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1646 at Leipzig. Entered the University of 
Leipzig at the age of fifteen. Obtained a 
professorship at the University of Altdorf 
before he was twenty-one. Elected F.R.S. 
in 1670. In 1676 went to live at the Court 
of Hanover and died in 1716. 




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Made in Great Britain 

at The Temple Press Letchworth 

and decorated by Eric Ravilious 


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Aldine House Bedford St. London 

First Published in this Edition 1934 


GOTTFRIED WILHELM LEIBNIZ has been described as a man 
of universal attainments and of almost universal genius. 
A courtier, diplomat, scholar, mathematician and philo- 
sopher, he is perhaps the most brilliant figure among modern 
philosophers. The history of philosophy has always 
recognized him as one of the greatest of system-builders. 
Now in the twentieth century he receives in addition an 
even higher esteem for the brilliance of some of his particular 
ideas and for the close thinking of some of his detailed 
arguments. With Descartes he shares the merit of having 
a more authoritative insight into the method and value of 
mathematics and physics than any other philosopher of the 
first rank. And with Hume he shares the honour of setting 
the stage for the rejuvenation of modern philosophy in the 
critical philosophy of Kant. 

Life and Character. Leibniz was born at Leipzig in 
July 1646, thirteen years after the birth of Spinoza, and 
four years before the death of Descartes. His father, who 
died in 1652, had been for some years Professor of Moral 
Philosophy at Leipzig. At the age of fifteen Leibniz 
entered the university of that city; and in 1666 he became 
a Doctor of Laws, but at Altdorf, the university town of 
Nuremburg, where he declined the offer of a professorship. 
In the following year he entered the political service of 
the powerful Elector-Archbishop of Mainz. Sent to Paris 
in 1672 on a diplomatic mission to Louis XIV, he was 
enabled to have some intercourse with learned men of his 
day, notably with Arnauld and Malebranche. Early in the 
next year he paid a short visit to London, where he met 
Oldenburg, the first secretary of the Royal Society, and 
Boyle. On his return to Paris he devoted himself to the 
study of geometry under the guidance of Huygens. 



Previously he had mainly concerned himself with problems 
of logic and metaphysic. In 1676 he completed his dis- 
covery of the Differential Calculus. There is no doubt 
that Newton had been using a similar method for some years 
previously. But it seems probable that Leibniz discovered 
it independently; and the form in which he presented it has 
been universally adopted in preference to that of Newton. 

After the death of the Elector of Mainz, he accepted in 
1676, after some hesitation, the position of librarian to the 
learned John Frederick, Duke of Brunswick, and Hanover 
became his headquarters for the remaining forty years of 
his life. He thus lived in the atmosphere of the local 
politics of a German principality. But his writings make 
it clear that he was primarily interested in the wider 
development of European civilization. For a time he was 
connected with the learned life of Berlin through his friend- 
ship with the Electress Sophia and her daughter Sophia- 
Charlotte, afterwards Queen of Prussia. With the help of 
the latter he was largely responsible for the institution in 
1700 of an Academy in Berlin, of which he was made life 
President. He made some attempts to secure the founda- 
tion of similar academies in Dresden, St. Petersburg, and 
Vienna ; but Europe was too much interested in wars, and he 
met with no ultimate success. In 1712, on his last visit to 
Vienna, he received the honour of a Privy Councillorship 
and Barony of the Empire. 

When he returned to Hanover, the Elector George had 
already gone to England. Leibniz wished to go to London 
for the coronation, but was ordered to remain at Hanover 
and to continue his work on his history of Brunswick. He 
seems never to have found favour with George I, whose 
displeasure increased after his accession to the throne of 
England; this was possibly due to the influence of friends 
of Newton. In the last years of his life Leibniz was almost 
entirely neglected, and his death in 1716 aroused no interest 
in London or Berlin. No one from the Court attended 
his funeral, his coffin being followed to the grave by his 
secretary alone. In Paris, however, a fitting memorial 
oration was pronounced by Fontenelle. 

Throughout his life Leibniz was indefatigably industrious, 


and was impatient of the ill-health that his long hours 
sometimes caused. He enjoyed social intercourse of all 
kinds, thinking that there must always be something that 
he could learn from everybody. This did not prevent him 
from being extremely proud of his own ideas, and extremely 
confident of the correctness of his own opinions. But he 
never lost his enthusiasm to learn, nor relaxed his deter- 
mination to examine every problem which occupied him 
with complete thoroughness. In controversy he showed 
himself to be exceptionally patient and good-tempered; 
and in general, his secretary tells us, he spoke well of 
everybody and made the best of everything. 

Philosophical System : the Monadology, etc. It has already 
been said that to-day the main philosophic interest of 
Leibniz lies less in his system, considered as a system, than 
in the particular arguments by which the development of 
that system was influenced. We shall therefore give here 
only a brief summary of his systematic doctrines, and then 
turn to consider at greater length his treatment of some 
special problems in his less formal writings. 
/ Everything which has any reality, according to Leibniz, 
must itself either be a real unity or be made up of real 
unities. It is evident at once that bodies are not them- 
selves real unities; they must therefore be aggregates of 
real unities. A real unity must be simple, indivisible, 
imperishable in the ordinary course of nature, and capable 
of variety without having parts. There is one thing in 
experience which we know to have all these characteris- 
tics, namely, a soul. Now the unities of which bodies 
are composed cannot actually be souls because they have 
no consciousness; they must therefore be, as it were, 
souls-without-consciousness, entities which have all the 
characteristics of souls except consciousness. We may say 
then that these souls-without-consciousness and souls, 
properly so called, are the only real unities conceivable to 
us. The name which Leibniz uses to cover all real unities 
is monads. J 

Since the/ monad has no parts it can only come into 
being all at once and end all at once; that is, it can come 


into being only by being created by God, and can come 
to an end only by being annihilated by God. For the same 
reason, Leibniz says, it cannot be changed internally by the 
action upon it of things outside it, as a compound could. Yet 
every monad has some character to distinguish it from 
every other monad, and is subject to change. Its character 
and its changes must therefore be determined by sonW 
internal principle, which is essential to it. So from thi 
moment of its creation every monad is pregnant with its 
own future. No other monad can affect it in any wayj 
what happens to it is determined by its own nature alonei 
The action by which it passes from one state to another 
Leibniz calls qpfetition. 

Though the monads cannot act upon one another, they 
are nevertheless adapted to one another, so that taken 
all together they form a universe; in a word, they are 
connected together and adapted to one another as if they 
acted upon one another. This connection and adaptation 
is governed by two laws: the principle of contradiction, 
which determines what is possible and what is impossible, 
and the principle of sufficient reason, in accordance with 
which the Author of the universe, by free decisions of His 
will, selects out of the infinite possibilities that which is 
best and most fitted for existence. Each monad, in pro- 
ducing its own changes by its own internal principle, 
since its changes fit in with the changes which are produced 
in themselves by all the other monads may be said to 
express or represent the universe from its own point of 
view. The passing state of the monad, representing as it 
does the whole universe, is called perception. 

Not every perception is apperceived. There are monads 
which never have any consciousness at all ; and even minds 
have an infinite number of unconscious perceptionsyilonads 
without consciousness, of which bodies are composed, act 
according to the laws of efficient causes; souls act according 
to the laws of final causes. Since the changes of every 
monad of whatever kind are adapted to the changes of every 
otl^er, it is clear that the kingdom of efficient causes and the 
kingdom of final causes are in harmony with one another. 

Among souls a distinction must be made between minds 


and ordinary souls. In ordinary souls, for instance the 
souls of brutes, there is some connection between conscious 
perceptions, in accordance with the laws of memory and 
imagination; but minds, which have clear and distinct 
apperceptions, are further gifted with reason. Ordinary 
souls are the living mirrors of the universe of created 
things, whereas minds are also images of the Divinity 
himself, the Author of nature, and are capable of knowing 
the system of the universe. This makes minds capable of 
entering into a kind of society with God, so that they are 
members of the City of Minds, the most perfect state under 
the most perfect of monarchs. Just as within the world of 
nature there is harmony, as we saw above, between the two 
kingdoms of efficient and of final causes, so there is a 
harmony between the physical kingdom of nature and the 
moral kingdom of grace; that is, there is accord between 
God as Architect of the machine of the universe and God 
as Monarch of the divine City of Minds. 

By reason of this harmony, there is no good action 
without reward, and no evil action without punishment. 
All things work together for the good of the righteous in a 
universe which is the image of the infinite perfections of God. 

Correspondence with Arnauld. Let us now attempt to 
discover what considerations led Leibniz to the main con- 
clusions which are basic to the structure of his system; in 
other words, let us examine his more detailed discussion 
of some particular points, and try to find out what special 
problems he was primarily considering when he made up 
his mind on the most essential matters. 

It is clear that one of the most fundamental of Leibniz's 
doctrines it is certainly one of the most curious is that 
every substance is a real unity, simple in the sense of 
having no parts, incapable of being acted upon by anything 
outside itself, nd therefore productive of its own changes 
by an internal principle. It is generally recognized to-day 
that the best light on the development of this thesis is to be 
found in the letters to Arnauld, where Leibniz seems to be 
arguing that his whole view of the nature of substance 
follows from a basic principle of logic, which he takes to be 


axiomatic ; namely, verae propositionis semper praedicatum 
inest subjecto in a true proposition the predicate is always 
included in the subject. The implications of this in regard 
to general propositions have no doubt been recognized 
previously, says Leibniz; but its implications in regard to 
singular propositions are more startling. Certainly they 
startled Arnauld, part-author of the Port-Royal Logic. 
It has always been recognized, Leibniz argues, that the 
predicates which can truly be asserted of a sphere must be 
contained within the essential notion of a sphere; but it has 
not been seen that the same must hold of the actual indivi- 
dual sphere which Archimedes had placed upon his tomb. 
It must have been included within the original notion of that 
sphere that it would on a particular day be set upon that 
grave. To take a more striking instance, everything which 
can truly be predicated of Adam must be contained within 
the essential notion of Adam; that is, the original notion 
of Adam included once for all the notion of everything 
that was going to happen to him, and thereby to the rest 
of mankind, his descendants. 

This doctrine at once stirred the theologian in Arnauld, 
by raising in his mind difficulties about the freedom of God ; 
and Leibniz had to attempt to show that he was not a 
determinist in any theologically objectionable sense. But 
with this dispute we are not for the moment concerned. 
What concerns us is that Leibniz is arguing that the 
principle praedicatum inest subjecto involves the denial of 
any interaction between substances; and that in making 
his point he is emphasizing a distinction between predicates 
asserted of general concepts (sub specie generalitatis) and 
predicates asserted of individuals (singularite r) . It is im- 
portant to notice that he refuses to identify or confuse 
the individual with a highly differentiated general concept 
(i.e. with an infima species). Adam is not just the first 
man, the husband of Eve, or an inhabitant of the garden 
of Eden. He is the one unique Adam. And everything 
which happened to him happened to him because it followed 
from the essential motion of that one unique Adam by an 
absolute necessity. 

