 
ing to our light, is the eternal peace of the grave. *' Lord, 
give them an eternal rest." 

Any impartial scholar who is acquainted with geological 
calculations of time, and has reflected on the long series 
of millions of years the organic history of the earth has 
occupied, must admit that the crude notion of an eternal 
life is not a comfort, but a fearful menace, to the best of 
men. Only want of clear judgment and consecutive 
thought can dispute it. 

The best and most plausible ground for athanatism is 
found in the hope that immortality will reunite us to the 
beloved friends who have been prematurely taken from us 
by some grim mischance. But even this supposed good 
fortune proves to be an illusion on closer inquiry ; and in 
any case it would be greatly marred by the prospect of 
meeting the less agreeable acquaintances anfl the enemies 
who have troubled our existence here below. Even the 
closest family ties would involve many a difficulty. There 
are plenty of men who would gladly sacrifice all the glories 
of Paradise if it meant the eternal companionship of their 
"better half " and their mother-in-law. It is more than 
questionable whether Henry VIII. would like the prospect 
of living eternally with his six wives ; or Augustus the 
Strong of Poland, who had a hundred mistresses and three 
hundred and fifty-two children. As he was on good terms 
with the Vicar of Christ, he must be assumed to be in 
Paradise, in spite of his sins, and in spite of the fact that 
his mad military ventures cost the lives of more than a 
hundred thousand Saxons. 

Another insoluble difficulty faces the athanatist when 
he asks in what ttage of their individual development the 
disembodied souls will spend their eternal life. Will the 
new-born infant develop its psychic powers in heaven 
under the same hard conditions of the " struggle for life " 
which educate man here on earth? Will the talented 
youth who has fallen in the wholesale murder of war un- 
fold his rich, unused mental powers in Walhalla? Will 
the feeble, childish old man, who has filled the world with 


the fame of his deeds in the ripeness of his age, live for 
ever in mental decay? Or will be return to an earlier 
stage of development? If the immortal souls in Olympus 
are to live in a condition of rejuvenescence and perfectness, 
then both the stimulus to the formation of, and the 
interest in, personality disappear for them. 

Not less impossible, in the light of pure reason, do we 
find the anthropistic myth of the "last judgment," and 
the separation of the souls of men into two great groups, 
of which one is destined for the eternal joys of Paradise 
and the other for the eternal torments of hell and that 
from a personal God who is called the "Father of Love " ! 
And it is this " Universal Father " who has himself 
created the conditions of heredity and adaptation, in virtue 
of which the elect, on the one side, were bound to pursue 
the path towards eternal bliss, and the luckless poor and 
miserable, on the other hand, were driven into the paths 
of the damned. 

A critical comparison of the countless and manifold 
fantasies which belief in immortality has produced during 
the last few thousand years in the different races and 
religions yields a most remarkable picture, An intensely 
interesting presentation of it, based on most extensive 
original research, may be found in Adalbert Svoboda's 
distinguished works, The Illusion of the Soul and Forms 
of Faith. However absurd and inconsistent with modern 
knowledge most of these myths seem to be, they still play 
an important part, and, as " postulates of practical 
reason," they exercise a powerful influence on the opinions 
of individuals and on the destiny of races. 

The idealist and spiritualist philosophy of the day will 
freely grant that these prevalent materialistic forms of 
belief in immortality are untenable ; it will say that the 
refined idea of an immaterial soul, a Platonic "idea " or 
a transcendental psychic substance, must be substituted 
for them. But modem realism can have nothing whatever 
to do with these incomprehensible notions ; they satisfy 
neither the mind's feeling of causality nor the yearning of 
our emotions. If we take a comprehensive glance at all 
that modern anthropology, psychology, and cosmology 


i dp m li In bop ratii 
i fitl Ik most uttd ipirlal tntii i 



The fundamental chemical law of the constancy of matter. The 
fundamental physical law of the conservation of energy. Com- 
bination of both lawi in the law of substance. The kinetic, 
pyknotic, and dualistio ideas of substance. Monism of matter. 
Ponderable matter. Atoms and elements. Affinity of the 
elements. The soul of the atom (feeling and inclination). 
Existence and character of ether. Ether and ponderable matter. 
Force and energy. Potential and actual force. Unity of natural 
forces. Supremacy of the Law of Substance. 

THE supreme and all-pervading law of nature, the true 
and only cosmological law, is, in my opinion, the law of 
substance; its discovery and establishment is the greatest 
intellectual triumph of the nineteenth century, in the 
sense that all other known laws of nature are subordinate 
to it. Under the name of " law of substance " we 
embrace two supreme laws of different origin and age 
the older is the chemical law of the " conservation of 
matter," and the younger is the physical law of the "con- 
servation of energy." It will be self-evident to many 
readers, and it is acknowledged by most of the scientific 
men of the day, that these two great laws are essentially 
inseparable. This fundamental thesis, however, is still 
much contested in some quarters, and we must proceed 
to furnish the proof of it. But we will first devote a few 
words to each of the two laws. 

The law of the "pertistence " or " indettructibility of 
matter," established by Lavoisier in 1789, may be formu- 
lated thus : The sum of matter, which fills infinite space, 
is unchangeable. A body has merely changed its form 
when it seems to have disappeared. When coal burns it 

1 Of. Monism, by Ernst Hteckel. 


is changed into carbonic acid gas by combination with the 
oxygen of the atmosphere; when a piece of sugar melts 
in winter, it merely passes from the solid to the fluid 
condition. In the same way, it is merely a question of 
change of form iu the cases where a new body seems to 
be produced. A shower of rain is the moisture of the 
atmosphere cast down in the form of drops of water ; when 
a piece of iron rusts, the surface layer of the metal has 
combined with water and with atmospheric oxygen, and 
formed a "rust," or oxy-hydrate of iron. Nowhere in 
nature do we find an example of the production, or " crea- 
tion," of new matter; nowhere does a particle of existing 
matter pass entirely away. This empirical truth is now 
the unquestionable foundation of chemistry ; it may be 
directly verified at any moment by means of the balance. 
To the great French chemist Lavoisier belongs the high 
merit of first making this experiment with the balance. 
At the present day the scientist, who is occupied from 
one end of the year to the other with the study of natural 
phenomena, is so firmly convinced of the absolute "con- 
stancy " of matter that he is no longer able to imagine the 
contrary state of things. 

We may formulate the " law of the persistence of force " 
or " conservation of energy n thus : The sum of force, 
which is at work in infinite space and produces all pheno- 
mena, is unchangeable. When the, locomotive rushes 
along the line, the potential energy of the steam is trans- 
formed into the kinetic or actual energy of the mechanical 
movement ; when we hear its shrill whistle, as it speeds 
along, the sound-waves of the vibrating atmosphere are 
conveyed through the tympanum and the three bones of 
the ear into the inner labyrinth, and thence transferred by 
the auditory nerve to the acoustic ganglionic cells which 
form the centre of hearing in the temporal lobe of the 
grey bed of the brain. The whole marvellous panorama of 
life that spreads over the surface of our globe is, in the 
last analysis, transformed sun-light. It is well known how 
the remarkable progress of technical science has made it 
possible for us to convert the different physical forces 
from one form to another ; heat may be changed into molar 


movement, or movement of mass; thus in turn into light 
or sound, and then into electricity, and so forth. Accurate 
measurement of the quantity of force which is used in this 
metamorphosis has shown that it is "constant" or un- 
changed. No particle of living energy is ever extin- 
guished ; no particle is ever created anew. Friedrich 
Mohr, of Bonn, was very near to the discovery of this 
great fact in 1837, but the discovery was actually made 
by the able Swabian physician Robert Mayer, of Heil- 
bronn, in 1842. Independently of Mayer, however, the 
principle was reached almost at the same time by the 
famous physiologist Hermann Helmholtz ; five years after- 
wards he pointed out its general application to, and 
fertility in, every branch of physics. We ought to say 
to-day that it rules also in the entire province of physio- 
logy that is, of "organic physics "; but on that point 
we meet a strenuous opposition from the vitalistic biolo- 
gists and the dualistic and spiritualist philosophers. For 
these the peculiar "spiritual forces " of human nature are 
a group of "free" forces, not subject to the law of 
energy ; the idea is closely connected with the dogma of 
the "freedom of the will." We have, however, already 
seen (p. 167) that the dogma is untenable. Modern physics 
draws a distinction between "force " arid "energy," but 
our general observations so far have not needed a reference 
to it. 

The conviction that these two great cosmic theorems, 
the chemical law of the persistence of matter and the 
physical law of the persistence of force, are fundamentally 
one, is of the utmost importance in our monistic system. 
The two theories are just as intimately united as their 
objects matter and force or energy. Indeed, this funda- 
mental unity of the two laws is self-evident to many 
monistic scientists and philosophers, since they merely 
relate to two different aspects of one and the same object, 
the cosmos. But, however natural the thought may be, 
it Is still very far from being generally accepted. It is 
stoutly contested by the entire dualistic philosophy, vital- 
istic biology, and parallelistic psychology; even, in fact, 
by A few (inconsistent) monista, who think they find a 


check to it in "consciousness," in the higher mental 
activity of man, or in other phenomena of our "free 
mental life." 

For my part, I am convinced of the profound import- 
ance of the unifying "law of substance, " as an expression 
of the inseparable connection in reality of two laws which 
are only separated in conception. That they were not 
originally taken together and their unity recognised from 
the beginning is merely an accident of the date of their 
respective discoveries. The earlier and more accessible 
chemical law of the persistence of matter was detected by 
Lavoisier in 1789, and, after a general application of the 
balance, became the basis of exact chemistry. On the 
other hand, the more recondite law of the persistence of 
force was only discovered by Mayer in 1842, and only laid 
down as the basis of exact physics by Helmholtz. The 
unity of the two laws still much disputed is expressed 
by many scientists who are convinced of it in the formula : 
" Law of the persistence of matter and force." In order 
to have a briefer and more convenient expression for this 
fundamental thought, I proposed some time ago to call it 
the "law of substance," or the "fundamental cosmic 
law "; it might also be called the "universal law," or the 
"law of constancy," or the "axiom of the constancy of 
the universe." In the ultimate analysis it is found to be 
a necessary consequence of the principle of causality. 1 

The first thinker to introduce the purely monistic con- 
ception of substance into science and appreciate its pro- 
found importance was the great philosopher Baruch 
Spinoza ; his chief work appeared shortly after his prema*- 
tare death in 1677, just one hundred years before Lavoisier 
gave empirical proof of the constancy of matter by means 
of the chemist's principal instrument, the balance. In 
hia stately pantheistic system the notion of the world (the 
universe, or the cosmos) is identical with the all-pervading 
notion of God ; it is at one and the same time the purest 
and most rational monism and the clearest and most 
abstract mojiotheirm. This universal substance, this 
"divine nature of the world, " shows us two different 
1 Of. Jfaitim, by Breit HeckL 


aspects of its being, or two fundamental attributes 
matter (infinitely extended substance) and spirit (the all- 
embracing energy of thought). Ail the changes which 
have since come over the idea of substance are reduced, 
on a logical analysis, to this supreme thought of Spinoza's ; 
with Goethe I take it to be the loftiest, profoundest, and 
truest thought of all ages. Every single object in the 
world which comes within the sphere of our cognizance, 
all individual forms of existence, are but special transitory 
forms accident$ or mode* of substance. These modes 
are material things when we regard them under the attri- 
bute of extension (or "occupation of space "), but forces 
or ideas when we consider them under the attribute of 
thought (or "energy"). To this profound thought of 
Spinoza our purified monism returns after a lapse of two 
hundred years ; for us, too, matter (space-filling substance) 
and energy (moving force) are but two inseparable attri- 
butes of the one underlying substance. 

Among the various modifications which the fundamental 
idea of substance has undergone in modern physics, in 
association with the prevalent atomism, we shall select 
only two of the most divergent theories for a brief dis- 
cussion, the kinetic and the pyknotic. Both theories 
agree that we have succeeded in reducing all the different 
forces of nature to one common original force; gravity 
and chemical action, electricity and magnetism, light and 
heat, etc., are only different manifestations, forms, or 
dynamodes, of a single primitive force (prodynamit). 
This fundamental force is generally conceived as a vibrat- 
ory motion of the smallest particles of matter a vibration 
of atoms. The atoms themselves, according to the usual 
"kinetic theory of substance," are dead, separate particles 
of matter, which dance to and fro in empty space and 
act at a distance. The real founder and most distin- 
guished representative of the kinetic theory if Newton, 
the famous discoverer of the law of gravitation. In his 
great work, the Philosophise Naturali* Principia Mathe 
malice (1687), he showed that throughout the universe 
the same law of attraction controls the unvarying con- 
stancy of gravitation ; the attraction of two particles being 


in direct proportion to their mass and in inverse proportion 
to the square of their distance. This universal force of 
gravity is at work in the fall of an apple and the tidal 
wave no less than in the course of the planets round the 
sun and the movements of all the heavenly bodies. New- 
ton had the immortal merit of establishing the law of 
gravitation and embodying it in an indisputable mathe- 
matical formula. Yet this dead mathematical formula, on 
which most scientists lay great stress, as so frequently 
happens, gives us merely the quantitative demonstration of 
the theory ; it gives us no insight whatever into the 
qualitative nature of the phenomena. The action at a 
distance without a medium, which Newton deduced from 
his law of gravitation, and which became one of the most 
serious and most dangerous dogmas of later physics, does 
not afford the slightest explanation of the true causes of 
attraction ; indeed, it long obstructed our way to the 
real discovery of them. I cannot but suspect that his 
speculations on this mysterious action at a distance 
contributed not a little to the leading of the great 
English mathematician Into the obscure labyrinth of 
mystic dreams and theistic superstition In which he 
passed the last thirty-four years of his life; we find him, 
at the end, giving metaphysical hypotheses on the pre- 
dictions of Daniel and on the paradoxical fantasies of 
St. John. 

In fundamental opposition to the theory of vibration, or 
the kinetic theory of substance, we have the modern 
** theory of condensation," or the pyknotic theory of sub- 
stance. It is most ably established in the suggestive work 
of J. C. Vogt on The Nature of Electricity and Magnetism 
on the Bam of a Simplified Conception of Subitance 
(1891). Vogt assumes the primitive force of the world, 
the universal prodynami$, to be, not the vibration or oscil- 
lation of particles in empty space, but the condensation of 
a simple primitive substance, which fills the infinity of 
space in an unbroken continuity. Its sole inherent 
mechanical form of activity consists in a tendency to con- 
densation or contraction, which produces infinitesimal 
centres of condensation ; these may change their degree of 


thickness, and, therefore, their volume, but are constant as 
such. These minute parts of the universal substance, the 
centres of condensation, which might be called pyknatoms, 
correspond in general to the ultimate separate atoms of 
the kinetic theory; they differ, however, very consider- 
ably in that they are credited with sensation and inclina- 
tion (or will-movement of the simplest form), with souls f 
in a certain sense in harmony with the old theory of 
Empedocles of the 4< love and hatred of the elements. " 
Moreover, these "atoms with souls " do not float in empty 
space, but in the continuous, extremely attenuated inter- 
mediate substance, which represents the uncondensed 
portion of the primitive matter. By means of certain 
"constellations, centres of perturbation, or systems of 
deformation/' great masses of centres of condensation 
quickly unite in immense proportions, and so obtain a 
preponderance over the surrounding masses. By that pro- 
cess the primitive substance, which in its original state of 
quiescence had the same mean consistency throughout, 
divides or differentiates into two kinds. The centres of 
disturbance, which positively exceed the mean consistency 
in virtue of the pyknosi* or condensation, form the 
ponderable matter of bodies ; the finer, intermediate sub- 
stance, ^hich occupies the space between them, and 
negatively falls below the mean consistency, forms the 
ether, or imponderable matter. As a consequence of this 
division into mass and ether there ensues a ceaseless 
struggle between the two antagonistic elements, and this 
struggle is the source of all physical processes. The 
positive ponderable matter, the element with the feeling 
of like or desire, is continually striving to complete the 
process of condensation, and thus collecting an enormous 
amount of potential energy ; the negative, imponderable 
matter, on the other hand, offers a perpetual and equal 
resistance to the further increase of its strain and of the 
feeling of dislike connected therewith, and thus gathers 
the utmost amount of actual energy. 

We cannot go any further here into the details of the 
brilliant theory of J. C. Vogt. The interested reader 
cannot do better than have recourse to the second volume 


of the above work for a clear popular exposition of the 
difficult problem. I am myself too little informed in 
physics and mathematics to enter into a critical discussion 
of its lights and shades; still, I think that this pyknotic 
theory of substance will prove more acceptable to every 
biologist who is convinced of the unity of nature than the 
kinetic theory which prevails in physics to-day. A mis- 
understanding may easily arise from the fact that Vogt 
puts his process of condensation in explicit contradiction 
with the general phenomenon of motion ; but it must be 
remembered that he is speaking of vibratory movement in 
the sense of the physicist. His hypothetical " condensa- 
tion " is just as much determined by a movement of 
substance as is the hypothetical "vibration"; only the 
kind of movement and the relation of the moving elements 
are very different in the two hypotheses. Moreover, it is 
not the whole theory of vibration, but only an important 
section of it, that is contradicted by the theory of con- 

Modern physics, for the most part, still firmly adheres 
to the older theory of vibration, to the idea of an actio in 
distant and the eternal vibration of dead atoms in empty 
space; it rejects the pyknotic theory. Although Vogt's 
theory may be still far from perfect, and his original 
speculations may be marred by many errors, yet I think 
he has rendered a very good service in eliminating the 
untenable principles of the kinetic theory of substance. 
As to my own opinion and that of many other scien- 
tists I must lay down the following theses, which 
arc involved in Vogt's pyknotic theory, as indispens- 
able for a truly monistic view of substance, and one 
that covers the whole field of organic and inorganic 
nature : 

L The two fundamental forms of substance, ponder- 
able matter and ether, are not dead, and only moved by 
extrinsic force, but they are endowed with sensation and 
will (though, naturally, of the lowest grade); they ex- 
perience an inclination for condensation, a dislike of 
strain ; they strive after the one and struggle against the 


II. There is no such thing as empty space; that part 
of space which is not occupied witli ponderable atoms is 
filled with ether. 

III. There is no such thing as an action at a distance 
through perfectly empty space; all action of bodies upon 
each other is either determined by immediate contact or 
is effected by the mediation of ether. 

Both the theories of substance which we have just con- 
trasted are monistic in principle, since the opposition 
between the two conditions of substance mass and ether 
is not original ; moreover, they involve a continuous 
immediate contact and reciprocal action of the two ele- 
ments. It is otherwise with the dualistic theories of sub- 
stance which still obtain in the idealist and spiritualist 
philosophy, and which have the support of a powerful 
theology, in so far as theology indulges in such meta- 
physical speculations. These theories draw a distinction 
between two entirely different kinds of substance, material 
and immaterial. Material substance enters into the com- 
position of the bodies which are the object of physics and 
chemistry ; the law of the persistence of matter and force 
is confined to this world (apart from a belief in its 
"creation from nothing " and other miracles). Immaterial 
substance Is found in the " spiritual world/' to which the 
law does not extend ; in this province the laws of physics 
and chemistry are either entirely inapplicable or they are 
subordinated to a "vital force," or a "free will," or a 
"divine omnipotence," or some other phantom which is 
beyond the ken of critical science. In truth, these pro- 
found errors need no further refutation to-day, for experi- 
ence has never yet discovered for us a single immaterial 
substance, a single force which is not dependent on matter, 
or a single form of energy which is not exerted by material 
movement, whether it be of mass, or of ether, or of both. 
Even the most elaborate and most perfect forms of energy 
that we know the psychic life of the higher animals, the 
thought and reason of man depend on material pro- 
cesses, or changes in the neuroplasm of the ganglionic 
cells ; they are Inconceivable apart from such modifications. 
I have already shown (chap, xi.) that the physiological 


hypothesis of a special, immaterial " soul-substance " is 

The study of ponderable matter is primarily the con- 
cern of chemistry. Few are ignorant of the astonishing 
theoretical progress which this science has made in the 
course of the century and the immense practical influence 
it has had on every aspect of modern life. We shall con- 
fine ourselves here to a few remarks on the more important 
questions which concern the nature of ponderable matter. 
It Is well known that analytical chemistry has succeeded 
in resolving the immense variety of bodies in nature into 
a small number of simple elements that is, simple bodies 
which are incapable of further analysis. The number of 
these elements is about seventy. Only fourteen of them 
are widely distributed on the earth and of much practical 
importance; the majority are rare elements (principally 
uietals) of little practical moment. The affinity of these 
groups of elements, and the remarkable proportions of 
their atomic weights, which Lothar Meyer and Mendele- 
jeff have proved in their Periodic System of the Elements, 
make it extremely probable that they are not absolute 
species of ponderable matter that is, not eternally un- 
changeable particles. The seventy elements have in that 
system been distributed into eight leading groups, and 
arranged in them according to their atomic weight, so that 
the elements which have a chemical affinity are formed 
into families. The relations of the various groups in such 
a natural system of the elements recall, on the one hand, 
similar relations of the innumerable compounds of carbon, 
and, again, the relations of parallel groups in the natural 
arrangement of the animal and plant species. Since in 
the latter cases the " affinity " of the related forms is 
based on descent from a common parent form, it seems 
very probable that the same holds good of the families and 
orders of the chemical elements. We may, therefore, 
conclude that the " empirical elements " we now know 
are not really simple, ultimate, and unchangeable forms of 
matter, but compounds of homogeneous, simple, primitive 
atoms, variously distributed as to number and grouping. 


The recent speculations of Gustav Wendt, Wilhelm Preyer, 
Sir W. Crookes, and others, have pointed out how we 
may conceive the evolution of the elements from a simple 
primitive material, the prothyL 

The modern atomistic theory, which is regarded as an 
indispensable instrument in chemistry to-day, must be 
carefully distinguished from the old philosophic atomism 
which was taught more than two thousand years ago by a 
group of distinguished thinkers of antiquity Leucippus, 
Democritus, and Epicurus : it was considerably developed 
and modified later on by Descartes, Hobbes, Leibnitz, and 
other famous philosophers. But it was not until 1808 that 
modern atomism assumed n definite and acceptable form, 
and was furnished with an empirical basis by Dalton, who 
formulated the 'Maw of simple and multiple proportions " 
in the formation of chemical combinations. He first deter- 
mined the atomic weight of the different elements, and 
thus created the solid and exact foundation on which more 
recent chemical theories are based ; these are all atomistic, 
in the sense that they assume the elements to be made up 
of homogeneous, infinitesimally small, distinct particles, 
which are incapable of further analysis. That does not 
touch the question of the real nature of the atoms their 
form, size, psychology, etc. These atomic qualities are 
merely hypothetical ; while the chemistry of the atoms, 
their "chemical affinity " that is, the constant proportion 
in which they combine with the atoms of other elements 
is empirical. 1 

The different relation of the various elements towards 
each other, which chemistry calls " affinity," is one of the 
most important properties of ponderable matter ; it is 
manifested in the different relative quantities or propor- 
tions of their combination in the intensity of its con- 
summation. Every shade of inclination, from complete 
indifference to the fiercest passion, is exemplified in the 
chemical relation of the various elements towards each 
other, just as we find in the psychology of man, and 

Of. Monism, by E. Haeckel. 


especially in the life of the sexes. Goethe, in his classical 
romance, Affinitie$, compared the relations of pairs of 
lovers with the phenomenon of the same name in the 
formation of chemical combinations. The irresistible pas- 
sion that draws Edward to the sympathetic Ottilia, or 
Paris to Helen, and leaps over ail bounds of reason and 
morality, is the same powerful "unconscious" attractive 
force which impels the living spermatozoon to force an 
entrance into the ovum in the fertilisation of the egg of 
the animal or plant the same impetuous movement which 
unites two atoms of hydrogen to one atom of oxygen for 
the formation of a molecule of water. This fundamental 
unity of affinity in the whole of nature, from the simplest 
chemical process to the most complicated love story, was 
recognised by the great Greek scientist Empedocles, io 
the fifth century B.C., in his theory of "the love and 
hatred of the elements." It receives empirical confirma- 
tion from the interesting progress of cellular psychology, 
the great significance of which we have only learned to 
appreciate in the last thirty years. On those phenomena 
we base our conviction that even the atom is not without 
a rudimentary form of sensation and will, or, as it is 
better expressed, of feeling (icsthetit) and inclination 
(tropesis) that is, a universal " soul " of the simplest 
character. The same must be said of the molecules which 
are composed of two or more atoms. Further combina- 
tions of (1 1 (To rent kinds of these molecules give rise to 
simple and, subsequently, complex chemical compounds, 
in the activity of which the same phenomena are repeated 
in a more complicated form. 

The study of ether, or imponderable matter, pertains 
principally to physics. The existence of an extremely 
attenuated medium, filling the whole of space outside of 
ponderable matter, was known and applied to the elucida- 
tion of various phenomena (especially light) a long time 
ago ; but it was not until the second half of the nineteenth 
century that we became more closely acquainted with this 
remarkable substance, in connection with our astonishing 
empirical discoveries la the province of electricity, with 
their experimental detection, their theoretical interprets- 


tion, and their practical application. The path was opened 
in particular by the famous researches of Heinrich Hertz, 
of Bonn, in 1888. The premature death of a brilliant 
young physicist of so much promise cannot be sufficiently 
deplored* Like the premature death of Spinoza, Raphael, 
Schubert, and many other great men, it is one of those 
brutal facts of human history which are enough of them- 
selves to destroy the untenable myth of a " wise Provi- 
dence " and an "All-loving Father in heaven." 

The existence of ether (or cosmic ether) as a real element 
is a positive fact, and has been known as such for the last 
twelve years. We sometimes read even to-day that ether 
is a u pure hypothesis'*; this erroneous assertion comes 
not only from uninformed philosophers and ** popular" 
writers, but even from certain " prudent and exact physi- 
cists." But there would be just as much reason to deny 
the existence of ponderable matter. As a matter of fact, 
there are metaphysicians who accomplish even this feat, 
aud whose highest wisdom lies in denying or calling into 
question the existence of an external universe ; according 
to them only one real entity exists their own precious 
personality, or, to be more correct, their immortal soul. 
Several modern physiologists have embraced this ultra- 
idealist view, which is to be found in Descartes, Berkeley, 
Fichte, and others. Their '* psycho-monism " affirms: 
" One thing only exists, and that is my own mind." This 
audacious spiritualism seems to us to rest on an erroneous 
inference from Kant's correct critical theory, that we can 
know the outer world only in the phenomenal aspect which 
is accessible to our human organs of thought the brain 
and the organs of sense. If by those means we can attain 
only an imperfect and limited knowledge of the material 
world, that is no reason for denying its existence alto- 
gether. In my opinion, the existence of ether ii as 
certain as that of ponderable matter as certain as my 
own existence, as I reflect and write on it. As we assure 
ourselves of the existence of ponderable matter by its mass 
and weight, by chemical and mechanical experiments, o 
we prove that of ether by the experiences and ex peri men t 
of optics and electricity. 


Although, however, the existence of ether is now re- 
garded as a positive fact by nearly all physicists, and 
although many effects of this remarkable substance are 
familiar to us through an extensive experience, especially 
In the way of optical and electrical experiments, yet we 
are still far from being clear and confident as to its real 
character. The views of the most eminent physicists, who 
have made a special study of it, are extremely divergent ; 
they frequently contradict each other on the most im- 
portant points. One is, therefore, free to choose among 
the contradictory hypotheses according to one's knowledge 
and judgment. I will put in the following eight theses 
the view which has approved itself to me after mature 
reflection on the subject, though I am no expert in this 

I. Ether fills the whole of space, in so far as it is not 
occupied by ponderable matter, as a continuous tubstance ; 
it fully occupies the space between the atoms of ponder- 
able matter. 

II. Ether has probably no chemical quality, and is not 
composed of atoms. If it be supposed that it consists of 
minute homogeneous atoms (for instance, indivisible 
etheric particles of a uniform size), it must be further 
supposed that there is something else between these atoms, 
either "empty space'* or a third, completely unknown 
medium, a purely hypothetical "inter-ether"; the ques- 
tion as to the nature of this brings us back to the original 
difficulty, and so on in infinitum. 

111. As the idea, of an empty space and an action at a 
distance is scarcely possible in the present condition of 
our knowledge (at least, it does not help to a clear 
monistic view), I postulate for ether a special structure 
which is not atomistic, like that of ponderable matter, 
and which may provisionally be called (without further 
determination) etheric or dynamic structure. 

IV. The consistency of ether is also peculiar, on our 
hypothesis, and different from that of ponderable matter. 
It is neither gaseous, as some conceive, nor solid, as others 
suppose ; the best idea of it can be formed by comparison 
witli an extremely attenuated, elastic, and light jelly. 


V. Ether may be called imponderable matter in the 
sense that we have no means of determining its weight 
experimentally. If it really lias weight, as is very prob- 
able, it must be so slight as to be far below the capacity 
of our most delicate balance. Some physicists have 
attempted to determine its weight by the energy 
of the light-waves, and have discovered that it is 
some fifteen trillion times lighter than atmospheric air ; 
on that hypothesis a sphere of ether of the size of 
our earth would weigh at least two hundred and fifty 
pounds (?). 

VI. The etheric consistency may probably (in accord- 
ance with the pyknotic theory) pass into the gaseous state 
under certain conditions by progressive condensation, just 
as a gas may be converted into a fluid, and ultimately into 
a solid, by lowering its temperature. 

VII. Consequently, these three conditions of matter 
may be arranged (and it is a point of great importance in 
our monistic cosmogony) in a genetic, continuous order. 
We may distinguish five stages in it : (1) the etherio, (2) 
the gaseous, (3) the fluid, (4) the viscous (in the living 
protoplasm), and (5) the solid state. 

VIII. Ether is boundless and immeasurable, like the 
space it occupies. It is in eternal motion ; and this specific 
movement of ether (it is immaterial whether we conceive 
it as vibration, strain, condensation, etc.) in reciprocal 
action with mass-movement (or gravitation), is the 
ultimate cause of all phenomena. 

"The great question of the nature of ether," as Hertz 
justly calls it, includes the question of its relation to 
ponderable matter ; for these two forms of matter are not 
only always in the closest external contact, but also in 
eternal, dynamic, reciprocal action. We may divide the 
most general phenomena of nature, which are distin- 
guished by physics as natural forces or " functions of 
matter," into two groups; the first of them may be 
regarded mainly (though not exclusively) as a function of 
ether, and the second a function of ponderable matter 
as in the following scheme, which I take from my 
Monitm : 



ETHER Imponderable. 

1. Oonmtencjf ; 

Ktherlo (i.e., neither gaseoui, nor fluid, 
nor solid). 

2, Strueturtt 

Not atomistic, not made up of aeparate 
par tic Ian (atom*), but continuous. 

3. Chief Function* : 
Light, rad! Ati t heat, electricity, and 

MASS Ponderable. 

1. Comuttency .* 
Not therlc (but gaseous, fluid ,or lolid). 

i. Structure : 

Atomistic, made up of infinitesimal) y 
mail, dUtiuct particles (atoms), dia- 

3. Chief Function* ; 
Gravity, inertia, molecular heat, and 
chfimical affinity. 

The two groups of functions of matter, which we have 
opposed in this table, may, to some extent, be regarded 
as the outcome of the first " division of labour " in the 
development of matter, the " primary ergonomy of 
matter." But this distinction must not be supposed to 
involve an absolute separation of the two antithetic 
groups ; they always retain their connection, and are in 
constant reciprocal action. It is well known that the 
optical and electrical phenomena of ether are closely con- 
nected with mechanical and chemical changes in ponder- 
able elements ; the radiant heat of ether may be directly 
converted into the mechanical heat of the mass; gravita- 
tion is impossible unless the ether effects the mutual 
attraction of the separated atoms, because we cannot 
admit the idea of an act to in distans. In like manner, 
the conversion of one form of energy into another, as 
indicated in the law of the persistence of force, illustrates 
the constant reciprocity of the two chief types of 
substance, ether and mass. 

The great law of nature which, under the title of the 
"law of substance, " we put at the head of all physical 
considerations, was conceived as the law of " the persist- 
ence of force " by Robert Mayer, who first formulated 
it, and Helmholtz, who continued the work. Another 
German scientist. Fried rich Mohr, of Bonn, had clearly 
outlined it in Its main features ten years earlier (1837). 
The old idem of force was, after a time, differentiated 


by modern physics from that of energy t which was at first 
synonymous with it. Hence the law is now usually called 
the **law of the persistence of energy. " However, this 
finer distinction need not enter into the general considera- 
tion, to which I must confine myself here, and into the 
question of the great principle of the " persistence of sub- 
stance." The interested reader will find a very clear 
treatment of the question in TyndalPs excellent paper on 
"The Fundamental Law of Nature," in his Fragments of 
Science. It fully explains the broad significance of this 
profound cosmic law, and points out its application to the 
main problems of very different branches of science. We 
shall confine our attention to the important fact that the 
" principle of energy " and the correlative idea of the 
unity of natural forces, on the basis of a common origin, 
are now accepted by all competent physicists, and are 
regarded as the greatest advance of physics in the nine- 
teenth century. We now know that heat, sound, light, 
chemical action, electricity, and magnetism are ail modes 
of motion. We can, by a certain apparatus, convert any 
one of these forces into another, and prove by an accurate 
measurement that not a single particle of energy is lost 
in the process. 