Thus it seems to follow that if in a true proposition the 


predicate is included in the notion of the subject, and if 
there can be any true propositions asserted of Adam 
singulariter, then Adam cannot have been ever acted upon 
by anything external to himself; and, more generally, 
individual substances are incapable of interaction. But, 
even if we pass without comment Leibniz's acceptance of 
the first of these hypotheses, we naturally ask ourselves why 
he did not regard his argument as amounting to a reductio 
ad absurdum of the notion of individual substances. Why 
did he not conclude that individuals are not substances, 
and that we have no knowledge of any true singular 
propositions ? 

It seems that Leibniz was convinced by reading Spinoza 
that any view which denied the substantiality of individuals 
was inadmissible. Beyond this it is very difficult to say 
anything clear and definite. Up to a point he is very 
cautious about the imputation of substantiality; and he 
thinks that philosophers generally are too ready to allow 
that things are substances. A body, he says, is evidently 
not a substance; a crowd is not a substance. But he seems 
to take it for granted that individual selves are substances. 
He further takes it for granted that, though bodies are not 
substances, they are real existences of some kind, and 
therefore they must be aggregates of substances. He also 
holds that all general notions are incomplete notions. No 
notion is complete except the notion of an individual. Thus 
the notion of the First Man is not the notion of a substance; 
but the notion of Adam is the notion of a substance. All 
this, however, seems hardly to amount to any proof. 
Leibniz seems to be doing no more than simply affirming 
again and again his thesis that a substance is essentially an 
individual or real unity, and that there is in the universe a 
plurality of such substances. There is, however, a basic 
conviction involved in the argument, namely, the conviction 
that individual selves are real unities and must be repre- 
sented as substances. For this conviction Leibniz offers 
no defence, though perhaps he sometimes holds that we 
are directly conscious of being real unities. 

Dynamics and Physics. There is no doubt that Leibniz 


thought that his discoveries in regard to dynamics supported 
his general theory of substance. In view of the Cartesian 
doctrine that the essence of material substance was ex- 
tension, he always regarded his refutation of Descartes's 
mechanics as a vital part of the defence of his own system. 

Descartes taught that the total quantity of motion in 
nature is always the same. Leibniz argues that the 
quantity of motion in nature is not constant, but (what 
Descartes did not know) that the quantity of motion in any 
given direction is constant. This principle he formulated 
by saying that the total cause is equivalent to the total effect. 
It had always been recognized that effects were proportional 
to causes: but Leibniz now asserted that the total effect 
was not simply proportional, but equivalent to the total 
cause. In other words, to every action there is an equal 

Leibniz also regarded himself as having proved that the 
total quantity of force in nature remains constant, force 
being proportional not, as Descartes thought, to the pro- 
duct of the mass and the velocity (mv), but to the product 
of the mass and the square of the velocity (mv*, i.e. double 
what is now called kinetic energy). The two formulae 
(mv and mv 2 ) give the same result only in cases of equi- 
librium. In a system of moving bodies mv is demonstrably 
not constant; whereas mv* can be shown to be always the 
same. Since God has not made a faulty machine, it is 
evident that in nature the total quantity of force is 

Thus if we wish to understand the principle of change in 
the physical universe, Leibniz argues, what we have to 
consider is not motion but force. Now force is calculated 
by looking at its effects. But it cannot be maintained, of 
course, that the force is its effect. The effects are in the 
future, whereas the force is in the body now. But what 
exactly is meant by saying that the force is in the body? 
We do not mean, according to Leibniz, that the body is 
actually being active. To say that a body is endowed 
with a certain force is different from saying that it is actually 
doing work. On the other hand we do not mean by force 
the mere potency of the Schoolmen; for that which has mere 


potency requires the realization of some external condition 
(that is, it requires the action of something outside upon it) 
to turn its potency into actuality. Force is thus neither 
actual activity nor mere potency, but something between 
the two. 

Leibniz thus concludes that his dynamics forces him to 
maintain that physical objects are made up of units whose 
essence it is to be endowed with force (vis viva), and 
which, therefore, do not need the action of one unit upon 
another in order to produce change. Actually, of course, 
it is difficult to see how Leibniz can have thought that 
his dynamics supported the doctrine that each unit is a 
substance or real unity, quite incapable of being affected 
by any other unit. As he sometimes admits, dynamics 
must think in terms of interaction. But of this we shall 
have more to say presently, when we come to consider the 
Correspondence with Clarke. 

The New System, and the Controversy with Bayle. Here 
Leibniz is primarily concerned to explain and defend his 
doctrine of pre-established harmony, with special reference 
to the union of body and soul. In doing so he shows that 
his general view of substance partly depends on a careful 
investigation of the nature of the mind. 

The doctrine of pre-established harmony, he says, really 
follows from the conclusions already drawn about the 
nature of substance. Since no substance can act on any 
other substance, and yet the changes of the various sub- 
stances are adapted to one another as if they did interact, 
we must conclude that everything that happens to any 
individual substance 'springs from within itself by a 
perfect spontaneity with regard to itself, and yet in a 
perfect conformity with things outside '. Committed to this 
conclusion by his analysis of propositions, Leibniz here 
seeks to show that he can give a satisfactory account of 
the union of soul and body. He does this especially by 
examining the nature of the mind, and trying to show that 
the doctrine that the mind produces of itself its own ex- 
perience by virtue of its own inner nature agrees with the 
facts of experience. It accords well with the fact of free- 


will, as maintaining that all the soul's actions are produced 
by itself alone, and with the fact of immortality, since if 
nothing can affect the soul nothing can bring it to an end, 
except a miracle; and on careful investigation we see he 
alleges that it also accords with the facts of perception. 

There are two main objections to his doctrine which 
Leibniz here faces: first, that such automatism is in- 
conceivable; secondly, that even if such automatism is 
possible, the facts of experience show that the mind is not 
in reality such an automaton. 

To the first objection Leibniz urges that automata 
can actually be constructed which are capable of a great 
variety of behaviour. No doubt it is beyond the power of 
a human artificer to make an automaton which would 
behave as my body is behaving. But it certainly cannot 
be shown that such an automaton is in principle impossible. 
And we must remember that on any view there is a great 
difference between Nature's machines and ours, perhaps 
amounting to a difference in kind. In short, we must 
take it that there is no behaviour, however complicated, 
which is in principle beyond the power of automatism. 

In the course of answering the second objection, namely, 
that the mind is not in fact such an automaton, Leibniz 
conducts some important psychological investigations. He 
reminds us first that it is inconceivable to us how body 
can act on mind or mind on body. Though it may appear, 
therefore, that when I am stung by a wasp, the pain felt 
by my mind is immediately caused by what happens to 
my body, we cannot accept that explanation. It is evident 
that the cause of what happens in the mind, since it cannot 
be sought in the body, must be sought in the mind. Nor 
need we be disturbed by the fact that previous philosophers 
have rejected the view that minds are automata. What 
they were rejecting was the contention that minds are 
mechanical, that is, that they are corporeal automata. 
This we shall not maintain, says Leibniz. We hold that 
bodies are automata and minds are automata, but that 
between the two kinds there is a great difference. Every 
mind changes as determined by its own essence in accor- 
dance with the laws of its own nature; and every body does 


the same. But the laws of the nature of mind are different 
from those of the nature of body. 

We must look then for an explanation of the present 
state of a mind in previous states of the same mind, and 
nowhere else whatever. If this were not so, there could be 
no responsibility and no identity. Furthermore, we shall 
find that on this principle we can give some explanation of 
a number of obvious facts of experience which have hither- 
to been unexplained. But this Leibniz works out in more 
detail when he comes to consider the philosophy of Locke. 

New Essays. Here, in considering the Essay on the 
Human Understanding, Leibniz perforce gives his main 
attention to problems connected with the nature of know- 
ledge. His thought in this connection tends automatically 
to fall into two parts, the one part psychological and the 
other logical. In the first he argues rather in the manner 
of Locke, and seeks to propound an account of the nature 
of mind which will explain what he takes to be the observed 
facts of experience, e.g. memory, habit, etc. But, holding 
as he does that the conclusions of this part of his inquiry 
are not incompatible with the teaching of the established 
logic, he has, secondly, to expound what he takes to be the 
essential teaching of that logic. For though he does not 
think that the established logic needs any fundamental 
modification, it is obvious that he must needs give it a 
new and careful re-statement after studying Locke. This 
is an absolutely vital part of Leibniz's philosophy, because, 
as we have seen, his whole view of the nature of substance 
depends largely on pressing the implications of the logical 
principle praedicatum inest subjecto. 

Let us first briefly consider Leibniz's psychological 
teaching in the New Essays. Here the most striking thing 
is perhaps his application of his law of continuity to mental 
phenomena. Natura non facit saltum: there are no big 
sudden changes in nature. When there appear to be big 
sudden changes, the appearances must be deceiving us. 
When a tennis ball, for instance, strikes a wall, it may appear 
that at one moment the ball is moving forward with a 
velocity of say 70 f .s., at the next moment it is at rest, and 


at the next it is moving back again with a velocity of 50 f.s. 
But this cannot really be the case. In order to pass from 
a velocity of 70 f.s. to a state of rest, the ball must have 
slowed up gradually and have passed through all the 
intermediate velocities between 70 f.s. and zero; and 
similarly when it acquires a velocity of 50 f.s. in the other 
direction. The same must be true, Leibniz says, of the 
mind's experience. If we appear to pass immediately from 
a feeling of pleasure to a feeling of acute pain, the ap- 
pearance must be deceiving us. The mind must actually 
have passed through all the intermediate states. Since we 
are often not conscious of this gradual transition, we must 
admit that a great deal goes on in the mind of which we are 
not conscious. There are a great many perceptions which 
we do not apperceive, and all these perceptions go to make 
up the state of our minds at any given moment. The 
existence of such perceptions can often be inferred from the 
character of our conscious states, even though the percep- 
tions cannot be themselves brought into consciousness. 

All this brings Leibniz into conflict with Locke. To the 
latter it seems absurd to speak of something happening in 
the mind of which the mind is not conscious; though, as 
Leibniz points out, he modifies this later by saying that 
there can be nothing in the mind of which the mind has 
never been conscious without ever acknowledging, how- 
ever, the importance of this modification of his doctrine. 
But surely, Leibniz urges, it is Locke's view that is absurd. 
What are we to say of memory, and of habits and dis- 
positions? It is impossible to explain memory or habits 
without supposing that there may be in the mind, in some 
sense, things of which the mind is not conscious. And if 
this be granted in principle, it is purely a matter for detailed 
investigation to discover whether or not there must be in 
the mind some perceptions of which, as far as we can 
discover, we have never been conscious at all. Leibniz 
thinks that there certainly are such perceptions. Suppose 
that it has been established that a wasp-sting normally 
causes pain at the time; and suppose that on a particular 
occasion my attention is so much engaged with what I 
am doing that I do not notice any pain until the tension 


of my excitement relaxes, although I must actually have 
been stung some time before. Are we to say that in this 
case the mind had no pain at all during the intervening 
time, though it would have had pain if I had not been 
otherwise excited ? Are we to say, in fact, that a happening 
in my body is correlated with a happening in my mind at 
some times and not at others ? Surely not, Leibniz urges. 
When something happens in my body, there is always a 
corresponding happening in my mind. We must not 
conclude, just because I am not conscious of any previous 
event in my mind relevant to the explanation of my present 
state, that there was no such event. Rather we must 
examine my present state and seek to determine what must 
previously have occurred in my mind, even though it 
cannot be found in my conscious experience. 

It is evident that, though Leibniz is applying his principle 
of continuity over-crudely, he has here a very strong case. 
But what use does he make of it? His point is that since 
it cannot be maintained that there is nothing in the mind 
of which we are not conscious, Locke's attack on 'innate 
ideas' fails. Just as the veins, which are laid bare when 
a block of marble is cut, were there in the marble before 
they were discovered, so there are some ideas which are in 
the mind from the beginning whether or not they have 
yet been found there. Locke's argument fails to show that 
they cannot be there; and there are good, logical reasons 
for concluding that they must be there. For what account 
can be given otherwise of universal and necessary truths, 
such as are to be found in geometry and arithmetic? 
Knowledge of these cannot be derived from experience; for 
the observation of particular instances can never entitle 
us to assert a universal proposition. 

Thus according to Leibniz Locke's attack on the basis 
of the established logic fails; and it is therefore open to 
Leibniz to fall back on a doctrine which accords with that 
logic to explain those necessary truths of which Locke can- 
not consistently give an account. Necessary truths are 
arrived at by the analysis of clear and distinct notions; and 
these notions in turn are, by a special technique, simply 
found in the mind. From the analysis of the original 


clear and distinct notions we come, by way of identical 
propositions, to non-identical propositions, and then by 
analysis of these to further propositions, and so on to 
the whole body of knowledge. The most powerful engine 
for producing this happy result, he says, is the syllogism, 
though it is a mistake to regard it as the only one. 

Herein Leibniz shows himself to be a rationalist indeed. 
He even includes within this doctrine our knowledge of 
contingent fact. He distinguishes indeed between truths 
of reason and truths of fact. The first are in the sphere 
of necessity and are known a priori: the latter are in the 
sphere of contingency and are known a posteriori. But in 
the end these too, according to Leibniz, are arrived at by the 
analysis of clear and distinct notions which are found in the 
mind, and not by mere sense-observation. Because these 
truths are in the sphere of contingency, we must not make 
the mistake of thinking that they are any the less certain. 
True propositions about Adam follow as much from the 
original notion of Adam as true propositions about tri- 
angles follow from the original notion of triangularity. The 
latter follow in accordance with the law of contradiction, 
whereas the former follow by the law of sufficient reason. 
But both are equally certain. 

Thus in the end, according to Leibniz, none of our 
knowledge is really derived from observation by the senses; 
all of it springs from the analysis of original notions which 
are in some sense found in the mind. 

Correspondence with Clarke: Leibniz and Newton. In this 
controversy with an authoritative exponent of the views of 
Newton, Leibniz, in the closing years of his life, seeks 
finally to set in order and to defend his views with special 
reference to their bearing on mathematics and physics. 
In view of the intrinsic interest of this subject and of the 
at least superficial resemblance between Leibniz's teaching 
and modern physical theory, it is perhaps worth while to 
examine this issue at some length. 

Leibniz agreed with the Cartesians in rejecting atoms. 
The reasons which make, it impossible to believe that 
perceptible bodily masses are perfectly inelastic and indi- 


visible hold in the end with equal weight against atoms. In 
this modern physicists would agree with Descartes and 
Leibniz. But the latter goes on to reject the former's 
primary elements, which, he says, are nothing but mathe- 
matical points', they have position, but no magnitude and 
no other characteristics whatever. But how can such 
elements be put together in such a way as to aggregate into 
a bodily mass ? No number of nothings, when put together, 
can make a something. Yet this is what, according to 
Leibniz, the doctrine of Descartes requires. 

Now the truth is, Leibniz continues, that it is not to 
extension, but to that which is extended, that we must turn 
our attention. If we do so we shall see that the essence of 
that which is extended is not extension, but something 
else. Let us for the sake of argument suppose that matter 
is passive, as Descartes thought, and let us consider a 
piece of matter at rest. This is as a matter of fact, says 
Leibniz, to speak abstractly, since real matter is not 
passive and is never at rest. But let that pass for the 
moment. Let us suppose that matter is passive, and let us 
consider a body at rest. Now the essence of the matter of 
the body is not its extension, but its solidity. This solidity 
shows itself in two ways: the body resists penetration and 
resists movement. Without impenetrability and inertia it 
would not be a body; unless it had these characteristics it 
could not be extended. Solidity cannot be explained in 
terms of extension. Therefore even Descartes, who held 
that matter was inert and passive, should have seen that 
that which makes a body solid is an essential character 
of body. 

We have already seen how this criticism of the Cartesians 
is gathered up into Leibniz's constructive view that the 
essence of matter is vis viva, in terms of which both im- 
penetrability and inertia can be explained. 

At this point we should perhaps expect Leibniz to ask 
himself the question which he has just asked of Descartes 
with such destructive results. How can these elements, 
or metaphysical points, as he calls them, be compounded 
into a bodily mass? After all, they share with the Car- 
tesian elements the characteristic of having no extended 


magnitude. It is true that, while Descartes's elements have 
no characteristic but position, those of Leibniz have the 
positive characteristic of vis viva. But does this help to 
explain mass ? Can a number of parts, whose sole character- 
istic is active force, aggregate into a body ? 

To this problem modern readers, I think, will expect 
Leibniz to offer some such solution as the following : Each 
unit has a certain quantity of force, and, though it has no 
extension, it always has position; that is to say, at any 
given moment the force always operates at a point. The 
units act upon one another, acting of course not by impact, 
but at a distance, as Newton held gravitation to act; and 
the result of this interaction is that the elements, which 
must be thought of as centres of force, move in such a way 
as to present to the human observer the appearance of a 
number of continuous bodily masses of finite size behaving 
in certain ways. Perceptible bodies, together with then- 
changes and motions, are only appearances; the realities 
are the interacting centres of force. 

It is true that this view gives rise to very great difficulties. 
Suppose we allow that movements of invisible particles can 
give rise to the appearance of a continuous surface; how 
can there be motion without a body to move ? Can a centre 
of force move? But to the modern reader these are, for 
better or worse, accustomed difficulties; and he will 
probably expect Leibniz to inaugurate some such view. To 
do so would be to accept as ultimate realities the centres 
of force, space and time (as implied by their position and 
movement), and presumably a mind or minds (implied 
by the existence of appearances). And it would be allowed 
that the centres of force in moving could affect one another's 
motion by action at a distance. 

But it is evident that this was not Leibniz's view. He 
held that the only ultimate realities are individual sub- 
stances; that is, the metaphysical points, endowed with vis 
viva, and minds. Nothing else has ultimate reality; and it 
is clear to Leibniz that space and time are not individual 
substances. What then are space and time? In the first 
place Leibniz will have nothing to do with the notion of 
action at a distance, or with that of empty space. All 


motion takes place in a plenum, and all action of body 
on body is by impact. We have no experience, he says, of 
a vacuum in nature; and if there were such a thing as 
empty space, position or motion in it would be purposeless, 
since, as every point would be absolutely homogeneous with 
every other, there could be no reason for occupying one 
point rather than another, nor for moving from one point 
to another. Since there would be no reason for it, it would 
be contrary to reason. 

Moreover, in nature, Leibniz argues, position and motion 
are never purposeless. A body cannot be moved from one 
position to another and remain the same body in every 
respect other than its position. To change the situation of 
bodies is, contrary to the opinion of those who believe in 
empty space, to change the bodies. If you move a block 
of marble from Genoa to Paris, it may appear to make no 
difference to anything but the mere position in space of 
the marble. But this is not so. It really makes a difference 
to the marble and to everything else in the universe. What 
makes the difference is, of course, not change of position in 
empty space, but the change in the interrelations of bodies 
that is, in the end, a change in the order of active forces in 
the universe. 

Thus space and time are nothing but the order of real 
existences, according to Leibniz. Perhaps his view can be 
more clearly stated in this way: Bodies and movements of 
bodies are not real existences, but ideal existences created 
by the imagination. There is nothing real in the physical 
universe behind the curtain of sense except individual 
units of vis viva, which are not in space and time. Space 
and time themselves are even further removed from real 
existence than are bodies and movements of bodies. For 
the notions of bodies in space and of change in time can 
only be significant if there is empty space and empty time. 
If the physical world is a plenum, space is nothing but an 
arrangement of bodies, and time is nothing but an order 
of changes. Now the whole notion of empty space and 
empty time is a vulgar error. So space and time are not 
only not ultimately real like the monads; they are less real 
than bodies, being due to a confused perception of bodies. 


In a word, if we wish to understand the true nature of 
reality we must banish from our minds all notions of space 
and time. Instead we must conceive of an order of relations 
between entities whose essence is active force. In conceiv- 
ing of these entities as exercising their force in an ordered 
system we must not think of them as operating at points 
in space, or of the system as a mechanical system, excellently 
as such a fancy may seem to satisfy the imagination. We 
must think of real entities as acting intensively, rather in 
the manner that a soul acts, though without the conscious- 
ness which attends upon some of the activities of souls. If 
we think of the universe as a system, or ordered unity, of 
the activities of monads, we shall be in no danger of thinking 
of space and time as real existences. Such a mistaken 
notion would be entirely due to the action of the imagination. 

Summary of Leibniz's Philosophy. We may now make a 
tentative attempt to gather together the various strands of 
thought which go to make the finished product of Leibniz's 
system; though it will now be clear to the reader that any 
such attempt at a final judgment must rest on a very 
precarious basis. 

First, Leibniz was profoundly affected by his discovery 
of the implications of the fundamental principles of the 
Scholastic logic when applied to singular propositions. This 
convinced him that substances must be real unities, and 
cannot be affected by anything outside themselves. 
Secondly, he found that if the constituent elements of 
things are real unities, they must be the only real unities; 
since, if they are to keep their character as real unities, they 
can only be compounded by aggregation. Thirdly, he 
argued that we are given in experience an instance of such 
a real unity, namely, the self; this unity is thought of as 
indivisible into parts, but yet as capable of great variety. 
Fourthly, he considered that an examination of the nature 
of the mind bears out the view that it is unaffected in its 
experience by anything outside itself; this, so far as it 
goes, confirms the view that real unities are pregnant with 
their own future. Fifthly, a sound dynamics reveals that 
the essence of material substance is not extension, nor even 


motion, but force, a character in things which is presup- 
posed by solidity and motion; real unities must be conceived 
to be endowed with force in the same manner as the soul 
is endowed with activity. Sixthly, since there cannot be 
any interaction between real unities, it follows that there 
must be pre-established harmony, in order to give unity 
to the universe; without this there would be a chaotic 
plurality and everything would be purposeless, which is 
absurd. Lastly, reality as such is governed not by me- 
chanical laws, but by the law of sufficient reason ; the real 
world is not the only possible world, but the best of possible 
worlds; everything is ordered not by a mechanistic necessity, 
but by the moral necessity to work for the highest good of 
minds; this is achieved by making the kingdom of nature 
subservient to the kingdom of minds, God being at once the 
Architect of the one and the Monarch of the other. 