The sum-total of force or energy in the universe remains 
constant, no matter what changes take place around us ; 
it is eternal and infinite, like the matter on which it is in- 
separably dependent. The whole drama of nature appar- 
ently consists in an alternation of movement and repose ; 
yet the bodies at rest have an inalienable quantity of 
force, just as truly as those that are in motion. It is in 
this movement that the potential energy of the former is 
converted into the kinetic energy of the latter, "As 
the principle of the persistence of force takes into account 
repulsion as well as attraction, it affirms that the mechan- 
ical value of the potential energy and the kinetic energy 
in the material world is a constant quantity. To put it 
briefly, the force of the universe is divided into two parts, 
which may be mutually converted, according to a fixed 
relation of value. The diminution of the one involves the 
increase of the other; the total value remains unchanged 


in the universe." The potential energy and the actual, or 
kinetic, energy are being continually transformed from 
one condition to the other ; but the infinite sum of force 
in the world at large never suffers the slightest curtail- 

Once modern physics had established the law of sub- 
stance as far as the simpler relations of inorganic bodies 
are concerned, physiology took up the story, and proved 
its application to the entire province of the organic world. 
It showed that all the vital activities of the organism 
without exception are based on a constant " reciprocity 
of force " and a correlative change of material, or meta- 
bolism, just as much as the simplest processes in "life- 
less " bodies. Not only the growth and the nutrition of 
plants and animals, but even their functions of sensation 
and movement, their sense-action and psychic life, depend 
on the conversion of potential into kinetic energy, and 
mce Dend. This supreme law dominates also those 
elaborate performances of the nervous system which we 
call, in the higher animals and man, "the action of the 

Our monistic view, that the great cosmic law applies 
throughout the whole of nature, is of the highest moment. 
For it not only involves, on its positive side, the essential 
unity of the cosmos and the causal connection of all 
phenomena that come within our cognizance, but it also, 
in a negative way, marks the highest intellectual progress, 
In that It definitely rules out the three central dogmas of 
metaphysics God, freedom, and immortality. In assign- 
Ing mechanical causes to phenomena everywhere, the law 
of substance comes into line with the universal law of 



The notion of creation. Miracles. Creation of the whole universe 
and of its various parts. Creation of substance (cosmological 
creation). Deism : one creative day. Creation of separate 
entities. Five forma of ontological creationium. Theory of 
evolution. I. Monistic cosmogony. Beginning and end or the 
world. The infinity and eternity of the universe. Space and 
time. Universum pcrpfttium mobile. Entropy of the universe. 
II. Monistic geogeny. Flistory of the inorganic and organic 
worlds. III. Monistic biogeny. Tranformism and the theory of 
descent. Lamarck and Darwin. IV. Monistic anthropogeiiy. 
Origin of man, 

THE greatest, vastest, and most difficult of ail cosmic 
problems is that of the origin and development of the 
world the "question of creation/ 1 in a word. Even 
to the solution of this most difficult world-riddle the 
nineteenth century has contributed more than all its 
predecessors ; in a certain sense, indeed, it has found the 
solution. We have at least attained to a clear view of the 
fact that all the partial questions of creation are indivisibly 
connected, that they represent one single, comprehensive 
"cosmic problem," and that the key to this problem is 
found in the one magic word evolution. The great 
questions of the creation of man, the creation of the 
animals and plants, the creation of the earth and the sun, 
etc., are all parts of the general question, What is the 
origin of the whole world? Has it been created by 
supernatural power, or has it been evolved by a natural 
process? What are the causes and the manner of this 
evolution? If we succeed in finding the correct answer to 
one of these questions, we have, according to our monistic 
conception of the world, cast a brilliant light on the 
solution of them all, and on the entire cosmic problem. 



The current opinion as to the origin of the world in 
earlier ages was an almost universal belief in creation. 
This belief has been expressed in thousands of interesting, 
more or less fabulous, legends, poems, cosmogonies, and 
myths. A few great philosophers were devoid of it, espe- 
cially those remarkable freethinkers of classical antiquity 
who first conceived the idea of natural evolution. All 
the creation myths, on the contrary, were of a super- 
natural, miraculous, and transcendental character. In- 
competent as it was to investigate for itself the nature 
of the world and its origin by natural causes, the un- 
developed mind naturally had recourse to the idea of 
miracle. In most of these creation-myths anthropism was 
blended with the belief in the miraculous. The creator 
was supposed to have constructed the world on a definite 
plan, just as man accomplishes his artificial constructions ; 
the conception of the creator was generally completely 
anthropomorphic, a palpable " anthropistic creationism." 
The "almighty maker of heaven and earth," as he is 
called in Genesis and the Catechism, is just as humanly 
conceived as the modern creator of Agassix and Keinke, 
or the intelligent ** engineer " of other recent biologists. 

Entering more fully into the notion of creation, we can 
distinguish as two entirely different acts the production 
of the universe as a whole and the successive production 
of its various parts, in harmony with Spinoza's idea of 
tubstance (the universe) and accident* (or moeff, the in- 
dividual phenomena of substance). This distinction is of 
great importance, because there are many eminent philo- 
sophers who admit the one and reject the other. 

According to this creationist theory, then, God has 
" made the world out of nothing." It is supposed that 
God (a rational, but immaterial, being) existed by him- 
self for an eternity before he resolved to create the world. 
Some supporter! of the theory restrict God's creative 
function to one single act ; they believe that this extra- 
mundane God (the rest of whose life is shrouded in 
mystery) created the substance of the world in single 
moment, endowed it with the faculty of the most ex- 
tensive evolution, and troubled no further about it. This 


view may be found, for instance, IB the English Deists 
in many forms. It approaches very close to our monistic 
theory of evolution, only abandoning it in the one instance 
in which God accomplished the creation. Other creation- 
ists contend that God did not confine himself to the mere 
creation of matter, but that he continues to be operative 
as the "sustainer and ruler of the world." Different 
modifications of this belief are found, some approaching 
very close to pantheism and others to complete theiim. 
All these and similar forms of belief in creation are in- 
compatible with the law of the persistence of matter and 
force ; that law knows nothing of a beginning. 

It is interesting to note that E. du Bois-Reymond has 
identified himself with this cosmological creationism in his 
latest speech (on "Neovitalism," 1894). "It is more 
consonant with the divine omnipotence," he says, " to 
assume that it created the whole material of the world in 
one creative act, unthinkable ages ago, in such wise that 
it should be endowed with inviolable laws to control the 
origin and the progress of living things that, for in- 
stance, here on earth rudimentary organisms should arise 
from which, without further assistance, the whole of 
living nature could be evolved, from a primitive bacillus 
to the graceful palm- wood, from a primitive micrococcus 
to Solomon's lovely wives or to the brain of Newton. 
Thus we are content with one creative day, and we derive 
organic nature mechanically, without the aid of either old 
or new vitalism." Du Bois-Reymond here shows, as in 
the question of consciousness, the shallow and illogical 
character of his monistic thought. 

According to another still prevalent theory, which may 
be called "ontological creationism," God not only created 
the world at large, but also its separate contents. In 
the Christian world the old Semitic legend of creation, 
taken from Genesis, is still very widely accepted; even 
among modern scientists it finds an adherent hen and 
there. I have fully entered into the criticism of it in the 
firft chapter of my Natural Hiitory of Creation, The fol- 
lowing theories may be enumerated as the most interesting 
modification! of this ontological creationism. 


I. Dualistic creation. God restricted his interference 
to two creative acts. First he created the inorganic 
world, mere dead substance, to which alone the law of 
energy applies, working blindly and aimlessly in the 
mechansim of material things and the building of the 
mountains ; then God attained intelligence and communi- 
cated it to the purposive intelligent forces which initiate 
and control organic evolution. 1 

II. Trialistic creation. God made the world in three 
creative acts : (a) the creation of the heavens the extra- 
terrestrial world, (6) the creation of the earth (as the 
centre of the world) and of its living inhabitants, and (c) 
the creation of man (in the image and likeness of God). 
This dogma is still widely prevalent among theologians 
and other "educated " people: it is taught as the truth 
in many of our schools. 

III. Heptameral creation ; a creation in seven days 
(tesic Moses). Although few educated people really be- 
lieve in this Mosaic myth now, it is still firmly impressed 
on our children in the Biblical lessons of their earliest 
years. The numerous attempts that have been made, 
especially in England, to harmonise it with the modern 
theory of evolution have entirely failed. It obtained some 
importance in science when Linne adopted it in the estab- 
lishment of his system, and based his definition of organic 
gpeoies (which he considered to be unchangeable) on it : 
"There are as many different species of animals and plants 
as there were different forms created in the beginning by 
the Infinite." The dogma was pretty generally held until 
the time of Darwin (1859), although Lamarck had already 
proved its untenability in 1809. 

IV. Periodic creation. At the beginning of each period 
of the earth's history, the whole population of animals and 
plants was created anew, and destroyed by a general cata- 
strophe at its close; there were as many general creative 
acts as there are distinct geological periods (the cata- 
strophic theory of Cuvier [1818] and Louis Agassis 
[1858]). Palaeontology, which seemed in its more im- 

Reinke, Di* Wdt <*l* That (1899). 


perfect stage to support this theory, has since completely 
refuted it. 

V. Individual creation. Every single man and every 
individual animal and plant does not arise by a natural 
process of growth, but is created by the favour of God. 
This view of creation is still often met with in journals, 
especially in the " births " column. The special talents 
and features of our children are often gratefully acknow- 
ledged to be "gifts of God "; their hereditary defects fit 
into another theory. 

The error of these creation legends and the cognate 
belief in miracles must have been apparent to thoughtful 
minds at an early period ; more than two thousand years 
ago we find that many attempts were made to replace 
them by i rational theory, and to explain the origin of 
the world by natural causes. In the front rank, once 
more, we must place the leaders of the Ionic school, with 
Democritus, Heraclitus, Ernpedocles, Aristotle, Lucretius, 
and other ancient philosophers. The first imperfect at- 
tempts which they made astonish us, in a measure, by the 
flashes of mental light in which they anticipate modern 
ideas. It must be remembered that classical antiquity 
had not that solid groundwork for scientific speculation 
which has been provided by the countless observations and 
experiments of modern scientists. During the Middle 
Ages especially during the domination of the papacy 
scientific work in this direction entirely ceased. The 
torture and the stake of the Inquisition ensured that an 
unconditional belief in the Hebrew mythology should be 
the final answer to all the questions of creation. Even 
the phenomena which led directly to the observation of 
the facti of evolution the embryology of the plant and 
the animal, and of man remained unnoticed, or only 
excited the interest of an occasional keen observer, whose 
discoveries were ignored or forgotten. Moreover, the 
path to a correct knowledge of natural development was 
barred by the dominant theory of preformation, the 
dogma which held that the characteristic form and struc- 
ture of each animal and plant were already sketched in 
miniature in the germ (cf . p. 44). 


The science which we now call the science of evolution 
(in the broadest sense) is, both in its general outline and 
in its separate parts, a child of the nineteenth century ; it 
is one of its most momentous and most brilliant achieve- 
ments. Almost unknown in the preceding century, this 
theory has now become the sure foundation of our whole- 
world system. I have treated it exhaustively in my 
General Morphology (1866), more popularly in my Natural 
History of Creation (1868), and in itg special application 
to man in my Anthropogeny (1874). Here I shall restrict 
myself to a brief survey of the chief advances which the 
science has made in the course of the century. It falls 
into four sections, according to the nature of its object ; 
that is, it deals with the natural origin of (1) the cosmos, 
(2) the earth, (S) terrestrial forms of life, and (4) man. 


The first attempt to explain the constitution and the 
mechanical origin of the world in a simple manner by 
" Newtonian laws " that is, by mathematical and physical 
laws was made by Immanuel Kant in the famous work 
of his youth (1755), General Hittory of the Earth and 
Theory of the Heaven*. Unfortunately, this distinguished 
and daring work remained almost unknown for ninety 
years ; it was only disinterred in 1 845 by Alexander Hum- 
bold t in the first volume of his Cot mat. In the meantime 
the great French mathematician Pierre Laplace had arrived 
independently at similar views to those of Kant, and he 
gave them a mathematical foundation in his Exposition 
du Sytteme du Monde (1796). His chief work, the 
Mtcamqne Colette* appeared a hundred years ago. The 
analogous features of the cosmogony of Kant and Laplace 
consist, as is well known, in a mechanical explanation of 
the movements of the planets, and the conclusion which 
is drawn therefrom, that all the cosmic bodies were formed 
originally by a condensation of rotating nebulous spheres. 
This " nebular hypothesis " has been much improved and 
supplemented since, but it is still the best of all the 


attempt* to explain the origin of the world on monistic 
and mechanical lines. It has recently been strongly con- 
firmed and enlarged by the theory that this cosmogonic 
process did not simply take place once, but is periodically 
repeated. While new cosmic bodies arise and develop out 
of rotating masses of nebula in some parts of the universe, 
in other parts old, extinct, frigid suns come into collision, 
and are once more reduced by the heat generated to the 
condition of nebulas. 

Nearly all the older and the more recent cosmogonies, 
including most of those which were inspired by Kant and 
Laplace, started from the popular idea that the world had 
had a beginning. Hence, according to a widespread 
version of the nebular hypothesis, " in the beginning " 
was made a vast nebula of infinitely attenuated and light 
material, and at a certain moment ("countless ages ago ") 
a movement of rotation was imparted to this mass. Given 
this " first beginning " of the cosmogonic movement, it 
is easy, on mechanical principles, to deduce and mathe- 
matically establish the further phenomena of the founda- 
tion of the cosmic bodies, the separation of the planets, 
and so forth. This first " origin of movement " is Du 
Bois-Reymond's second " world-enigma " ; he regards it 
as transcendental. Many other scientists and philosophers 
are equally helpless before this difficulty ; they resign 
themselves to the notion that we have here a primary 
" supernatural impetus " to the scheme of things, a 

In our opinion, this second " world-enigma " is solved 
by the recognition that movement is as innate and original 
a property of substance as is sensation. The proof of this 
monistic assumption is found, first, in the law of sub- 
stance, and, secondly, in the discoveries which astronomy 
and physics have made in the latter half of the century. 
By the spectrum analysis of Bunsen and Kirchhoft (1860) 
we have found, not only that the millions of bodies which 
fill the infinity of space are of the same material as our 
own sun and earth, but also that they are in various stages 
of evolution ; we have obtained by its aid information as to 
the movements and distances of the stars, which the tele* 


scope would never have given us. Moreover, the telescope 
itself has been vastly improved, and has, in alliance with 
photography, made a host of scientific discoveries of which 
no one dreamed at the beginning of the century. In par- 
ticular, a closer acquaintance with comets, meteorites, 
star-clusters, and nebuhe has helped us to realise the great 
significance of the smaller bodies which are found in 
millions in the space between the stars. 

We now know that the paths of the millions of heavenly 
bodies are changeable, and to some extent irregular, 
whereas the planetary system was formerly thought to be 
constant, and the rotating spheres were described as pur- 
suing their orbits in eternal regularity. Astrophysics 
owes much of its triumph to the immense progress of 
other branches of physics, of optics, and electricity, and 
especially of the theory of ether. And here, again, our 
'supreme law of substance is found to be one of the most 
valuable achievements of modern science. We now kno>v 
that it rules unconditionally in the most distant reaches 
of space, just as it does in our planetary system, in the 
most minute particle of the earth as well as in the smallest 
cell of our human frame. We are, moreover, justified in 
concluding, if we are not logically compelled to conclude, 
that the persistence of matter and force has held good 
throughout all time as it does to-day. Through all 
eternity the infinite universe has been, and is, subject to 
the law of substance. 

From this great progress of astronomy and physics, 
which mutually elucidate and supplement each other, we 
draw a series of most important conclusions with regard 
to the constitution and evolution of the cosmos, and the 
persistence and transformation of substance. Let us put 
them briefly in the following theses : 

I. The extent of the universe is infinite and un- 
bounded j it is empty in no part, but everywhere filled 
with substance. 

II. The duration of the world is equally infinite and 
unbounded ; it has no beginning and no end ; it is eternity. 

III. Substance is everywhere and always in uninter- 
rupted movement and transformation : nowhere is there 


perfect repose and rigidity ; yet the infinite quantity of 
matter and of eternally changing force remains constant. 

IV. This universal movement of substance in space 
takes the form of an eternal cycle or of a periodical process 
of evolution. 

V. The phases of this evolution consist in a periodic 
change of consistency, of which the first outcome is the 
primary division into mass and ether the ergonomy of 
ponderable and imponderable matter. 

VI, This division is effected by a progressive condensa- 
tion of matter as the formation of countless infinitesimal 
"centres of condensation," in which the inherent primi- 
tive properties of substance feeling and inclination are 
the active causes. 

VII. While minute and then larger bodies are being 
formed by this pyknotic process in one part of space, and 
the intermediate ether increases its strain, the opposite 
process the destruction of cosmic bodies by collision 
is taking place in another quarter. 

VIII. The immense quantity of heat which is gener- 
ated in this mechanical process of the collision of swiftly- 
moving bodies represents the new kinetic energy which 
effects the movement of the resultant nebulae and the 
construction of new rotating bodies. The eternal drama 
begins afresh. Even our mother earth, which was formed 
of part of the gyrating solar system millions of ages ago, 
will grow cold and lifeless after the lapse of further 
millions, and, gradually narrowing its orbit, will fall 
eventually into the sun. 

It seems to me that these modern discoveries as to the 
periodic decay and re-birth of cosmic bodies, which we 
owe to the most recent advance of physics and astronomy, 
associated with the law of substance, are especially im- 
portant in giving us a clear insight into the universal 
cosmic process of evolution. In their light our earth 
shrinks into the slender proportions of a "mote in the 
sunbeam," of which unnumbered millions chase each other 
through the vast depths of space. Our own "human 
nature," which exalted itself into an image of God in its 
anthropistic illusion, sinks to the level of a placental 


mammal, which has no more value for the universe at 
large than the ant, the fly of a summer's day, the micro- 
scopic infusorium, or the smallest bacillus. Humanity 
is but a transitory ptiase of the evolution of an eternal 
substance, a particular phenomenal form of matter and 
energy, the true proportions of which we soon perceive 
when we set it on the background of infinite space and 
eternal time. 

Since Kant explained time and space to be merely 
*' forms of perception " space the form of external, time 
of internal, sensitivity there has been a keen controversy, 
which still continues, over this important problem. A 
large section of modern metaphysicians have persuaded 
themselves that this "critical fact " possesses a great im- 
portance as the starting-point of " a purely idealist theory 
of knowledge," and that, consequently, the natural 
opinion of the ordinary healthy mind as to the reality of 
time and space is swept aside. This narrow and ultra- 
idealist conception of time and space has become a prolific 
source of error. It overlooks the fact that Kant only 
touched one side of the problem, the tubjective side, in 
that theory, and recognised the equal validity of its 
objective side. "Time and space," he said, "have em- 
pirical reality, but transcendental ideality. Our modern 
monism is quite compatible with this thesis of Kant's, but 
not with the one-sided exaggeration of the suggestive 
aspect of the problem ; the latter leads logically to the 
absurd idealism that culminates in Berkeley's thesis, 
** Bodies are but ideas ; their essence is in their percep- 
tion." The thesis should be read thus : " Bodies are only 
ideas for my personal consciousness; their existence is 
just as real as that of my organs of thought, the gan- 
glionic cells in the grey bed of my brain, which receives 
the impress of bodies on my sense organs and form those 
ideas by association of the impressions." It is just as 
easy to doubt or to deny the reality of my own conscious- 
ness as to doubt that of time and space. In the delirium 
of fever, in hallucinations, In dreams, and in double* 
consciousness, I take ideas to be true which are merely 
fancies. ! mistake my own personality for another (vid* 


p. 151); Descartes' famous Cogito ergo sum applies no 
longer. On the other hand, the reality of time and space 
is now fully established by that expansion of our philo- 
sophy which we owe to the law of substance and to our 
monistic cosmogony. When we have happily got rid of 
the untenable idea of " empty space/' there remains as 
the infinite " space-filling " medium matter, in its two 
forms of ether and mass. So also we find a " time-filling " 
event in the eternal movement, or genetic energy, \vhich 
reveals itself in the uninterrupted evolution of substance 
in the perpetuum mobile of the universe. 

As a body which has been set in motion continues to 
move as long as no external agency interferes with it, the 
idea was conceived long ago of constructing apparatus 
which should illustrate perpetual motion. The fact was 
overlooked that every movement meets with external 
impediments and gradually ceases, unless a new impetus 
Is given to it from without and a new force is introduced 
to counteract the impediments. Thus, for instance, a 
pendulum would swing backwards and forwards for an 
eternity at the same speed if the resistance of the atmo- 
sphere, and the friction at the point it hangs from, did 
not gradually deprive it of the mechanical kinetic energy 
of its motion and convert it into heat. We have to furnish 
it with fresh mechanical energy by a spring (or, as in the 
pendulum-clock, by the drag of a weight). Hence it is 
impossible to construct a machine that would produce, 
without external aid, a surplus of energy by which it 
could keep itself going. Every attempt to make such 
perpetuum mobile must necessarily fail ; the discovery of 
the law of substance showed, in addition, the theoretical 
impossibility of it. 

The case is different, however, when we torn to the 
world at large, the boundless universe that is in eternal 
movement. The infinite matter, which fills it objectively, 
! what we call tpace in our subjective impression of it; 
time is our subjective conception of its eternal movement, 
which is, objectively, a periodic, cyclic evolution. These 
two " forms of perception " teach 01 the Infinity and 
eternity of the universe. That is, moreover, equal to 


saying that the universe itself is a perpetuum mobile. 
This infinite and eternal " machine of the universe " sus- 
tains itself in eternal and uninterrupted movement, because 
every impediment is compensated by an "equivalence of 
energy," and the unlimited sum of kinetic and potential 
energy remains always the same. The law of the persist- 
ence of force proves also that the idea of a perpetuum 
mobile is just as applicable to, and as significant for, the 
cosmos as a whole as it is impossible for the isolated 
action of any part of it. Hence the theory of entropy 
in likewise untenable. 

The able founder of the mechanical theory of heat 
(1850), Clausius, embodied the momentous contents of 
this important theory in two theses. The first runs : 
"The energy of the universe is constant" that is one 
half of our law of substance, the principle of energy 
(vide p. 189). The second thesis is: "The entrophy of 
the universe tends towards a maximum." In my opinion 
this second assertion is just as erroneous as the first is 
true. In the theory of Clausius the entire energy of the 
universe is of two kinds, one of which (heat of the higher 
degree, mechanical, electrical, chemical energy, etc.) is 
partly convertible into work, but the other is not, the 
latter energy, already converted into heat and distributed 
In the cooler masses, is irrevocably lost as far as any 
further work is concerned. Clausius calls this uncon- 
umed energy, which is no longer available for mechanical 
work, entropy (that is, force that is directed inwards) ; 
it is continually increasing at the cost of the other half. 
As, therefore, the mechanical energy of the universe is 
daily being transformed into heat, and this cannot be 
reconverted into mechanical force, the sum of heat and 
energy in the universe must continually tend to be reduced 
and dissipated. All differ en ce of temperature must ulti- 
mately disappear, and the completely latent heat must be 
equally distributed through one inert mass of motionless 
matter. AH organic life and movement must cease when 
this maximum of entropy has been reached. That would 
be a real "end of the world." 

If this theory of entropy were true, we should have s 


" beginning " corresponding to this assumed " end " of the 
world a minimum of entropy, in which the differences in 
temperature of the various parts of the cosmos would be 
at a maximum. Both ideas are quite untenable in the 
light of our monistic and consistent theory of the eternal 
cosmogenetic process ; both contradict the law of sub- 
stance. There is neither beginning nor end of the world. 
The universe is infinite, and eternally in motion ; the con- 
version of kinetic into potential energy, and vicissim, 
goes on uninterruptedly ; and the sum of this actual and 
potential energy remains constant. The second thesis of 
the mechanical theory of heat contradicts the first, and so 
must be rejected. 

The representatives of the theory of entropy are quite 
correct as long as they confine themselves to distinct pro- 
cesses, in which, under certain conditions, the latent heat 
cannot be reconverted into work. Thus, for instance, in 
the steam-engine the heat can only be converted into 
mechanical work when it passes from a warmer body 
(steam) into a cooler (water) ; the process cannot be 
reversed. In the world at large, however, quite other 
conditions obtain -conditions which permit the reconver- 
sion of latent heat into mechanical work. For instance, 
in tlie collision of two heavenly bodies, which rush towards 
each other at inconceivable speed, enormous quantities of 
heat are liberated, while the pulverised masses are hurled 
and scattered about space. The eternal drama begins 
afresh the rotating mass, the condensation of its parts, 
the formation of new meteorites, their combination into 
larger bodies, and so on. 


The history of the earth of which we are now going to 
make a brief survey is only a minute section of the history 
of the cosmos. Like the latter, it has been the object of 
philosophic speculation and mythological fantasy for many 
thousand years. Its true scientific study, however, is 
much younger ; it belongs, for the most part, to the nine- 


teenth century. The fact that the earth is a planet revolv- 
ing round the sun was determined by the system of 
Copernicus ( 154-3); Galileo, Kepler, and other great astro- 
nomers, mathematically determined its distance from the 
sun, the laws of its motions, and so forth, Kant and 
Laplace indicated, in their cosmogony, the w&y in which 
the earth had been developed from the parent sun. But 
the later history of the earth, the formation of its crust, 
the origin of its seas and continents, its mountains and 
deserts, was rarely made the subject of serious scientific 
research in the eighteenth century, and in the first two 
decades of the nineteenth. As a rule, men were satisfied 
with unreliable conjectures, or with the traditional story 
of creation; once more the Mosaic legend barred the way 
to an independent investigation. 

In 1822 an important work appeared, which followed 
the same method in the scientific investigation of the 
history of the earth that had already proved the most 
fertile the ontological method, or the principle of 
" actualisxn." It consists in a careful study and manipula- 
tion of actual phenomena with a view to the elucidation 
of the analogous historical processes of the past. The 
Society of Science at Gottingen had offered a prize in 
1818 for "the most searching and comprehensive inquiry 
Into the changes in the earth's crust which are historically 
demonstrable, and the application which may be made of 
t knowledge of them in the investigation of the terres- 
trial revolutions which lie beyond the range of history." 
This prize was obtained by Karl Hoff of Gotha for his 
distinguished work, History of the Natural Change* in the 
Crutt of the Earth in the Light of Tradition (1822-84). 
Sir Charles Lyell then applied this ontological or actual- 
i$tic method with great success to the whole province of 
geology; his Principles of Geology (18SO) laid the firm 
foundation on which the fabric of the history of the earth 
was so happily erected. The important geogenetic re- 
search of Alexander Humboldt, Leopold Buch, Gustav 
Bischof, Edward Suss, and other geologists, was wholly 
based on the empirical foundation and the speculative 
principles of Karl Hoff and Charles Lyell. They cleared 


the way for purely rational science in the field of geology ; 
they removed the obstacles that had been put in the path 
by mythological fancy and religious tradition, especially 
by the Bible and its legends. I have already discussed 
the merits of Lyell, and his relations with his friend 
Charles Darwin, in the sixteenth and seventeenth chapters 
of my Natural History of Creation, and must refer the 
reader to the standard works on geology for a further 
acquaintance with the history of the earth and the great 
progress which dynamical and historical geology have 
made during the century. 

The first division of the history of the earth must be a 
separation of inorganic and organic geogeny ; the latter 
begins with the first appearance of living things on our 
planet. The earlier section, the inorganic history of the 
earth, ran much the same course as that of the other 
planets of our system. They were all cast off as rings of 
nebula at the equator of the rotating solar mass, and 
gradually condensed into independent bodies. After cool- 
ing down a little, the glowing ball of the earth was formed 
out of the gaseous mass, and eventually, as the heat con- 
tinued to radiate out into space, there was formed at its 
surface the thin solid crust on which we live. When the 
temperature at the surface had gone down to a certain 
point, the water descended upon it from the environing 
clouds of steam, and thus the first condition was secured 
for the rise of organic life. Many million years certainly 
more than a hundred have passed since this important 
process of the formation of water took place, introducing 
the third section of cosmogony, which we call biogtny. 


The third phase of the evolution of the world opens 
with the advent of organisms of our planet, and continues 
uninterrupted from that point until the present day. The 
great problems which this most interesting part of the 
earth's history suggests to us were still thought insoluble 


at the beginning of the nineteenth century, or, at least, 
so difficult that their solution seemed to be extremely 
remote. Now, at the close of the century, we can affirm 
with legitimate pride that they have been substantially 
solved by modern biology and its theory of transformism ; 
indeed, many of the phenomena of the organic world are 
now interpreted on physical principles as completely as the 
familiar physical phenomena of inorganic nature. The 
merit of making the first important step in this difficult 
path, and of pointing out the way to the monistic solution 
of all the problems of biology, must be accorded to the 
great French scientist Jean Lamarck; it was in 1809, the 
year of the birth of Charles Darwin, that he published his 
famous Philosophic Zoologique. In this original work not 
only is a splendid effort made to interpret all the pheno- 
mena of organic life from a monistic and physical point of 
view, but the path is opened which alone leads to the 
solution of the greatest enigma of this branch of science 
the problem of the natural origin of organic species. 
Lamarck, who had an equally extensive empirical acquaint- 
ance with zoology and botany, drew the first sketch of the 
theory of descent; he showed that all the countless 
members of the plant and animal kingdoms have arisen 
by slow transformation from simple, common ancestral 
types, and that it is the gradual modification of forms by 
adaptation, in reciprocal action with heredity, which has 
brought about this secular metamorphosis. 

I have fully appreciated the merit of Lamarck in the 
fifth chapter, and of Darwin in the sixth and seventh 
chapters, of the Natural History of Creation. Darwin, 
fifty years afterwards, not only gave a solid foundation 
to all the essential parts of the theory of descent, but he 
filled up the lacunte of Lamarck's work by his theory of 
selection. Darwin reaped abundantly the success that 
Lamarck had never seen, with all his merit. His epoch- 
making work on The Origin of Species by Natural Sclcc- 
tiotj has transformed modern biology from its very founda- 
tions, in the course of the last forty years, and has raised 
it to a stage of development that yields to no other science 


in existence. Darwin is the Copernicus of the organic 
world, as I said in 1868, and E. du Bois-Reymond repeated 
fifteen years afterwards. 1 


The fourth and hist phase of the world's history must be 
for us men that latest period of time which has M'itnessed 
the development of our own race. Lamarck (1809) had 
already recognised that this evolution is only rationally 
conceivable as the outcome of a natural process, by 
"descent from the apes," our next of kin among the 
mammals, Huxley then proved, in his famous essay on 
The Place of Man In Nature, that this momentous thesis 
is an inevitable consequence of the theory of descent, and 
is thoroughly established by the facts of anatomy, em- 
bryology, and palaeontology. He considered this "ques- 
tion of all questions " to be substantially answered. 
Darwin followed with a brilliant discussion of the question 
under many aspects in his Descent of Man (1871). I had 
myself devoted a special chapter to this important problem 
of the science of evolution in my General Morphology 
(1866). In 1874? I published my Anthropogeny, which 
contains the first attempt to trace the descent of man 
through the entire chain of his ancestry right up to the 
earliest archigonous monera ; the attempt was based equally 
on the three great "documents " of evolutionary science 
anatomy, embryology, and palaeontology. The progress 
we have made in anthropogenetic research during the last 
few years is described in the paper which I read on " Our 
Present Knowledge of the Origin of Man " at the Inter- 
national Congress of Zoologists at Cambridge in 1898. 3 

1 Of, Monigm, by E. Haeckel. 

1 The Last Link, translated by Dr. Gadow, 



The monism of the cosmos. Essential unity of organic and inorganic 
nature, Carbon -theory. The hypothesis of abiogenesis. Me- 
chanical aud purposive causes. Mechanism and teleology in 
Kant's worki. Design in the organic and inorganic worlds. 
Vitalism. Neo vital ism. Dysteleology (the moral of the rudi- 
mentary organs). Absence of design in, and imperfection of, 
nature, Teiic action in organised bodies. Its absence in onto- 
geny and t>hylogeny. The Platonist "ideas." No moral order 
discoverable in tne history of the organic world, of the vertebrate*, 
or of the human race, Prevision. Design and chance. 

ONE of the first things to be proved by the law of iub- 
stance is the basic fact that any natural force can be 
directly or indirectly converted into any other. Mechanical 
and chemical energy, sound and heat, light and electricity, 
are mutually convertible; they seem to be but different 
modes of one and the same fundamental force or energy. 
Thence follows the important thesis of the unity of all 
natural forces, or, as it may also be expressed, the 
" monism of energy/' This fundamental principle is now 
generally recognised in the entire province of physics and 
chemistry, as far as it applies to inorganic substances. 

It seems to be otherwise with the organic world and iU 
wealth of colour and form. It is, of course, obvious that 
a great part of the phenomena of life may be immediately 
traced to mechanical and chemical energy, and to the 
effects of electricity and light. For other vital processes, 
however, especially for psychic activity and consciousness, 
such an interpretation is vigorously contested* Yet the 
modern science of evolution has achieved the task of 
constructing a bridge between these two apparently 
irreconcilable provinces. We are now certain that all the 
phenomena of organic life are subject to the universal law 



of substance no less than the phenomena of the inorganic 

The unity of nature which necessarily follows, and the 
demolition of the earlier dualism, are certainly among the 
most valuable results of modern evolution. Thirty-three 
years ago I made an exhaustive effort to establish this 
"monism of the cosmos" and the essential unity of 
organic and inorganic nature by a thorough critical demon- 
stration, and a comparison of the accordance of these two 
great divisions of nature with regard to matter, form, and 
force. 1 A short epitome of the result is given in the 
fifteenth chapter of my Natural History of Creation. The 
views I put forward are accepted by the majority of 
modern scientists, but an attempt has been made in many 
quarters lately to dispute them, and to maintain the old 
antithesis of the two divisions of nature. The ablest of 
these efforts is to be found in the recent Welt alt That of 
the botanist Reinke. It defends pure cosmological dualism 
with admirable lucidity and consistency, and only goes 
to prove how utterly untenable the teleological system is 
that is connected therewith. According to the author, 
physical and chemical forces alone are at work in the 
entire field of inorganic nature, while in the organic world 
we find "intelligent forces," regulative or dominant 
forces. The law of substance is supposed to apply to the 
one, but not to the other. On the whole, it is a question 
of the old antithesis of a mechanical and a teleological 
system. Before we go more fully into it, let us glance 
briefly at two other theories, which seem to me to be of 
great importance in the decision of that controversy the 
carbon- theory and the theory of spontaneous generation. 