Remarks and Criticisms. It is now time to suggest a few 
brief criticisms at each point of the argument as we have 
here represented it. First, if Leibniz's view of substance 
follows from the doctrine praedicatum inest stibjecto, he 
seems to offer no reason for subscribing to that doctrine 
itself; he simply takes it as common ground between him- 
self and the established logic. Secondly, when he maintains 
that if parts are real unities wholes of those parts can only 
be aggregates, he is arguing too much a priori, and is 
reflecting too little on the implications of his own view that 
all individual minds taken together form a unity in the 
City of Minds under the monarchy of God. Moreover, his 
contention that a simple being which has no parts is yet 
capable of variety is insufficiently worked out; it is not 
sufficient to refer to an instance in experience, namely, the 
soul; he ought at least to indicate, for example, just how an 
infinity of little perceptions go to make up the present state 
of the soul. Thirdly, it is doubtful, as Hume emphasized, 
whether it is clear in experience that the soul is entirely 
simple and without parts. Fourthly, while Leibniz makes 
good ground against Locke when he maintains that the 
present experience of a particular mind is always partly 
determined by the intrinsic nature of mind as such and 


partly by the previous experience of the particular mind, 
and is never wholly determined (as it would be if the mind 
were a tabula rasa) by the present action of things outside it; 
yet his arguments stop short of proving that its experience 
is entirely determined by the mind's own original nature. 
Fifthly, though Leibniz was no doubt right in principle in 
urging that physics must explain everything in terms of 
force or activity of some kind, he seems to have been wrong 
in thinking that dynamical theory could conform to his 
doctrine of real unities; indeed he himself sometimes allows 
that as far as dynamics is concerned its objects behave 
as if there was interaction between them. Sixthly, since 
Leibniz allows that everything in the universe, even in- 
cluding minds, behaves in every way, because of the pre- 
established harmony, as if there was interaction, he seems 
to be left with no argument against the real interaction of 
body on body and of mind on mind except the logical 
argument from the principle praedicatum inest subjecto ; and 
this principle seems to be open to objection. Lastly, Leibniz 
can show that many who argue that this is not the best of 
all possible worlds take insufficient account of the all- 
inclusive, all-pervading unity of the universe; but he has 
no argument to prove that this is the best possible world; 
the most that he can do is to show that his optimism 
cannot be finally refuted. 

A brief note must be added here about Leibniz's teaching 
in regard to freedom. His stress on the principle of 
sufficient reason inevitably makes his ethical views central 
to his system. Yet his ethics, for whatever reason, is 
certainly the weakest part of his thought. It is really quite 
clear that he must believe in some kind of predestination; 
that is, he is, in ordinary non-Leibnizian language, some 
kind of a determinist. Yet he will never say so. He can 
pour scorn, of course, on the suggestion that God might leave 
the future of the universe to chance. He can show, more- 
over, that the principles underlying the determination of 
my actions are different from the principles of geometry or 
of mechanics. But though he may multiply distinctions 
between the various kinds of determination, the important 
fact remains that on his view my actions are determined, 


and are in principle predictable. It is difficult to see how 
such a doctrine can leave room for any real freedom of the 
will. It is true that, according to Leibniz, my actions are 
determined by nothing but my own nature. But so are 
the actions of the brutes, and of those monads which have 
no consciousness. He sometimes tries to mark the dif- 
ference between the determination of minds and physical 
determination by saying that motives 'incline without 
necessitating*. But, as far as its bearing on freedom is 
concerned, this is nothing but words. The fact that I shall 
do this action freely, he says, does not mean that it is 
uncertain whether I shall do it. Nothing in the universe 
is uncertain, because nothing can occur without a sufficient 
reason. And this is Leibniz's last word. He points out 
some important distinctions, but they do not enable him to 
make out a case for free-will. 

Influence of Leibniz. It may safely be said that until the 
twentieth century Leibniz's influence on the development 
of philosophy was exercised chiefly through Kant. Kant 
was brought up on the systematized Leibnizianism of 
Wolff. But the latter made no important original contri- 
bution, and it was on the basis of the ideas of Leibniz 
himself that Kant sought to revivify philosophy after the 
sceptical influence of Hume. 

There is no doubt that, especially in the New Essays, 
Leibniz goes far towards leading up to Kant's Copernican 
revolution in logic. He carefully examines Locke's 
empiricism, and lays down the principle that the tabula 
rasa theory of mind cannot account for the existence of 
knowledge of universal and necessary truths, such as are 
found in geometry and arithmetic. This point is accepted 
without more ado as a starting-point by Kant and Hegel. 
So also is the method, here used by Leibniz, of attempting 
to refute a psychological theory of knowledge by arguing 
from the possibility of the existence of universal and 
necessary truths. Kant, who presses the method much 
further, calls it the 'transcendental method 1 . 

Leibniz agrees with Kant in conceding to Locke that all 
knowledge must start with sense-experience, and also in 


denying that it can be wholly derived from sense-experience. 
He goes further and makes the pregnant suggestion, nihil 
est in intellects, quod non fuerit in sensu, excipe, nisi ipse 
intellectus there is nothing in the understanding which was 
not previously in the senses, except the understanding itself. 
But it must be admitted that his happy phrase does not 
suggest to him, though it may well have suggested to Kant, 
the Kantian view that what is necessary to the possibility 
of universal truths is the existence of categories, that is, 
forms of spontaneous activity. 

Leibniz further shows the way to Kant by emphasizing 
the distinction between truths of reason on the one hand, 
which are a priori , in the sphere of necessity, and concerned 
with general notions of possibilities, and on the other truths 
of fact, which are a posteriori, in the sphere of contingency, 
and concerned with individuals or real existences. He did 
not, however, see the necessity for abandoning what Kant 
called the 'dogmatic* position in regard to truths of fact. 
He recognized, with Kant, that particular facts cannot be 
deduced from original notions in accordance with the laws 
of contradiction; only general truths can be arrived at 
in this way, and these suffer under the disadvantage that 
their objects are not real existences. But he thought that 
he could save 'dogmatic* rationalism by introducing the 
new refinement of the principle of sufficient reason to 
bridge the gap between knowledge of general truths and 
knowledge of individuals. He did not see, what Kant 
learned from Hume, that in the sphere of real existences 
we cannot progress without a knowledge of causal relations, 
which is clearly not arrived at by any analysis of original 
notions. We have as a matter of fact no insight into the 
sufficient reason for the happening of any event to any 
individual. Because he did not see this, he did not recog- 
nize that our knowledge of truths of fact is synthetic. 
Instead, he stood by the established logic, and performed 
the service of showing Kant how that logic must be stated 
if it is to meet the difficulties, which he himself exhibited, 
in regard to our knowledge of the physical world. 

In a word, Leibniz showed, as against Locke, that we 
cannot explain scientific knowledge if we suppose the mind 


to be a tabula rasa; nor can we do so if we suppose 
that nothing goes on in the mind except what meets the 
eye of introspection. So far he indicated to Kant what 
line he should take in meeting Locke's psychological 
approach. But he allowed himself to be too much en- 
couraged by his discovery that the doctrine of innate 
ideas cannot be certainly refuted by an empirical inventory 
of the contents of the mind; and so he thought that thia 
doctrine could be defended absolutely, and that, with the 
added refinement of the principle of sufficient reason, 
'dogmatic* rationalism could be made to stand in despite 
of Locke. It is quite true that the mind might be born 
with some kind of innate knowledge of certain universal 
notions; but, as Hume shows, even if this were so, it could 
not help to explain our knowledge of real existences, since 
it could not explain our knowledge of causal relations. 
It is on this rock that Leibniz's rationalism breaks. 



In the lifetime of Leibniz only one complete work of his on philosophy 
was published: Essais de Theodicee sur la bonU de Dieu, la liberU de 
?homme t et I'originc du mal, 1710. Other important philosophical 
works are : the correspondence with Samuel Clarke on the principles of 
natural philosophy and religion (published by Clarke, 1717); La 
Mpnadologie, a sketch of his philosophic system (German trans. 1720, 
original French not until 1840 in Erdmann's edition); Nouveaux Essais 
sur VEntendement Humain (Raspe edition, 1765), being an answer to 
John Locke's Essay on the Human Understanding] the Sy sterna Theo- 
logicum (1819), which is an exposition of the doctrines of the Roman 
Catholic Church, written in the cause of re-union between Protestantism 
and Catholicism (the title was probably given to the work by an over- 
zealous Catholic). 

Translations of the above (other than the Clarke correspondence, 
which contained a translation by Clarke of Leibniz's words in the 
original 1717 edition) are: A System of Theology, trans, by C. W. Russell, 
1850; The Philosophical Works of Leibnitz, trans, by G. M. Duncan 
(containing the Monadology, the Clarke correspondence, many of the 
shorter philosophical papers, an abridgment of the Theodicy, and 
selections from the New Essays), 1890; The New Essays, trans, by 
A. G. Langley (1896). Other translations: The Monadology, etc., 
trans, by R. Latta, 1898 and 1925; The Monadology, by H. W. Carr r 


1930; A summary Account of Leibnitz's Memoir, addressed to Louis XIV, 
recommending the Conquest of Egypt, 1803; Discourse on Metaphysics, 
Correspondence with Arnauld, and The Monadology, trans, by G. R. 
Montgomery, 1902; Early Mathematical Manuscripts of Leibnitz, trans, 
by J. M. Child, 1920. 

There exists at present no complete edition of the works of Leibniz, 
and it may be said that all editions are supplementary in some way or 
other. The best edition is that of C. J. Gerhardt (philosophical writings, 
1875-90; mathematical writings, 1855-63). Next comes Onno Klopp's 
edition of the historical and political writings (1864-77); and then that 
of Foucher de Careil, which contains the theological works besides the 
political works, and the writings bearing on the foundation of academies. 
To these should be added the first 'collected' edition of L. Dutens 
(1768), and that of G. H. Pertz (1843-63); the editions of the philo- 
sophical works by Kaspe (1765), Erdmann (1840), Jacques (1846), and 
Janet (1866). There is, however, in course of preparation, a complete 
edition of the works of Leibniz, including all the papers in the Library 
of Hanover, under the direction of the Akademie der Wissenschaften 
of Berlin. It is intended to consist of forty quarto volumes, arranged 
in seven series: (i) General, Political, and Historical Correspondence 
(i i vols.) ; (2) Philosophical Correspondence (6 vols.) ; (3) Mathematical, 
Scientific, and Technical Correspondence (5 vols.) ; (4) Political Writings 
'4 vols.); (5) Historical Writings (4 vols.); (6) Philosophical Writings 
6 vols.); (7) Mathematical, Scientific, anc Technical (4 vols.). Only 
ive volumes have so far been issued (1934). 

The standard biography is that by G. E. Guhrauer (1842). Works 
in English are: The Life of G. W. von Leibnitz, by J. M. Mackie (1845), 
a short book based on Guhrauer's; Leibniz, by J. T. Merz (1884); 
A Critical Exposition of the Philosophy of Leibniz, by Bertrand Russell 
(1900); Leibniz, by H. W. Carr (1929); The Reunion of the Churches, by 
G. J. Jordan (1927), is a study of Leibniz's attempt at reunion. The 
Dawn of Modern Thought, by S. H. Mallone (1930) contains a study of 
Leibniz. Mention should also be made of E. Bodemann's catalogue, Die 
Leibnizschnften in der Koniglichen Bibliothek zu Hannover (1895) from 
which are translated one or two extracts in this volume. 


THE passages from Leibniz's philosophical writings given in 
this book are almost all taken from the seven volumes of 
Gerhardt's edition. A few extracts in Part III are not taken 
from Gerhardt, but their sources are indicated in footnotes. 

Part I contains the three best known works among Leibniz's 
more formal expositions of his system The Monadology 
(1714), Principles of Nature and of Grace (1714), and On the 
Ultimate Origination of Things (1697). These are given 
complete. The Monadology is printed first in spite of its 
date, because in addition to being the most famous of 
Leibniz's writings, it is also, so to speak, his title-piece. 

Part II represents an attempt to give evidence for a 
balanced judgment about the scope and development of the 
thought of Leibniz, and is arranged chronologically. Except 
in the case of the Letter to Foucher (1676), the Letter to 
Bayle (1687), and the New System of the Nature and 
Communication of Substances (1695), substantial abridgment 
has been necessary. Where the omissions are not made 
clear by the numbering of the chapters or paragraphs, they 
have been indicated by dots (....) or by footnotes. I 
have tried, in abridging, only to cut out arguments which 
are better or more appropriately dealt with elsewhere, so as 
to concentrate attention on what seemed the central points 
in the various works. In the Correspondence with Arnauld 
(1686-7) I have regarded Leibniz as chiefly concerned with 
deriving his doctrine of substance from the analysis of 
propositions; in the controversy with Bayle (1695-1702) I 
have represented his mathematician's interest in machines 
and automata; in the New Essays (1702-3) passages are 
given showing the development of his psychology and 
indicating his statement of his logical doctrines, with special 



reference to his attitude to the syllogism; and in the Corre- 
spondence with Clarke (1715) I have concentrated attention on 
his defence of his physical and dynamical ideas, and of his 
doctrines about space and time, since these writings represent 
Leibniz's last and greatest attempt to state his case against 
the theories of Newton. 

Part III consists of short extracts which are intended to 
illustrate the breadth and variety of Leibniz's interests, and 
also his attitude to other men of learning of his time. A few 
passages are included as specimens of his more fanciful 
writing. The last (taken from the concluding pages of the 
Theodicy) also gives as clear an idea as any other passage 
of his standpoint with regard to freedom and predestination. 

In translating I have thought it better to come to a 
definite decision on all occasions, rather than to cumber 
the text with footnotes about difficulties of interpretation. 
The disadvantages of this method are perhaps seen at their 
greatest in 12, 13 of the Monadology. Here, as elsewhere, 
I have tried to give an exact rendering of the text rather 
than to tighten it up, as it were, into accuracy or consistency. 
Where Leibniz uses a vague word or phrase, I have tried to 
give a correspondingly vague word or phrase in English. 
Even so, however, I am aware that my translation is through- 
out affected by my own interpretation of the author's 
meaning; but I have tried to make it as philosophically 
exact as possible. 

To avoid multiplying footnotes I have given short notes 
on the persons mentioned in the text in the Index of Proper 
Names, and have added a full Philosophical Index to take 
the place of cross references at the bottom of the page. 

Of the existing English versions I have found Latta's to 
be the best; though I have sometimes differed from him. 
I have also consulted the translations of Wildon-Carr, 
Montgomery, Duncan, and Langley. 

1934. M. M. 



INTRODUCTION ........ vii 






ON REASON. 1714 ...... 21 










PHILOSOPHICAL INDEX . . . . . . 279 

C95 xxxili 




1. The monad, of which we shall speak here, is nothing 
but a simple substance which enters into compounds; simple, 
that is to say, without parts. 

2. And there must be simple substances, because there are 
compounds; for the compound is nothing but a collection or 
aggregatum of simples. 

3. Now where there are no parts, there neither extension, 
nor shape, nor divisibility is possible. And these monads 
are the true atoms of nature and, in a word, the elements of 

4. Moreover, there is no fear of dissolution, and there is no 
conceivable way in which a simple substance could perish 
in the course of nature. 

5. For the same reason there is no way in which a simple 
substance could begin in the course of nature, since it cannot 
be formed by means of compounding. 

6. Thus it may be said that monads can only begin and 
end all at once, that is to say they can only begin by creation 
and end by annihilation, whereas what is compound begins 
or ends by parts. 

7. There is also no means of explaining how a monad can 
be altered or changed within itself by any other created thing, 
since it is impossible to displace anything in it or to conceive 
of the possibility of any internal motion being started, 
directed, increased, or diminished within it, as can occur 
in compounds, where change among the parts takes place. 
Monads have no windows, by which anything could come in 
or go out. Accidents cannot become detached, or wander 
about outside substances, as the 'sensible species' of the 


Scholastics used to do. Thus neither substance nor accident 
can enter a monad from without. 

8. Monads, however, must have some qualities, otherwise 
they would not be beings at all. And if simple substances 
did not differ by their qualities, there would be no way of 
perceiving any change in things, since what is in the com- 
pound can only come from its simple ingredients; and if 
monads were without qualities, they would be indistinguish- 
able from one another, since they do not differ in quantity 
either. And consequently, supposing space to be a plenum, 
each place would always only receive, when motion occurred, 
the equivalent of what it had before; and one state of things 
would be indistinguishable from another. 

9. Indeed, every monad must be different from every other. 
For there are never in nature two beings, which are precisely 
alike, and in which it is not possible to find some difference 
which is internal, or based on some intrinsic quality. 

10. I also take it as granted that every created thing, and 
consequently the created monad also, is subject to change, 
and indeed that this change is continual in each one. 

11. It follows from what we have just said, that the natural 
changes of monads come from an internal principle , since an 
external cause would be unable to influence their inner being. 

12. But besides the principle of change, there must be 
differentiation within that which changes, to constitute as it 
were the specification and variety of simple substances. 

13. This differentiation must involve a plurality within 
the unity or the simple. For since every natural change 
takes place by degrees, something changes, and something 
remains; and consequently the simple must contain a large 
number of impressions and relations, although it has no 

14. The passing state, which involves and represents a 
plurality within the unity or simple substance, is nothing 
other than what is called perception) which must be carefully 


distinguished from apperception, as will appear presently. 
And herein lies the great mistake of the Cartesians, that they 
took no account of perceptions which are not apperceived. 
It is this also which made them believe that minds alone are 
monads, and that neither 'brutes nor other entelechies have 
souls. For the same reason also they fell into the common 
error of confusing death, properly so called, with a prolonged 
unconsciousness; and this made them favour the Scholastic 
conviction that souls are entirely separate from bodies, and 
even confirmed some ill-balanced minds in the opinion that 
souls are mortal. 

15. The action of the internal principle which produces the 
change or passage from one perception to another may be 
called appetition; it is true that the appetite cannot always 
attain completely the whole of the perception at which it 
aims, but it always attains something of it, and arrives at 
new perceptions. 

16. We ourselves experience plurality within a simple 
substance, when we find that the least thought of which we 
are conscious involves a variety in its object. So everyone 
who acknowledges that the soul is a simple substance must 
acknowledge this plurality within the monad; and M. Bayle 
should not have found any difficulty in this, as he does in his 
Dictionary, in the article 'Rorarius'. 

17. We are moreover obliged to confess that perception and 
that which depends on it cannot be explained mechanically, 
that is to say by figures and motions. Suppose that there 
were a machine so constructed as to produce thought, feeling, 
and perception, we could imagine it increased in size while 
retaining the same proportions, so that one could enter as 
one might a mill. On going inside we should only see the 
parts impinging upon one another; we should not see any- 
thing which would explain a perception. The explanation 
of perception must therefore be sought in a simple substance, 
and not in a compound or in a machine. Moreover, there is 


nothing else whatever to be found in the simple substance 
except just this, viz. perceptions and their changes. It is in 
this alone that all the internal actions of simple substances 
must consist. 

18. We may give the name entelechies to all created simple 
substances or monads. For they have in themselves a certain 
perfection (e^ouo-t TO oreAes); there is a self-sufficiency 
(avrdpKCia) in them which makes them the sources of their 
internal actions incorporeal automata, if I may so 
put it. 

19. If we wish to give the name 'soul' to everything which 
has perceptions and appetites in the general sense I have just 
explained, all created simple substances or monads might be 
called souls; but as feeling is something more than a simple 
perception, I agree that the general name monad or en- 
telechy should be enough for simple substances which have 
no more than that, and that those only should be called souls, 
whose perception is more distinct and is accompanied by 

20. For there is to be found in our ordinary experience a 
state, in which we remember nothing and have no distinguish- 
able perception; as when we fall into a swoon, or when we are 
overcome by a deep dreamless sleep. In this state the soul 
does not sensibly differ from a simple monad; but as this 
state is not permanent, and as the soul emerges from it, the 
soul is something more. 

21. And it does not follow that when in that state the 
simple substance has no perception at all. Indeed, that is 
not possible for the above reasons; for it cannot perish, nor 
can it subsist without being affected in some way, and this 
affection is nothing but its perception. But when there are 
a very great number of small perceptions with nothing to 
distinguish them, we are stupefied, just as it happens that if 
we go on turning round in the same direction several times 
running, we become giddy and go into a swoon, so that we 


can no longer distinguish anything at all. And death can 
throw animals 1 into this state for a time. 

22. And as every state of a simple substance is a natural 
consequence of its preceding state, so that the present state 
of it is big with the future, 

23. and since, on awakening from our stupor, we are 
conscious of our perceptions, it must be the case that we 
received the perceptions the moment before, though we were 
not conscious of them; for a perception cannot arise in the 
course of nature except from another perception, as one 
motion can only arise in the course of nature from another 

24. From this we see that if we had nothing in our percep- 
tions to distinguish them, nothing so to speak heightened 
and of a keener savour, we should always be in this stupor. 
And this is the state of bare monads. 