Physiological chemistry has, after countless analyses, 
established the following five facts during the last forty 
years : 

I. No other elements are found in organic bodies than 
those of the inorganic world. 

II. The combination of elements which are peculiar to 
organisms, and which are responsible for their vital pheno- 

1 Qvural Morphology, bk. 2, oh. r. 


men a, are compound protoplasmic substances, of the group 
of albuminoids. 

III. Organic life itself is a chemico-physical process, 
based on the metabolism (or interchange of material) of 
these albuminoids. 

IV. The only element which is capable of building up 
these compound albuminoids, in combination with other 
elements (oxygen, hydrogen, nitrogen, and sulphur), is 

V. These protoplasmic compounds of carbon are dis- 
tinguished from most other chemical combinations by their 
very intricate molecular structure, their instability, and 
their jelly-like consistency. 

On the basis of these five fundamental facts the follow- 
ing " carbon-theory " was erected thirty-three years ago : 
"The peculiar chemico-physical properties of carbon 
especially the fluidity and the facility of decomposition of 
the most elaborate albuminoid compounds of carbon are 
the sole and the mechanical causes of the specific pheno- 
mena of movement, which distinguish organic from in- 
organic substances, and which are called life, in the usual 
sense of the word " (see The Natural History of Creation). 
Although this ** carbon-theory " is warmly disputed hi 
some quarters, no better monistic theory has yet appeared 
to replace it. We have now a much better and more 
thorough knowledge of the physiological relations of cell- 
life, and of the chemistry and physics of the living proto- 
plasm, than we had thirty-three years ago, and so it is 
possible to make a more confident and effective defence of 
the carbon-theory. 

The old idea of spontaneous generation is now taken in 
many different senses. It is owing to this indistinctness 
of the idea, and its application to so many different 
hypotheses, that the problem is one of the most con- 
tentious and confused in the science of the day. I restrict 
the idea of spontaneous generation also called abiogenesis 
or archigony to the first development of living proto- 
plasm out of inorganic carbonates, and distinguish two 
phases in this "beginning of biogenesis " : (1) autogony, 
or the rise of the simplest protoplasmic substances in a 


formative fluid, and (2) plasmogony, the differentiation of 
individual primitive organisms out of these protoplasmic 
compounds in the form of monera. I have treated this 
important, though difficult, problem so exhaustively in the 
fifteenth chapter of my Natural History of Creation that I 
may content myself here with referring to it. There is 
also a very searching and severely scientific inquiry into 
it in my General Morphology (1866). Naegeli has also 
treated the hypothesis in quite the same sense in his 
mechani co-physiological theory of descent (1884), and has 
represented it to be an indispensable thesis in any natural 
theory of evolution. 1 entirely agree with his assertion 
that "to reject abiogenesis is to admit a miracle." 

The hypothesis of spontaneous generation and the allied 
carbon-theory are of great importance in deciding the long- 
standing conflict between the ideological (dualistic) and 
the mechanical (monistic) interpretation of phenomena. 
Since Darwin gave us the key to the monistic explanation 
of organisation in his theory of selection forty years ago, 
it has become possible for us to trace the splendid variety 
of orderly tendencies of the organic world to mechanical, 
natural causes, just as we could formerly in the inorganic 
world alone. Hence the supernatural and telic forces, to 
which the scientist had had recourse, have been rendered 
superfluous. Modern metaphysics, however, continues to 
regard the latter as indispensable and the former as 

No philosopher has done more than Immanuel Kant in 
defining the profound distinction between efficient and final 
causes, with relation to the interpretation of the whole 
cosmos. In his well-known earlier work on The General 
Natural History and Theory of the Heavens he made a 
bold attempt " to treat the constitution and the mechanical 
origin of the entire fabric of the universe according to 
Newtonian laws." This "cosmological nebular theory" 
was based entirely on the mechanical phenomena of gravita- 
tion. It was expanded and mathematically established 
later on by Laplace. When the famous French astronomer 
was asked by Napoleon I. where God, the creator and 
sustamer of all things, came in in his system, he clearly 


and honestly replied : " Sire, I have managed without that 
hypothesis." That indicated the atheistic character which 
this mechanical cosmogony shares with all the other In- 
organic sciences. This is the more noteworthy because 
the theory of Kant and Laplace is now almost universally 
accepted ; every attempt to supersede it has failed. When 
atheism is denounced as a grave reproach, as it so often 
is, it is well to remember that the reproach extends to 
the whole of modern science, in so far as it gives a purely 
mechanical interpretation of the inorganic world. 

Mechanism (in the Kantian sense) alone can give us a 
true explanation of natural phenomena, for it traces them 
to their real efficient causes, to blind and unconscious 
agencies, which are determined in their action only by 
the material constitution of the bodies we are investigat- 
ing, Kant himself emphatically affirms that " there can 
be no science without this mechanism of nature," and that 
the capacity of human reason to give a mechanical inter- 
pretation of phenomena is unlimited. But when he came 
subsequently to give an elucidation of the complex pheno- 
mena of organic nature in his critique of the teleologies) 
system, he declared that these mechanical causes were 
inadequate; that in this we must call final cautet to our 
assistance. It is true, he laid, that even here we must 
recognise the theoretical faculty of the mind to give a 
mechanical interpretation, but its actual competence to do 
so is restricted. He grants it this capacity to some extent ; 
but for the majority of the vital processes (and especially 
for man's psychic activity) he thinks we are bound to 
postulate final causes. The remarkable 79 of the critique 
of judgment bears the characteristic heading : ** On the 
Necessity for the Subordination of the Mechanical Prin- 
ciple to the Teleological in the Explanation of a Thing as 
a Natural End.' 1 It seemed to Kant so impossible to 
explain the orderly processes in the living organism with- 
out postulating supernatural final causes (that is, a pur- 
posive creative force) that he said : " It is quite certain 
that we cannot even satisfactorily understand, much less 
elucidate, the nature of an organism and its internal 
faculty on purely mechanical natural principles; it is so 


certain, Indeed, that we may confidently say, ' It is absurd 
for a man to conceive the idea even that some day a 
Newton will arise who can explain the origin of a single 
blade of grass by natural laws which are uncontrolled by 
design ' such a hope is entirely forbidden us." Seventy 
years afterwards this impossible "Newton of the organic 
world " appeared in the person of Charles Darwin, and 
achieved the great task that Kant had deemed impracti- 

Since Newton (1682) formulated the law of gravitation, 
and Kant (1755) established "the constitution and 
mechanical origin of the entire fabric of the world on 
Newtonian laws," and Laplace (1706) provided a mathe- 
matical foundation for this law of cosmic mechanism, the 
whole of the inorganic sciences have become purely 
mechanical, and at the same time purely atheistic. Astro- 
nomy, cosmogony, geology, meteorology, and inorganic 
physics and chemistry are now absolutely ruled by 
mechanical laws on a mathematical foundation. The idea 
of "design " has wholly disappeared from this vast pro- 
vince of science. At the close of the nineteenth century, 
now that this monistic view has fought its way to general 
recognition, no scientist ever asks seriously of the "pur- 
pose " of any single phenomenon in the whole of this 
great field. Is any astronomer likely to inquire seriously 
to-day into the purpose of planetary motion, or a mineral- 
ogist to seek design in the structure of a crystal? Does 
the physicist investigate the purpose of electric force, or 
the chemist that of atomic weight? We may confidently 
answer in the negative certainly not, in the sense thai 
God, or a purposive natural force, had at some time 
created these fundamental laws of the mechanism of the 
universe with a definite design, and causes them to work 
daily in accordance with his rational will. The anthro- 
pomorphic notion of a deliberate architect and ruler of the 
world has gone for ever from this field ; the " eternal, iron 
laws of nature " have taken his place. 

But the idea of design has a very great significance and 
application in the organic world. We do undeniably per- 
ceive a purpose in the structure and in the life of an 


organism. The plant and the animal seem to be controlled 
by a definite design in the combination of their several 
parts, just as clearly as we see in the machines which man 
invents and constructs; as long as life continues the 
functions of the several organs are directed to definite 
ends, just as is the operation of the various parts of a 
machine. Hence it was quite natural that the older nai've 
study of nature, in explaining the origin and activity of 
the living being, should postulate a creator who had 
"arranged all things with wisdom and understanding," 
and had constructed each plant and animal according to 
the special purpose of its life. The conception of this 
" almighty creator of heaven and earth " was usually quite 
anthropomorphic; he created "everything after its kind." 
As long as the creator seemed to man to be of human 
shape, to think with his brain, see with his eyes, and 
fashion with his hands, it was possible to form a definite 
picture of this "divine engineer" and his artistic work 
in the great workshop of creation. This was not so easy 
when the idea of God became refined, and man saw in his 
"invisible God" a creator without organs a gaseous 
being. Still more unintelligible did these anthropomorphic 
ideas become when physiology submitted for the conscious, 
divine architect and unconscious, creative " vital force " 
a mysterious, purposive, natural force, which differed 
from the familiar forces of physics and chemistry, and 
only took these in part, during life, into its service. This 
vitalism prevailed until about the middle of the nineteenth 
century. Johannes Miiller, the great Berlin physiologist, 
was the first to menace it with a destructive dose of facts. 
It is true that the distinguished biologist had himself 
(like all others in the first half of the century) been 
educated in a belief in this vital force, and deemed it 
indispensable for an elucidation of the ultimate sources 
of life ; nevertheless, in his classical and still unrivalled 
Manual of Phytiology (18S3) he gave a demonstrative 
proof that there is really nothing to be said for this vital 
force. Miiller himself, in a long series of remarkable 
observations and experiments, showed that most of the 
vital processes in the human organism (and in the other 


Animals) take place according to physical and chemical 
laws, and that many of them are capable of mathematical 
determination. That was no less true of the animal func- 
tions of the muscles and nerves, and of both the higher 
and the lower sense-organs, than of the vegetal functions 
of digestion, assimilation, and circulation. Only two 
branches of the life of the organism, mental action and 
reproduction, retained any element of mystery, and seemed 
inexplicable without assuming a vital force. But imme- 
diately after Muller's death such important discoveries 
and advances were made in these two branches that the 
uneasy "phantom of vital force " was driven from its last 
refuge. By a very remarkable coincidence Johannes 
Miiiler died in the year 1858, which saw the publication 
of Darwin's first communication concerning his famous 
theory. The theory of selection solved the great problem 
that had mastered Miiiler the question of the origin of 
orderly arrangements from purely mechanical causes. 

Darwin, as we have often said, had a twofold immortal 
merit in the field of philosophy firstly, the reform of 
Lamarck's theory of descent, and its establishment on the 
mass of facts accumulated In the course of the half-cen- 
tury ; secondly, the conception of the theory of selection, 
which first revealed to us the true causes of the gradual 
formation of species. Darwin was the first to point out 
that the "struggle for life" is the unconscious regulator 
which controls the reciprocal action of heredity and adapta- 
tion in the gradual transformation of species ; it is the 
great "selective divinity " which, by a purely "natural 
choice/' without preconceived design, creates new forms, 
just as selective man creates new types by an "artificial 
choice," with a definite design. That gave us the solution 
of the great philosophic problem : "How can purposive 
contrivances be produced by purely mechanical processes 
without design? " Kant held the problem to be insoluble, 
although Empedocles had pointed out the direction of the 
solution two thousand years before. His principle of 
" teieologic&l mechanicism " has become more and more 
accepted of late years, and has furnished a mechanical 
explanation even of the finest and most recondite processes 


of organic life by "the functional self -production of the 
purposive structure." Thus have we got rid of the trans- 
cendental " design " of the teleological philosophy of the 
schools, which was the greatest obstacle to the growth of 
a rational and monistic conception of nature. 

Very recently, however, this ancient phantom of a 
mystic vital force, which seemed to be effectually banished, 
has put in a fresh appearance; a number of distinguished 
biologists have attempted to reintroduce it under another 
name. The clearest presentation of it is to be found in 
the Welt alt That of the Kiel botanist, J. Rienke. He 
taken upon himself the defence of the notion of miracle, 
of theism, of the Mosaic story of creation, and of the 
constancy of species; he calls ** vital forces," in opposition 
to physical forces, the directive or dominant forces. Other 
neovitalists prefer, in the good old anthropomorphic 
style, a " supreme " engineer, who has endowed organic 
substance with a purposeless structure, directed to the 
realisation of a definite plan. These curious teleological 
hypotheses, and the objections to Darwinism which 
generally accompany them, do not call for serious scientific 
refutation to-day. 

Thirty-three years ago I gave the title of " dystele- 
ology " to the science of those extremely interesting and 
significant biological facts which, in the most striking 
fashion, gave a direct contradiction to the teleological idea 
**of the purposive arrangement of the living organism." l 
This " science of rudimentary, abortive, arrested, dis- 
torted, atrophied, and cataplastic individuals " is based 
oo an immense quantity of remarkable phenomena, which 
were long familiar to zoologists and botanists, but were 
not properly interpreted, and their great philosophic 
significance appreciated, until Darwin. 

All the higher animals and plants, or, in general, all 
organisms which are not entirely simple in structure, but 
are made up of n number of organs in orderly co-operation, 
are found, on close examination, to possess a number of 
useless or inoperative members, sometimes, indeed, hurtful 

1 Of. Oen*r*l Morphology, ToL ii, and Th* Natural ffi*t#ry of 


and dangerous. In the flowers of most plants we find, 
besides the actual sex-leaves that effect reproduction, a 
number of other leaf -organs which have no use or meaning 
(arrested or "miscarried " pistils, fruit, corona and calix- 
1 eaves, etc.). In the two large and variegated classes of 
flying animals, birds and insects, there are, besides the 
forms which make constant use of their wings, a number 
of species which have undeveloped wings and cannot fly. 
In nearly every class of the higher animals which have 
eyes there are certain types that live in the dark ; they 
have eyes, as a rule, but undeveloped and useless for 
vision. In our own human organism we have similar 
useless rudimentary structures in the muscles of tiie ear, 
in the eye-lid, in the nipple and milk- gland of the male, 
and in other parts of the body ; indeed, the vermiform 
appendix of our caecum is not only useless, but extremely 
dangerous, and inflammation of it is responsible for a 
number of deaths every year. 

Neither the old mystic vitalism nor the new, equally 
irrational, neovitalism can give any explanation of these 
and many other purposeless contrivances in the structure 
of the plant and the animal ; but they are very simple in 
the light of the theory of descent. It shows that these 
rudimentary organs are atrophied, owing to disuse. Jutt 
as our muscles, nerves, and organs of sense are strength- 
ened by exercise and frequent use, so, on the other hand, 
they are liable to degenerate more or less by disuse or 
suspended exercise. But, although the development of the 
organs is promoted by exercise and adaptation, they by 
no means disappear without leaving a trace after neglect ; 
the force of heredity retains them for many generations, 
and only permits their gradual disappearance, after a lapse 
of a considerable time. The blind "struggle for existence 
between the organs " determines their historical dis- 
appearance, just as it effected their first origin and develop* 
ment. There U no internal " purpose '* whatever in the 

The life of the animal and the plant bears the same 
universal character of incompleteness as the life of man. 
This is directly attributed to the circumstance that nature 


organic as well as inorganic is in a perennial state of 
evolution, change, and transformation. This evolution 
seems on the whole at least as far as we can survey the 
development of organic life on our planet to be a pro- 
gressive improvement, an historical advance from the 
simple to the complex, the lower to the higher, the im- 
perfect to the perfect. I have proved in my General 
Morphology that this historical progress or gradual per- 
fecting (teleosis) is the inevitable result of selection, and 
not the outcome of a preconceived design. That is clear 
from the fact that no organism is perfect ; even if it does 
perfectly adapt itself to its environment at a given 
moment, this condition would not last very long ; the 
conditions of existence of the environment are themselves 
subject to perpetual change, and they thus necessitate a 
continuous adaptation on the part of the organism. 

Under the title of Design in the Living Organism, the 
famous embryoiogist Carl Ernst itaer published a work in 
187C which, together with the article on Darwinism which 
accompanied it, proved very acceptable to our opponents, 
and is still much quoted in opposition to evolution. It 
was a revival of the old teleological system under a new 
name, and we must devote a line of criticism to it. We 
must premise that, though Baer was a scientist of the 
highest order, his original monistic views were gradually 
marred by a tinge of mysticism with the advance of age, 
and he eventually became a thorough dualist. In his pro- 
found work on Th* Evolution of Animal$ (1828), which 
he himself entitled Obtcrvation and Experiment , these 
two methods of investigation are equally applied. By 
careful observation of the various phenomena of the de- 
velopment of the animal ovum Baer succeeded in giving 
the first consistent presentation of the remarkable changes 
which take place in the growth of the vertebrate from a 
simple egg-cell. At the same time he endeavoured, by 
far-seeing comparison and keen reflection, to learn the 
causes of the transformation, and to reduce them to 
general constructive laws. He expressed the general 
result of his research in the following thesis: "The 
evolution of the individual is the story of the growth of 


individuality in every respect." He meant that ** the one 
great thought that controls all the different aspect! of 
animal evolution is the same that gathered the scattered 
fragments of space into spheres, and linked them into 
solar systems. This thought is no other than life itself, 
and the words and syllables in which it finds utterance are 
the varied forms of living things." 

Baer, however, did not attain to a deeper knowledge of 
this great genetic truth and a clearer insight into the real 
efficient causes of organic evolution, because his attention 
was exclusively given to one half of evolutionary science, 
the science of the evolution of the individual, embryology, 
or, in a wider sense, ontogeny. The other half, the 
science of the evolution of species, phylogeny, was not 
yet in existence, although Lamarck had already pointed 
out the way to it in 1809. When it was established by 
Darwin in 1859 the aged Baer was no longer in a position 
to appreciate it; the fruitless struggle which he led against 
the theory of selection clearly proved that he understood 
neither its real meaning nor its philosophic importance* 
Teleological and, subsequently, theological speculations 
had incapacitated the ageing scientist from appreciating 
this greatest reform of biology. The teleologicui observa- 
tions which he published against it in his Species and 
Studies in his eighty-fourth year are mere repetitions of 
errors which the teleology of the dualists has opposed to 
the mechanical or monistic system for more than 2000 
years. The **teiic idea" which, according to Baer, con- 
trols the entire evolution of the animal from the ovum is 
only another expression for the eternal "idea" of Plato 
and the entelecheia of his pupil Aristotle, 

Our modern biogeny gives a purely physiological ex- 
planation of the facts of embryology, in assigning the 
functions of heredity and adaptation as their causes. 
The great biogenetic law, which Baer failed to appreciate, 
reveals the intimate causal connection between the onto- 
genesis of the individual and the phylogenetis of its 
ancestors ; the former seems to be a recapitulation of the 
latter. Nowhere, however, in the evolution of animals 
and plants do we find any trace of design, but merely the 


inevitable outcome of the struggle for existence, the blind 
controller, instead of the provident God, that effects the 
changes of organic forms by a mutual action of the laws of 
heredity and adaptation. And there is no more trace of 
41 design " in the embryology of the individual plant, 
animal, or man. This ontogeny is but a brief epitome of 
phylogeny, an abbreviated and condensed recapitulation of 
it, determined by the physiological lawi of heredity. 

Baer ended the preface to his classical Evolution of 
Animals (1828) with these words: "The palm will be 
awarded to the fortunate scientist who succeeds in re- 
ducing the constructive forces of the animal body to the 
general forces or life-processes of the entire world. The 
tree has not yet been planted which is to make his cradle." 
The great embryoiogist erred once more. That very year, 
1828, witnessed the arrival of Charles Darwin at Cam- 
bridge University (for the purpose of studying theology!) 
the u fortunate scientist " who richly earned the palm 
thirty years afterwards by his theory of selection. 

In the philosophy of history that is, in the general 
reflections which historians make on the destinies of 
nations and the complicated course of political evolution 
there still prevails the notion of a " moral order of the 
universe." Historians seek in the vivid drama of history 
a leading design, an ideal purpose, which has ordained 
one or other race or State to a special triumph, and to 
dominion over the others. This teleological view of his- 
tory has recently become more strongly contrasted with 
our monistic view in proportion as monism has proved to 
be the only possible interpretation of inorganic nature. 
Throughout the whole of astronomy, geology, physics, 
and chemistry there is no question to-day of a "moral 
order," or a personal God, whose " hand hath disposed all 
things in wisdom and understanding." And the same 
must be said of the entire field of biology, the whole 
constitution and history of organic nature, if we set aside 
the question of man for the moment. Darwin has not 
only proved by his theory of selection that the orderly 
processes in the life and structure of animals and plants 
hare arisen by mechanical laws without any preconceived 


design, but he has shown us in the " struggle for life " 
the powerful natural force which has exerted supreme 
control over the entire course of organic evolution for 
millions of years. It may he said that the struggle for 
life is the "survival of the fittest" or the "victory of 
the best'*; that is only correct when we regard the 
strongest as the best (in a moral sense). Moreover, the 
whole history of the organic world goes to prove that, 
besides the predominant advance towards perfection, there 
are at all times cases of retrogression to lower stages. 
Even Baer's notion of "design" has no moral feature 

Do we find a different state of things in the history of 
peoples, which man, in his anthropocentric presumption, 
loves Lo call "the history of the world "? Do we find in 
every phase of it a lofty moral principle or a wise ruler, 
guiding the destinies of nations? There can be but one 
answer in the present advanced stage of natural and 
human history : No. The fate of those branches of the 
human family, those nations and races which have 
struggled for existence and progress for thousands of 
years, is determined by the same " eternal laws of iron " 
as the history of the whole organic world which has 
peopled the earth for millions of years. 

Geologists distinguish three great epochs in the organic 
history of the earth, as far as we can read it in the 
monuments of the science of fossils the primary, second- 
ary, and tertiary epochs. According to a recent calcula- 
tion, the first occupied at least 34,000,000, the second 
11,000,000, and the third 3,000,000 years. The history of 
the family of vertebrates, from which our own race has 
sprung, unfolds clearly before our eyes during this long 
period. Three different stages in the evolution of the 
vertebrate correspond to the three epochs; the fithei 
characterised the primary (palaeozoic) age, the reptilet the 
secondary (mesoxoic), and the mammal* the tertiary (caeno- 
xoic). Of the three groups the fishes rank lowest in 
organisation, the reptiles come next, and the mammals 
take the highest place. We find, on nearer examination 
of the history of the three classes, that their various 


orders arid families also advanced progressively during the 
three epochs towards a higher stage of perfection. May 
we consider this progressive development as the outcome 
of a conscious design or a moral order of the universe? 
Certainly not. The theory of selection teaches us that 
this organic progress, like the earlier organic differentia- 
tion, is an inevitable consequence of the struggle for 
existence. Thousands of beautiful and remarkable species 
of animals and plants have perished during those 4?8,000000 
years, to give place to stronger com peti tors, and the 
victors in this struggle for life were not always the noblest 
or most perfect forms in a moral sense. 

It has been just the same with the history of humanity. 
The splendid civilisation of classical antiquity perished 
because Christianity, with its faith in a loving God and its 
hope of a better life beyond the grave, gave a fresh, strong 
impetus to the soaring human mind. The Papal Church 
quickly degenerated into a pitiful caricature of real Chris- 
tianity, and ruthlessly scattered the treasures of know- 
ledge which the Hellenic philosophy had gathered ; it 
gained the dominion of the world through the ignorance 
of the credulous masses. In time the Reformation broke 
the chains of this mental slavery, and assisted reason to 
secure its right once more. But in the new, as in the 
older, period the great struggle for existence went on in 
its eternal fluctuation, with no trace of a moral order. 

And it is just as impossible for the impartial and 
critical observer to detect a " wise providence " in the 
fate of individual human beings as a moral order in the 
history of peoples. Both are determined with iron neces- 
sity by a mechanical causality which connects every single 
phenomenon with one or more antecedent causes. Even 
the ancient Greeks recognised ananke, the blind heimar- 
ntene, the fate "that rules gods and men,' 1 as the 
iupreme principle of the universe. Christianity replaced 
it by a conscious Providence, which is not blind, but sees, 
and which governs the world in patriarchal fashion. The 
anthropomorphic character- of this notion, generally 
clotely connected with belief in a personal God, is quite 
obvious. Belief in a 'Moving Father," who unceasingly 


guides the destim'ef of 1,500,000,000 men on our planet, 
and is attentive at all times to their millions of contra- 
dictory prayers and pious wishes, is absolutely impossible ; 
that is at once perceived on laying aside the coloured 
spectacles of " faith " and reflecting rationally on the 

As a rule, this belief in Providence and the tutelage of 
a " loving Father " is more intense in the modern civilised 
man just as in the uncultured savage when some good 
fortune has befallen him : an escape from peril of life, 
recovery from a severe illness, the winning of the first 
prize in a lottery, the birth of a long-delayed child, and 
so forth. When, on the other hand, a misfortune is met 
with, or an ardent wish is not fulfilled, " Providence " is 
forgotten. The wise ruler of the world slumbered or 
refused his blessing. 

In the extraordinary development of commerce in the 
nineteenth century the number of catastrophes and acci- 
dents has necessarily increased beyond all imagination; 
of that the journal is a daily witness. Thousands are 
killed every year by shipwreck, railway accidents, mine 
accidents, etc. Thousands slay each other every year in 
war, and the preparation for this wholesale massacre 
absorbs much the greater part of the revenue in the 
highest civilised nations, the chief professors of "Chris- 
tian charity. And among these hundreds of thousands 
of annual victims of modern civilisation strong, indus- 
trious, courageous workers predominate. Yet the talk of a 
"moral order" goes on. 

Since impartial study of the evolution of the world 
teaches us that there is no definite aim and no special 
purpose to be traced in it, there seems to be no alternative 
but to leave everything to " bl incLMFer:^rh is re- 
proach has been made to the 
and Darwin, as it had been 
Kant and Laplace; there are/ 
sophers who lay great strq 
worth while to make a brie 

One group of philosophej 
tts Ideological conception, 


orderly lystem, in which every phenomenon has its aim 
and purpose ; there is no such thing as chance. The other 
group, holding a mechanical theory, expresses itself thus : 
The development of the universe is a monistic mechanical 
process, in which we discover no aim or purpose whatever ; 
what we call design in the organic world is a special result 
of biological agencies; neither in the evolution of the 
heavenly bodies nor in that of the crust of our earth do we 
find any trace of a controlling purpose all is the result of 
chance. Each party is right according to its definition 
of chance. The general law of causality, taken in con- 
junction with the law of substance, teaches us that every 
phenomenon has a mechanical cause; in this sense there 
is no such thing as chance. Yet it is not only lawful, 
but necessary, to retain the term for the purpose of ex- 
pressing the simultaneous occurrence of two phenomena, 
which are not causally related to each other, but of which 
each has its own mechanical cause, independent of that 
of the other, Everybody knows that chance, in this 
monistic sense, plays an important part in the life of 
man and in the universe at large. That, however, does 
not prevent us from recognising in each " chance " event, 
M we do in the evolution of the entire cosmos, the 
universal sovereignty of nature's supreme law, the totr 
o/ lubitance. 



The idea of God in general Antithesis of God and the world ; the 
supernatural ana nature. Theism and Pantheism. Chief forrai 
of Theism. Polytheism. Triplotheisra. Aniphi theism. Mono- 
theism. Religious statistics. Naturalistic Monotheism. Solar- 
ism. Anthropiatic Monotheism. The three great Mediterranean 
religions. Moeaism. Christianity The oult of the Madonna 
and the saints. Papal Polytheism. Islam. Mixotheism. Nature 
of Theism. An extrainundane .nd anthropomorphic God 
gaseous vertebrate. Pantheism, Ultramundane God (nature). 
The byloxoism of the Ionic Monists (Anaximander). Conflict of 
Pantheism and Christianity. Spinoza. Modem Monism. 

FOR thousands of years humanity has placed the last and 
supreme basis of all phenomena in an efficient cause, to 
which it gives the title of God (tkui, t/ieoi). Like all 
general ideas, this notion of God has undergone A seriei 
of remarkable modifications and transformations in the 
course of the evolution of reason* Indeed, it may be said 
that no other idea has had so many metamorphoses ; for 
no other belief affects in so high a degree the chief object! 
of the mind and of rational science, as well as the deepest 
interests of the emotion and poetic fancy of the believer. 
A comparative criticism of the many different forms of 
the idea of God would be extremely interesting and in- 
structive; but we have not space for it in the present 
work. We must be content with a passing glance tt the 
most important forms of the belief and their relation to 
the modern thought that has been evoked by a sound 
study of nature. For further information on this inter- 
esting question the reader would do well to consult the 
distinguished work of Adalbert Svoboda, Form* of Faith 



When we pass over the finer shades and the variegated 
clothing of tlie God-idea and confine our attention to its 
chief element, we can distrihute all the different presenta- 
tions of it in two groups the theistic and pantheistic 
groups. The latter is closely connected with the monistic, 
or rational, view of things, and the former is associated 
with dualism and mysticism. 


In this view God is distinct from, and opposed to, the 
world as its creator, sustainer, and ruler. He is always 
conceived in a more or less human form, as an organism 
which thinks and acts like a man only on a much higher 
scale. This anthropomorphic God, polyphyleticaily 
evolved by the different races, assumes an infinity of 
shapes in their imagination, from fetichism to the refined 
monotheistic religions of the present day. The chief 
forms of theism are polytheism, triplotheism, amphi- 
theisin, arid monotheism. 

The polytheist peoples the world with a variety of 
gods arid goddesses, which enter into its machinery more 
or less independently. Fetichism sees such subordinate 
deities in the lifeless bodies of nature, in rocks, in water, 
in the air, in human productions of every kind (pictures, 
statues, etc.). De monism sees gods in living organisms 
of every species trees, animals, arid men. This kind of 
polytheism is found in innumerable forma even in the 
lowest tribes. It reaches its highest stage in Hellenic 
polytheism, in the myths of ancient Greece, which still 
furnish the finest images to the modern poet and artist. 
At a much lower stage we have Catholic polytheism, in 
which innumerable " saints " (many of them of very 
equivocal repute) are venerated as subordinate divinities, 
and prayed to exert their mediation with the supreme 

The dogma of the "Trinity," which still comprise* 
three of the chief articles pf faith in the creed of Chris- 
tian peoples, culminates in the notion that the one God 


of Christianity is really made up tx three different 
persons: (1) God the Father, the omnipotent creator of 
heaven and earth (this untenable myth was refuted long 
ago by scientific cosmogony, astronomy, and geology); 
(2) Jesus Christ; and (3) the Holy Ghost, a mystical 
being, over whose incomprehensible relation to the Father 
and the Son millions of Christian theologians have racked 
their brains in vain for the last 1900 years. The 
Gospels, which are the only ciear sources of this triplo- 
t/ieifm, are very obscure as to the relation of these three 
persons to each other, and do not give a satisfactory 
answer to the question of their unity. On the other 
hand, it must be carefully noted what confusion this 
obscure and mystic dogma of the Trinity must necessarily 
cause in the minds of our children even in the earlier 
years of instruction. One morning they learn (in their 
religious instruction) that three times one are one, and 
the very next hour they are told in their arithmetic class 
that three times one are three. I remember well the 
reflection that this confusion led me to in my early school 

For the rest, the " Trinity " is not an original element 
in Christianity ; like most of the other Christian dogmas, 
it has been borrowed from other religions. Out of the 
sun-worship of the Chaldaean magi was evolved the 
Trinity of Ilu, the mysterious source of the world; its 
three manifestations were Ami, primeval chaos, Bel, the 
architect of the world, and A a, the heavenly light, the 
all-enlightening wisdom. In the Brahmanic religion the 
Trimurti is also conceived as a "divine unity M made up of 
three persons Brahma (the creator), Vishnu (the sus- 
tainer), and Shiva (the destroyer). It would secna that 
in this and other ideas of a Trinity the u sacred number, 
three," as such as a " symbolical number " has counted 
for something. The three first Christian virtues Faith, 
Hope, Charity form a similar triad. 

According to the amphitheitt*, the world is ruled by 
two different gods, a good and an evil principle, God and 
the Devil. They are engaged in a perpetual struggle, 
like rival emperors, or pope and anti-pope. The condition 


of the world is the result of this conflict. The loving 
God, or good principle, is the source of all that is good 
and beautiful, of joy and of peace. The world would be 
perfect if his work were not continually thwarted by the 
evil principle, the Devil; this being is the cause of all 
that is bad and hateful, of contradiction and of pain. 

Amphi theism is undoubtedly the most rational of all 
forms of belief in God, and the one which is least incom- 
patible with a scientific view of the world. Hence we find 
it elaborated in many ancient peoples thousands of years 
before Christ. In ancient India Vishnu, the preserver, 
struggles with Shiva, the destroyer. In ancient Egypt 
the good Osiris is opposed by the wicked Typhon. The 
early Hebrews had a similar dualism of Aschera (or 
Keturah), the fertile mother-earth, and Elion (Moloch 
or Sethos), the stern heavenly father. In the Zend 
religion of the ancient Persians, founded by Zoroaster 2000 
years before Christ, there is a perpetual struggle between 
Ormuzd, the good god of light, and Ahriman, the wicked 
god of darkness. 

In Christian mythology the devil is scarcely less con- 
spicuous as the adversary of the good deity, the tempter 
and seducer, the prince of hell and lord of darkness. A 
personal devil was still an important element in the belief 
of most Christians at the beginning of the nineteenth 
century. Towards the middle of the century he was 
gradually eliminated by being progressively explained 
away, or he was restricted to the subordinate role he plays 
as Mephistopheles in Goethe's great drama. To-day the 
majority of educated people look upon "belief in a per- 
sonal devil " as a mediaeval superstition, while " belief in 
God " (that is, the personal, good, and loving God) is 
retained as an indispensable element of religion. Yet 
the one belief is just as much (or as little) justified as the 
other. In any case, the much-lamented "imperfection 
of our earthly life," the "struggle for existence" and 
all that pertains to it, are explained much more simply 
and naturally by this struggle of a good and an evil god 
than by any other form of theism. 