25. We see also that Nature has given heightened per- 
ceptions to animals from the care she has taken to provide 
them with organs which collect several rays of light, or 
several undulations of the air, so as to make these effective 
by being united. There is something of the kind in smell, 
taste, and touch, and perhaps in many other senses which are 
unknown to us. I will explain later how what occurs in the 
soul represents what takes place in the organs. 

26. Memory provides souls with a kind of consecutiveness, 
which copies reason but must be distinguished from it. What 
I mean is this: we often see that animals, when they have a 
perception of something which strikes them, and of which 
they had a similar perception previously, are led, by the 
representation of their memory, to expect what was united 
with this perception before, and are carried away by feelings 
similar to those they had before. For example, when dogs 

1 By ' animals ' Leibniz means all living creatures up to and 
including man. The lower animals, as distinguished from man, 
he refers to as ' brutes '. 


are shown a stick, they remember the pain which it has 
caused them in the past, and howl or run away. 

27. The powerful imagination, which strikes and moves 
them, arises either from the magnitude or from the number 
of the preceding perceptions. For often a vivid impression 
has in a moment the effect of long habit, or of many ordinary 
perceptions oft repeated. 

28. Men act like brutes in so far as the sequences of their 
perceptions arise through the principle of memory only, like 
those empirical physicians who have mere practice without 
theory. We are all merely empiricists as regards three- 
fourths of our actions. For example, when we expect it to 
be day tomorrow, we are behaving as empiricists, because 
until now it has always happened thus. The astronomer 
alone knows this by reason. 

29. But it is the knowledge of necessary and eternal 
truths which distinguishes us from mere animals, and gives 
us reason and the sciences, raising us to knowledge of our- 
selves and God. It is this in us which we call the rational 
soul or mind. 

30. Further it is by the knowledge of necessary truths 
and by their abstractions that we are raised to acts of re- 
flection, which make us think of what is called the self, and 
consider that this or that is within us. And it is thus that in 
thinking of ourselves, we think of being, of substance, of the 
simple and the compound, of the immaterial and of God 
Himself, conceiving that what is limited in us, in Him is 
limitless. And these acts of reflection provide the chief 
objects of our reasonings. 

31. Our reasonings are based on two great principles: the 
principle of contradiction, by virtue of which we judge to be 
false that which involves a contradiction, and true that 
which is opposed or contradictory to the false; 

32. and the principle of sufficient reason, by virtue of which 
we consider that no fact can be real or existing and no pro- 


position can be true unless there is a sufficient reason, why 
it should be thus and not otherwise, even though in most 
cases these reasons cannot be known to us. 

33. There are also two kinds of truths: truths of reasoning 
and truths oifact. Truths of reasoning are necessary and 
their opposite is impossible; those of fact are contingent and 
their opposite is possible. When a truth is necessary, the 
reason for it can be found by analysis, that is, by resolving 
it into simpler ideas and truths until the primary ones are 

34. It is in this way that in mathematics speculative 
theorems and practical canons are reduced by analysis to 
definitions, axioms, and postulates. 

35. Finally there are simple ideas of which no definition 
can be given; there are also axioms or postulates, or in a word 
primary principles, which cannot be proved and have no 
need of proof. These are identical propositions, whose 
opposite contains an express contradiction. 

36. But a sufficient reason also must be found in the case of 
contingent truths or truths of fact; that is to say, in the case of 
the series of things spread over the universe of created 
things; otherwise resolution into particular reasons might 
go on into endless detail on account of the immense variety 
of things in nature and the division of bodies ad infinitum. 
There are an infinite number of shapes and motions, both 
present and past, which enter into the efficient cause of my 
present writing; and there are an infinite number of minute 
inclinations and dispositions of my soul, both present and 
past, which enter into its final cause. 

37. And as all this differentiation involves only other prior 
or more differentiated contingent things, all of which need a 
similar analysis to explain them, we are no further advanced : 
and the sufficient or ultimate reason must be outside the 
series of this differentiation of contingent things, however 
infinite it may be. 


38. This is why the ultimate reason of things must lie in 
a necessary substance, in which the differentiation of the 
changes only exists eminently as in their source; and this is 
what we call God. 

39. Now since this substance is a sufficient reason of all this 
differentiation, which is itself likewise all connected, there is 
only one God, and this God is enough. 

40. We may also judge that since this Supreme Substance, 
who is unique, universal, and necessary, has nothing outside 
Himself independent of Himself, and is a simple series of 
possible being, He must be incapable of being limited, and 
must contain just as much reality as is possible. 

41. Whence it follows that God is absolutely perfect, since 
perfection is nothing but magnitude of positive reality, in the 
strict sense, setting aside the limits or bounds in things which 
are limited. And there, where there are no bounds, that is 
to say in God, perfection is absolutely infinite. 

42. It follows also that created things owe their per- 
fections to the influence of God, but that they owe their 
imperfections to their own nature, which is incapable of 
being without limits. For it is in this that they are dis- 
tinguished from God. 

43. It is true likewise, that in God is the source not only of 
existences but also of essences, in so far as they are real, that 
is of all the reality there is in possibility. This is because 
the Understanding of God is the region of eternal truths 
and of the ideas on which they depend, and because without 
Him there would be nothing real in the possibilities not only 
nothing existent, but also nothing possible. 

44. For if there is a reality in essences or possibilities, or 
indeed in eternal truths, this reality must be founded on 
something existent and actual; and consequently on the 
existence of the Necessary Being in whom essence involves 
existence, or in whom to be possible is itself to be actual. 

45. Thus God alone (or the Necessary Being) has the 


privilege that He must exist if He is possible. And as nothing 
can prevent the possibility of that which has no limits, no 
negation, and consequently no contradiction, this alone is 
necessary to make us know the existence of God a priori. 
We have proved it also by the reality of eternal truths. And 
we have now just proved it a posteriori also, since there exist 
contingent beings, which can only have their ultimate or 
sufficient reason in the Necessary Being, who has the reason 
for His being in Himself. 

46. We must not, however, imagine, as some do, that 
because the eternal truths are dependent on God, they are 
therefore arbitrary and depend on His will, as Descartes, 
and after him M. Poiret, seem to have thought. This is true 
only of contingent truths, whose principle is fitness or the 
choice of the best] whereas necessary truths depend solely on 
His understanding, of which they are the internal object. 

47. Thus God alone is the primary Unity, or original simple 
substance, from which all monads, created and derived, are 
produced, and are born, so to speak, by continual figurations 
of the Divinity from moment to moment, limited by the 
receptivity of the created being, which is of its essence 

48. There is in God power, which is the source of every- 
thing, knowledge, which contains the differentiation of the 
ideas, and finally will, which causes change and production 
according to the principle of what is best. And these 
correspond to what provides the ground or basis in created 
monads, the perceptive faculty and the appetitive faculty. 
But in God these attributes are absolutely infinite or perfect, 
while in created monads or in entelechies (or perfectihdbiae, 
as Hermolaus Barbarus translated this word) there are only 
limitations of them, in proportion to the perfection there is 
in the monad. 

49. The created thing is said to act outwardly in so far as 
it has perfection, and to be passively affected by another in so 


far as it is imperfect. Thus activity is attributed to the 
monad in so far as it has distinct perceptions, and passivity 
in so far as it has confused perceptions. 

50. And one created thing is more perfect than another 
when there is found in it that which explains a priori what 
happens in the other; and it is because of this that we say 
that it acts upon the other. 

51. But in simple substances the influence of one monad 
over another is ideal only; it can have its effect only through 
the intervention of God, inasmuch as in the ideas of God a 
monad rightly demands that God, in regulating the rest from 
the beginning of things, should have regard to itself. For 
since it is impossible for a created monad to have a physical 
influence on the inner nature of another, this is the only way 
in which one can be dependent on another. 

52. And this is why actions and passions are mutual 
between created things. For when God compares two 
simple substances he finds in each reasons which oblige Him 
to adapt the other to it, and consequently what is active in 
certain aspects is passive from another point of view: active 
in so far as what is distinctly known in it explains what 
occurs in another, and passive in so far as what occurs in 
it is distinctly known in another. 

53. Now as there is an infinite number of possible uni- 
verses in the ideas of God, and as only one can exist, there 
must be a sufficient reason for God's choice, determining 
Him to one rather than to another. 

54. And this reason can only be found in the fitness, or 
in the degrees of perfection, which these worlds contain, 
each possible world having the right to claim existence in 
proportion to the perfection which it involves. 

55. And it is this which causes the existence of the best, 
which God knows through His wisdom, chooses through His 
goodness, and produces through His power. 

56. Now this connection or adaptation of all created 


things with each, and of each with all the rest, means that 
each simple substance has relations which express all the 
others, and that consequently it is a perpetual living mirror 
of the universe. 

57. And just as the same town, when looked at from 
different sides, appears quite different and is, as it were, 
multiplied in perspective, so also it happens that because of 
the infinite number of simple substances, it is as if there were 
as many different universes, which are however but different 
perspective representations of a single universe from the 
different points of view of each monad. 

58. And this is the means of obtaining as much variety as 
possible, but with the greatest order possible ; that is to say, 
it is the means of obtaining as much perfection as possible. 

59. Further it is this hypothesis alone (which I venture to 
regard as proved) which properly exalts the greatness of God. 
This M. Bayle recognized, when in his Dictionary (in the 
article 'Rorarius') he made objections, in which he was even 
inclined to believe that I attributed too much to God, and 
more than is possible. But he could not advance any reason 
why this universal harmony, which causes each substance 
exactly to express all the others through the relations which 
it has with them, should be impossible. 

60. Moreover, it is evident from what I have just said that 
there are a priori reasons why things could not be otherwise 
than they are: namely, because God in regulating the whole 
had regard to each part, and particularly to each monad. 
The nature of the monad is representative, and consequently 
nothing can limit it to representing a part of things only, 
although it is true that its representation is confused as 
regards the detail of the whole universe and can only be 
distinct as regards a small part of things; that is to say as 
regards those which are either the nearest or the largest in 
relation to each of the monads ; otherwise each monad would 
be a divinity. It is not in the object, but in the modification 


of the knowledge of the object, that monads are limited. In 
a confused way they all go towards the infinite, or towards 
the whole; but they are limited and distinguished from one 
another by the degrees of their distinct perceptions. 

61. And in this the compounds symbolize the simples. 
For as the whole is a plenum, which means that the whole 
of matter is connected, and as in a plenum every movement 
has some effect on distant bodies in proportion to their dis- 
tance, so that each body not only is affected by those which 
touch it, and is in some way sensitive to whatever happens 
to them, but also by means of them is sensitive to those which 
touch the first bodies by which it is itself directly touched; 
it follows that this communication stretches out indefinitely. 
Consequently every body is sensitive to everything which is 
happening in the universe, so much so that one who saw 
everything could read in each body what is happening every- 
where, and even what has happened or what will happen, by 
observing in the present the things that are distant in time 
as well as in space; av^irvoia iravra, as Hippocrates said. 
But a soul can only read in itself what is distinctly represented 
there; it is unable to develop all at once all the things that 
are folded within it, for they stretch to infinity. 

62. Thus although each created monad represents the 
whole universe, it represents more distinctly the body which 
is particularly affected by it, and whose entelechy it is: and 
as this body expresses the whole universe by the connection 
of all matter in the plenum, the soul represents the whole 
universe also in representing the body which belongs to it in 
a particular way. 

63. The body belonging to a monad, which is that body's 
entelechy or soul, constitutes together with the entelechy 
what may be called a living thing, and with the soul what is 
called an animal. Now this body of a living thing or animal 
is always organic; for since every monad is in its way a mirror 
of the universe, and since the universe is regulated in a 


perfect order, there must also be an order in that which 
represents it, that is to say in the perceptions of the soul, 
and consequently in the body, according to which order the 
universe is represented therein. 

64. Thus each organic body of a living thing is a kind 
of divine machine, or natural automaton, which infinitely 
surpasses all artificial automata. Because a machine, which 
is made by the art of man, is not a machine in each of its parts ; 
for example, the tooth of a metal wheel has parts which as 
far as we are concerned are not artificial and which have 
about them nothing of the character of a machine, in relation 
to the use for which the wheel was intended. But the 
machines of nature, that is to say living bodies, are still 
machines in the least of their parts ad infinitum. This it is 
which makes the difference between nature and art, that is 
to say between Divine art and ours. 

65. And the Author of nature was enabled to practise this 
divine and infinitely marvellous artifice, because each portion 
of matter is not only infinitely divisible, as the ancients 
recognized, but is also actually subdivided without limit, 
each part into further parts, of which each one has some 
motion of its own: otherwise it would be impossible for each 
portion of matter to express the whole universe. 

66. Whence it is evident that there is a world of created 
beings living things, animals, entelechies, and souls in the 
least part of matter. 

67. Each portion of matter may be conceived as a garden 
full of plants, and as a pond full of fish. But every branch 
of each plant, every member of each animal, and every drop 
of their liquid parts is itself likewise a similar garden or pond. 

68. And although the earth and the air interspersed be- 
tween the plants in the garden, or the water interspersed 
between the fish in the pond, are neither plant nor fish, yet 
they still contain them, though most usually of a subtlety 
which renders them imperceptible to us. 



69. Thus there is nothing waste, nothing sterile, nothing 
dead in the universe; no chaos, no confusions, save in appear- 
ance. We might compare this to the appearance of a pond 
in the distance, where we can see the confused movement and 
swarming of the fish, without distinguishing the fish them- 

70. Thus we see that each living body has a dominant 
entelechy, which in the case of an animal is the soul, but the 
members of this living body are full of other living things, 
plants and animals, of which each has in turn its dominant 
entelechy or soul. 

71. But we must not imagine, as some have done who 
have misunderstood my view, that each soul has a mass or 
portion of matter appropriate or attached to itself for ever, 
and that it consequently possesses other inferior living things, 
for ever destined to its service. For all bodies are in a 
perpetual flux like rivers, and parts are passing in and out 
of them continually. 

72. Thus the soul only changes its body bit by bit and by 
degrees, so that it is never despoiled of all its organs all 
together; in animals there is often metamorphosis, but never 
metempsychosis, nor transmigration of souls: neither are 
there any entirely separate souls, nor superhuman spirits 
without bodies. God alone is entirely detached from body. 

73. It is because of this also that there is never, strictly 
speaking, absolute generation nor perfect death, consisting 
in the separation of the soul. And what we call generation 
is a development and a growth, while what we call death is an 
envelopment and a diminution. 

74. Philosophers have been much embarrassed over the 
origin of forms, entelechies or souls. But to-day when 
exact researches on plants, insects, and animals have revealed 
the fact that the organic bodies of nature are never produced 
from a chaos or from putrefaction, but always from seeds, 
wherein there was certainly some preformationj we conclude 


not only that the organic body was already present before 
conception, but also that there was a soul in this body; that, 
in a word, the animal itself was present, and that by means 
of conception it was merely prepared for a great transforma- 
tion, so as to become an animal of another kind. We even 
see something of this kind apart from birth, as when worms 
become flies, and caterpillars become butterflies. 

75. The animals, of which some are raised by means of 
conception to the rank of the larger animals, may be called 
spermatic-, but those among them which remain in their own 
kind (and they are the greater number) are born, multiply, 
and are destroyed like the large animals; and there is only a 
small number of elect ones who pass to a wider sphere. 

76. But this is only half the truth. And so I judged that 
if the animal never begins naturally, neither does it end 
naturally; and that not only will there be no birth, but also 
no complete destruction, no death, strictly speaking. And 
these reasonings, which are a posteriori and derived from 
experience, agree perfectly with the principles I previously 
deduced a priori. 

77. Thus one may say that not only is the soul (the mirror 
of an indestructible universe) itself indestructible, but so also 
is the animal itself, although its machine may often perish in 
part, and cast off or put on particular organic integuments. 

78. These principles provide me with a way of explaining 
naturally the union, or rather the conformity, of the soul and 
the organic body. The soul follows its own laws, and the 
body its own likewise, and they accord by virtue of the 
harmony pre-established among all substances, since they are 
all representations of one and the same universe. 

79. Souls act according to the laws of final causes by 
appetitions, ends, and means. Bodies act according to the 
laws of efficient causes by motions. And the two kingdoms, 
of efficient and of final causes, are in harmony with one 


80. Descartes recognized that souls cannot give force to 
bodies because there is always the same quantity of force in 
matter. He believed, however, that the soul could change 
the direction of bodies. But this is because in his day the 
law of nature was not known which affirms the conservation 
of the same total direction in matter. Had he noticed this, 
he would have stumbled upon my system of Pre-established 

8 1 . Under this system, bodies act as though, per tmposstbtle, 
there were no souls: and souls act as if there were no bodies, 
and both act as if each influenced the other. 

82. As for minds or rational souls, although I find that 
what I have just been saying is at bottom true of all living 
beings and animals (that is to say that the animal and the 
soul only begin with the world and do not come to an end 
any more than the world comes to an end), yet rational 
animals are peculiar in this, that their little spermatic 
animals, so long as they are that merely, have only ordinary 
or sensitive souls; but as soon as those which are, so to speak, 
elect arrive by an actual conception at human nature, then 
their sensitive souls are raised to the rank of reason and to 
the prerogative of minds. 

83. Among other differences which exist between ordinary 
souls and minds, some of which I have already pointed out, 
there is also this, that souls in general are the living mirrors 
or images of the universe of created things, whereas minds 
are also images of the Divinity Himself, or the Author of 
nature, capable of knowing the system of the universe, and 
of imitating something of it by architectonic patterns, each 
mind being as it were a little divinity in its own department. 

84. This it is which renders minds capable of entering 
into a kind of society with God, and makes His relation to 
them not only that of an inventor to his machine (which is 
God's relation to the rest of created things) but also that of a 
prince to his subjects, and even of a father to his children. 


85. From this it is easy to conclude that the assemblage 
of all minds must make up the City of God, that is to say 
the most perfect possible state under the most perfect of 

86. This City of God, this truly universal monarchy, is a 
moral world in the natural world, and is the most exalted 
and the most divine of God's works, and in it truly consists 
His glory, since He could not be glorified if His greatness and 
goodness were not known and wondered at by minds: it is 
also in relation to this divine City that He may properly be 
said to have goodness, whereas His wisdom and power are 
manifested everywhere. 

87. As we have established above a perfect harmony 
between two natural kingdoms, the one of efficient and the 
other of final causes, we ought here also to point out another 
harmony between the physical kingdom of nature and the 
moral kingdom of grace; that is to say between God as 
Architect of the machine of the universe, and God as 
Monarch of the divine City of Minds. 

88. This harmony means that things conduce to grace by 
the very ways of nature, and that this globe, for example, 
must be destroyed and repaired by natural ways at the times 
demanded by the government of minds for the chastisement 
of some and the reward of others. 

89. It can further be said that God as Architect satisfies 
God as Lawgiver in everything, and that thus sins carry their 
punishment with them by the order of nature, and by virtue 
of the mechanical structure of things itself; and that in the 
same way noble actions will attract their rewards by ways 
which are mechanical as far as bodies are concerned, although 
this cannot and should not always happen immediately. 

90. Finally, under this perfect government there will be no 
good action without reward, no evil action without punish- 
ment, and everything must turn out for the good of the 
righteous, of those, that is, who are not dissatisfied in this 


great State, who trust in Providence when they have done 
their duty, and who love and imitate fittingly the Author of 
all good, delighting in the consideration of His perfections 
after the manner of true pure love, which makes us take 
pleasure in the happiness of the beloved. This it is which 
makes the wise and virtuous work for whatever seems to 
conform with the presumptive or antecedent will of God, and 
yet leaves them satisfied with what God in fact causes to 
happen by His secret will, which is consequent and decisive, 
recognizing as they do that if we could sufficiently understand 
the order of the universe, we should find that it surpasses the 
desires of the most wise, and that it is impossible to make it 
better than it is, not only for the whole in general, but also 
for ourselves in particular, if we are attached as we should be 
to the Author of the whole, not merely as to the Architect and 
efficient Cause of our being, but also as to our Master and the 
final Cause which must constitute the whole end of our will, 
and which alone can constitute our happiness. 

ON REASON. 1714 

1. Substance is a being capable of action. It is simple or 
compound. Simple substance is that which has no parts. 
Compound substance is the combination of simple substances 
or monads. Monas is a Greek work which signifies unity or 
that which is one. Compounds or bodies are pluralities, and 
simple substances that is lives, souls, minds are unities. 
There must necessarily be simple substances everywhere, 
because without simple substances there could be no com- 
pounds; consequently the whole of nature is full of life. 