The dogma of the unity of God may in some respects 


be regarded as the simplest and most natural type of 
theism ; it is popularly supposed to be the most widely 
accepted element of religion, and to predominate in the 
ecclesiastical systems of civilised countries. In reality 
that is not the case, because this alleged '* monotheism " 
usually turns out on closer inquiry to be one of the other 
forms of theism we have examined, a number of subordin- 
ate deities being generally introduced besides the supreme 
one. Most of the religions which took a purely mono- 
theistic standpoint have become more or less polytheistic 
in the course of time. Modern statistics assure us that 
of the 1,500,000,000 men who people the earth the great 
majority are monotheists ; of these, nominally, about 
600,000,000 are Brahma- Buddhists, 500,000,000 are called 
Christians, 200,000,000 are heathens {of various types), 
180,000,000 are Mohammedans, 10,000,000 are Jews, and 
10,000,000 have no religion at all. However, the vast 
majority of these nominal monotheists have very confused 
ideas about the deity, or believe in a number of gods and 
goddesses besides the chief god angels, devils, etc. 

The different forms which monotheism has assumed in 
the course of its polyphyletic development may be dis- 
tributed in two groups those of naturalistic and anthrop- 
ittic monotheism. Naturalistic monotheism finds the 
embodiment of the deity in some lofty and dominating 
natural phenomenon. The sun, the deity of light and 
warmth, on whose influence all organic life insensibly and 
directly depends, was taken to be such a phenomenon 
many thousand years ago. Sun-worship (solarium or 
hediotheism) seems to the modern scientist to be the best 
of all forms of theism, and the one which may be most 
easily reconciled with modern monism. For modern 
Astrophysics and geogeny have taught us that the earth 
is a fragment detached from the sun, and that it will 
eventually return to the bosom of its parent. Modern 
physiology teaches us that the first source of organic life 
on the earth is the formation of protoplasm, and that this 
fynthesis of simple inorganic substances, water, carbonic 
acid, and ammonia, only takes place under the influence 
of tun-light. On the primary evolution of the plasmo- 


doraous plants followed, secondarily, that of the plasmo- 
phagous animals, which directly or indirectly depend on 
them for nourishment ; and the origin of the human race 
itself is only a later stage in the development of the animal 
kingdom. Indeed, the whole of our bodily and mental 
life depends, in the last resort, like all other organic life, 
on the light and heat rays of the sun. Hence, in the light 
of pure reason, sun-worship, as a form of naturalistic 
monotheism, seems to have a much better foundation than 
the anthropistic worship of Christians and of other mono- 
theisU who conceive their god in human form. As a 
matter of fact, the sun-worshippers attained, thousands 
of years ago, a higher intellectual and moral standard 
than most of the other theists. When I was in Bombay 
in 3881 I watched with the greatest sympathy the elevat- 
ing rites of the pious Parsees, who, standing on the sea- 
shore, or kneeling on their prayer-rugs, offered their 
devotion to the sun at its rise and setting. 1 

Moon-worship (lunarism and selenotheism) is of much 
less Importance than sun-worship. There are a few un- 
civilised races that have adored the moon as their only 
deity, but it has generally been associated with a worship 
of the stars and the sun. 

The hurnanisation of God, or the idea that the 
** Supreme Being " feels, thinks, and acts like man 
(though in a higher degree), has played a most important 
part, as anthropomorphic monoi/iewm, in the history of 
civilisation. The most prominent in this respect arc the 
three great religions of the Mediterranean peoples the 
old Mosaic religion, the intermediate Christian religion, 
and the younger Mohammedanism. These three great 
Mediterranean religions, all three arising on the east coast 
of the most interesting of all seas, and originating in an 
imaginative enthusiast of the Semitic race, are intimately 
connected, not only by this external circumstance of an 
analogous origin, but by many common features of their 
internal contents. Just as Christianity borrowed a good 
deal of 1U mythology directly from ancient Judaism, so 

i Vide A Vim* to ftyfcm, E. Hseckal, translated by a Bell. 


Islam has inherited much from both its predecessors. Ail 
the three were originally monotheistic ; all three were sub- 
sequently overlaid with a great variety of polytheistic 
features, in proportion as they extended, first along the 
coast of the Mediterranean with its heterogeneous popula- 
tion, and eventually into every part of the world. 

The Hebrew monotheism, as it was founded by Moses 
(about 1600 B.C.), is usually regarded as the ancient faith 
which has been of the greatest importance in the ethical 
and religious development of humanity. This high his- 
torical appreciation is certainly valid in the sense that 
the two other world-conquering Mediterranean religions 
issued from it ; Christ was just as truly a pupil of Moses 
as Mohammed was afterwards of Christ. So also the New 
Testament, which has become the foundation of the belief 
of the highest civilised nations in the short space of 1900 
years, rests on the venerable basis of the Old Testament. 
The Bible, which the two compose, has had a greater 
influence and a wider circulation than any other book in 
the world. Even to-day the Bibie in spite of its curious 
mingling of the be4?t and the worst elements is in a 
certain sense the " book of books/' Yet, when we make 
an impartial and unprejudiced study of this notable his- 
torical source, we find it very different in several important 
respects from the popular impression. Here again modern 
criticism and history have come to certain conclusions 
which destroy the prevalent tradition in its very 

The monotheism which Moses endeavoured to establish 
in the worship of Jehovah, and which the prophets the 
philosophers of the Hebrew race afterwards developed 
with great success, had at first to sustain a long and 
severe struggle with the dominant polytheism which was 
in possession. Jehovah, or Yahveh, was originally derived 
from the heaven-god, which, under the title of Moloch, or 
Baal, was one of the most popular of the Oriental deities 
(the Sethof or Typhon of the Egyptians, and the Saturn 
or Cronos of the Greeks). There were, however, other 
gods in great favour with the Jewish people, and so the 
struggle with "idolatry " continued. Still, Jehovah was, 


in principle, the only God, explicitly claiming, in the first 
precept of the decalogue : "I am the Lord thy God ; 
thou shalt have no other gods beside me." 

Christian monotheism shared the fate of its mother, 
Mosaism ; it was generally only monotheistic in theory, 
while it degenerated practically into every kind of poly- 
theism. In point of fact, monotheism was logically aban- 
doned in the very dogma of the Trinity which was adopted 
as an indispensable foundation of the Christian religion. 
The three persons, which are distinguished as Father, 
Son, and Holy Ghost, are three distinct individuals (and, 
indeed, anthropomorphic persons), just as truly as the 
three Indian deities of the Trimurti (Brahma, Vishnu, 
and Shiva) or the Trinity of the ancient Hebrews (Anu, 
Bel, and Aa). Moreover, in the most widely-distributed 
form of Christianity the " virgin " mother of Christ plays 
an important part as a fourth deity ; in many Catholic 
countries she is practically taken to be much more powerful 
and influential than the three male persons of the celestial 
administration. The cult of the madonna has been 
developed to such an extent in these countries that we 
may oppose it to the usual masculine form of monotheism 
as one of a feminine type. The " Queen of Heaven " 
becomes so prominent, as is seen in so many pictures and 
legends of the madonna, that the three male persons 
practically disappear. 

In addition, the imagination of the pious Christian 
soon came to increase this celestial administration by a 
numerous company of "saints" of all kinds, and bands 
of musical angels, who should see that " eternal life " 
should not prove too dull. The Popes the greatest char- 
latans that any religion ever produced have constantly 
studied to increase this band of celestial satellites by 
repeated canonisation. This curious company received its 
most interesting acquisition in 1870, when the Vatican 
Council pronounced the Popes, as the vicars of Christ, 
to be infallible, and thus raised them to a divine dignity. 
When we add the "personal Devil" that they acknow- 
ledge, and the " bad angels " who form his court, we have 
in modern Catholicism, still the most extensive branch of 


Christianity, a rich and variegated polytheism that dwarfs 
the Olympic family of the Greeks. 

Islam, or the Mohammedan monotheism, is the 
youngest and purest form of monotheism. When the 
young Mohammed (born 570) learned to despise the poly- 
theistic idolatry of his Arabian compatriots, and became 
acquainted with the Nestorian Christianity, he adopted 
its chief doctrines in a general way ; but he could not 
bring himself to see anything more than a prophet in 
Christ, like Moses. He found in the dogma of the Trinity 
what every emancipated thinker finds on impartial reflec- 
tion an absurd legend, which is neither reconcilable with 
the first principles of reason, nor of any value whatever 
for our religious advancement. He justly regarded the 
worship of the immaculate mother of God as a piece of 
pure idolatry, like the veneration of pictures and images. 
The longer he reflected on it, and the more he strove after 
a purified idea of deity, the clearer did the certitude of 
his great maxim appear: "God is the only God " there 
are no other gods beside him. 

Yet Mohammed could not free himself from the anthro- 
pomorphism of the God-idea. His one only God was an 
idealised, almighty man, like the stern, vindictive God of 
Moses, and the gentle, loving God of Christ. Still, we 
must admit that the Mohammedan religion has preserved 
the character of pure monotheism throughout the course 
of its historical development and its inevitable division 
much more faithfully than the Mosaic and Christian reli- 
gions. We see that to-day, even externally, in its forms 
of prayer and preaching, and in the architecture and 
adornment of its mosques. When I visited the East for 
the first time in 1875, and admired the noble mosques of 
Cairo, Smyrna, Brussa, and Constantinople, I was inspired 
with a feeling of real devotion by the simple and tasteful 
decoration of the interior, and the lofty and beautiful 
architectural work of the exterior. How noble and in- 
spiring do these mosques appear in comparison with the 
majority of Catholic churches, which are covered internally 
with gaudy pictures and gilt, and are outwardly disfigured 
by an immoderate crowd of human and animal figures! 


Not less elevated are the silent prayers and the simple 
devotional acts of the Koran, when compared with the 
loud, unintelligible verbosity of the Catholic Mass and the 
blatant music of their theatrical processions. 

Under the title of mixo theism we may embrace all the 
forms of theistic belief which contain mixtures of religious 
notions of different, sometimes contradictory, kinds. In 
theory this most widely diffused type of religion is not 
recognised at all ; in the concrete it is the most important 
and most notable of all. The vast majority of men who 
have religious opinions have always been, and still are, 
mixotheittt ; their idea of God is picturesquely com- 
pounded from the impressions received in childhood from 
their own sect, and a number of other impressions which 
are received later on, from contact with members of other 
religions, and which modify the earlier notions. In 
educated people there is also sometimes the modifying 
influence of philosophic studies in maturer years, and 
especially the unprejudiced study of natural phenomena, 
which reveals the futility of the theistic idea. The con- 
flict of these contradictory impressions, which is very 
painful to a iensitive soul, and which often remains un- 
decided throughout life, clearly shows the immense power 
of the heredity of ancient myths on the one hand, and 
the early adaptation to erroneous dogmas on the other. 
The particular faith in which the child has been brought 
up generally remains in power, unless a ** conversion " 
takes place subsequently, owing to the stronger influence 
of some other religion. But even in this supersession of 
one faith by another the new name, like the old one, 
prove! to be merely an outward label covering a mixture 
of the most diverse opinions and errors. The greater 
part of those who call themselves Christians are not mono- 
t heists (as they think), but amphitheists, triplotheists, or 
polytheiuts. And the same must be said of Islam and 
Mosaism, and other monotheistic religions. Everywhere 
we find associated with the original idea of a "sole and 
triune God " later beliefs in a number of subordinate 
deities angels, devils, saints, etc. a picturesque assort- 
ment of the most diverse theistic forms. 


Ail the above forms of theism, in the proper senate of 
the word whether the belief assumes a naturalistic or an 
anthropistic form represent God to be an extramundane 
or a supernatural being. He is always opposed to th? 
world, or nature, as an independent being ; generally as 
its creator, susUiner, and ruler. In most religions he has 
the additional character of personality, or, to put it more 
definitely still, God as a person is likened to man. "Ir* 
his gods man paints himself/' This anthropomorphic 
conception of God as one who thinks, feel'*, and acts lik< 
man prevails with the great majority of theists, sometimes 
in a cruder and more naive form, sometimes in a more 
refined and abstract degree. In any casr the form of 
theosophy we have described is sure to affirm that God, 
the supreme being, is infinite in perfection, and, therefore, 
far removed from the imperfection of humanity. Yet, 
when we examine closely, we always find the same psychic 
or mental activity in the two. God feels, thinks, and 
acts as man does, although it be in an infinitely more 
perfect form. 

The personal anthropum of God has become so natural 
to the majority of believers that they experience no shock 
when they find God personified in human form in pictures 
and statues, and in the varied images of the poet, in 
which God takes human form that is, is changed into a 
vertebrate. In some myths even Owl takes the form of 
other mammals (an ape, lion, bull, etc.), and more rarely 
of a bird (eagle, dove, or stork), or of some lower vert* 
brate (serpent, crocodile, dragon, etc.). 

In the higher and more abstract forma of religion this 
idea of bodily appearance is entirely abandoned, and God 
is adored as a "pure spirit" without a body. "God is 
a spirit, and they who worship him must worship him in 
spirit and in truth." Nevertheless, the psychic activity 
of this ** pure spirit " remains just the same as that of 
the anthropomorphic God. In reality, even this im- 
material spirit is not conceived to be incorporeal, but 
merely invisible, gaseous. We thus arrive at the para- 
doxical conception of God as a gaseous vertebrate. 



Pantheism teaches that God and the world are one. 
The idea of God is identical with that of nature or sub* 
stance. This pantheistic view is sharply opposed in prin- 
ciple to all the systems we have described, and to all 
possible forms of theism ; although there have been many 
attempts made from both sides to bridge over the deep 
chasm that separates the two. There is always this funda- 
mental contradiction between them, that in theism God 
is opposed to nature as an extramundane being, as creating 
and sustaining the world, and acting upon it from with- 
out, while in Pantheism God, as an intramundane being, 
is everywhere identical with nature itself, and is operative 
within the world as "force" or "energy." The latter 
view alone is compatible with our supreme law the law 
of substance. It follows necessarily that pantheism is 
the world-system of the modern scientist. There are, it 
is true, still a few men of science who contest this, and 
think it possible to reconcile the old theistic theory of 
human nature with the pantheistic truth of the law of 
substance. All these effects rest on confusion or sophistry 
when they are honest. 

As pantheism is a result of an advanced conception of 
nature in the civilised mind, it is naturally much younger 
than theism, the crudest forms of which are found in 
great variety in the uncivilised races of ten thousand 
years ago. We do, indeed, find the germs of pantheism 
In different religions at the very dawn of philosophy in 
the earliest civilised peoples (in India, Egypt, China, and 
Japan), several thousand years before the time of Christ ; 
still, we do not meet a definite philosophical expression of 
it until the hylozoism of the Ionic philosophers, in the 
first half of the sixth century before Christ. All the great 
thinkers of this flourishing period of Hellenic thought are 
surpassed by the famous Anaximander of Miletus, who 
conceived the essential unity of the infinite universe 
(apeiron) more profoundly and more clearly than his 


master, Thales, or his pupil, Anaximenes. Not only the 
great thought of the original unity of the cosmos and the 
development of all phenomena out of the all-pervading 
primitive matter found expression in Anaximander, but 
he even enunciated the bold idea of countless worlds in a 
periodic alternation of birth and death. 

Many other great philosophers of classical antiquity, 
especially Democritus, Heraclitus, and Empedocles, had, 
in the same or an analogous sense, a profound conception 
of this unity of nature and God, of body and spirit, which 
has obtained its highest expression in the law of substance 
of our modern monism. The famous Roman poet and 
philosopher Lucretius Cams has presented it in a highly 
poetic form in his poem, De Rerum Natura. However, 
this true pantheistic monism was soon entirely displaced 
by the mystic dualism of Plato, and especially by the 
powerful influence which the idealistic philosophy obtained 
by its blending with Christian dogmas. When the papacy 
attained to its spiritual despotism over the world, pan- 
theism was hopelessly crushed; Giordano Bruno, its most 
gifted defender, was burnt alive by the " Vicar of Christ " 
in the Campo dei Fiori at Rome, on February 17th, 1600. 

It was not until the middle of the seventeenth century 
that pantheism was exhibited in its purest form by the 
great Baruch Spinoza; he gave for the totality of things 
a definition of substance in which God and the world are 
inseparably united. The clearness, confidence, and con- 
sistency of Spinoza's monistic system are the more re- 
markable when we remember that this gifted thinker of 
250 years ago was without the support of all those Bound 
empirical bases which have been obtained in the second 
half of the nineteenth century. We have already spoken, 
in the first chapter, of Spinoza's relation to the material- 
ism of the eighteenth and the monism of the nineteenth 
century. The propagation of his views, especially in 
Germany, is due, above all, to the immortal works of our 
greatest poet and thinker, Wolfgang Goethe. His 
splendid God and the World, Prometheus, Faust, etc., 
embody the great thoughts of pantheism in the most 
perfect poetic creations. 


Atheism affirms that there are no gods or goddesses, 
assuming that god means a personal, extramundane entity. 
This " godless world-system" substantially agrees with 
the monism or pantheism of the modern scientist; it is 
only another expression for it, emphasising its negative 
aspect, the non-existence of any supernatural deity. In 
this sense Schopenhauer justly remarks: " Pantheism is 
only a polite form of atheism, The truth of pantheism 
lies in its destruction of the dualist antithesis of God and 
the world, in its recognition that the world exists in virtue 
of its own inherent forces. The maxim of the pantheist, 
4 God and the world are one,' is Merely a polite way of 
giving the Lord God his congt." 

During the whole of the Middle Ages, under the bloody 
despotism of the popes, atheism was persecuted with fire 
and sword as a most pernicious system. As the "god- 
less " man is plainly identified with the "wicked " in the 
Gospel, and is threatened simply on account of his 
" want of faith " with the eternal fires of hell, it was 
very natural that every good Christian should be anxious 
to avoid the suspicion of atheism. Unfortunately, the 
idea still prevails very widely. The atheistic scientist, 
who devotes his strength and his life to the search for 
the truth, is freely credited with all that is evil; the 
theistic church-goer, who thoughtlessly follows the empty 
ceremonies of Catholic worship, is at once assumed to be 
a good citizen, even if there be no meaning whatever in 
his faith, and his morality be deplorable. This error will 
only be destroyed when, in the twentieth century, the 
prevalent superstition gives place to rational knowledge 
and to a monistic conception of the unity of God and the 



The knowledge of the truth and its sources ; the activity of the 
senses tnrl the association of presentations Organs of senift and 
orgaus of thought. Sense-organs and their specific energy. 
Their evolution. The philosophy of sensibility. Inestimable 
value of the senses. Limits of sensitive knowledge. Hypothesis 
and faith. Theory and faith. Essential diilerenoe of scientific 
(natural) and religious (supernatural) faith. Superstition of 
savage and of civilised races. Coufosaiona of faith. Unsectarian 
schools. The faith of our father*. Spiritism. Revelation, 

EVERY effort of genuine science makes for a knowledge 
of the truth. Our only real and valuable knowledge is a 
knowledge of nature itself, and consists of presentations 
which correspond to external things. We are incom- 
petent, it is true, to penetrate into the innermost nature 
of this real world the " tiling in itself " but impartial 
critical observation and comparison inform us that in the 
normal action of the brain and the organs of sense the 
impressions received by them from the outer world are 
the same in all rational men, and that in the normal 
function of the organs of thought certain presentations 
are formed which are everywhere the same. These pre- 
sentations we call true t and we are convinced that their 
content corresponds to the knowable aspect of things. 
We know that these facts are not imaginary, but real. 

All knowledge of the truth depends on two different, 
but intimately connected, groups of human physiological 
functions : firstly, on the scnte-imprctsion* of the object 
by means of sense-action, and, secondly, on the com- 
bination of these impressions by an association into 
presentation in the subject. The instruments of sensa- 
tion are the sense-organs (jenitUa or xttheta) ; the instru- 
ments which form and link together the presentations are 



the organs of thought (phroneta). The latter are part of 
the central, and the former are part of the peripheral, 
nervous system that Important and elaborate system of 
organs in the higher animals which alone effects their 
entire psychic activity. 

Man's sense-activity, which is the starting-point of all 
knowledge, has been slowly and gradually developed from 
that of his nearest mammal relatives, the primates. The 
sense-organs are of substantially the same construction 
throughout this highest animal group, and their function 
takes place always according to the same physical and 
chemical laws. They have had the same historical 
development in all cases. In the mammals, as in the case 
of all other animals, the tensilla were originally parts of 
the skin ; the sensitive cells of the epidermis are the 
sources of all the different sense-organs, which have 
acquired their specific energy by adaptation to different 
stimuli (light, beat, sound, chemical action, etc.). The 
rod-cells in the retina of the eye, the auditory cells in the 
cochlea of the ear, the olfactory cells in the nose, and the 
taste-cells on the tongue, are all originally derived from 
the simple, indifferent cells of the epidermis which cover 
the entire surface of the body. This significant fact can 
be directly proved by observation of the embryonic 
development of man or any of the higher animals. And 
from this ontogenetic fact we confidently infer, in virtue 
of the great biogenetic law, the important phylogenetic 
proposition, that in the long historical evolution of our 
ancestors, likewise, the higher sense-organs with their 
specific energies were originally derived from the epidermis 
of lower animals, from a simple layer of cells which had 
no trace of such differentiated s en si 1 la. 

A particular importance attaches to the circumstance 
that different nerves are qualified to perceive different 
properties of the environment, and these only. The optic 
nerve accomplishes only the perception of light, the 
auditory nerve the perception of sound, the olfactory nerve 
the perception of smell, and so on. No matter what 
stimuli impinge on and irritate a given sense-organ, its 
reaction is always of the same character. From this 


specific energy of the sense-nerves, which was first fully 
appreciated by Johannes Muller, very erroneous inferences 
have been drawn, especially in favour of a dualistic and 
a priori theory of knowledge. It has been affirmed that 
the brain, or the soul, only perceives a certain condition 
of the stimulated nerve, and that, consequently, no con- 
clusion can be drawn from the process as to the existence 
and nature of the stimulating: environment. Sceptical 
philosophy concluded that the very existence of an outer 
world is doubtful, and extreme idealism went on positively 
to deny it, contending that things only exist in our 
impressions of them. 

In opposition to these erroneous views, we must recall 
the fact that the "specific energy " was not originally an 
innate, special quality of the various nerves, but it has 
arisen by adaptation to the particular activity of the 
epidermic cells in which they terminate. In harmony 
with the great law of "division of labour " the originally 
indifferent "sense-cells of the skin " undertook different 
tasks, one group of them taking over the stimulus of the 
light-rays, another the impress of the sound-waves, a third 
the chemical impulse of odorous substances, and so on. 
In the course of a very long period these external stimuli 
effected a gradual change in the physiological, and later 
in the morphological, properties of these parts of the 
epidermis, and there was a correlative modification of the 
sensitive nerves which conduct the impressions they 
receive to the brain. Selection improved, step by step, 
such particular modifications as proved to be useful, and 
thus eventually, in the course of many millions of years, 
created those wonderful instruments, the eye and the ear, 
which we prize so highly ; their structure is so remarkably 
purposive that they might well lead to the erroneous 
assumption of a "creation on a preconceived design." 
The peculiar character of each fense-organ and its specific 
nerve has thus been gradually evolved by use and exercise 
that is, by adaptation and has then been transmitted 
by heredity from generation to generation. Albrecht Rau 
has thoroughly established this view In his excellent work 
on Sensation and Thought, a physiological inquiry into the 


nature of the human understanding (1890). It points out 
the correct significance of Muller's law of specific iense- 
energies, adding searching investigations into their rela- 
tion to the brain ; and in the last chapter there is an able 
"philosophy of sensitivity," based on the ideas of Ludwig 
Feuerbach. I thoroughly agree with his convincing 

Critical comparison of sense-action in man and the other 
vertebrates has brought to light a number of extremely 
important facts, the knowledge of which we owe to the 
penetrating research of the nineteenth century, especially 
of tlie second half of the century. This is particularly true 
of the two most elaborate "aesthetic " organs, the eye and 
the ear. They present a different and more complicated 
structure in the vertebrates than in the other animals, and 
have also a characteristic development in the embryo. 
This typical ontogenesis and structure of the serisilla of 
all the vertebrates is only explained by heredity from a 
common ancestor. Within the vertebrate group, however, 
we find a great variety of structure in points of detail, and 
this is due to adaptation to their manner of life on the 
part of the various species, to the increasing or diminish- 
ing use of various parts. 

In respect of the structure of his sense-organs man is 
by no means the most perfect and most highly -developed 
vertebrate. The eye of the eagle is much keener, and can 
distinguish small objects at a distance much more clearly 
than the human eye. The hearing of many mammals, 
especially of the carnivora, ungulate, and rodenta of the 
desert, is much more sensitive than that of man, and 
perceives slight noises at a much greater distance; that 
may be seen at a glance by their large and very sensitive 
cochlea. Singing birds have attained a higher grade of 
development, even in respect of musical endowment, than 
the majority of men. The sense of smell is much more 
developed in most of the mammals, especially in the 
carnivora and the ungulata, than in man ; if the dog could 
compare his own fine scent with that of man, he would 
look down on us with compassion. Even with regard to 
the lower senses taste, sex-sense, touch, and temperature 


man has by no means reached the highest stage in every 

We can naturally only pass judgment on the sensations 
which we ourselves experience. However, anatomy in- 
forms us of the presence in the bodies of many animals of 
other senses than those, we are familiar with. Thus fishes 
and other lower aquatic vertebrates have peculiar sensiila 
ia the skin which are in connection with special sense- 
nerves. On the right and left sides of the fish's body 
there is a long canal, branching into a number of smaller 
canals at the head. In this " mucous canal " there are 
nerves with numerous branches, the terminations of which 
are connected with peculiar nerve-aggregates. This ex- 
tensive epidermic sense-organ probably serves for the 
perception of changes in the pressure, or in other pro- 
perties, of the water. Some groups are distinguished by 
the possession of other peculiar sensiila, the meaning of 
which is still unknown to us. 

But it is already clear from the above facts that our 
human sense-activity is limited, not only in quantity, but 
in quality also. We can thus only perceive with our 
senses, especially with the eye and the sense of touch, a 
part of the qualities of the objects in our environment. 
And even this partial perception is incomplete, in the 
sense that our organs are imperfect, and our sensory 
nerves, acting as interpreters, communicate to the brain 
only a translation of the impressions received. 

However, this acknowledged imperfection of our senses 
should not prevent us from recognising their instruments, 
and especially the eye, to be organs of the highest type ; 
together with the thought-organs in the brain, they are 
nature's most valuable gift to man. Very truly does 
Aibrecht Rau say : " All science is sensitive knowledge in 
the ultimate analysis ; it does not deny, but interprets the 
data of the senses. The senses are our first and best 
friends. Long before the mind is developed the senses 
tell man what he must do and avoid. He who makes a 
general disavowal of the senses in order to meet their 
dangers acts as thoughtlessly and as foolishly as the man 
who plucks out his eyes because they once fell on shame- 


fui things, or the man who cuts off his hand lest at any 
time it should reach out to the goods of his neighbour." 
Hence, Feuerhach is quite right in calling all philosophies, 
religions, and systems which oppose the principle of sense- 
action not only erroneous, but really pernicious. Without 
the senses there is no knowledge " Nihil est in intellectu 
quod non fuerit in tentu," as Locke said. Twenty years 
ago I pointed out, in my chapter "On the Origin and 
Development of the Sense-Organs," * the great service of 
Darwinism in giving us a profounder knowledge and a 
juster appreciation of the senses. 

The thirst for knowledge of the educated thinker is not 
contented with the defective acquaintance with the outer 
world which is obtained through our imperfect sense- 
organs. He endeavours to build up the sense-impressions, 
which they have brought him, into valuable knowledge. 
He transforms them into specific sense-perceptions In the 
sense-centres of the cortex of the brain, and combines 
them into presentations, by association, in the thought- 
centres. Finally, by a further concatenation of the groups 
of presentations he attains to connected knowledge. But 
this knowledge remains defective and unsatisfactory until 
the imagination supplements the inadequate power of 
combination of the intelligence, and, by the association 
of stored -up images, unites the isolated elements into a 
connected whole. Thus are produced new general pre- 
sentative images, and these suffice to interpret the facts 
perceived and satisfy "reason's feeling of causality." 

The presentations which fill up the gaps in our know- 
ledge, or take its place, may be called, in a broad sense, 
"faith." That is what happens continually in daily life. 
When we are not sure about a thing we say, I believe it. 
In this sense we are compelled to make use of faith even 
in science itself; we conjecture or assume that a certain 
relation exists between two phenomena, though we do 
not know it for certain. If it is a question of a cause, we 
form a hypothesis; though in science only such hypo- 
theses are admitted as lie within the sphere of human 

1 Collected Popular Ledwr*; Bonn, 1878. 


cognizance, and do not contradict known facto. Such 
hypotheses are, for instance in physics the theory of the 
vibratory movement of ether ; in chemistry the hypothesis 
of atoms and their affinity ; in biology the theory of the 
molecular structure of living protoplasm, and so forth. 

The explanation of a great number of connected pheno- 
mena by the assumption of a common cause ia called a 
theory. Both in theory and hypothesis "faith " (in the 
scientific sense) is indispensable; for here again it is the 
imagination that fills up the gaps left by the intelligence 
in our knowledge of the connection of things. A theory, 
therefore, must always be regarded only as an approxima- 
tion to the truth ; it must be understood that it may be 
replaced in time by another and better-grounded theory. 
But, in spite of this admitted uncertainty, theory is indis- 
pensable for all true science; it elucidates facts by postu- 
lating a cause for them. The man who renounces a theory 
altogether, and seeks to construct a pure science with 
certain facts alone (as often happens with wrong-headed 
representatives of our "exact sciences "), must give up 
the hope of any knowledge of causes, and, consequently, 
of the satisfaction of reason's demand for causality. 

The theory of gravitation in astronomy (Newton), the 
nebular theory in cosmogony (Kant and Laplace), the 
principle of energy in physics (Mayer and Helm hoi tz), 
the atomic theory in chemistry (Dal tori), the vibratory 
theory in optics (Huyghens), the cellular theory in his- 
tology (Schleiden and Schwann), and the theory of 
descent in biology (Lamarck and Darwin), are all im- 
portant theories of the first rank ; they explain a whole 
world of natural phenomena by the assumption of a 
common cause for all the several facts of their respective 
provinces, and by showing that all the phenomena 
thereof are inter-connected and controlled by iawg which 
issue from this common cause. Yet the cause itself may 
remain obscure IB character, or be merely a "provisional 
hypothesis." The "force of gravity " in the theory of 
gravitation and in cosmogony, " energy " itself in it* 
relation to matter, the " ether " of optics and electricity, 
the "atom " of the chemist, the living "protoplasm " of 


histology, the " heredity " of the evolutionist these and 
similar conceptions of other great theories may be regarded 
by a sceptical philosophy as " mere hypotheses " and the 
outcome of scientific " faith," yet they are indispensable 
for us, until they are replaced by better hypotheses. 

The dogmas which are used for the explanation of 
phenomena in the various religions, andwhich go by the 
name of " faith " (in the narrower sense), are of a very 
different character from the forms of scientific faith we 
have enumerated. The two types, however the 
"natural " faith of science and the " supernatural " faith 
of religion are not infrequently confounded, so that we 
must point out their fundamental difference. Religious 
faith always means belief in a miracle, and as such is in 
hopeless contradiction with the natural faith of reason. 
In opposition to reason it postulates supernatural agencies, 
and therefore may be justly called superstition. The 
essential difference of this superstition from rational faith 
lies in the fact that it assumes supernatural forces and 
phenomena, which are unknown and inadmissible to 
science, and which are the outcome of illusion and fancy; 
moreover, superstition contradicts the well-known laws of 
nature, and is therefore irrational. 

Owing to the great progress of ethnology during the 
century, we have learned a vast quantity of different kinds 
and practices of superstition, as they still survive in un- 
civilised races. When they are compared with each other 
and with the mythological notions of earlier ages, a mani- 
fold analogy is discovered, frequently a common origin, 
and eventually one simple source for them all. This is 
found in the ''demand of causality in reason," in the 
search for an explanation of obscure phenomena by the 
discovery of a cause. That applies particularly to such 
phenomena as threaten us with danger and excite fear, 
like thunder and lightning, earthquakes, eclipses, etc. 
The demand for a causal explanation of such phenomena 
is found in uncivilised races of the lowest grade, trans- 
mitted from their primate ancestors by heredity. It is 
even found in many other vertebrates. When a dog barks 
at the full moon, or at a ringing bell, of which it sees the 


hammer moving , or at a flag that flutter! in the breeze, 
it expresses not only fear, but also the mysterious impulse 
to learn the cause of the obscure phenomenon. The crude 
beginnings of religion among primitive races spring partly 
from this heredity superstition of their primate ancestors, 
and partly from the worship of ancestors, from various 
emotional impulses, and from habits which have become 

The religious notions of modern civilised peoples, which 
they esteem so highly, profess to be on a much higher 
level than the "crude superstition " of the savage; we 
are told of the great advance which civilisation has made 
in sweeping it aside. That is a great mistake. Impartial 
comparison and analysis show that they only differ in their 
special "form of faith " and the outer shell of their creed. 
In the clear light of reason the refined faith of the most 
liberal ecclesiastical religion inasmuch as it contradicts 
the known and inviolable laws of nature is no less irra- 
tional a superstition than the crude spirit-faith of primitive 
fetichism on which it looks down with proud disdain. 

And if, from this impartial standpoint, we take a 
critical glance at the kinds of faith that prevail to-day in 
civilised countries, we find them everywhere saturated 
with traditional superstition. The Christian belief in 
Creation, the Trinity, the Immaculate Conception, the 
Redemption, the Resurrection and Ascension of Christ, 
ami so forth, is just as purely imaginative as the belief in 
the various dogmas of the Mohammedan, Mosaic, Bud- 
dhistic, and B rah manic religions, and is just as incapable 
of reconciliation with a rational knowledge of nature. 
Each of these religions is for the sincere believer an in- 
disputable truth, and each regards the other as heresy and 
damnable error. The more confidently a particular sect 
considers itself "the only ark of salvation, " and the more 
ardently this conviction is cherished, the more zealously 
does it contend against ail other sects and give rise to the 
fearful religious wars Chat form the saddest pages in the 
book of history. And all the time the unprejudiced 
" critique of pure reason " teaches us that all these 
different forms of faith are equally false and irrational, 


mere creatures of poetic fancy and uncritical tradition* 
Rational science must reject them all alike as the outcome 
of superstition. 

The incalculable injury which irrational superstition has 
done to credulous humanity is conspicuously revealed in 
the ceaseless conflict of confessions of faith. Of all the 
wars which nations have waged against each other with 
fire and sword the religious wars have been the bloodiest ; 
of all the forms of discord that have shattered the happi- 
ness of families and of individuals those that arise from 
religious differences are still the most painful. Think of 
the millions who have lost their lives in Christian persecu- 
tions, in the religious conflicts of Islam and of the Re- 
formation, by the Inquisition, and under the charge of 
witchcraft. Or think of the still greater number of luck- 
less men who, through religious differences, have been 
plunged into family troubles, have lost the esteem of 
their fellow citizens and their position in the community, 
or have even been compelled to fly from their country. 
The official confession of faith becomes most pernicious 
of all when it is associated with the political aims of a 
modern state, and is enforced as " religious instruction " 
in our schools. The child *s mind is thus early diverted 
from the pursuit of the truth and impregnated with 
superstition. Every friend of humanity should do all in 
his power to promote unsectarian schools as one of the 
most valuable institutions of the modern State. 

The great value which is, nonetheless, still very widely 
attached to sectarian instruction is not only due to the 
compulsion of a reactionary State and its dependence on a 
dominant clericalism, but also to the weight of old tradi- 
tions and ** emotional cravings" of various kinds. One 
of the strongest of these is the devout reverence which is 
extended everywhere to sectarian tradition, to the " faith 
of our fathers." In thousands of stories and poems 
fidelity to it is extolled as a spiritual treasure and a sacred 
duty. Yet a little impartial study of the history of faith 
suffices to show the absurdity of the notion. The domi- 
nant evangelical faith of the second half of the nineteenth 
century is essentially different from that of the first half, 


and this again from that of the eighteenth century. The 
faith of the eighteenth century diverges considerably from 
the " faith of our fathers " of the seventeenth, and still 
more from that of the sixteenth century. The Reforma- 
tion, releasing enslaved reason from the tyranny of the 
popes, is naturally regarded by them as darkest heresy; 
but even the faith of the papacy itself had been com- 
pletely transformed in the course of a century. And how 
different is the faith of a Christian from that of his 
heathen ancestors ! Every man with some degree of in- 
dependent thought frames a more or less personal religion 
for himself, which is always different from that of his 
fathers; it depends largely on the general condition of 
thought in his day. The further we go back in the history 
of civilisation, the more clearly do we find this esteemed 
"faith of our fathers " to be an indefensible superstition 
which is undergoing continual transformation. 

One of the most remarkable forms of superstition, which 
still takes a very active part in modern life, is spiritism. 
It is a surprising and a lamentable fact that millions of 
educated people are still dominated by this dreary super- 
stition ; even distinguished scientists are entangled in it. 
A number of spiritualist journals spread the faith far and 
wide, and our " superior circles " do not scruple to hold 
teancet in which " spirits" appear, rapping, writing, 
giving messages from "the beyond, " and so on. It is a 
frequent boast of spiritists that even eminent men of 
science defend their superstition. In Germany A. Zollner 
and Fechner are quoted as instances ; in England, Wallace 
and Crookes. The regrettable circumstance that physicists 
and biologists of such distinction have been led astray by 
spiritism is accounted for partly by their excess of imagina- 
tion and defect of critical faculty, and partly by the 
powerful influence of dogmas which a religious education 
imprinted on the brain in early youth. Moreover, it was 
precisely through the famous fiances st Leipzig, in which 
the physicists Zollner, Fechner, and Wilhelm Weber were 
imposed on by the clever American conjurer Slade, that 
the fraud of the latter was afterwards fully exposed ; he 
was discovered to be a common impostor. In other cases, 


too, where the alleged marvels of spiritism have been 
thoroughly investigated, they have been traced to a more 
or less clever deception; the mediums (generally of the 
weaker sex) have been found to be either smart swindlers 
or nervous persons of abnormal irritability. Their sup- 
posed gift of "telepathy" (or "action at a distance of 
thought without material medium ") has no more exist- 
ence than the "voices " or the "groans " of spirits, etc. 
The vivid pictures which Carl du Prel, of Munich, and 
other spiritists give of their phenomena must be regarded 
as the outcome of a lively imagination, together with a 
lack of critical power and of knowledge of physiology. 

The majority of religions have, in spite of their great 
differences, one common feature, which is, at the same 
time, one of their strongest supports in many quarters. 
They declare that they can elucidate the problem of exist- 
ence, the solution of which is beyond the natural power of 
reason, by the supernatural way of revelation; from that 
they derive the authority of the dogmas which, in the 
guise of " divine laws," control morality and the practical 
conduct of life. " Divine " inspirations of that kind form 
the basis of many myths and legends, the human origin of 
which is perfectly clear. It is true that the God who 
reveals himself does not always appear in human shape, 
but in thunder and lightning, storm and earthquake, fiery 
bush or menacing cloud. Yet the revelation which he is 
supposed to bring to the credulous children of men is 
always anthropomorphic ; it invariably takes the form of a 
communication of ideas or commands which are formulated 
and expressed precisely as is done in the normal action 
of the human brain and larynx. In the Indian and 
Egyptian religions, in the mythologies of Greece and 
Rome, in the Old and the New Testaments, the gods 
think, talk, and act just as men do; the revelations, in 
which they are supposed to unveil for us the secrets of 
existence and the solution of the great world-enigma, are 
creations of the human imagination. The " truth " which 
the credulous discover in them is a human invention ; the 
" childlike faith " In these irrational revelation! if mere 


Tie true revelation-that is, the true source of rational 
knowledge-l! to be sought ID nature alone, Tke rich 
heritage of truth which forms the most valuable part of 
human culture is derived delusively from the experiences 
acquired In i searching study of nature, and from the 
rational conclusions which it has reached by tke just 
association of these empirical presentations, Every intel- 
ligent man with normal brain and senses finds this true 
revelation in nature on impartial study, and thus frees 
himself from the superstition with which the "revela- 
tions' 1 of religion had burdened him, 



Increasing opposition between modern science and Christian theology. 
The old and the new faith, Defence of rational science against 
the attacks of Christian superstition, especially against Catholi- 
cism. Four period* in the evolution of Christianity : I. Primitive 
Christianity {the first three centuries). The four canonical 
gospels. The epistlws of Paul. II, The papacy (ultramontane 
Christianity). Ketrogres&ion of civilisation in tie Middle Age*. 
Ultranvmtane falsification of history. The papacy and icicnce. 
The papacy and Christianity, III The Reformation. Luther 
and Calvin. The year of emancipation. IV. The psetido- 
Christiauity of the nineteenth century. The papal declaration of 
war against reason and science j (a) Infallibility, (b) The En- 
cyeliea, (c) The Immaculate Conception. 

ONE of the most distinctive features of the expiring 
century is the increasing vehemence of the opposition 
between science and Christianity. That is both natural 
and inevitable. In the same proportion in which the 
victorious progress of modern science has surpassed all 
the scientific achievements of earlier ages has the untena- 
bility been proved of those mystic views which would 
subdue reason under the yoke of an alleged revelation ; 
and the Christian religion belongs to that group. The 
more solidly modern astronomy, physics, and chemistry 
have established the sole dominion of inflexible natural 
laws in the universe at large, and modern botany, zoology, 
and anthropology have proved the validity of those laws 
in the entire kingdom of organic nature, so much the 
more strenuously has the Christian religion, in association 
with dualistic metaphysics, striven to deny the application 
of these natural laws in the province of the so-called 
"spiritual life " that is, in one section of the physiology 
of the brain, 



No one has more clearly, boldly, and unanswerably 
enunciated this open and irreconcilable opposition between 
the modern scientific and the outworn Christian view than 
David Friedrich Strauss, the greatest theologian of the 
nineteenth century. His last work, The Old Faith and 
the New, is a magnificent expression of the honest con- 
viction of all educated people of the present day who 
understand this unavoidable conflict between the dis- 
credited, dominant doctrines of Christianity and the illu- 
minating, rational revelation of modern science all those 
who have the courage to defend the right of reason 
against the pretensions of superstition, and who are 
sensible of the philosophic demand for a unified system 
of thought. Strauss, as an honourable and courageous 
freethinker, has expounded far better than I could the 
principal points of difference between " the old and the 
new faith." The absolute irreconcilability of the oppo- 
nents and the inevitability of their struggle ("for life or 
death ") have been ably presented on the philosophic side 
by E. Hartmann in his interesting work on The Self- 
Destruction of Christianity. 

When the works of Strauss and Feuerbach and The 
History of the Conflict between Religion and Science of 
J. W. Draper have been read, it may seem superfluous for 
us to devote a special chapter to the subject. Yet we 
think it useful, and even necessary for our purpose, to 
cast a critical glance at the historical course of this great 
struggle ; especially seeing that the attacks of the " Church 
militant " on science in general, and on the theory of 
evolution in particular, have become extremely bitter and 
menacing of late years. Unfortunately, the mental 
relaxation which has lately set in, and the rising flood of 
reaction in the political, social, and ecclesiastical world, 
are only too well calculated to give point to those dangers. 
If anyone doubts it, he has only to look over the conduct 
of Christian synods and of the German Reichstag during 
the last few years. Quite in harmony are the recent 
efforts of many secular Governments to get on as good 
a footing as possible with the "spiritual regiment," their 
deadly enemy that is, to submit to its yoke. The two 


forcci find a common aim in the suppression of free 
thought and free scientific research, for the purpose of 
thus more easily securing a complete despotism. 

Let us first emphatically protest that it is a question 
for us of the necessary defence of science and reason 
against the vigorous attacks of the Christian Church and 
its vast army, not of an unprovoked attack of science on 
religion. And, in the first place, our defence must be 
prepared against Romanism or Ultramontanism. This 
"one ark of salvation," this Catholic Church "destined 
for all," is not only much larger and more powerful than 
the other Christian sects, but it has the exceptional 
advantage of a vast, centralised organisation and an un- 
rivaiWl political ability. Men of science are often heard 
to say that the Catholic superstition is no more astute 
than the other forms of supernatural faith, and that all 
these insidious institutions are equally inimical to reason 
and science. As a matter of general theoretical principle 
the statement may pass, but it is certainly wrong when 
we look to its practical side. The deliberate and indis- 
criminate attacks of the ultramontane Church on science, 
supported by the apathy and ignorajice of the masses, 
are, on account of its powerful organisation, much more 
severe and dangerous than those of other religions. 

In order to appreciate correctly the extreme importance 
of Christianity in regard to the entire history of civilisa- 
tion, and particularly its fundamental opposition to reason 
and science, we must briefly run over the principal stages 
of its historical evolution. It may be divided into four 
periods : (1) primitive Christianity (the first three cen- 
turies), (2) papal Christianity (twelve centuries, from the 
fourth to the fifteenth), (3) the Reformation (three cen- 
turies, from the sixteenth to the eighteenth), and (4) 
modern pseudo-Christianity. 


Primitive Christianity embraces the first tliree centuries. 
Christ himself, the noble prophet and enthusiast, so full 
of the love of humanity, was far below the level of 


classical culture; he knew nothing beyond the Jewish 
traditions; he has not left a single line of writing. He 
had, indeed, no suspicion of the advanced stage to which 
Greek philosophy and science had progressed five hundred 
years before. 

AH that we know of him and of his original teaching 
is taken from the chief documents of the New Testament 
the four gospels and the Pauline epistles. As to the 
four canonical gospels, 1 we know that they were selected 
from a host of contradictory and forged manuscripts of 
the first two centuries. The canon seems to have been 
settled before the end of the second century, though 
doubts and of opinion lasted well into the 
fourth century; the Council of Nicaea, in 82.5, is quoted 
by St. Jerome as including a certain book in the canon, 
thus indicating an uncertainty even to that late date. 
Recent scholarship puts the dale of the three synoptic 
gospels (Matthew, Mark, and Luke written, it is 
acknowledged, after and not by those persons) between 
65 and 100 A.D., and the gospel of St. John some time 
before 125 A.D. But it must be borne in mind that when 
Biblical scholars speak of these dates (in detail 65~70 
for Mark, 70-75 for Matthew, 78-96 for Luke [Julicher 
sayg 80-120], and 80~120 for John) they are not thinking 
of the gospels as we have them to-day. The English 
reader would do well to consult Dr. SchmiedePs article 
on the gospels in the Encyclopedia Bihlica to see how 
very slender is the base on which scholarship proceeds. 
Until we reach the time of St. Justin, at least and even 
he cannot be quoted as a witness to the actual gospel of 
St. John that is to say, the middle of the second century, 
we find nothing but quotations (often very questionable) 

1 The remainder of this section has been rewritten in the present 
edition. Until Professor Haeckel WRJ convinced of the unreliability 
of the authority for bin statements in this section and the closing 
page* of this chapter, the translatoi did not feel justified in interfering 
with the text. Pro fewer Haeckel haa now recognised that he had 
been misled aa to the weight of his author, and has withdrawn several 
of the statements in the present chapter. The translator ha, there- 
fore, BOW amended the text and brought it up to date on the^t point*. 
[Fobrti. Chtap JSdUim*] 


of sayings that are found in the gospels. In other words, 
we have no authority whatever in support of the gospei- 
narratives until more than a century after the death of 
Christ. No one who is acquainted with the conditions of 
the growth of legends in an oriental atmosphere can place 
the least reliance on documents of so late a date. Even 
if the earliest synoptic gospel were dated 70 A.D. (and 
we must always remember that this is only as regards 
"the sayings of Jesus "), there would be the ample 
margin of forty years. In Persia, in the nineteenth cen- 
tury, this has proved quite sufficient for the accretion of 
a mass of myths and miracles about the memory of a 
reformer of the type of Christ the founder of Babiism. 

The Pauline epistles, of which seven to nine are now 
claimed to be genuine (Romans, Corinthians [2], Gala- 
tians, Ephesians, Phiiippians, Colossi ans, and Thessa- 
lonians [2]), add very little to our knowledge of the 
events of Christ's life. We are, therefore, reduced to 
very slender and precarious speculations about the acts 
and person of the founder of Christianity. The most 
cherished beliefs of Christian tradition are being totally 
abandoned. The story of the miraculous birth of Christ 
is rejected by the leading Christian scholars of Germany, 
and by an increasing number of Christian scholars in 
England, as belonging to " the latest and least reliable 
strata of the Biblical narrative " in other words, as a 
late and worthless interpolation. The Resurrection and 
Ascension are now meeting the same fate. The New 
Testament is being broken up like the Old Testament, 
and the figure of Jesus is rapidly dissolving. 

As to the real teaching and aims of Christ (and as to 
many important aspects of his life) the views of conflicting 
theologians diverge more and more, as historical criticism 
(Strauss, Feuerbach, Baur, Renan, etc.) puts the acces- 
sible facts in their true light, and draws impartial con- 
clusions from them. Two things, certainly, remain 
beyond dispute the lofty principle of universal charity 
and the fundamental maxim of ethics, the "golden rule," 
that issues therefrom ; both, however, existed in theory 
and in practice centuries before the time of Christ (cf. 


chap. xix.). For the rest, the Christians of the early cen- 
turies were generally pure Communists, sometimes 
"Social Democrats," who, according to the prevailing 
theory in Germany to-day, ought to have been extermi- 
nated with fire and sword. 


Latin Christianity, variously called Papistry, Romanism, 
Vaticanism, Ultramontanism, or the Roman Catholic 
Church, is one of the most remarkahle phenomena in the 
history of civilised man ; in spite of the storms that have 
swept over it, it still exerts a most powerful influence. 
Of the 500,000,000 Christians who are scattered over the 
earth, the majority that is, more than 250,000,000 are 
Roman Catholics, During a period of 1200 years, from 
the fourth to the sixteenth century, the Papacy almost 
absolutely controlled and tainted the spiritual life of 
Europe; on the other hand, it has won but little territory 
from the ancient religions of Asia and Africa. In Asia 
Buddhism still counts 503,000,000 followers, the Brah- 
manic religion more than 100,000,000, and Islam 

It was the despotism of the Papacy that lent its darkest 
character to the Middle Ages : it meant death to all free- 
dom of mental life, decay to all science, corruption to all 
morality. From the noble height to which the life of the 
human mind had attained in classical antiquity, in the 
centuries before Christ and the first century after Christ, 
it soon sank, under the rule of the Papacy, to a level 
which, in respect of the knowledge of the truth, can only 
be termed barbarism. It is often protested that other 
aspects of mental life poetry and architecture, scholastic 
learning and patristic philosophy were richly developed 
in the Middle Ages. But this activity was in the service 
of the Church; it did not tend to the cultivation, but to 
the suppression, of free mental research. The exclusive 
preparing for an unknown eternity beyond the tomb, the 
contempt of nature, the withdrawal from the study of it, 


which arc essential elements of Christianity, were urged* 
as a sacred duty by the Roman hierarchy. It was not 
until the beginning of the sixteenth century that a change 
for the better came in with the Reformation- 
It is impossible for us to describe here the pitiful retro- 
gression of culture and morality during the twelve cen- 
turies of the spiritual despotism of Rome. It is very 
pithily expressed in a saying of the greatest and ablest of 
the Ilohenzollerns ; Frederick the Great condensed his 
judgment in the phrase that the study of history led one 
to think that from Constautine to the date of the Reforma- 
tion the whole world was insane. L. Buchner has given 
us an admirable brief description of this " period of in- 
sanity " in his work on Religious and Scientific Systems. 
The reader who desires a closer acquaintance with the 
subject would do well to consult the historical works of 
Rankc, Draper, Kolb, Svoboda, etc. The truthful descrip- 
tion of the awful condition of the Christian Middle Ages, 
which is given by these and other unprejudiced historians, 
is confirmed by all the reliable sources of investigation, 
and by the historical monuments which have come down 
from this saddest period of human history. Educated 
Catholics who are sincere truthseekers cannot be too 
frequently recommended to study these historical sourcef 
for themselves. This is the more necessary as ultramon- 
tane literature has still a considerable influence. The old 
trick of deceiving the faithful by a complete reversal of 
facts and an invention of miraculous circumstances is still 
worked by it with great success. We will only mention 
Lourdes and the "Holy Coat" of Troves. The ultra- 
montane professor of history at Frankfurt, Johannes 
Janssen, affords a striking example of the length they will 
go in distorting historical truth; his much-read works 
(especially his History of the German People tine* the 
Middle Ages) are marred by falsification to an incredible 
extent. The untruthfulness of these Jesuitical productions 
is on a level with the credulity and the uncritical judg- 
ment of the simple German nation that takes them for 
One of the most interesting of the historical facts which 


clearly prove the evil of the ultramontane despotism is its 
vigorous and consistent struggle with science. This was 
determined on, in principle, from the very beginning of 
Christianity, inasmuch as faith was set above reason and 
the blind subjection of the one to the other was preached ; 
that was natural, seeing that our whole life on earth was 
held to be only a preparation for the legendary life be- 
yond, and thus scientific research was robbed of any real 
value. The deliberate and successful attack on science 
began in the early part of the fourth century, particularly 
after the Council of Nicaea (325), presided over by Con- 
stantine called the " Great " because he raised Christian- 
ity to some prestige in tiie State, and founded Constan- 
tinople, though a worthless character, a falsehearted 
hypocrite, and a murderer. The success of the Papacy in 
its conflict with independent scientific thought and inquiry 
is best seen in the distressing condition of science and its 
literature during the Middle Ages. Not only were the 
rich literary treasures that classical antiquity had be- 
queathed to the world destroyed for the most part, or 
withdrawn from circulation, but the rack and the stake 
ensured the silence of every heretic that is, every in- 
dependent thinker. If he did not keep his thoughts to 
himself, he had to look forward to being burnt alive, as 
was the fate of the great monistic philosopher Giordano 
Bruno, the reformer John Huss, and more than a hundred 
thousand other "witnesses to the truth." The history 
of science in the Middle Ages teaches us on every page 
that independent thought and empirical research were 
completely burled for twelve sad centuries under the 
oppression of the omnipotent Papacy. 

All that we esteem in true Christianity, in the sense of 
its founder and of his noblest followers, and that we must 
endeavour to save from the inevitable wreck of this great 
world-religion for our new monistic religion, lies on its 
ethical and social planes. The principles of true human- 
ism, the golden rule, the spirit of tolerance, the love of 
man, in the best and highest sense of the word all these 
true graces of Christianity were not, indeed, first dis- 
covered and given to the world by that religion, but were 


ucccssfully developed in the critical period when classical 
antiquity was hastening to its doom. The Papacy, how- 
ever, has attempted to convert all those virtues into the 
direct contrary, and still to hang out the sign of the old 
firm. Instead of Christian charity, it introduced a 
fanatical hatred of the followers of all other religions; 
with fire and sword it has pursued, not only the heathen, 
but every Christian sect that dared resist the imposition 
of ultramontane dogma. Tribunals for heretics were 
erected all over Europe, yielding unnumbered victims, 
whose torments seemed only to fill their persecutors, with 
all their Christian charity, with a peculiar satisfaction. 
The power of Rome was directed mercilessly for centuries 
gainst everything that stood in its way. Under the 
notorious Torquemada (1481-98) in Spain alone 8000 
heretics were burnt alive and 90,000 punished with the 
confiscation of their goods and the most grievous eccle- 
siastical fines; in the Netherlands, under the rule of 
Charles V., mt least 50,000 men fell victims to the clerical 
bloodthirst. And while the heavens resounded with the 
cry of the martyrs, the wealth of half the world was 
pouring into Rome, to which the whole of Christianity 
paid tribute, and the self-styled representatives of God 
on earth and their accomplices (not infrequently Atheists 
themselves) wallowed in pleasure and vice of every descrip- 
tion. "And all these privileges," said the frivolous, 
syphilitic Pope Leo X., "have been secured to us by the 
fable of Jesus Christ." 

Yet, with all the discipline of the Church and the fear 
of God, the condition of European society was pitiable. 
Feudalism, serfdom, the grace of God, and the favour of 
the monks ruled the land ; the poor helots were only too 
glad to be permitted to raise their miserable huts under 
the shadow of the castle or the cloister, their secular and 
spiritual oppressors and exploiters. Even to-day we suffer 
from the aftermath of these awful ages and conditions, in 
which there was no question of care for science or higher 
mental culture save In rare circumstances and in secret. 
Ignorance, poverty, and superstition combined with the 
Immoral operation of the law of celibacy, which had been 


enforced in the eleventh century, to consolidate the ever- 
growing power of the Papacy. It has been calculated that 
there were more than 10,000,000 victims of fanatical 
religious hatred during this " Golden Age " of Papal 
domination ; and how many more million human victims 
must be put to the account of celibacy, oral confession, 
and moral constraint, the most pernicious and accursed 
institutions of the Papal despotism ! Unbelieving philo- 
sophers, who have collected disproofs of the existence of 
God, have overlooked one of the strongest arguments in 
that sense the fact that the Roman " Vicar of Christ " 
could for twelve, centuries perpetrate with impunity the 
most shameful and horrible deeds **in the name of God." 


The history of civilisation, which we are so fond of 
calling 4k the history of the world," enters upon its third 
period with the Reformation of the Christian Church, 
just as its second period begins with the founding of 
Christianity. With the Reformation begins the new birth 
of fettered reason, the reawakening of science, which the 
iron hand of the Christian Papacy had relentlessly crushed 
for 1200 years. At the same time the spread of general 
education had already commenced, owing to the invention 
of printing about the middle of the fifteenth century; 
and towards its close several great events occurred, espe- 
cially the discovery of America in 1492, which prepared 
the way for the " renaissance " of science in company 
with that of art. Indeed, certain very important advances 
were made in the knowledge of nature during the first 
half of the sixteenth century, which shook the prevailing 
system to its very foundations. Such were the circum- 
navigation of the globe by Magellan in 1522, which 
afforded empirical proof of its rotundity, and the founding 
of the new system of the world by Copernicus in 1543. 

Yet the 31st of October in the year 1517, the day on 
which Martin Luther nailed his ninety-five theses to the 
wooden door of Wittenberg Cathedral, must be regarded 
aa the commencement of a new epoch ; for on that day 


wai forced the iron door of the prison La which the Papal 
Church had detained fettered reason for 1200 years. The 
merits of the great reformer have been partly exaggerated, 
partly under-estimated. It has been justly pointed out 
that Luther, like ail the other reformers, remained in 
manifold subjection to the deepest superstition. Thus he 
was throughout life a supporter of the rigid dogma of the 
verbal inspiration of the Bible; he zealously maintained 
the doctrines of the resurrection, original sin, predestina- 
tion, justification by faith, etc. He rejected as folly the 
great discovery of Copernicus, because in the Bible 
" Joshua bade the sun, not the earth, stand still." He 
utterly failed to appreciate the great political revolutions 
of his time, especially the profound and just agitation of 
the peasantry. Worse still was the fanatical Calvin, of 
Geneva, who had the talented Spanish physician Serveto 
burnt alive in 1553, because he rejected the absurd dogma 
of the Trinity. The fanatical "true believers" of the 
reformed Church followed only too frequently in the blood- 
stained footsteps of their Papal enemies ; as they do even 
In our own day. Deeds of unparalleled cruelty followed 
in the train of the Reformation the massacre of St. 
Bartholomew and the persecution of the Huguenots in 
France, bloody heretic-hunts in Italy, civil war in Eng- 
land, and the Thirty Years* War in Germany. Yet, in 
spite of those grave blemishes, to the sixteenth arid 
seventeenth centuries belongs the honour of once more 
opening a free path to the thoughtful mind, and delivering 
reason from the oppressive yoke of the Papacy. Thus 
only was made possible that great development of different 
tendencies in critical philosophy and of new paths in 
science which won for the subsequent eighteenth century 
the honourable title of "the century of enlightenment." 


As the fourth and last stage in the history of Christian- 
ity we oppose our nineteenth century to all its pre- 
decessors. It is true that tke enlightenment of preceding 


centuries had promoted critical thought in every direction, 
and the rise of science itself had furnished powerful em- 
pirical weapons ; yet it seems to us that our progress along 
both lines has been quite phenomenal during the nine- 
teenth century. It has inaugurated an entirely new 
period in the history of the human mind, characterised by 
the development of the monistic philosophy of nature. 
At its very commencement the foundations were laid of a 
new anthropology (by the comparative anatomy of Cuvier) 
and a new biology (by the Philosophic Zoologique of 
Lamarck). The two great French scientists were quickly 
succeeded by two contemporary German scholars Baer, 
the founder of the science of evolution, and Johannes 
Miiller, the founder of comparative morphology and 
physiology. A pupil of Miiller, Theodor Schwann, crealed 
the far-reaching cellular theory in 1838, in conjunction 
with M. Schleiden. Lyell had already traced the evolu- 
tion of the earth to natural causes, and thus proved the 
application to our planet of the mechanical cosmogony 
which Kant had sketched with so much insight in 1755. 
Finally, Robert Mayer and Helinholtz established the 
principle of the conservation of energy in 184-2 the 
second, complementary half of the great law of substance, 
the first half of which (the persistence of matter) had been 
previously discovered by Lavoisier. Forty years ago 
Charles Darwin crowned all these profound revelations of 
the intimate nature of the universe by his new theory of 
evolution, the greatest natural-philosophical achievement 
of our century. 

What is the relation of modern Christianity to this vast 
and unparalleled progress of science? In the first place, 
the deep gulf between its two great branches, conservative 
Romanism and progressive Protestantism, has naturally 
widened. The ultramontane clergy (and we must asso- 
ciate with them the orthodox "evangelical alliance M ) had 
naturally to offer a strenuous opposition to this rapid 
advance of the emancipated mind; they continued 
unmoved in their rigid literal belief, demanding the 
unconditional surrender of reason to dogma. Liberal Pro- 
testantism, on the other hind, took refuge in a kind of 


monistic pantheism, and sought a means of reconciling 
two contradictory principles. It endeavoured to combine 
the unavoidable recognition of the established laws of 
nature, and the philosophic conclusions that followed from 
them, with a purified form of religion, in which scarcely 
anything remained of the distinctive teaching of faith. 
There were many attempts at compromise to be found 
between the two extremes ; but the conviction rapidly 
spread that dogmatic Christianity had lost every founda- 
tion, and that only its valuable ethical contents should be 
saved for the new monistic religion of the twentieth cen- 
tury. As, however, the existing external forms of the 
dominant Christian religion remained unaltered, and as, 
in spite of a progressive political development, they are 
more intimately than ever connected with the practical 
needs of the State, there has arisen that widespread reli- 
gious profession in educated spheres which we can only 
call " Pseudo-Christianity " at the bottom of it is a 
*' religious lie " of the worst character. The great dangers 
which attend this conflict between sincere conviction and 
the hypocritical profession of modern pseudo-Christians 
are admirably described in Max Nordau's interesting work 
on The Conventional Lies of Civilisation. 

In the midst of this obvious falseness of -prevalent 
pseudo-Christianity there is one favourable circumstance 
for the progress of a rational study of nature : its most 
powerful and bitterest enemy, the Roman Church, threw 
off its mask of ostensible concern for higher mental de- 
velopment about the middle of the nineteenth century, 
and declared a guerre a outrance against independent 
science. This happened in three important challenges to 
reason, for the explicitness and resoluteness of which 
modern science and culture cannot but be grateful to the 
" Vicar of Christ." (1) In December, 1854, the Pope 
promulgated the dogma of the immaculate conception 
of Mary. (2) Ten years afterwards in December, 
1864 the Pope published, in his famous encyclica, an 
absolute condemnation of the whole of modern civilisa- 
tion and culture; in the syllabus that accompanied it he 
enumerated and anathematised all the rational theses and 


philosophical principles which are regarded by modern 
science as lucid truths. (S) Finally, six years afterwards 
on July 18th, 1870 the militant head of the Church 
crowned his folly by claiming infallibility for himself and 
ail his predecessors in the Papal chair. This triumph of 
the Roman curia was communicated to the astonished world 
on the very day before that on which France declared war 
with Prussia. Two months later the temporal power of 
the Pope was taken from him in consequence of the war. 

These three stupendous acts of the Papacy were such 
obvious assaults on the reason of the nineteenth century 
that they gave rise, from the very beginning, to a most 
heated discussion even within orthodox Catholic circles. 
When the Vatican Council first approached the dogma of 
infallibility on July 13th, 1870, only three-fourths of the 
bishops declared in its favour, 451 out of 601 assenting; 
many other bishops, who wished to keep clear of the 
perilous definition, were absent from the Council. But 
the shrewd Pontiff had calculated better than the timid 
4 * discreet Catholics "; even this extraordinary dogma was 
blindly accepted by the credulous and uneducated masses 
of the faithful. 

The whole history of the Papacy, as it is substantiated 
by a thousand reliable sources and accessible documents, 
appears to the impartial student as an unscrupulous tissue 
of lying and deceit, a reckless pursuit of absolute mental 
despotism and secular power, a frivolous contradiction of 
all the high moral precepts which true Christianity enun- 
ciates charity and toleration, truth and chastity, poverty 
and self-denial. When we judge the long series of Popes 
and of the Roman princes of the Church, from whom the 
Pope is chosen, by the standard of pure Christian morality, 
it is clear that the great majority of them were pitiful 
impostors, many of them utterly worthless and vicious. 
These well-known historical facts, however, do not prevent 
millions of educated Catholics from admitting the infal- 
libility which the Pope has claimed for himself; they do 
not prevent Protestant princes from going to Rome and 
doing reverence to the Pontiff (their most dangeroui 
enemy); they do not prevent the fate of the German 


people from being entrusted to-day to the hands of the 
servants and followers of this *' pious impostor " in the 
Reichstag thanks to the incredible political indolence and 
credulity of the nation. 

The most interesting of the three great events by which 
the Papacy has endeavoured to maintain and strengthen 
its despotism in the nineteenth century is the publication 
of the encyclica and the syllabus in December, 1864. In 
these remarkable documents all independent action was 
forbidden to reason and science, and they were com- 
manded to submit implicitly to faith that is, to the 
decrees of the infallible Poj>e. The great excitement 
which followed this sublime piece of effrontery in educated 
and independent circles was in proportion to the stupend- 
ous contents of the encyclica. Draper has given us an 
excellent discussion of its educational and political signifi- 
cance in his History of the Conflict between Science and 

The dogma of the immaculate conception seems, 
perhaps, to be less audacious and significant than the 
encyciica and the dogma of the infallibility of the Pope. 
It is, in fact, one of those barren formulas on which the 
faculty of infallibility can be judiciously exercised. It 
means that Mary was exempted at her birth, or con- 
ception, from the law by which every child of Adam incurs 
the guilt of original sin, according to the teaching of the 
Catholic Church. Neither the law nor the exemption is 
ever likely to fall under critical examination. 

With regard to the doctrine of the miraculous con- 
ception of Christ by Mary (or the doctrine of **the Virgin 
Birth "), comparative religion has shown that this myth 
has even less claim to originality than most of the other 
stories in the Christian mythology ; it has been borrowed 
from older religions, especially Buddhism. Similar myths 
were widely circulated in India, Persia, Asia Minor, and 
Greece several centuries before the birth of Christ* 
Whenever a king's unwedded daughter, or some other 
maid of high degree> gave birth to a child, the father was 
a 1 wars pronounced to be a god, or a denii-god; in the 
Christian ease it was the Holy Ghost, 


The special endowments of mind or body whicii often 
distinguished these " love-children " above ordinary off- 
spring were thus partly explained by "heredity." Dis- 
tinguished " sons of God " of this kind were held in high 
esteem both in antiquity and during the Middle Ages, 
while the moral code of modern civilisation reproaches 
them with their want of honour of parentage. This 
applies even more forcibly to "daughters of God," though 
the poor maidens are just as little to blame for their want 
of a father. For the rest, every one who is familiar with 
the beautiful mythology of classical antiquity knows that 
these sons and daughters of the Greek and Roman gods 
often approached nearest to the highest ideal of humanity. 
Recollect the large legitimate family, and the still more 
numerous illegitimate offspring, of Zeus. 

To return to the particular question of the impregnation 
of the Virgin Mary by the Holy Ghost, we are referred 
to the gospels for testimony to the fact. The only two 
evangelists who speak of it, Matthew and Luke, relate in 
harmony that the Jewish maiden Mary was betrothed to 
the carpenter Joseph, but became pregnant without his 
co-operation, and, indeed, " by the Holy Ghost." As we 
have already related, the four canonical gospels, which are 
regarded as the only genuine ones by the Christian Church, 
and adopted as the foundation of faith, were deliberately 
chosen from a much larger number of gospels, the details 
of which contradict each other sometimes just as freely 
as the assertions of the four. The Fathers of the Church 
enumerate a large number of these spurious or apocryphal 
gospels ; some of them are written both in Greek and 
Latin for instance, the gospel of James, of Thomas, of 
Nicodemus, and so forth. The details which these 
apocryphal gospels give of the life of Christ, especially 
with regard to his birth and childhood, have just as much 
(or, on the whole, just as little) claim to historical validity 
as the four canonical gospels. They were generally re- 
jected on the ground of the extravagance of their legends 
and miracles, but in some cases their date is as early as 
that of the canonical gospels (as we have them to-day). 
When, therefore, we find in one of them, the gospel of 


Nicodemug (which is assigned by some scholars to the 
second century), a statement that Jesus was accused by 
the Jews of being "begotten in sin " a statement that 
is somewhat enlarged by the second-century Piatonist 
writer Celsus (as indicated by Origen, Contra Celsum, I., 
82), into the charge that " the mother of Jesus was 
divorced by the carpenter who had married her, because 
she was convicted of adultery, and had borne a child to 
a certain soldier named Pantheras " we naturally con- 
nect it with the later Jewish story (in the Sepher Toldoth 
Jetchua traces of which exist from about the year 800) 
of Christ being the issue of an illicit union of Mary and 
a Greek officer in the Roman army. It has long been an 
argument of theologians for the supernatural character of 
Christ that the ideal depicted in the gospels is not Hebraic. 
It is, as a matter of fact, certainly Greek in many respects, 
and so the theory of a Greek parentage might seem to 
have some plausibility in a matter where reliable docu- 
mentary evidence is wholly wanting. 

But critics are generally agreed in rejecting the Pan- 
theras or Pandera version of Christ's fatherhood. The 
present study of the gospels, even by Christian scholars, 
amply allows for Greek elements, since it admits that we 
cannot trace the gospel narratives as we have them to-day 
until long after the dispersal of the Jews through the 
Greek world. On the other hand, the Jews cannot be 
regarded as ideal or disinterested witnesses to the life and 
person of Christ. The opposition of the orthodox to the 
Christianising Jews would naturally lead to the growth 
of such unflattering legends. Biblical scholars prefer to 
award the paternity of Christ to the carpenter Joseph. 
Some of the early Christian writers observe that this 
belief is shared by many Christians in their day. Mark, 
John, and Paul know nothing of a miraculous theory of 
Christ's birth ; and the passages in Matthew and Luke can 
be proved, as most of the modern German theologians 
admit, to have a late origin. Once the supernatural theory 
of Christ's origin is abandoned, as it is being rapidly 
abandoned in scholarly circles in the Churches, it is per- 


haps not a matter of great importance to discover the 
human father of the founder of Christianity. 

It is interesting to see the different reception that the 
love-story of Miriam has met with at the hands of the 
four great Christian nations of civilised Europe. The 
stern morality of the Teutonic races entirely repudiated 
it ; the righteous German and the prudish Briton preferred 
to believe blindly in the impossible thesis of a conception 
"by the Holy Ghost." It is well known that this 
strenuous and carefully-paraded prudery of the higher 
classes (especially in England) is by no means reflected in 
the true condition of sexual morality in high quarters. 
The revelations which the Pall Mall Gazette, for instance, 
made on the subject twelve years ago vividly recalled the 
condition of Babylon. 

The Romantic races, which ridicule this prudery and 
take sexual relations less seriously, find Mary's Romance 
attractive enough ; the special cult which " Our Lady " 
enjoys in France and Italy is often associated with this 
love-story with curious naivete". Thus, for example, Paul 
de Regla (Dr. Desjardin), author of Jesus of Nazareth 
Considered from a Scientific, Historical, and Social Stand- 
point (1894), finds precisely in the illegitimate birth of 
Christ a special "title to the halo that irradiates his noble 

It seems to me necessary to enter fully into this 
important question of the origin of Christ in the sense 
of impartial historical science, because the Church militant 
itself lays great emphasis on it, and because it regards 
the miraculous structure which has been founded on it as 
one of its strongest weapons against modern thought. 
The high ethical value of pure primitive Christianity and 
the ennobling influence of this " religion of love " on the 
history of civilisation are quite independent of those 
mythical dogmas. The so-called "revelations " on which 
these myths are based are incompatible with the firmest 
results of modern science. 



Monism as a connecting link bet-ween religion and science. The 

culiur-kampf. The relations of Church and ^jte. Principles of 

the monistic religion. Its three- fold ideal : the good, the true, 
and the beautiful. Contradiction between scientific and Christian 
truth. Harmony of the monistic and the Christian idea of 
virtue. Opposition between monistic and Christian vwwi of art. 
Modern expansion and enrichment of our idea of the world. 
Landscape-painting and the modern enjoyment of nature. The 
beauties of nature. This world and beyond- Monistic churches^ 

MANY distinguished scientists and philosophers of the 
day, who share our monistic views, consider that religion 
is generally played out. Their meaning is that the clear 
insight into the evolution of the world which the great 
scientific progress of the nineteenth century has afforded 
us will satisfy, not only the causal feeling of our reason, 
but even our highest emotional cravings. This view is 
correct In the sense that the two ideas, religion and 
science, would indeed blend into one if we had a perfectly 
clear and consecutive system of monism. However, there 
are but a few resolute thinkers who attain to this most 
pure and lofty conception of Spinoza and Goethe. Most 
of the educated people of our time (as distinct from the 
uncultured masses) remain in the conviction that religion 
is a separate branch of our mental life, independent of 
science, and not less valuable and indispensable. 

If we adopt this view, we can find a means of recon- 
ciling the two great and apparently quite distinct branches 
in the idea I put forward in "Monism, as a connecting- 
link between religion and science," in 1892. In the 
preface to this Con/enton of Faith of a Man of Science 
I expressed myself in the following terms with regard to 



its double object : " In the first place, I must give expres- 
sion to the rational system which is logically forced upon 
us by the recent progress of science; it dwells in the 
intimate thoughts of nearly every impartial and thoughtful 
scientist, though few have the courage or the disposition 
to avow it. In the second place, I would make of it a 
connecting-link between religion and science, and thus do 
away with the antithesis which has been needlessly main- 
tained between these two branches of the highest activity 
of the human mind. The ethical craving of our emotion 
is satisfied by monism no less than the logical demand for 
causality on the part of reason." 

The remarkable interest which the discourse enkindled 
Is a proof that in this monistic profession of faith I 
expressed the feeling not only of many scientists, but of 
a large number of cultured men and women of very 
jjlfferent circles. Not only was 1 rewarded by hundreds 
tar sympathetic letters, but by a wide circulation of the 
printed address, of which six editions were required within 
six months. I had the more reason to be content with 
this unexpected success, as this " confession of faith " was 
originally merely an occasional speech which I delivered 
unprepared on October 9th, 1892, at Altenburg, during 
the jubilee of the Scientific Society of East Germany. 
Naturally there was the usual demonstration on the other 
side ; I was fiercely attacked, not only by the ultra- 
montane Press, the sworn defenders of superstition, but 
also by the "liberal " controversialists of evangelical 
Christianity, who profess to defend both scientific truth 
and purified faith. In the seven years that have ensued 
since that time the great struggle between modern science 
and orthodox Christianity has become more threatening ; 
it has grown more dangerous for science in proportion 
as Christianity has found support in an increasing mental 
and political reaction. In some countries the Church has 
made such progress that the freedom of thought and 
conscience, which is guaranteed by the laws, is in practice 
gravely menaced (for instance, hi Bavaria). The great 
historic struggle which Draper has so admirably depicted 
in his Conflict between Religion and Science is to-day 


more acute and significant than ever. For the last twenty- 
seven years it has been rightly called the CMltur-kampf. 

The famous encyclica and syllabus which the militant 
Pope Pius IX. sent out into the entire world in 1864 were 
a declaration of war on the whole of modern science; 
they demanded the blind submission of reason to the 
dogmas of the infallible Pope. The enormity of this 
crude assault on the highest treasures of civilisation even 
roused many indolent minds from the slumber of belief. 
Together with the subsequent promulgation of the Papal 
infallibility (1870), the encyclica provoked a deep wave of 
irritation and an energetic repulse which held out high 
hopes. In the new German Empire, which had attained 
its indispensable national unity by the heavy sacrifices of 
the wars of 1866 and 1871, the insolent attacks of the 
Pope were felt to be particularly offensive. On the one 
hand, Germany is the cradle of the Reformation and thf 
modern emancipation of reason ; on the other hand, if 
unfortunately has in its 18,000,000 Catholics a vast host 
of militant believers, who are unsurpassed by any other 
civilised people in blind obedience to their chief shepherd. 

The dangers of such a situation were clearly recognised 
by the great statesmen who had solved the political 
" world-riddle " of the dismemberment of Germany, and 
had led us by a marvellous statecraft to the long- desired 
goal of national unity and power. Prince Bismarck 
began the famous struggle with the Vatican, which is 
known as the cultur-hampf, in 1872, and it was conducted 
with equal ability and energy by the distinguished Minister 
of Worship, Falk, author of the May Laws of 1873. 
Unfortunately, Bismarck had to desist six years after- 
wards. Although the great statesman was a remarkable 
judge of men and a realistic politician of immense tact, 
he had under-estimated the force of three powerful 
obstacles firstly, the unsurpassed cunning and unscrupu- 
lous treachery of the Roman curia; secondly, the corre- 
lative ingratitude and credulity of the uneducated Catholic 
masses, on which the Papacy built; and, thirdly, the 
power of apathy, the continuance of the irrational simply 
because it is in possession. Hence, in 1878, when the 


abler Leo XIII. had ascended the pontifical throne, the 
fatal "To Canossa " was heard once more. From that 
time the newly-established power of Rome grew in 
strength ; partly through the unscrupulous intrigues and 
serpentine bends of its slippery Jesuitical politics, partly 
through the false Church-politics of the German Govern- 
ment and the marvellous political incompetence of the 
German people. We have, therefore, at the close of the 
nineteenth century to endure the pitiful spectacle of the 
Catholic " Centre " being the most important section of 
the Reichstag, and the fate of our humiliated country 
depending on a Papal party, which does not constitute 
numerically a third part of the nation. 

When the cuUur-hampf began in 1872, it was justly 
acclaimed by all independent thinkers as a political renewal 
of the Reformation, a vigorous attempt to free modern 
ivilisation from the yoke of Papal despotism. The whole 
the Liberal Press hailed Bismarck as a " political 
Luther " as the great hero, not only of the national 
unity, but also of the rational emancipation, of Germany. 
Ten years afterwards, when the Papacy had proved vic- 
torious, the same " Liberal Press " changed its colours, 
and denounced the cultur-kampf as a great mistake ; and it 
does the same thing to-day. The facts show how short 
is the memory of our journalists, how defective their 
knowledge of history, and how poor their philosophic 
education. The so-called "Peace between Church and 
State " is never more than a suspension of hostilities. 
The modern Papacy, true to the despotic principles it has 
followed for the last 1000 years, is determined to wield 
sole dominion over the credulous souls of men ; it must 
demand the absolute submission of the cultured State, 
which, as such, defends the rights of reason and science. 
True and enduring peace there cannot be until one of the 
combatants lies powerless on the ground. Either the 
Church wins, and then farewell to all "free science and 
free teaching " then are our universities no better than 
gaols, and our colleges become cloistral schools; or else 
the modern rational State proves victorious then, in the 
twentieth century, human culture, freedom, and pros- 


perity will continue their progressive development until 
they far surpass even the height of the nineteenth century. 

In order to compass these high aims, it is of the first 
importance that modern science not only shatter the false 
itructures of superstition and sweep their ruins from the 
path, but that it also erect a new abode for human emotion 
on the ground it has cleared a " palace of reason,* 1 in 
which, under the influence of our new monistic views, we 
do reverence to the real trinity of the nineteenth century 
the trinity of "the true, the good, and the beautiful." 
In order to give a tangible shape to the cult of this divine 
ideal, we must first of all compare our position with the 
dominant forms of Christianity, and realise the changes 
that are involved in the substitution of the one for the 
other. For, in spite of its errors and defects, the Christian 
religion (in its primitive and purer form) has so high an 
ethical value, and has entered so deeply into the niGgfe 
important social and political movements of civiliseW 
history for the last 1500 years, that we must appeal as 
much as possible to its existing institutions in the establish- 
ment of our monistic religion. We do not seek a mighty 
revolution, but a rational reformation, of our religious 
life. And just as, 2000 years ago, the classic poetry of 
the ancient Greeks incarnated their ideals of virtue in 
divine shapes, so may we, too, lend the character of noble 
goddesses to our three rational ideals. We must inquire 
into the features of the three goddesses of the monist 
truth, beauty, and virtue ; and we must study their relation 
to the three corresponding ideals of Christianity which 
they are to replace. 

I. The preceding inquiries (especially those of the first 
and third sections) have convinced us that truth unadulter- 
ated is only to be found in the temple of the study of 
nature, and that the only available paths to it are critical 
observation and reflection the empirical investigation of 
facts and the rational study of their efficient causes. In 
this way we arrive, by means of pure reason, at true 
science, the highest treasure of civilised man. We must, 
in accordance with the arguments of our sixteenth chapter, 
reject what is called "revelation," the poetry of faith, 


that affirms the discovery of truth in a supernatural 
fashion, without the assistance of reason. And since the 
entire structure of the Juda>o-Christian religion, like thai 
of the Mohammedan and the Buddhistic, rests on these 
so-called revelations, and these mystic fruits of the imagi- 
nation directly contradict the clear results of empirical 
research, it is obvious that we shall only attain to a know- 
ledge of the truth by the rational activity of genuine 
science, not by the poetic imagining of a mystic faith. 
In this respect it is quite certain that the Christian system 
must give way to the monistic. The goddess of truth 
dwells in the temple of nature, in the green woods, on 
the blue sea, and on the snowy summits of the hilis not 
in the gloom of the cloister, nor in the narrow prisons 
of our gaol-like schools, nor in the clouds of incense of 
the Christian Churches. The paths which lead to the 
divinity of truth and knowledge are the loving study 
nature and its laws, the observation of the infinitely 
great star-world with the aid of the telescope, and the 
infinitely tiny cell-world with the aid of the microscope 
not senseless ceremonies and unthinking prayers, not alms 
and Peter 's-pence. The rich gifts which the goddess of 
truth bestows on us are the noble fruits of the tree of 
knowledge and the inestimable treasure of a clear, unified 
view of the world not belief in supernatural miracles and 
the illusion of an eternal life. 

II. It is otherwise with the divine ideal of eternal 
goodness. In our search for the truth we have entirely 
to exclude the " revelation " of the Churches, and devote 
ourselves solely to the study of nature; but, on the other 
hand, the idea of the good, which we call virtue, in our 
monistic religion coincides for the most part with the 
Christian idea of virtue. We are speaking, naturally, of 
the primitive and pure Christianity of the first three 
centuries, as far as we learn its moral teaching from the 
gospels and the epistles of Paul; it does not apply to the 
Vatican caricature of that pure doctrine which hag domi- 
nated European civilisation, to its infinite prejudice, for 
1200 years. The best part of Christian morality, to which 
we firmly adhere, is represented by the humanist precepts 


of charity and toleration, compassion and assistance. 
However, these noble commands, which are set down as 
" Christian " morality (in its best sense), are by no means 
original discoveries of Christianity ; they were derived 
from earlier religions. The Golden Rule, which sums up 
these precepts in one sentence, is centuries older than 
Christianity. In the conduct of life this law of natural 
morality has been followed just as frequently by non- 
Christians and atheists as it has been neglected by pious 
believers. Moreover, Christian ethics was marred by the 
great defect of a narrow insistence on altruism and a 
denunciation of egoism. Our monistic ethics lays equal 
emphasis on the two, and finds perfect virtue in the just 
balance of love of self and love of one's neighbour (cf. 
chap. xix.). 

IIT. But monism enters into its strongest opposition 
to Christianity on the question of beauty. PrimitijjSi 
Christianity preached the worthlessness of earthly li 
regarding it merely as a preparation for an eternal life 
beyond. Hence it immediately followed that all we find 
in the life of a man here below, all that is beautiful in 
art and science, in public and in private life, is of no real 
value. The true Christian must avert his eyes from them ; 
he must think only of a worthy preparation for the life 
beyond. Contempt of nature, aversion from all its inex- 
haustible charms, rejection of every kind of fine art, are 
Christian duties ; and they are carried out to perfection 
when a man separates himself from his fellows, chastise* 
his body, and spends all his time in prayers in the cloister 
or the hermit's cell. 

History teaches us that this ascetical morality that 
would scorn the whole of nature had, as a natural conse- 
quence, the very opposite effect to that it intended. 
Monasteries, the homes of chastity and discipline, soon 
became dens of the wildest orgies ; the sexual commerce 
of monks and nuns has inspired shoals of novels, as it is 
so faithfully depicted in the literature of the Renaissance. 
The cult of the " beautiful " which was then practised 
was in flagrant contradiction with the vaunted "abandon- 
ment of the world " ; and the same must be said of the 


pomp and luxury which soon developed in the immoral 
private lives of the higher ecclesiastics and in the artistic 
decoration of Christian churches and monasteries. 

It may be objected that our view is refuted by the 
splendour of Christian art, which, especially in the best 
days of the Middle Ages, created works of undying 
beauty. The graceful Gothic cathedrals and Byzantine 
basilicas, the hundreds of magnificent chapels, the thou- 
sands of marble statues of saints and martyrs, the millions 
of fine pictures of saints, of profoundly conceived repre- 
sentations of Christ and the madonna all are proofs of 
the development of a noble art in the Middle Ages, which 
is unique of its kind. All these splendid monuments of 
mediaeval art are untouched in their high aesthetic value, 
whatever we say of their mixture of truth and fancy. 
Yes ; but what has all that to do with the pure teaching 
jfti Christianity with that religion of sacrifice that turned 
Bbrnfully away from all earthly parade and glamour, from 
all material beauty and art; that made light of the life 
of the family and the love of woman ; that urged an 
exclusive concern as to the immaterial goods of eternal 
life? The idea of a Christian art is a contradiction in 
terms a contradictio in adjecto. The wealthy princes of 
the Church who fostered it were candidly aiming at very 
different ideals, and they completely attained them. In 
directing the whole interest and activity of the human 
mind in the Middle Ages to the Christian Church and its 
distinctive art they were diverting it from nature and 
from the knowledge of the treasures that were hidden 
in it, and would have conducted to independent science. 
Moreover, the daily sight of the huge images of the saints 
and of the scenes of " sacred history " continually 
reminded the faithful of the vast collection of myths that 
the Church had made. The legends themselves were 
taught and believed to be true narratives, and the stories 
of miracles to be records of actual events. It cannot be 
doubted that in this respect Christian art has exercised 
an immense influence on general culture, and especially 
in the strengthening of Christian belief an influence 
which still endures throughout the entire civilised world. 


The diametrical opposite of this dominant Christian art 
is the new artistic tendency which has been developed 
during the present century in connection with science. 
The remarkable expansion of our knowledge of nature, and 
the discovery of countless beautiful forms of life which it 
includes, have awakened quite a new aesthetic sense in 
our generation, and thus given a new tone to painting and 
sculpture. Numerous scientific voyages and expeditions 
for the exploration of unknown lands and seas, partly in 
earlier centuries, but more especially in the nineteenth, 
have brought to light an undreamed abundance of new 
organic forms. The number of new species of animals 
and plants soon became enormous, and among them 
(especially among the lower groups that had been neg- 
lected before) there were thousands of forms of great- 
beauty and interest, affording an entirely new inspiration 
for painting, sculpture, architecture, and technical agttj 
In this respect a new world was revealed by the grflP 
advance of microscopic research in the second half of the 
century, and especially by the discovery of the marvellous 
inhabitants of the deep sea, which were first brought to 
light by the famous expedition of the Challenger (1872- 
76). Thousands of graceful radiolaria and thalamophora, 
of pretty medusae and corals, of extraordinary molluscs 
and crabs, suddenly introduced us to a wealth of hidden 
organisms beyond all anticipation, the peculiar beauty and 
diversity of which far transcend all the creations of the 
human imagination. In the fifty large volumes of the 
account of the Challenger expedition a vast number of 
these beautiful forms are delineated on 8000 plates ; and 
there are millions of other lovely organisms described In 
other great works that are included in the fast-growing 
literature of zoology and botany of the last ten years. I 
began on a small scale to select a number of these beauti- 
ful forms for more popular description in my Art Form* 
in Nature (1899). 

However, there is now no need for long voyages and 
costly works to appreciate the beauties of this world. A 
mim need only keep his eyea open and his mind disci- 
plined. Surrounding nature offers us everywhere a 


marvellous wealth of lovely and interesting objects of all 
kinds. In every bit of moss and blade of grass, in every 
beetle and butterfly, we find, when we examine it care- 
fully, beauties which are usually overlooked. Above all, 
when we examine them with a powerful glass, or, better 
still, with a good microscope, we find everywhere in nature 
a new world of inexhaustible charms. 

But the nineteenth century has not only opened our 
eyes to the aesthetic enjoyment of the microscopic world ; 
it has shown us the beauty of the greater objects in nature. 
Even at its commencement it was the fashion to regard 
the mountains as magnificent but forbidding, and the sea 
as sublime but dreaded. At its close the majority of 
educated people especially they who dwell in the great 
cities are delighted to enjoy the glories of the Alps and 
the crystal splendour of the glacier-world for a fortnight 
jtasry year, or to drink in the majesty of the ocean and 
Be lovely scenery of its coasts. All these sources of the 
Keenest enjoyment of nature have only recently been 
revealed to us in all their splendour, and the remarkable 
progress we have made in facility and rapidity of convey- 
ance has given even the less wealthy an opportunity of 
approaching them. All this progress in the aesthetic 
enjoyment of nature and, proportionately, in the 
scientific understanding of nature implies an equal ad- 
vance in higher mental development, and, consequently, 
in the direction of our monistic religion. 

The opposite character of our naturalistic century to 
that of the anthropistic centuries that preceded is espe- 
cially noticeable in the different appreciation and spread 
of illustrations of the most diverse natural objects. In 
our own dajrs a lively interest in artistic work of that kind 
has been developed, which did not exist in earlier ages; 
it has been supported by the remarkable progress of com- 
merce and technical art which have facilitated a wide 
popularisation of such illustrations. Countless illustrated 
periodicals convey along with their general information a 
sense of the inexhaustible beauty of nature in all its 
departments. In particular, landscape-painting hat ac- 
quired an importance that surpassed all imagination. In 


the first half of the century one of oar greatest and most 
erudite scientists, Alexander Humboldt, had pointed out 
that the development of modern landscape-painting is 
not only of great importance as an incentive to the study 
of nature and as a means of geographical description, but 
that it is to be commended in other respects as a noble 
educative medium. Since that time the taste for it has 
considerably increased. It should be the aim of every 
school to teach the children to enjoy scenery at an early 
age, and to give them the valuable art of imprinting on 
the memory by a drawing or water-colour sketch. 

The infinite wealth of nature in what is beautiful and 
sublime offers every man with open eyes and an aesthetic 
sense an incalculable sum of choicest gifts. Still, how- 
ever valuable and agreeable is the immediate enjoyment of 
each single gift, its worth is doubled by a knowledge of 
its meaning and its connection with the rest of natudB 
When Humboldt gave us the "outline of a physical 
description of the world " in his magnificent Cosmos forty 
years ago, and when he combined scientific and aesthetic 
consideration so happily in his standard Prospects of 
Nature, he justly indicated how closely the higher enjoy- 
ment of nature is connected with the "scientific estab- 
lishment of cosmic laws," and that the conjunction of the 
two serves to raise human nature to a higher stage of 
perfection. The astonishment with which we gaze upon 
the starry heavens and the microscopic life in a drop of 
water, the awe with which we trace the marvellous work- 
ing of energy in the motion of matter, the reverence with 
which we grasp the universal dominance of the law of 
substance throughout the universe all these are part of 
our emotional life, falling under the heading df "natural 

This progress of modern times in knowledge of the true 
and enjoyment of the beautiful expresses, on the one hand, 
a valuable element of our monistic religion, but is, on 
the other hand, in fatal opposition to Christianity. For 
the human mind is thus made to live on this side of the 
grave; Christianity would have it ever gaze beyond. 
Monism teaches that we are perishable children of the 


earth, who, for one or two, or, at the most, three genera- 
tions, have the good fortune to enjoy the treasures of our 
planet, to drink of the inexhaustible fountain of its beauty, 
and to trace out the marvellous play of its forces. 
Christianity would teach us that the earth is "a vale of 
tears," in which we have but a brief period to chasten 
and torment ourselves in order to merit the life of eternal 
bliss beyond. Where this " beyond " is, and of what joys 
the glory of this eternal life is compacted, no revelation 
has ever told us. As long as " heaven " was thought 
to be the blue vault that hovers over the disk of our 
planet, and is illumined by the twinkling light of a few 
thousand stars, the human imagination could picture to 
itself the ambrosial banquets of the Olympic gods above 
or the laden tables of the happy dwellers in Valhalla. 
But now all these deities and the immortal souls that sat 
||t their tables are " houseless and homeless," as David 
Ktrauss has so ably described ; for we know from astro- 
physical science that the immeasurable depths of space are 
filled with a prosaic ether, and that millions of heavenly 
bodies, ruled by eternal laws of iron, rush hither and 
thither in the great ocean, in their endless rhythm of life 
and death. 

The places of devotion, in which men seek the satisfac- 
tion of their religious emotions and worship the objects 
of their reverence, are regarded as sacred "churches." 
The pagodas of Buddhistic Asia, the Greek temples of 
classical antiquity, the synagogues of Palestine, the 
mosques of Egypt, the Catholic cathedrals of the south, 
and the Protestant cathedrals of the north of Europe all 
these "houses of God " serve to raise man above the 
misery and the prose of daily life, to lift him into the 
sacred, poetic atmosphere of a higher, ideal world. They 
attain this end in a thousand different ways, according to 
their various forms of worship and their age. The modern 
man who "has science and art," and therefore "religion," 
needs no special church, no narrow, enclosed portion of 
space. For through the length and breadth of free 
nature, wherever he turns his gaze, to the whole universe 
or to any single part of it, he finds, indeed, the grim 

"struggle for life," but by its side are ever "tbe good, 
tbe true, and tbe beautiful " ; bis cburcb is commensurate 
witb tbe wbole of glorious nature. Still, tbere will always 
be men of special temperament wbo will desire to bave 
decorated temples or cburcbes as places of devotion, to 
wbicb tbey may withdraw. lust as tbe Catholics bad to 
relinquish a number of cburcbes to tbe Reformation in the 
siiteentb century, so a still larger number will pass over 
to "free societies '' of monists in tbe coming years. 



Monistic and dualistic ethics. Contradiction of pure and practical 
reason in Kant. His categorical imperative. The neo-Kantiani. 
Herbert Spenoer. Egoism and altruism. Equivalence of the two 
instincts. The fundamental law of ethics: the Golden Rule. 
Its antiquity. Christian ethics. Contempt of self, the body, 
nature, civilisation, the family, woman. Roman Catholic ethics. 
Immoral results of celibacy. Necessity for the abolition of the 
laws of celibacy, oral confession, and indulgences. State and 

^ Church. Religion a private concern. Church and school. State 

and school Need of school reform. 

THE practical conduct of life makes a number of definite 
ethical claims on a man which can only be duly and natur- 
ally satisfied when they are in complete harmony with 
his view of the world. In accordance with this funda- 
mental principle of our monistic philosophy, our whole 
system of ethics must be rationally connected with the 
unified conception of the cosmos which we have formed 
by our advanced knowledge of the laws of nature. Just 
as the infinite universe is one great whole in the light of 
our monistic teaching, so the spiritual and moral life of 
man is a part of this cosmos, and our naturalistic order- 
ing of it must also be monistic. There are not two 
different, separate worlds the one physical and material, 
and the other moral and immaterial. 

The great majority of philosophers and theologians still 
hold the contrary opinion. They affirm, with Kant, that 
the moral world is quite independent of the physical, and 
is subject to very different laws; hence, a man's con- 
science, as the basis of his moral life, must also be quite 
independent of our scientific knowledge of the world, and 
must be based rather on his religious faith. On that 
theory the study of the moral work] belongs to practical 


reason, while that of nature, or of the physical world, is 
referred to pure or theoretical reason. This unequivocal 
and conscious dualism of Kant's philosophy was its greatest 
defect; it has caused, and still causes, incalculable mis- 
chief. First of all the "critical Kant " had built up the 
splendid and marvellous palace of pure reason, and con- 
vincingly proved that the three great central dogmas of 
metaphysics a personal God, free will, and the immortal 
soul had no place whatever in it, and that no rational 
proof could be found of their reality. Afterwards, how- 
ever, the "dogmatic Kant" superimposed on this true 
crystal palace of pure reason the glittering, ideal castle 
in the air of practical reason, in which three imposing 
church-naves were designed for the accommodation of 
those three great mystic divinities. When they had been 
put out at the front door by rational knowledge they 
returned by the back door under the guidance of irrational! 
faith. * 

The cupola of his great cathedral of faith was crowned 
by Kant with his curious idol, the famous "categorical im- 
perative." According to it, the demand of the universal 
moral law is unconditional, independent of any regard to 
actuality or potentiality. It runs : " Act at all times in 
such wise that the maxim (or the subjective law of thy 
will) may hold good as a principle or a universal law." 
On that theory all normal men would have the same sense 
of duty. Modern anthropology lias ruthlessly dissipated 
that pretty dream ; it has shown that conceptions of duty 
differ even more among uncivilised than among civilised 
nations. All the actions and customs which we regard 
as sins or loathsome crimes (theft, fraud, murder, 
adultery, etc.) are considered by other nations in certain 
circumstances to be virtues, or even sacred duties. 

Although the obvious contradiction of the two forms 
of reason in Kant's teaching, the fundamental antagonism 
of pure and practical reason, was recognised and attacked 
at the very beginning of the century, it is still pretty 
widely accepted. The modern school of neo-Kantians 
urges a " return to Kant " so pressingly precisely on 
account of this agreeable dualism; the Church militant 


zealously supports it because it fits in admirably with its 
own mystic faith. But it met with an effective reverse 
at the hands of modern science in the second half of the 
nineteenth century, which entirely demolished the theses 
of the system of practical reason. Monistic cosmology 
proved, on the basis of the law of substance, that there 
is no personal God; comparative and genetic psychology 
showed that there cannot be an immortal soul; arid 
monistic physiology proved the futility of the assumption 
of "free will." Finally, the science of evolution made it 
clear that the same eternal iron laws that rule in the in- 
organic world are valid, too, in the organic and moral 

But modern science gives not only a negative support 
to practical philosophy and ethics in demolishing the 
Kantian dualism, but it renders the positive service of 

^substituting for it the new structure of ethical monism. 

It shows that the feeling of duty does not rest on an 
illusory "categorical imperative," but on the solid ground 
of tocid instinct, as we find in the case of all social 
animals. It regards as the highest aim of all morality the 
re-establishment of a sound harmony between egoism and 
altruism, between self-love and the love of one's neigh- 
bour. It is to the great English philosopher Herbert 
Spencer 1 that we owe the founding of this monistic ethics 
on a basis of evolution. 

Man belongs to the social vertebrates, and has, there- 
fore, like all social animals, two sets of duties firstly to 
himself, and secondly to the society to which he belongs. 
The former are the behests of self-love or egoism, the 
latter of love for one's fellows or altruism. The two sets 
of precepts are equally just, equally natural, and equally 
indispensable. If a man desire to have the advantage of 
living in an organised community, he has to consult not 
only his own fortune, but also that of the society, and of 
the "neighbours" who form the society. He must 
realise that its prosperity is his own prosperity, and that 

1 Professor Haeckel places Mr. Spencer's works at the head of the 
bibliography in the German edition. We have omitted these lista, as 
they tre chiefly German. TRANS. 


it cannot suffer without his own injury. This funda- 
mental law of society is so simple and so inevitable that 
one cannot understand how it can be contradicted in theory 
or in practice ; yet that is done to-day, and has been done 
for thousands of years. 

The equal appreciation of these two natural impulses, 
or the moral equivalence of self-love and love of others, 
is the chief and the fundamental principle of our morality. 
Hence the highest aim of all ethics is very simple it is 
the re-establishment of "the natural equality of egoism 
and altruism, of the love of oneself and the love of one's 
neighbour." The Golden Rule says: "Do unto others 
as you would that they should do unto you." From this 
highest precept of Christianity it follows of itself that 
we have just as sacred duties towards ourselves as we have 
towards our fellows. I have explained my conception of 
this principle in my Monism, and laid down three im^ 
port ant theses. (1) Both these concurrent impulses arr 
natural laws of equal importance and necessity for the 
preservation of the family and the society ; egoism secures 
the self-preservation of the individual, altruism that of 
the species, which is made up of the chain of perishable 
individuals. (2) The social duties which are imposed by 
the social structure of the associated individuals, and by 
means of which it secures its preservation, are merely 
higher evolutionary stages of the social instincts, which 
we find in all higher social animals (as " habits which have 
become hereditary "). (3) In the case of civilised man all 
ethics, theoretical or practical, being "a science of rules," 
is connected with his view of the world at large, and 
consequently with his religion. 

From the recognition of the fundamental principle of 
our morality we may immediately deduce its highest pre- 
cept, that noble command which is often called the Golden 
Rule of mortals, or, briefly, the Golden Rule. Christ 
repeatedly expressed it in the simple phrase : " Thou shalt 
love thy neighbour as thyself." Mark adds that "there 
Is no greater commandment than this," and Matthew 
says : '* In these two commandments is the whole law and 
the prophets." In this greatest and highest command- 


ment our monistic ethics is completely at one with 
Christianity. We must, however, recall the historical fact 
that the formulation of this supreme command is not an 
original merit of Christ, as the majority of Christian 
theologians affirm and their uncritical supporters blindly 
accept. The Golden Rule is 500 years older than Christ ; 
it was laid down as the highest moral principle by many 
Greek and Oriental sages. Pittacus of Mytilene, one of 
the seven wise men of Greece, said 620 years before 
Christ : " Do not that to thy neighbour that thou vvouldst 
not suffer from him/' Confucius, the great Chinese 
philosopher and religious founder (who rejected the idea 
of a personal God and of the immortality of the soul), said 
500 years B.C. : " Do to every man as thou wouldst have 
him do to thee ; and do not to another what thou wouldst 
not have him do to thee. This precept only dost thou 
need; it is the foundation of all other commandments." 
Aristotle taught, about the middle of the fourth century 
B.C. : " We must act towards others as we wish others 
to act towards us." In the same sense, and partly in the 
same words, the Golden Rule was given by Thales, 
Isocrates, Aristippus, Sextus the Pythagorean, and other 
philosophers of classic antiquity several centuries before 
Christ. From this collection it is clear that the Golden 
Rule had a polyphyletic origin that is. it was formulated 
by a number of philosophers at different times and in 
different places quite independently of each other. Other- 
wise it must be assumed that Jesus derived it from some 
other oriental source, from ancient Semitic, Indian, 
Chinese, or especially Buddhistic traditions, as has 
been proved in the case of most of the other Christian 

As the great ethical principle is thus 2500 years old, 
and as Christianity itself has put it at the head of its moral 
teaching as the highest and all-embracing commandment, 
it follow! that our monistic ethics is in complete harmony 
on this important point, not only with the ethics of the 
ancient heathens, but also with that of Christianity. Un- 
fortunately this harmony is disturbed by the fact that the 
gospels and the Pauline epistles contain many other points 


of moral teaching which contradict our first and supreme 
commandment. Christian theologians have fruitlessly 
striven to explain away these striking and painful contra- 
dictions by their ingenious interpretations. We need not 
enter into that question now, but we must briefly consider 
those unfortunate aspects of Christian ethics which are 
incompatible with the better thought of the modern age, 
and which are distinctly injurious in their practical con- 
sequences. Of that character is the contempt which Chris- 
tianity has shown for self, for the body, for nature, for 
civilisation, for the family, and for woman. 

1. The supreme mistake of Christian ethics, and one 
which runs directly counter to the Golden Rule, is its 
exaggeration of love of one's neighbour at the expense of 
self-love. Christianity attacks and despises egoism on 
principle. Yet that natural impulse is absolutely indis- 
pensable in view of self-preservation ; indeed, one may say 
that even altruism, its apparent opposite, is only an 
enlightened egoism. Nothing great or elevated has ever 
taken place without egoism, and without the passion that 
urges us to great sacrifices. It is only the excesses of the 
impulse that are injurious. One of the Christian precepts 
that were impressed upon us in our early youth as of 
great importance, and that are glorified in millions of 
sermons, is : " Love your enemies, bless them that curse 
you, do good to them that hate you, and pray for them 
which despitefully use you and persecute you." It is a 
very ideal precept, but as useless in practice as it is un- 
natural. So it is with the counsel, " If any man will take 
away thy coat, let him have thy cloak also." Translated 
into the terms of modern life, that means : " When some 
unscrupulous scoundrel has defrauded thee of half thy 
goods, let him have the other half also." Or, again, in 
the language of modern politics : " When the pious Eng- 
lish take from you simple Germans one after another of 
your new and valuable colonies in Africa, let them have 
all the rest of your colonies also or, best of all, give 
them Germany itself." And, while we touch on the 
marvellous world -politics of modern England, we may 


note in passing its direct contradiction of every precept 
of Christian charity, which is more frequently on the lips 
of that great nation than of any other nation in the world. 
However, the glaring contradiction between the theo- 
retical, ideal, altruistic morality of the human individual 
and the real, purely selfish morality of the human com- 
munity, and especially of the civilised Christian state, is 
a familiar fact. It would be interesting to determine 
mathematically in what proportion among organised men 
the altruistic ethical ideal of the individual changes into 
its contrary, the purely egoistic " real politics " of the 
state and the nation. 

II. Since the Christian faith takes a wholly dualistic 
view of the human organism and attributes to the im- 
mortal soul only a temporary sojourn in the mortal frame, 
it very naturally sets a much greater value on the soul than 
on the body. Hence results that neglect of the care of 
the body, or training, and of cleanliness, which contrasts 
the life of the Christian Middle Ages so unfavourably with 
that of pagan classical antiquity. Christian ethics contains 
none of those firm commands as to daily ablutions which 
are theoretically laid down and practically fulfilled in the 
Mohammedan, Hindoo, and other religions. In many 
monasteries the ideal of the pious Christian is the man 
who does not wash and clothe himself properly, who never 
changes his malodorous gown, and who, instead of regular 
work, fills up his useless life with mechanical prayers, 
senseless fasts, and so forth. As a special outgrowth of 
this contempt of the body we have the disgusting dis- 
cipline of the flagellants and other ascetics. 

III. One source of countless theoretical errors and 
practical blemishes, of deplorable crudity and privation, 
is found in the false anthropism of Christianity that is, 
in the unique position which it gives to man, as the image 
of God, in opposition to all the rest of nature. In this 
way it has contributed, not only to an extremely injurious 
isolation from our glorious mother "nature," but also to 
a regrettable contempt of all other organisms. Christian- 
ity has no place for that well-known love of animals, that 


sympathy with the nearly related and friendly mammals 
(dogs, horses, cattle, etc.), which is urged in the ethical 
teaching of many of the older religions, especially Bud- 
dhism. Whoever has spent much time in the south of 
Europe must have often witnessed those frightful suffer- 
ings of animals which fill us friends of animals with the 
deepest sympathy and indignation. And when one ex- 
postulates with these brutal *" Christians " on their cruelty, 
the only answer is, with a laugh : " But the beasts are 
not Christians." Unfortunately, Descartes gave some 
support to the error in teaching that man only has a 
sensitive soul, not the animal. 

How much more elevated is our monistic ethics than the 
Christian in this regard! Darwinism teaches us that we 
have descended immediately from the primates, and, in a 
secondary degree, from a long series of earlier mammals, 
and that, therefore, they are "our brothers " ; physiology 
informs us that they have the same nerves and sense- 
organs as we, and the same feelings of pleasure and pain. 
No sympathetic monistic scientist would ever be guilty of 
that brutal treatment of animals which comes so lightly 
to the Christian in his anthropistic illusion to the " child 
of the God of love." Moreover, this Christian contempt 
of nature on principle deprives man of an abundance of 
the highest earthly joys, especially of the keen, ennobling 
enjoyment of nature. 

IV. Since, according to Christ's teaching, our planet 
is "a vale of tears," and our earthly life is valueless and 
a mere preparation for a better life to come, it has suc- 
ceeded in inducing men to sacrifice all happiness on this 
side of eternity and make light of all earthly goods. 
Among these "earthly goods," in the case of the modern 
civilised man, we must include the countless great and 
mall conveniences of technical science, hygiene, com- 
merce, etc., which have made modern life cheerful and 
comfortable; we must include all the gratifications of 
painting, sculpture, music, and poetry, which flourished 
exceedingly even during the Middle Ages (in spite of its 
principles), and which we esteem as " ideal pleasures " ; 
we must include all that invaluable progress of science, 


especially of the study of nature, of which the nineteenth 
century is justly proud. All these "earthly goods," that 
have so high a value in the eyes of the monist, are worth- 
less nay, injurious for the most part, according to 
Christian teaching; the stern code of Christian morals 
should look just as unfavourably on the pursuit of these 
pleasures as our humanistic ethics fosters and encourages 
it. Once more, therefore, Christianity is found to be an 
enemy to civilisation, and the struggle which modern 
thought and science are compelled to conduct with it is, 
in this additional sense, a cultur-kampf. 

V. Another of the most deplorable aspects of Chris- 
tian morality is its belittlement of the life of the family, 
of that natural living together with our next of kin which 
is just as necessary in the case of man as in the case of all 
the higher social animals. The family is justly regarded 
as the "foundation of society," and the healthy life of the 
family is a necessary condition of the prosperity of the 
State. Christ, however, was of a very different opinion : 
with his gaze ever directed to "the beyond," he thought 
as lightly of woman and the family as of all other goods 
of "this life." Of his infrequent contact with his parents 
and sisters the Gospels have very little to say ; but they 
are far from representing his relations with his mother to 
have been so tender and intimate as they are poetically 
depicted in so many thousands of pictures. He was not 
married himself. Sexual love, the first foundation of the 
family union, seems to have been regarded by Jesus as a 
necessary evil. His most enthusiastic apostle, Paul, went 
still farther in the same direction, declaring it to be better 
not to marry than to marry : " It is good for a man not 
to touch a woman." If humanity were to follow this 
excellent counsel, it would soon be rid of ail earthly 
misery and suffering ; it would be killed off by such a 
" radical cure " within half a century. 

VI. As Christ never knew the love of woman, he had 
no personal acquaintance with that refining of man's true 
nature that comes only from the intimate life of man with 
woman. The intimate sexual union, on which the pre- 
servation of the human race depends, is just as important 


on that account as the spiritual penetration of the two 
sexes, or the mutual complement which they bring to each 
other in the practical wants of daily life as well as in the 
highest ideal functions of the soul. For man and woman 
are two different organisms, equal in worth, each having 
its characteristic virtues and defects. As civilisation ad- 
vanced, this ideal value of sexual love was more appre- 
ciated, and women held in higher honour, especially 
among the Teutonic races ; she is the inspiring source of 
the highest achievements of art and poetry. But Christ 
was as far from this view as nearly the whole of antiquity ; 
he shared the idea that prevailed everywhere in the East 
that woman is subordinate to man, and intercourse with 
her is "unclean." Long-suffering nature has taken a 
fearful revenge for this blunder; its sad consequences are 
written in letters of blood in the history of the papal 
Middle Ages. 

The marvellous hierarchy of the Roman Church, that 
never disdained any means of strengthening its spiritual 
despotism, found an exceptionally powerful instrument in 
the manipulation of this "unclean" idea, and in the 
promotion of the ascetic notion that abstinence from 
intercourse with women is a virtue in itself. In the first 
few centuries after Christ a number of priests voluntarily 
abstained from marriage, and the supposed value of celi- 
bacy soon rose to such a degree that it was obligator j r . 
In the Middle Ages the seduction of women of good 
repute and of their daughters by Catholic priests (the 
confessional was an active agency in the business) was a 
public scandal; many communities, in order to prevent 
guch things, pressed for a license of concubinage to be 
given to the clergy. And it was done in many, and some- 
times very romantic, ways. Thus, for instance, the canon 
law that the priest's cook should not be less than forty 
years old was very cleverly " explained " in the sense that 
the priest might have two cooks, one in the presbytery, 
another without; if one was twenty-four and the other 
eighteen, that made forty-two altogether two years 
above the prescribed age. At the Christian councils, at 
which heretics were burnt alive, the cardinals and bishops 


sat down with whole troops of prostitutes. The private 
and public debauchery of the Catholic clergy was so 
scandalous and dangerous to the commonwealth that there 
was a general rebellion against it before the time of 
Luther, and a loud demand for a " reformation of the 
Church in head and members." It is well known that 
these immoral relations still continue in Roman Catholic 
lands, although more in secret. Formerly, proposals were 
made from time to time for the definite abrogation of 
celibacy, as was done, for instance, in the chambers of 
Baden, Bavaria, Hesse, Saxony, and other lands ; but they 
have, unfortunately, hitherto proved unavailing. In the 
German Reichstag, in which the ultramontane Centre is 
now proposing the most ridiculous measures for tiie sup- 
pression of sexual immorality, there is now no party that 
will urge the abolition of celibacy in the interest of public 
morality. The so-called " Freethought " Party and the 
Utopian social democracy coquette with the favour of the 

The modern State that would lift not only the material, 
but the moral, life of its people to a higher level is en- 
titled, and indeed bound, to sweep away such unworthy 
and harmful conditions. The obligatory celibacy of the 
Catholic clergy is as pernicious and immoral as the practice 
of auricular confession or the sale of indulgences. All 
three have nothing whatever to do with primitive Chris- 
tianity. All three are directly opposed to true Christian 
morality. All three are disreputable inventions of the 
Papacy, designed for the sole purpose of strengthening 
its despotic rule over the credulous masses and making as 
much material profit as possible out of them. 

The Nemesis of history will sooner or later exact a 
terrible account of the Roman Papacy, and the millions 
who have been robbed of their happiness by this degene- 
rate religion will help to give it its death-blow in the 
coming twentieth century at least in every truly civilised 
state. It has been recently calculated that the number of 
men who lost their lives in the Papal persecutions of 
heretics, the Inquisition, the Christian religious wars, 
etc., is much more than 10,000,000. But what is this in 


comparison with the tenfold greater number of the unfor- 
tunate moral victims of the institutions and the priestly 
domination of the degenerate Christian Church with the 
unnumbered millions whose higher mental life was extin- 
guished, whose conscience was tortured, whose family life 
was destroyed, by the Church? We may with truth apply 
the words of Goethe, in his Bride of Corinth : 

Victims fall, nor lamba nor bulls, 
But human victims numberless. 

In the great cultur-kampf, which must go on as long 
as these sad conditions exist, the first aim must be the 
absolute separation of Church and State. There shall be 
a "free Church in a free State " that is, every Church 
shall be free in the practice of its special worship and 
ceremonies, and in the construction of its fantastic poetry 
and superstitious dogmas with the sole condition that 
they contain no danger to social order or morality. Then 
there will be equal rights for all. Free societies and 
monistic religious bodies shall be equally tolerated, and 
just as free in their movements as Liberal Protestant and 
orthodox ultramontane congregations. But for all these 
" faithful " of the most diverse sects religion will have to 
be a private concern. The State shall supervise them and 
prevent excesses ; but it must neither oppress nor support 
them. Above all, the ratepayers shall not be compelled 
to contribute to the support and spread of a "faith" 
which they honestly believe to be a harmful superstition. 
In the United States such a complete separation of Church 
and State has long been accomplished, greatly to the 
satisfaction of all parties. They have also the equally 
important separation of the Church from the school ; 
that is, undoubtedly, a powerful element in the great 
advance which science and culture have recently made in 

It goes without saying that this exclusion of the Church 
from the school only refers to its sectarian principles, the 
particular form of belief which each Church has evolved 
in the course of its life. This sectarian education is a 
purely private concern, and should be left to parents and 


tutors, or to such priests or teachers as may have the 
personal confidence of the parents. Instead of the re- 
jected sectarian instruction, two important branches of 
education will be introduced monistic or humanist ethics 
and comparative religion. During the last thirty yean an 
extensive literature has appeared dealing with the new 
system of ethics which has been raised on the basis of 
modern science especially evolutionary science. Com- 
parative religion will be a natural companion to the actual 
elementary instruction in '* Biblical history " and in the 
mythology of Greece and Rome. Both of these will 
remain in the curriculum. The reason for that is obvious 
enough ; the whole of our painting and sculpture, the chief 
branches of monistic aesthetics, are intimately blended 
with the Christian, Greek, and Roman mythologies. 
There will only be this important difference that the 
Christian myths and legends will not be taught as truths, 
but as poetic fancies, like the Greek and Roman myths ; 
the high value of the ethical and aesthetical material they 
contain will not be lessened, but increased, by this means. 
As regards the Bible, the " book of books " will only be 
given to the children in carefully-selected extracts (a sort 
of "school Bible"); in this way we shall avoid the be- 
smirching of the child's imagination with the unclean 
stories and passages which are so numerous in the Old 

Once the modern State has freed itself and its schools 
from the fetters of the Church, it will be able to devote 
more attention to the improvement of education. The 
incalculable value of a good system of education has forced 
itself more and more upon us as the many aspects of 
modern civilised life have been enlarged and enriched in 
the course of the century. But the development of 
educational methods has by no means kept pace with life 
in general. The necessity for a comprehensive reform of 
our school IB making itself felt more and more. On this 
question, too, a number of valuable works have appeared 
in the course of the last forty years. We shall restrict 
ourselves to making a few general observations which we 
think of special importance. 


1. In all education up to the present time man has 
played the chief part, and especially the grammatical 
study of his language; the study of nature was entirely 

2. In the school of the future nature will be the chief 
object of study ; a man shall learn a correct view of the 
world he lives in ; he will not be made to stand outside 
and opposed to nature, but be represented as its highest 
and noblest product. 

S. The study of the classical tongues (Latin and Greek), 
which has hitherto absorbed most of the pupil's time and 
energy, is indeed valuable ; but it will be much restricted, 
and confined to the mere elements (obligatory for Latin, 
optional for Greek). 

4. In consequence, modern languages must be all the 
more cultivated in all the higher schools (German, Eng- 
lish, and French to be obligatory, Italian optional). 

5. Historical instruction must pay more attention to the 
inner mental and spiritual life of a nation, and to the 
development of its civilisation, and less to its external 
history (the vicissitudes of dynasties, wars, and so forth). 

6. The elements of evolutionary science must be learned 
in conjunction with cosmology, geology must go with 
geography, and anthropology with biology. 

7. The first principles of biology must be familiar to 
every educated man ; the modern training in observation 
furnishes an attractive introduction to the biological 
sciences (anthropology, zoology, and botany). A start 
must be made with descriptive system (in conjunction 
with aetiology or bionomy) ; the elements of anatomy and 
physiology to be added later on. 

8. The first principles of physics and chemistry must 
also be taught, and their exact establishment with the aid 
of mathematics. 

9. Every pupil must be taught to draw well, and from 
nature ; and, wherever it is possible, the use of water- 
colours. The execution of drawings and of water-colour 
sketches from nature (of flowers, animals, landscapes, 
clouds, etc.) not only excites interest In nature and helps 
memory to enjoy objects, but it gives the pupil his first 


lesson in teeing correctly and understanding what he has 

10. Much more care and time must be devoted than has 
been done hitherto to corporal exercise, to gymnastics and 
swimming; but it is especially important to have walks 
in common every week, and journeys on foot during the 
holidays. The lesson in observation which pupils obtain 
in this way is invaluable. 

The chief aim of higher education up to the present 
time, in most countries, has been a preparation for the 
subsequent profession, and the acquisition of a certain 
amount of information and direction for civic duties. The 
school of the twentieth century will have for its main 
object the formation of independent thought, the clear 
understanding of the knowledge acquired, and an insight 
into the natural connection of phenomena. If the modern 
State gives every citizen a vote, it should also give him 
the means of developing his reason by a proper education, 
in order to make a rational use of his vote for the common 



A glance at the progress of the nineteenth century in solving cosmic 
problems. 1. Progress of astronomy and cosmology. Physical 
and chemical unity of the universe. Cosmic metamorphoses. 
Evolution of the planetary system. Analogy of the phylogenetio 
processes on the earth and on other planets. Organic inhabitants 
of other heavenly bodies. Periodic variation in the making of 
worlds. II. Progress of geology and palaeontology. Neptunism 
and Vulcan ism. Theory of continuity. Ill, Progress of physics 
and chemistry, IV. Progress of biology. Cellular theory and 
theory of descent V. Anthropology. Origin of man. General 

AT the close of our philosophic study of the riddles of 
the universe we turn with confidence to the answer to the 
momentous question, How nearly have we approached to 
a solution of them? What is the value of the immense 
progress which the nineteenth century has made in the 
knowledge of nature? And what prospect does it open 
out to us for the future, for the further development of 
our system in the twentieth century? Every unprejudiced 
thinker who impartially considers the solid progress of 
our empirical science, and the unity and clearness of our 
philosophic interpretaton of it, will share our view : the 
nineteenth century has made greater progress in know- 
lege of the world and in grasp of its nature than all its 
predecessors; it has solved many great problems that 
seemed insoluble a hundred years ago; it has opened out 
to us new provinces of learning, the very existence of 
which was unsuspected at the beginning of the century. 
Above all, it has put clearly before our eyes the lofty aim 
of monistic cosmology, and has pointed out the path 
which alone will lead us towards it the way of the exact 
empirical investigation of facts, and of the critical, genetic 


study of their causes. The great abstract law of me- 
chanical causality, of which our cosmological law the law 
of substance is but another and a concrete expression, 
now rules the entire universe, as it does the mind of man ; 
it is the steady, immovable pole-star, whose clear light 
falls on our path through the dark labyrinth of the count- 
less separate phenomena. To see the truth of this more 
clearly, let us cast a brief glance at the astonishing pro- 
gress which the chief branches of science have made in 
this remarkable period. 


The study of the heavens is the oldest, the study of 
man the youngest, of the sciences. With regard to him- 
self and the character of his being, man only obtained a 
clear knowledge in the second half of the present century ; 
with regard to the starry heavens, the motions of the 
planets, and so on, he had acquired astonishing informa- 
tion 4*500 years ago. The ancient Chinese, Hindoos, 
Egyptians, and Chaldseans in the distant East knew more 
of the science of the spheres than the majority of educated 
Christians did injthe West 4000 years after them. An 
eclipse of the sun was astronomically observed in China 
in the year 2697 B.C., and the plane of the ecliptic was 
determined by means of a gnome 1100 years B.C., while 
Christ himself had no knowledge whatever of astronomy 
indeed, he looked out upon heaven and earth, nature 
and man, from the very narrowest geocentric and anthro- 
pocentric point of view. The greatest advance of 
astronomy is generally, and rightly, said to be the found- 
ing of the heliocentric system of Copernicus, whose famous 
work, DC Revolutionibu* Orbium Ce/exttum, of itself 
caused a profound revolution in the minds of thoughtful 
men. In overthrowing the Ptolemaic system he destroyed 
the foundation of the Christian theory, which regarded 
the earth as the centre of the universe and man as the 
god-like ruler of the earth. It was natural, therefore, 
that the Christian clergy, with the Pope at its head, should 


enter upon a fierce struggle with the invaluable discovery 
of Copernicus. Yet it soon cleared a path for itself, when 
Kepler and Galileo grounded it on their true u mechanics 
of the heavens," and Newton gave it a solid foundation 
by his theory of gravitation (1686). 

A further great advance, comprehending the entire 
universe, was the application of the idea of evolution to 
astronomy. It was done by the youthful Kant in 1755 ; 
in his famous general natural history and theory of the 
heavens he undertook the discussion, not only of the 
"constitution," but also of the " mechanical origin" of 
the whole world-structure on Newtonian principles. The 
splendid Systeme du Monde of Laplace, who had inde- 
pendently come to the same conclusions as Kant on the 
world-problem, gave so firm a basis to this new Mtcanique 
Celeste in 1796 that it looked as if nothing entirely new 
of equal importance was left to be discovered in the nine- 
teenth century. Yet here again it had the honour of 
opening out entirely new paths and infinitely enlarging 
our outlook on the universe. The invention of photo- 
graphy and photometry, and especially of spectrum 
analysis (in 1860, by Bunsen and Kirchoff), introduced 
physics and chemistry into astronomy, and led to cosmo- 
logical conclusions of the utmost importance. It was now 
made perfectly clear that matter is the same throughout 
the universe, and that its physical and chemical properties 
In the most distant stars do not differ from those of the 
earth under our feet. 

The monistic conviction, which we thus arrived at, of 
the physical and chemical unity of the entire cosmos is 
certainly one of the most valuable general truths which 
we owe to astrophysics, the new branch of astronomy 
which is honourably associated with the name of Friedrich 
Zollner. Not less important is the clear knowledge we 
have obtained that the same laws of mechanical develop- 
ment which we have on the earth rule throughout the 
infinite universe. A vast, all-embracing metamorphosis 
goes on continuously in all parts of the universe, just as 
it is found in the geological history of the earth ; it can be 
traced in the evolution of its living inhabitants as surely 


as in the history of peoples or in the life of each human 
individual. In one part of space we perceive, with the 
aid of our best telescopes, vast nebulae of glowing, in- 
finitely attenuated gas; we see in them the embryos of 
heavenly bodies, billions of miles away, in the first stage 
of their development. In some of these "stellar 
embryos " the chemical elements do not seem to be 
differentiated yet, but still to be buried in the homo- 
geneous primitive matter (prothyl) at an enormous 
temperature (calculated to run into millions of degrees) ; 
it is possible that the original basic " substance " (vide 
p. 186) is not yet divided into ponderable and imponderable 
matter. In other parts of space we find stars that have 
cooled down into glowing fluid, and yet others that are 
cold and rigid ; we can tell their stage of evolution 
approximately by their colour. We find stars that are 
surrounded with rings and moons like Saturn ; and we 
recognise in the luminous ring of the nebula the embryo 
of a new moon, which has detached itself from the mother- 
planet, just as the planet was released from the sun. 

Many of the stars, the light of which has taken thou 
sands of years to reach us, are certainly suns like our own 
mother-sun, and are girt about with planets and moons, 
just as in our own solar system. We are justified in sup- 
posing that thousands of these planets are in a similar 
stage of development to that of our earth that is, they 
have arrived at a period when the temperature of the 
surface lies between the freezing and boiling point of 
water, and so permits the existence of water in its liquid 
condition. That makes it possible that carbon has entered 
into the same complex combinations on those planets as 
it has done on our earth, and that from its nitrogenous 
compounds protoplasm has been evolved that wonderful 
substance which alone, as far as our knowledge goes, is 
the possessor of organic life. The monera (for instance, 
chromacea and bacteria), which consist only of this primi- 
tive protoplasm, and which arise by spontaneous genera- 
tion from these inorganic nitrocarbonates, may thus have 
entered upon the same course of evolution on many other 
planets as on our own; first of all, living cells of the 


simplest character would be formed from their homo- 
geneous protoplasmic body by the separation of an inner 
nucleus from the outer cell-body (cytostoina). Further, 
the analogy that we find in the life of all cells whether 
plasmodomous plant-cells or plasmophagous animal cells 
justifies the inference that the further course of organic 
evolution on these other planets has been analogous to 
that of our own earth always, of course, given the same 
limits of temperature which permit water in a liquid form. 
In the glowing liquid bodies of the stars, where water can 
only exist in the form of steam, and on the cold extinct 
suns, where it can only be in the shape of ice, such 
organic life as we know is impossible. 

The similarity of phylogeny, or the analogy of organic 
evolution, which we may thus assume in many stars which 
are at the same stage of biogenetic development, naturally 
opens out a wide field of brilliant speculation to the con- 
structive imagination. A favourite subject for such 
speculation has long been the question whether there are 
men, or living beings like ourselves, perhaps much more 
highly developed, in other planets? Among the many 
works which have sought to answer the question, those 
of Cam] lie Flammarion, the Parisian astronomer, have 
recently been extremely popular ; they are equally distin- 
guished by exuberant imagination and b-illiant style, and 
by a deplorable lack of critical judgment and biological 
knowledge. We may condense in the following theses 
the present condition of our knowledge on the subject : 

I. It is very probable that a similar biogenetic process 
to that of our own earth is taking place on some of the 
other planets of our solar system (Mars and Venus), and 
on many planets of other golar systems; first simple 
rnonera are formed by spontaneous generation, and 
from these arise unicellular protista (first plasmodomous 
primitive plants, and then plasmophagous primitive 

II. It is very probable that from these unicellular pro- 
tists arise, in the further course of evolution, first social 
cell-communities (cosnobia), and subsequently tissue-form- 
Incr olants and animals (metaphyta and metazoa). 


III. It is also very probable that thallophyta (algae and 
fungi) were the first to appear in the plant-kingdom, then 
diaphyta (mosses and ferns), finally anthophyta (gymno- 
sperm and angiosperm flowering plants). 

IV. It is equally probable that the biogenetic process 
took a similar course in the animal kingdom that from 
the blastieads (catallacta) first gastrieads were formed, and 
from these lower animal forms (coelenteria) higher organ- 
isms (coelomaria) were afterwards evolved. 

V. On the other hand, it is very questionable whether 
the different stems of these higher animals (and those of 
the higher plants as well) run through the same course 
of development on other planets as on our earth. 

VI. In particular, it is wholly uncertain whether there 
are vertebrates on other planets, and whether, in the 
course of their phyletic development, taking millions of 
years, mammals are formed as on earth, reaching their 
highest point in the formation of man ; in such an event, 
millions of changes would have to be just the same in 
both cases. 

VII. It la much more probable, on the contrary, that 
other planets have produced other types of the higher 
plants and animals, which are unknown on our earth ; per- 
haps from some higher animal stem, which is superior 
to the vertebrat^in formation, higher beings have arisen 
who far transcend us earthly men in intelligence. 

VIII. The possibility of our ever entering into direct 
communication with such inhabitants of other planets 
seems to be excluded by the immense distance of our earth 
from the other heavenly bodies, and the absence of the 
requisite atmosphere in the intervening space, which 
contains only ether. 

But while many of the stars are probably in a similar 
stage of biogenetic development to that of our earth (for 
the last 100,000,000 years at least), others have advanced 
far beyond this stage, and, in their planetary old age, are 
hastening towards their end the same end that inevitably 
awaits our own globe. The radiation of heat into space 
gradually lowers the temperature until all the water in 
turned into ice; that is the end of all organic life. The 


substance of the rotating mass contracts more and more; 
the rapidity of its motion gradually falls off. The orbits 
of the planets and of their moons grow narrower. At 
length the moons fall upon the planets, and the planets 
are drawn into the sun that gave them birth. The colli- 
sion again produces an enormous quantity of heat. The 
pulverised mass of the colliding bodies is distributed 
freely through infinite space, and the eternal drama of 
sun-birth begins afresh. 

The sublime picture which modern astrophysics thus 
unveils before the mind's eye shows us an eternal birth 
and death of countless heaven'y bodies, a periodic change 
from one to the other of the different cosmogenetic con- 
ditions, which we observe side by side in the universe. 
While the embryo of a new world is being formed from 
a nebula in one corner of the vast stage of the universe, 
another has already condensed into a rotating sphere of 
liquid fire in some far distant spot; a third has already 
cast off rings at its equator, which round themselves into 
planets ; a fourth has become a vast sun whose planets 
have formed a secondary retinue of moons, and so on. 
And between them are floating about in space myriads of 
smaller bodies, meteorites, or shooting-stars, which cross 
and re-cross the paths of the planets, apparently like law- 
less vagabonds, and of which a great 'dumber fall on to 
the planets every day. Thus there is a continuous but 
slow change in the velocities and the orbits of the revolv- 
ing spheres. The frozen moons fall on to the planets, the 
planets on to their suns. Two distant suns, perhaps 
already stark and cold, rush together with inconceivable 
force and melt away into nebulous clouds. And such pro- 
digious heat is generated by the collision that the nebula 
is once more raised to incandescence, and the old drama 
begins again. Yet in this *' perpetual motion " the in- 
finite substance of the universe, the sum-total of its 
matter and energy, remains eternally unchanged, and we 
have an eternal repetition in infinite time of the periodic 
dance of the worlds, the metamorphosis of the cosmos 
that ever returns to its starting-point. Over all rules the 
law of substance. 



The earth and its origin were much later than the 
heavens in becoming the object of scientific investigation. 
The numerous ancient and modern cosmogonies do, in- 
deed, profess to give us as good an insight into the origin 
of the earth as into that of the heavens ; but the mytho- 
logical raiment, in winch all alike are clothed, betrays 
their origin in poetic fancy. Among the countless legends 
of creation which we find in the history of religions and 
of thought there is one that soon took precedence of all 
the rest the Mosaic story of creation as told in the first 
book of the Hexateuch. It did not exist in its present 
form until long after the death of Moses (probably not 
until 800 years afterwards) ; but its sources are much 
older, and are to be found for the most part in Assyrian, 
Babylonian, and Hindoo legends. This Hebrew legend 
of creation obtained its great influence through its adop- 
tion into the Christian faith and its consecration as the 
"Word of God." Greek philosophers had already, five 
hundred years before Christ, explained the natural origin 
of the earth in the same way as that of other cosmic 
bodies. Xenophlfhes of Colophon had even recognised 
the true character of the fossils which were afterwards 
to prove of such moment ; the great painter Leonardo da 
Vinci, of the fifteenth century, also explained the fossils 
as the petrified remains of animals which had lived in 
earlier periods of the earth's history. But the authority 
of the Bible, especially the myth of the deluge, prevented 
any further progress in this direction, and ensured the 
triumph of the Mosaic legend until about the middle of 
the last century. It survives even at the present day 
among orthodox theologians. However, in the second 
half of the eighteenth century scientific inquiry into the 
structure of the crust of the earth set to work independ- 
ently of the Mosaic story, and it soon led to certain 
conclusions as to the origin of the earth. The founder 
of geology, Werner of Freiberg, thought that all the rocks 
were formed in water, while Voigt and Hutton (1788) 


rightly contended that only the stratified, fossil-bearing 
rocks had had an aquatic origin, and that the Vulcanic 
or Plutonic mountain ranges had been formed by the 
cooling down of molten matter. 

The heated conflict of these " Neptunian " and " Plu- 
tonic " schools was still going on during the first three 
decades of the present century ; it was only settled when 
Karl Hoff (1822) established the principle of "actuaiism," 
and Sir Charles Lyell applied it with signal success to 
the entire natural evolution of the earth. The Principle* 
of Geology of Lyell (1830) secured the full recognition of 
the supremely important theory of continuity in the 
formation of the earth's crust, as opposed to the cata- 
strophic theory of Cuvier. 1 Palaeontology, which had 
been founded by Cuvier's work on fossil bones (1812), 
was of the greatest service to geology ; by the middle of 
the present century it had advanced so far that the chief 
periods in the history of the earth and its inhabitants 
could be established. The comparatively thin crust of the 
earth was now recognised with certainty to be the hard 
surface formed by the cooling of an incandescent fluid 
planet, which still continues its slow, unbroken course of 
refrigeration and condensation. The crumpling of the 
stiffened crust, " the reaction of the molten fiery contents 
on the cool surface," and especially the 'unceasing geolo- 
gical action of water, are the natural causes which are 
daily at work in the secular formation of the crust of the 
earth and its mountains. 

To the brilliant progress of modern geology we owe 
three extremely important results of general import. In 
the first place, it has excluded from the story of the earth 
all question of miracle, all question of supernatural 
agencies, in the building of the mountains and the shaping 
of the continents. In the second place, our idea of the 
length of the vast period of time which has been absorbed 
in their formation has been considerably enlarged. We 
now know that the huge mountains of the paiaeosoic, 
mesoKoic, and cenozoic formations have taken not thou- 

1 Of. Th* Natural ffiitory of Crtation, chaps, iii., ri., xv., and xvi 


sands, but millions of years in their growth. In the third 
place, we now know that all the countless fossils that are 
found in those formations are not "sports of nature," as 
was believed 150 years ago, but the petrified remains of 
organisms that lived in earlier periods of the earth's 
history, and arose by gradual transformation from a long 
series of ancestors. 


The many important discoveries which these funda- 
mental sciences have made during the nineteenth century 
are so well known, and their practical application in every 
branch of modern life is so obvious, that we need not 
discuss them in detail here. In particular, the application 
of steam and electricity has given to our nineteenth 
century its characteristic " machinist-stamp. " But the 
colossal progress of inorganic and organic chemistry is not 
less important. All branches of modern civilisation 
medicine and technology, industry and agriculture, mining 
and forestry, land and water transport have been so 
much improved in the course of the century, especially 
in the second half, that our ancestors of the eighteenth 
century would find themselves in a new world, could they 
return. But moffe valuable and important still is the great 
theoretical expansion of our knowledge of nature, which 
we owe to the establishment of the law of substance. 
Once Lavoisier (1789) had established the law of the per- 
sistence of matter, and Dal ton (1808) had founded his 
new atomic theory with its assistance, a way was open to 
modern chemistry along which it has advanced with a 
rapidity and success beyond all anticipation. The same 
must be said of physics in respect of the law of the con- 
servation of energy. Its discovery by Robert Mayer 
(1842) and Hermann Helmholtz (1847) inaugurated for 
this science also a new epoch of the most fruitful develop- 
ment; for it put physics in a position to grasp the uni- 
versal unity of the forces of nature and the eternal play 
of natural processes, in which one force may be converted 
into another at any moment. 



The great discoveries which astronomy and geology 
have made during the nineteenth century, and which are 
of extreme importance to our whole system, are, neverthe- 
less, far surpassd by those of biology. Indeed, we may 
say that the greater part of the many branches which 
this comprehensive science of organic life has recently 
produced have seen the light in the course of the present 
century. As we saw in the first section, during the 
century all branches of anatomy and physiology, botany 
and zoology, ontogeny and phylogeny, have been so mar- 
vellously enriched by countless discoveries that the present 
condition of biological science is immeasuraby superior to 
its condition a hundred years ago. That applies first of 
all quantitatively to the colossal growth of our positive 
information in all those provinces and their several parts. 
But it applies with even greater force qualitatively to the 
deepening of our comprehension of biological phenomena, 
and our knowledge of their efficient causes. In this 
Charles Darwin (1859) takes the palm of victory; by his 
theory of selection he has solved the M <Treat problem of 
" organic creation," of the natural origin of the countless 
forms of life by gradual transformation. It is true that 
Lamarck had recognised fifty years earlier that the mode 
of this transformation lay in the reciprocal action of 
heredity and adaptation. However, Lamarck was ham- 
pered by his ignorance of the principle of selection, and 
on that deeper insight into the true nature of organisation 
which was only rendered possible after the founding of 
the theory of evolution and the cellular theory. When 
we collated the results of these and other disciplines, and 
found the key to their harmonious interpretations in the 
ancestral development of living beings, we succeeded in 
establishing the monistic biology, the principles of which 
I have endeavoured to lay down securely in my General 



In a certain sense, the true science of man, rational 
anthropology, takes precedence of every other science. 
The saying of the ancient sage, "Man, know thyself," 
and that other famous maxim, "Man is the measure of 
all things," have been accepted and applied from all 
time. And yet this science taking it in its widest sense 
has languished longer than all other sciences in the 
fetters of tradition and superstition. We saw in the first 
section how slowly and how late the science of the human 
organism was developed. One of its chief branches 
embryology was not firmly established until 1828 (by 
Baer), and another, of equal importance the cellular 
theory until 1838 (by Schwann). It was even later still 
when the answer was given to the " question of all ques- 
tions,'* the great riddle of the origin of man. Although 
Lamarck had pointed out the only path to a correct solu- 
tion of it in 1809, and had affirmed the descent of man 
from the ape, it fell to Darwin to establish the affirmation 
securely fifty years afterwards, and to Huxley to collect 
the most important proofs of it in 1863, in his Man'* 
Place in Nature. I have myself made the first attempt in 
my Anthropogeny (1874) to present in their historical 
connection the entire series of ancestors through which our 
race has been slowly evolved from the animal kingdom 
in the course of many millions of years. 


The number of world -riddles has been continually 
diminishing in the course of the nineteenth century 
through the aforesaid progress of a true knowledge of 
nature. Only one comprehensive riddle of the universe 
now remains the problem of substance. What is the 
real character of this mighty world-wonder that the 
realistic scientist calls Nature or the Universe, the idealist 


philosopher calls Substance or the Cosmos, the pious 
believer calls Creator or God? Can we affirm to-day that 
the marvellous progress of modern cosmology has solved 
this "problem of substance," or at least that it has 
brought us nearer to the solution? 

The answer to this final question naturally varies con- 
siderably according to the standpoint of the philosophic 
inquirer and his empirical acquaintance with the real 
world. We grant at once that the innermost character 
of nature is just as little understood by us as it was by 
Anax inlander and Empedocles 2400 years ago, by Spinoza 
and Newton 200 years ago, and by Kant and Goethe 100 
years ago. We must even grant that this essence of sub- 
stance becomes more mysterious and enigmatic the deeper 
we penetrate into the knowledge of its attributes, matter 
and energy, and the more thoroughly we study its count- 
less phenomenal forms and their evolution. We do not 
know the " thing in itself " that lies behind these know- 
able phenomena. But why trouble about this enigmatic 
** thing in itself " when we have no means of investigating 
it, when we do not even clearly know whether it exists 
or not? Let us, then, leave the fruitless brooding over 
this ideal phantom to the "pure metaphysician," and let 
us instead, as "real physicists," rejoice in the immense 
progress which has been actually made* "by our monistic 
philosophy of nature. 

Towering above all the achievements and discoveries 
of the century we have the great, comprehensive " law of 
substance," the fundamental law of the constancy of 
matter and force. The fact that substance is everywhere 
subject to eternal movement and transformation gives it 
the character also of the universal law of evolution. As 
this supreme law has been firmly established, and all 
others are subordinate to it, we arrive at a conviction of 
the universal unity of nature and the eternal validity of 
ita laws. From the gloomy problem of substance we have 
evolved the clear law of substance. The monism of the 
cosmos which we establish thereon proclaims the absolute 
dominion of " the great eternal iron laws " throughout 
the universe. It thus shatters, at the same time, the 


three central dogmas of the dualistic philosophy the 
personality of God, the immortality of the soul, and the 
freedom of the will. 

Many of us certainly view with sharp regret, or even 
with a profound sorrow, the death of the gods that were 
so much to our parents and ancestors. We must console 
ourselves in the words of the poet : 

The times are changed, old systems fall, 
And new life o'er their ruins dawns. 

The older view of idealistic dualism is breaking up with 
all its mystic and anthropistic dogmas; but upon the vast 
field of ruins rises, majestic and brilliant, the new sun of 
our realistic monism, which reveals to us the wonderful 
temple of nature in all its beauty. In the sincere cult of 
"the true, the good, and the beautiful," which is the 
heart of our new monistic religion, we find ample com- 
pensation for the anthropistic ideals of "God, freedom, 
and immortality " which we have lost. 

Throughout this discussion of the riddles of the universe 
I have clearly defined my consistent monistic position 
and its opposition to the still prevalent dualistic theory. 
In this I am supported by the agreement of nearly all 
modern scientists who have the courage to accept a 
rounded philosopTTtcal system. I must not, however, take 
leave of my readers without pointing out in a conciliatory 
way that this strenuous opposition may be toned down 
to a certain degree on clear and logical reflection may, 
indeed, even be converted into a friendly harmony. In 
a thoroughly logical mind, applying the highest prin- 
ciples with equal force in the entire field of the cosmos 
in both organic and inorganic nature the antithetical 
positions of theism and pantheism, vitalism and mechanism, 
approach until they touch each other. Unfortunately, 
consecutive thought is a rare phenomenon in nature. The 
great majority of philosophers are content to grasp with 
the right hand the pure knowledge that is built on experi- 
ence, but they will not part with the mystic faith based 
on revelation, to which they cling with the left. The best 
type of this contradictory dualism is the conflict of pure 


and practical reason in the critical philosophy of the most 
famous of modern thinkers, Immanuel Kant. 

On the other hand, the number is always small of the 
thinkers who will boldly reject dualism and embrace pure 
monism. That is equally true of consistent idealists and 
theists, and of logical realists and pantheists. However, 
the reconciliation of these apparent antitheses, and, conse- 
quently, the advance towards the solution of the funda- 
mental riddle of the universe, is brought nearer to us every 
year in the ever-increasing growth of our knowledge of 
nature. We may, therefore, express a hope that the 
twentieth century will complete the task of resolving the 
antitheses, and, by the construction of a system of pure 
monism, spread far and wide the long-desired unity of 
world-conception. Germany's greatest thinker and poet, 
whose 150th anniversary will soon be upon us Wolfgang 
Goethe gave this " philosophy of unity " a perfect poetic 
expression, at the very beginning of the century, In his 
immortal poems, Foust, Promef/ietu, and God and the 

By eternal laws 
Of iron ruled, 
Must all fulfil 
The cycle of 
Their destiny, f " 


ABIOGBNBSI3, 210, 300 

Abortive organs, 216 
Accidents, 177 
Acrania, 136 
Actio in distant, 111 
Actualism, 203 
^sthesis, 184 
Affinity, 183 
Altruism, 285 
Amphibia, 136 
Amphimixis, 115 
Amphitheism, 228 
Ananke, 222 
Anatomy, 18, etc. 

Comparative, 20 

Anaximander, 236, 310 
Anthropism, 9 
Anthropistic illusion, 10 

world-theory, 14 

Anthropocentric d<^na, 9 
Anthropogeny, 68 
Anthropolatno dogma, 10 
Anthropomorpha, 29 
Anthropomorphic dogma, 10 
Apes, 29, 138 

Anthropoid, 29, 30 

Archseus, 35 
Archigony, 210 
Aristotle, 19, 219 
Association, Centres of, 149 

of ideas, 99 

of presentations, 98 

Astronomy, Progress of, 299 
Astrophysics, 300 
Atavism, 116 
Athanatism, 154 
Athanatistic illusions, 169 
Atheism, 238 
Atheistic science, 211 

Atom, The, 183 
Atomism, 182 

Atomistic consciousness, 146 
Attributes of ether, 184 

of substance, 177 

Augustine of Hippo, 106 
Auricular confession, 261, 293 
Autogony, 210 

BAIB (Carl Ernst), 46, 263 
Bastian (Adolf), 85 
Beginning of the world, 196, 204 
Bible, The, 231, 295 
Biogenesis, 210 
Biogenetic law, 66, 116 
Bismarck, 272 
Blastoderm, 123, 127 
Blastosphere, 127 
Blastula, 127 
Bruno (Giordano), 259 
Biichner (Ludwig), 76 
Buddhism, 266 

CALVIN, 106 
Canonical gospels, 255 
Carbon as creator, 210 

theory, 210 

Catarrhinee, 28 
Catastrophic theory, 60 
Categorical imperative, 285 
Causes, Efficient, 211 

Final, 211 

Celibacy, 291 
CelMove, 112 

community, soul of the, 


soul, 123 

state, 128 

Cellular pathology, 40 



Cellular physiology, 39 

psychology, 123, 145 

theory, 21 

Cenogenesis, 66 

of the psyche, 116 

Crance, 223 

Chemicotropism, 52, 112 
Chordula, 52 
Chorion, 55 
Christ, Father of, 267 
Christian art, 277 

contempt of the body, 289 

animals, 290 

civilisation, 291 

the family, 291 

nature, 290 

self, 288 

woman, 291 

ethics, 288 

Christianity, 283 
Church and school, 294 

and State, 294 

Cnidaria, 132 
Conception, 49 

Concubinage of the clergy, 292 
Confession of faith, 248 
Consciousness, 139 

Animal, 143 

Atomistic, 146 

Biological, 144 

---- Cellular, 63, 145 

Development of, 151 

Dualistic, 147 

Human, 140 

Monistic, 148 

Neurological, 142 

Ontogeny of, 151 

Pathology of, 150 

Physiological, 147 

Transcendental, 147 

Constancy of energy, 173, 189 

matter, 173 

Constantine the Great, 258 
Constellations of substance, 179 
Conventional lies, 264 
Copernicus, 19, 262, 299, 300 
Cosmic immortality, 156 
Cosmogonies, 192 
Coimofogioal creationism, 191 

Cosmological dualism, 209 

law, 173 

perspective, 12 

Cosmos, The, 188 
Creation, 59, 65, 191 

Cosmological, 193 

Dualistic, 194 

lleptameral, 194 

Individual, 195 

Myths of, 193 

Periodic, 194 

Trialistic, 194 

Cultur-kampf, 272 
Cuvier, 60 
Cyclostomata, 136 
Cytology, 22 
Cytopsyche, 123 
Cytula, 51 

DABWIN (Charles), 63, etc. 
Decidua, 55 
Deduction, 13 
Demonism, 226 
Descartes, 78, 290 
Descent of the ape, 69 

of man, 71 

Theory of, 61 

Design, 216 

in nature, 213 

in orgftpisms, 216 

in selection, 215 

Destruction of heavenly bodies. 


Determinists, 106 
Diaphragm, 25 
Division of labour in matter. 


Draper, 253, 271 
Dualism, 16 

Du Boia Reymond, 12, 147, 193 
Du Prel (Carl), 250 
Duty, Feeling of, 285 
Dynamodes, 177 
Dysteleology, 216 


Ectoderm, 131 

Sense- cellf in the, 240 

Egoism, 285 



Elements, Chemical, 182 

System of the, 182 

Embryo, Human, 53 
Embryology, 43 
Embryonic psychogeny, 118 

sleep, 119 

Empedocles, 18, 184 
Encyclica (of Pius IX.), 264 
End of the world, 202 
Energy, Kinetic, 189 

Principle of, 189 

Potential, 190 

Specific, 241 

Entelecheia, 219 

Endoderm, 131 

Entropy of the universe, 202 

Epigenesis, 45, 110 

Ergonomy of matter, 188 

Eternity of the world, 198 

Ether, 184 

Etheric souls, 163 

Ethics, Fundamental law of, 

Evolution, Theory of, 43, 196 

Chief element in, 218 

Experience, 13 
Extra-mundane God, 235 

FAITH, Confession of, 248 

of our fatheri^g48 

Family, The, and Christianity, 


Fate, 219 
Fechner, 79 
Fecundation, 49 
Fetichism, 226 
Feuerbach (Ludwig), 242 
Flechsig, 149 
Foetal membranes, 54 
Folk-psychology, 84 
Forces, Conversion of, 189 
Frederick the Great, 158, 258 

GALEN, 19, 34 
Gaseous souls, 163 

vertebrate, 235 

Gastrsea, 131 

Theory of the, 49 

Gastraeads, 130 

Gastrula, 49 

Gegenbaur, 21, 24 

Generation, Theory of, 45, 46 

Genus, 59 

Geology, Periods of, 221 

Progress of, 305 

Germinal disc, 45 
Gills, 53 
God, 225 

the Father, 227 

the Son, 227, 267 

Goethe, 17, etc. 
Goethe's monism, 270 
Golden Ilule, The, 286 
Gospels, 255 

Gravitation, Theory of, 177 
Gut-layer, 131 

Harvey, 34 
Helrnholtz (Hermann), 175, 

188, 263 

Heredity, Psychic, 113 
Hertz (Heinrich), 185 
Hippocrates, 19 
Histology, 19 
Histopsyche, 128 
Hoff (Carl), 204 
Holbach (Paul), 158 
Holy Ghost, 227, 266 
Humboldt (Alexander), 280 
Hydra, 132 
Hylozoism, 236 
Hypothesis, 244 

latromechanicists, 37 
Ideal of beauty, 276 

of truth, 274 

of virtue, 275 

Ignorabimus, 147 
Immaculate conception, 266 
Immaterial substance, 181 
Immortality of animals, 164 

of the human soul, 154 

Personal, 157 

of unicellular organisms, 

Imperfection of nature, 216 



Imponderable matter, 184 
Impregnation, 49 
Inueterminists, 106 
Induction, 13 
Indulgences, 293 
Infallibility of the Pope, 265 
Instinct, 84, 100 
Intellect, 102 
Intramundane God, 236 
Introspective psychology, 77 
Islam, 233 

JANSSEN (Johannes), 258 
Jehovah, 231 
Journeys on foot, 297 

KANT, 211, 284, etc. 
Kant's metamorphosis, 75 
Kinetic energy, 189, 190 

theory of substance, 177 

Kolliker, 17, 21, 39 

LAMARCK, 63, etc. 
Lamettrie, 158 
Landscape-painting, 280 
Language, 102 

Study of, 296 

Last judgment, 171 

Lavoisier, 174, 263 

Leydie, 22 

Life, Definition of, 32 

Limits of our knowledge, 149, 

Love, 291 

of animals, 289 

of neighbour, 286 

of self, 288 

Lucretius Cams, 237 
Lunarism, 230 
Luther, 261 
Lyell, 63, 204 

MADONNA, Cult of the, 232, 


Malphigi, 44 
Mammals, 25, etc. 
Mammary glands, 25 
Man, ancestors of, 67 
Marsupials, 26, 68 

Mass, 181 

Materialism, 181 

Mayer (Robert), 175, 263, 307 

Mechanical causality, 299 

explanation, 212 

theory of heat, 202 

Mechanicism, 212 
Mediterranean religions, The, 

Memory, Cellular, 97 

Conscious, 99 

Histionic, 98 

Unconscious, 98 

Mephistppheles, 228 
Metabolism, 190 
Metamorphoses of the cosmos, 


of philosophers, 76 

Metaphyta, 128 
Metasitism, 125 
Metazoa, 49, 128 
Middle Ages, 257, 292 
Mixotheism, 234 
Mohammedanism, 233 
Mohr (Friedrich), 175 
Monera, 211 
Monism, 16, and passim 

of energy, 208 

of the cosmos, 209 

of Spr^za, 270 

Monistic anthropogeny, 207 

art, 278 

biogeny, 205 

cosmology, 300 

churches, 281 

ethics, 283 

geogeny, 203 

Monotheism, 229 
Monotrema, 24 
Moon-worship, 230 
Moral order of the universe, 


Morula, 126 
Mosaism, 231 
Miiller (Johannes), 21, 37, 214, 

Mythology of the soul, 110 




Navel-cord, 56 
Neo-Kantians, 284 
Neovitalism, 216 
Neptunian geology, 306 
Neuromuscular cells, 93 
Neuroplasm, 74, 89 
Neuropsyche, 132 
Nomocracy, 7 

ONTOGENETIC psychology, 85 
Ontological creationism, 193 

methods, 204 

Orbits of the heavenly bodies, 

Origin of movement, 12, 197 

of feeling, 6, 12, 197 

Ovary, 49 


of the psyche, 117 

Pandera (the father of Christ), 


Pantheism, 236 
Papacy, 257 
Papal ethics, 292 
Papiomorpha, 30 
Paul, 256, 291 

Epistles of, 275 

Paulinism, 256 
Pedicle of the allXois, 56 
Perpetual motion, 201 
Persistence of force, 174, 189 

of matter, 173 

Phroneta, 240 
Phylogeny, 58, 66 

Systematic, 66 

of the apes, 42 

Physiology, o2 
Phytopsyche, 128 
Pithecanthropus, 71 
Pithecoid theory, 67 
Pithecometra-thesis, 56, 69 
Placenta. 26, 55 
Placentals, 26, 70 
Plasmodoma, 125 
Plasmogony, 211 
Plasmophaga, 125 
Plato, 81, 162 
Plato's theory of ideas, 210 

Platodaria, 130 
Platodes, 131 
Platyrrhinue, 28 
Pneuma zoticon, 33 
Polytheism, 226 
Ponderable matter, 182 
Preformation theory, 44 
Primaria, 27 
Primates, 27, 70 
Primitive Christianity, 254 

gut, 50, 131 

Prodynarnis, 178 
Progaster, 131 
Proplacentals, 70 
Prosimise, 28 
Prostoma, 131 
Prothyl, 183 
Protoplasm, 73 
Protozoa, 49 
Pro vertebra, 135 
Pseudo-Christianity, 262 
Psychade-theory, 145 
Psyche, 72 
Psychogeny, 110 

Phyletic, 121 

Post-embryonic, 120 

Psychology, 72, segq. 

Ontogenetic, 85 

Phylo^enetic, 85 

Psychomonism, 185 
Psychophysics, 79 
Psycho-plasm, 74, 89 
Pupa, Sleep of the, 119 
Pyknosis, 178 

Pyknotic theory of substance, 

REASON, 14, 100 
Reflex action, 91 

arches, 93 

Reformation, The, 261 
Religion a private concern, 

Remak, 47 

Revelation, 251 

Reversion, 116 

Romance of the Virgin Mary, 

Romanes, 86 


Rudimentary organs, 216 

SAINTS, 232 

Scale of emotion, 103 

of memory, 97 

of movement, 90 

of presentation, 95 

of reason, 99 

of reflex action, 91 

of will, 104 

Scatnlation theory, 45 

Schleiden, 21, 39 

School, Reform of the, 295 

and Church, 294 

and State, 295 

Schwann, 21, 39 
Selachii, 136 
Selection, Theory of, 65 
Self-consciousness, 140 
Sense-knowledge, 242 

organs, 239 

Senses, Philosophy of the, 242 
Sentiment, 14, 269 
Siebold, 22 
Simi, 28 
Social duties, 285 

instincts, 285 

Solarism, 229 
Solar systems, 196, 299 
Sources of knowledge, 239 
Soul, 72, teqq. 

Apparatus of the, 133 

Blending of the, 115 

Creation of the, 111 

Division of the, 111 

Etheric, 163 

Gaseous, 163 

Histionic, 128 

History of the, 137 

Hydra, 132 

Liquid, 164 

Life of the, 72 

Mammal, 137 

Nerve, 132 

Origin of the, 110 

Personal, 132 

of the plant, 128 

Solid, 163 

Substance of the, 162 

Soul, Transmigration of the, 

Space and time, 198 

Infinity of, 198 

Reality of, 198 

Species, 59 

Spectrum analysis, 197 
Spermarium, 51 
Spermatozoa, 51 
Spinal cord, 135 
Spinoza, 17 ; 176, 237 
Spirit-rapping, 249 

world, 181 

Spiritism, 249 
Spiritualism. 17 
Sponge, Soul of the, 131 
Stem-cell, 51, 112, 124 
Stimulated movement, 91, 94 
Stimuli, Conduction of, 129 
Strauss (David), 111, 253, 256 
Struggle for life, 221 
Substance, 176 

Law of, 173, etc. 

Structure of, 186 

Superstition, 247 
Suss (Eduard), 204 
Syllabus, 264 

Teleological explanation, 209 
Teleology, Zil 
Tetrapoda, 25 
Thanatism, 155 

primary, 157 

secondary, 157 

Theism, 226 

Theocracy, 7 

Theory, 245 

Thought, Organs of, 102, 149, 

Time and space, 198 

Reality of, 198 

Tissue, Theory of, 21 

forming animals, 128 

forming plants, 128 

Transformism, 62 
Trimurti, 227 

Trinity, Dogma of the, 227 
Monistic, 274 

INDEX 319 

Triplotheisin,22I Vibration, Theory of, 17? 

Tropesis,184 Virchow, 21, 41 

Tropismata, 104 Virchow's metamorphosis, 76 

Tunicata, 135 Vital Force, 35, 214 

Turbellaria, 131 Vitalism, 35, 214 

Vivisection, 33 

ULTRAMONTANISM, 254 Vogt (Carl), 76 

Understanding, 100 Vogt (J,C,), 178 
Unity of Natural Forces, 189 

of Substance, 176 _ WATER-COLOUR Drawing, 296 

Pnireriw Ptffttuum M\k Weismann, 156 

201 Will, Liberty of the, 105 

Utenu,26 Scale of the, 104 

Wolff (C, F.), 45 

VATICANISM, 257 Woman and Christianity, 291 

Vertebrates, 22, mm World-conscionsness, 140 

Ve rworn (Mai), M, 95 riddles, Number of, 12 

Venliu, 19 Wundt (Wilhelm), 82, 140 


Abiogen'esis : the spontaneous generation of life, 

Acra nia : animals without skulls. 

Acrogan'glion : a rudimentary vertical brain. 

Ac'tualism : the system of development by actually existing agencies. 

jEtiol'ogy : the science of causes. 

Amce'boid : after the manner of the amoeba, a microscopic organism. 

Araphig'ony : the coalescence of cells and their properties. 

Ananlce : fate, necessity. 

An'thropism : a system of thought which makes man the measure of 

all things. 

Anthropocen'tric : making man the centre of the universe. 
Anthropo'^eny : the science of the origin of man. 
An'thropoid: man-like. 

Anthroporatric : " man-worshipping," exaggerating man's importance. 
Anthropol'ogy : the science (or sciences) of man. 
Anthropomorphism : the tendency to conceive God in human form. 
Archig'onous : born by spontaneous generation. 
Archig'ony : spontaneous generation, "primitive birth." 
At'avism : reversion in heredity to earlier tyj>es. 
Autog'ony : spontaneous generation, "self-birth," 

Bio'geny : the science of the origin of life, 
Biogenet'ic : belof!^!hg to biogeny. 
Bion'omy : the science of the laws of life. 

Bion'tic : relating to the development of the individual. 
Bi'oplasm : protoplasm as the material of organisms. 
Blasta'ades : certain primitive multicellular organisms. 
Blast'odenn : the cellular covering of the early embrvo. 
Blast 'omere : the stems into which the stem -cell divides. 
Blast'osphere or Blast'ula : the interior of the early embryo, 

Oataplast'ic : deformed. 

Cenobit'io : living in communities. 

Oeno'bium : a colony or community of cells. 

Oenogen'esifl : " new-birth," the embryonic development of the indi- 


Cenogenet'ic : pertaining to cenogenesis. 
Ohemicotro'pism : see " erotic chemicotropism." 
Chor'dula : the stage of development at which the spinal column 


Chorion : a portion of the womb to which the embryo attache*. 
Ooelous : clothing the visceral cavity. 



Oor'tex : the uppermost or grey layer in the brain. 

Gosmog'ony : tne science of the formation of the world. 

Oranio ta : animals with skulls. 

Cultur'-kampf ' : the struggle with the Church of Rome in Germany in 

the 'seventies. 
Cy'tula : the stem-cell, or embryonic cell. 

Determinism : the system which rejects the liberty of the will. 
Du'alism : the system which admits two ultimate realities. 
Dysteleol'ogy : the science of those features of organisms which ex- 
clude the idea of a plan. The opposite of teleology. 

Ec'toderm : the outer envelope or skin. 

Entelechei'a : the purposive principle in the organism according to 

En'tropy : the using up (or " involution") of cosmic energy by con- 
version into heat. 

Epigen'esis : the internal development of organs in the fostus. 

Epithelium : the internal skin or lining of organisms. 

Ergon 'omy : sphere of work. 

Erot'ic chemicotro'pism : the physical property by which the ovum 
and spermatozoon seek to coalesce. 

Ganglion 'ic : of the ganglia, or knots of centres of the nerve-system. 

Gastrse'a: a primitive extinct organism from which all the higher 
animals are descended. 

Gast'rula: the form which the embryo takes immediately after im- 

Oastnila'tion : the process of the formation of the gastrula. 

Gcmnia'tion : birth by budding from the parent-form. 

Genet 'ic : pertaining to development or birth. p?> 

Geocen'trie theory : the system which takes the earth to be the 
centre of the universe. 

Geo'geny : the science of the formation of the earth. 

Germ-plasm : the protoplasmic matter of the embryonic germ. 

Histion'ic : pertaining to the tissues (hista). 
Histol'ogy : microscopic anatomy, or the anatomy of the tissues. 
Hoinorogy : likeness or parallel in organisms of different species. 
Hylozo'ism : the theory which regards the world as an organism, or 
all matter as animated. 

latrochem'icists : biologists who reduced all vital processes to chemical 

latromechan'icists : biologists who reduced all vital processes to 

physical or mechanical action. 
Indeter'mimsm : the theory of the freedom of the will. 

Karyokine'sis : a stage in the development of the nucleus of the celL 

Kor'mal : communal or cenobitic. 

Kinet'io energy : energy at work, or in "motion " (kinesis). 


Law of Substance : the law that matter and force are constant or 
unchanging in their quantity. 

Metab'olism : the circulation of matter in the living organism, 

Metamor'phism : the evolution of species or transforinism. 

Metamor'phosis : change or transformation, 

Metaph'vta : multicellular, tissue- forming plants. 

Metas'itism : the circulation of nutritive matter in the organism. 

Metazo'a : multicellular, tissue-forming animals without nerves. 

Metempsycho'sis : the transmigration of souls. 

Mito'sis : the splitting of the cell -nucleus. 

Mo'nism : the system which holds that the ultimate reality is one 


Mon'otremes : the lowest order of mammals. 

Morphology : comparative anatomy, or the science of organic forms. 
Mo'rula : a stage of embryonic development when a mulberry -like 

(morula) appearance is presented. 
Multicell'ular : organisms which consist of many cells. 

Nee-vitalism : a revived and modified belief in a specific vital principle 

in organisms. 

Neurology : the science of nerve. 
Neu'roplasm : the material of nerve-tissue. 

Ontogen'esis : the development of the individual organism, and its 


Ontogenet'ic : pertaining to ontogenesis. 
Onto geny : ontogenesis. 
Os'mosis : the interchange of fluids through a porous medium. 

Palaontol'ogy : the science of fossilised organisms. 

Palingen'esis : "older birth," the development of the species in past 


Paiingenet'ic : pertaining to palingenesis. 
Parallelis'tic psychology : the theory which regards mental and 

cerebral changes as parallel but distinct series. 
PcrjDet'uum mo' bile : a thing endowed with perpetual motion. 
Photo 'metry : the measurement of light. 
Phylet'ic : pertaining to the history or development of the speciei 


Phylogenet'ic : pertaining to phylogeny. 
Phylo^eny : the development of the species, and its science. 
Pithecan thro 'pus : " ape-man," the specie* intermediate between man 

and his ape-like ancestors. 
Pith'ecoid : ape-like. 
Pitheco'metra-thesis : the thesis which expresses the relation (mttrons* 

measure) of the ape to man. 
Plank 'ton : organisms floating in water. 
Plasma : pro'toplasm. 


Plasmat'io : of protoplasm. 

Plasmo'domous : organisms that build up protoplasm from inorganic 

Plasmog'ony : the formation of protoplasm. 

Plasmo phagous : organisms that lire on the plasma-forming plants. 

Plas'tidules : the smallest elements or molecules of protoplasm. 

Polyphylet'io : having more than one source of origin. 

Prochoria'ta : mammals with a rudimentary chorion. 

Prody'namis : the fundamental force or energy (dynamis) of which all 
specific forces are several aspects. 

Progast'er : a primitive gut (gaster). 

Pro stoma : a primitive mouth (stoma). 

Pro'thyl : the fundamental matter (hyle) of which our chemical ele- 
ments are diverse forms. 

Pro'tifits : the simplest and earliest forms of life. 

Proto'phyta : the earliest, unicellular plant-organisms. 

Pro'toplasm : the complex, jelly-like substance of which all organisms 
are composed. 

Protozo'a : the earliest, unicellular animal-organisms. 

Psy'chade : a group of cells with a common consciousness. 

Psy'che : the " soul " or mind. 

Psy'chogenetic : pertaining to the development of mind. 

Psy'cho-mo'nism : subjective-idealism, the theory that mind only 

Psy'cho-plasm : protoplasm as the basis of mind. 

Pyknot'ic : from pykno'sis = a thickening or condensation. 

Bcatula'tion : an encasing, or enclosing (scatula = a box). 
Seba'ceeus : fatty. 

Teleol'ogy : the theory of design in nature. * ST> 

Tel'ic : purposive. 

Tetrap'oda : four-footed. 

Than atism : disbelief in personal immortality. 

Thorac'io: of the chest. 

Trans'formism : the evolution of species. 

Triasa'io : * geological period. 

Tro'pisms, or tropis'mata : inclinations manifested by lowly organisms. 

Ultramon'tanism : allegiance to Rome. 
Uniceirular : consisting of one cell. 
U'terus : the womb. 

Yi'taliam : the theory of a specific (non-mechanical) principle in living 
Yi'talifits : biologists who admit the vital principle. 

A Selection from 


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THE STREAM OF LIFE By Prof. Julian S. Huxley 

CONCERNING MAN'S ORIGIN By Prof. Sir Arthur Keith 


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