2. Monads, having no parts, cannot be made or unmade. 
They can neither begin nor end naturally, and consequently 
they last as long as the universe, which will be changed but 
not destroyed. They cannot have shapes, otherwise they 
would have parts. Thus one monad, in itself and at a par- 
ticular moment, can only be distinguished from another by 
internal qualities and activities, which can be nothing else 
but its perceptions (that is to say, the representations in the 
simple of the compound or of that which is outside) and its 
appetitions (that is to say, its tendencies to pass from one 
perception to another), which are the principle of change. 
For the simplicity of substance does not preclude the pos- 
sibility of a multiplicity of modifications, which indeed 
necessarily exist together in the same simple substance, and 
these modifications must consist in the variety of the relations 
of the simple substance to things which are outside. Just 
as in a centre or point, in itself perfectly simple, are found an 
infinite number of angles formed by the lines which meet 



3. All nature is a plenum. Everywhere there are simple 
substances, effectively separated from one another by actions 
of their own which are continually altering their relations; 
and each simple substance or distinct monad, which forms 
the centre of a compound substance (e.g. of an animal) and 
the principle of its oneness, is surrounded by a mass composed 
of an infinite number of other monads which constitute the 
body belonging to this central monad; corresponding to the 
affections of its body it represents, as in a kind of centre, the 
things which are outside of it. And this body is organic, when 
it forms a kind of automaton or natural machine, which is a 
machine not only as a whole but also in its smallest observ- 
able parts. And since because the world is a plenum every- 
thing is connected together, and each body acts on every other 
body more or less according to the distance, and is affected by 
it by reaction, it follows that every monad is a mirror that is 
alive or endowed with inner activity, is representative of the 
universe from its own point of view, and is as much regulated 
as the universe itself. The perceptions in the monad spring 
from one another according to the laws of the appetites or 
the final causes of good, and evil, which consist in the observable 
perceptions, regulated or unregulated in the same way as 
the changes of the bodies and the phenomena outside spring 
from one another according to the laws of efficient causes, 
that is to say of motions. Thus there is a perfect harmony 
between the perceptions of the monad and the motions of the 
bodies, pre-established at the outset between the system of 
efficient causes and the system of final causes. Herein 
consists the concord and the physical union of the soul and 
the body, which exists without the one being able to change 
the laws of the other. 

4. Each monad, together with a particular body, makes a 
living substance. Thus there is not only life everywhere, 
joined to members or organs, but there are also infinite 
degrees of it in the monads, some of them more or less 


dominating over others. But when the monad has its 
organs adjusted in such a way that by means of them the 
impressions they receive, and consequently the perceptions 
which represent them, are distinguished and heightened (as, 
for example, when by means of the shape of the humours of 
the eye rays of light are concentrated and act with more 
force), this may amount to sensation, that is to say, to a per- 
ception accompanied by memory a perception, to wit, of 
which a certain echo long remains to make itself heard on 
occasion. Such a living being is called an animal, as its 
monad is called a soul. And when this soul is raised to the 
level of reason, it is something more sublime, and is reckoned 
as a mind, as will be explained later. It is true that animals 
are sometimes in the condition of simple living beings and 
their souls in the condition of simple monads, to wit, when 
their perceptions are not sufficiently distinguished to be 
remembered, as occurs in a deep dreamless sleep or in a swoon. 
But perceptions which have become entirely confused must 
necessarily be developed again in animals, for reasons I 
shall give below (12). Thus it is well to distinguish be- 
tween perception which is the inner state of the monad 
representing external things, and apperception, which is 
consciousness, or the reflective knowledge of this inner state, 
and which is not given to all souls, nor at all times to the 
same soul. It is for want of this distinction that the 
Cartesians made the mistake of taking no account of per- 
ceptions which are not apperceived, as common people take 
no account of insensible bodies. It is this also which made 
these same Cartesians believe that minds alone are monads, 
and that there are no souls in animals, and still less other 
principles of life. And while, in thus denying sensations to 
animals, they have gone against the common opinion of men 
too much, so they have, on the other hand, taken too much 
account of the prejudices of the vulgar, in confusing a long 
stupor, which arises from a great confusion of perceptions, 


with actual death, in which all perception would cease. This 
teaching of theirs has confirmed the ill-founded belief in the 
destruction of some souls, and the pernicious view of certain 
people, supposed to be free-thinkers, who have denied the 
immortality of ours. 

5. There is a connection between the perceptions of 
animals, which bears some resemblance to reason: but it is 
based only on the memory of facts or effects, and not at all 
on the knowledge of causes. Thus a dog runs away from 
the stick with which he has been beaten, because memory 
represents to him the pain which was caused by that stick. 
And men, in so far as they are empiricists, that is to say 
in three-fourths of their actions, only act like brutes. For 
example, we expect that day will dawn tomorrow, because 
we have always experienced it to be so; it is only the 
astronomer who foresees it by reason, and even this pre- 
diction will ultimately fail when the cause of daylight, which 
is not eternal, ceases. But true reasoning depends on 
necessary or eternal truths (like the truths of logic, numbers, 
and geometry) which make the connection of ideas indubit- 
able, and the sequences inevitable. Animals in which such 
sequences cannot be observed are called brutes; but those 
which know these necessary truths are called rational 
animals, and their souls are called minds. These souls are 
capable of performing acts of reflection, and of considering 
what is called self, substance, soul, mind those things and 
truths, in short, which are immaterial. It is this which 
makes us capable of understanding science or demonstrative 

6. The researches of the moderns have taught us, and it is 
approved by reason, that the living things whose organs we 
know, that is to say plants and animals, do not come from 
putrefaction or chaos as the ancients believed, but from 
pre-f armed seeds, and consequently from the transformation 
of pre-existing living things. There are little animals in the 


seeds of the large ones, which by means of conception assume 
a new vesture, which they appropriate, and which enables 
them to be nourished and to grow, so as to pass on to a wider 
stage, and propagate the large animal. It is true that the 
souls of human spermatic animals are not rational and only 
become so when through conception these animals are 
destined for human nature. And as animals are usually not 
born completely in conception or generation, so neither do 
they perish completely in what we call death, for it is reason- 
able that what does not begin naturally should not come to 
an end in the order of nature either. Thus, casting off their 
masks or their rags, they merely return to a more subtle scene, 
on which, however, they can be as sensible and as well ordered 
as on the greater one. And what has just been said of large 
animals occurs also in the generation and death of these 
spermatic animals themselves; that is to say, they have grown 
from other smaller spermatic animals, in comparison with 
which they can be reckoned large; for everything in nature 
proceeds ad infinitum. Thus not only souls but animals also 
are ingenerable and imperishable: they are only developed, 
enveloped, reclad, stripped, transformed; souls never leave 
the whole of their body, and do not pass from one body to 
another which is entirely new to them. Thus there is no 
metempsychosis, but there is metamorphosis. Animals change, 
take on and put off parts only: in nutrition this takes place 
bit by bit, and by small insensible parts, but continually, 
while in conception and death when much is acquired or 
lost all at one time the change takes place rarely, but all at 
once and in a way that can be noticed. 

7. Up till now we have spoken as physicists merely; now 
we must rise to metaphysics, making use of the great principle, 
commonly but little employed, which holds that nothing takes 
place without sufficient reason, that is to say that nothing 
happens without its being possible for one who has enough 
knowledge of things to give a reason sufficient to determine 


why it is thus and not otherwise. This principle having been 
laid down, the first question we are entitled to ask will be: 
Why is there something rather than nothing ? For 'nothing' is 
simpler and easier than 'something'. Further, supposing 
that things must exist, it must be possible to give a reason 
why they must exist just as they do and not otherwise. 

8. Now this sufficient reason of the existence of the 
universe cannot be found in the series of contingent things, 
that is to say, of bodies and of their representations in souls. 
For since matter is in itself indifferent to motion or to rest, 
and to one motion rather than another, it cannot itself 
contain the reason of motion, still less of a particular motion. 
And although the present motion which is in matter arises 
from the one before it, and this in its turn from the one 
before that, we are no further on however far we go; for the 
same question always remains. Thus the sufficient reason, 
which needs no further reason, must be outside this series of 
contingent things, and must lie in a substance which is the 
cause of this series, or which is a being that bears the reason 
of its existence within itself; otherwise we should still not 
have a sufficient reason, with which we could stop. And 
this final reason of things is called God. 

9. This simple primary substance must include eminently 
the perfections which are contained in the derivative sub- 
stances which are its effects. Thus it will have perfect power, 
knowledge, and will; that is to say, it will have omnipotence, 
omniscience, and supreme goodness. And as justice, taken in 
a very general sense, is nothing other than goodness in con- 
formity with wisdom, there must clearly also be supreme 
justice in God. Reason, which has made things exist 
through Him, makes them also depend on Him in their 
existence and operation; and they are continually receiving 
from Him that which endows them with some perfection; 
but any imperfection which they retain comes from the 
essential and original limitations of the created thing. 


10. It follows from the supreme perfection of God that in 
producing the universe He chose the best possible plan, con- 
taining the greatest variety together with the greatest order; 
the best arranged situation, place; and time, the greatest 
effect produced by the simplest means; the most power, the 
most knowledge, the most happiness and goodness in created 
things of which the universe admitted. For as all possible 
things have a claim to existence in the understanding of 
God in proportion to their perfections, the result of all these 
claims must be the most perfect actual world which is 
possible. Otherwise it would not be possible to explain 
why things have happened as they have rather than 

11. The supreme wisdom of God has made Him choose 
especially the laws of motion, which are the best adjusted 
and the most fitted to abstract and metaphysical reasons. 
According to them there is always conserved the same 
quantity of total and absolute force or activity; the same 
quantity of relative force or reaction; the same quantity, 
finally, of force of direction. Moreover the activity is 
always equal to the reaction, aud the whole effect is always 
equivalent to its full cause. It is surprising that those 
laws of motion discovered in our day, some of which I 
have myself discovered, cannot be explained merely by the 
consideration of efficient causes or of matter. For I have 
found that it is necessary to have recourse to final causes, 
and that these laws do not depend on the principle of necessity 
as do the truths of logic, arithmetic, and geometry, but on 
the principle of fitness, that is to say on the choice of wisdom. 
Thus it is one of the most effective and sensible proofs of the 
existence of God for those who are able to go deeply into 
these matters. 

12. It follows, further, from the perfection of the Supreme 
Author, that not only is the order of the whole universe the 
most perfect possible, but also that each living mirror which 


represents the universe from its own point of view, that is 
to say each monody each substantial centre, must have its 
perceptions and appetites regulated in the best way which is 
compatible with all the rest. From which it follows that 
sotdsj that is to say the most dominant monads, or rather 
animals themselves, cannot fail to wake up from the state of 
stupor in which they may be placed by death or by some 
other accident. 

13. For everything is regulated in things once for all with 
as much order and agreement as possible, since supreme 
wisdom and goodness cannot act without perfect harmony: 
the present is big with the future, what is to come could be 
read in the past, what is distant expressed in what is near. 
The beauty of the universe could be learnt in each soul, 
could one unravel all its folds which develop perceptibly 
only with time. But as each distinct perception of the 
soul includes an infinite number of confused perceptions 
which embrace all the universe, the soul itself does not know 
the things which it perceives, except in so far as it has per- 
ceptions of them which are distinct and heightened: and it 
has perfection in proportion to its distinct perceptions. Each 
soul knows the infinite, knows everything, but confusedly. 
Just as when I am walking along the shore of the sea and 
hear the great noise it makes, though I hear the separate 
sounds of each wave of which the total sound is made up, I 
do not discriminate them one from another; so our confused 
perceptions are the result of the impressions which the whole 
universe makes on us. It is the same with each monad. 
God alone has a distinct knowledge of everything, for He is 
the source of everything. It has been very well said that as 
a centre He is everywhere; but His circumference is nowhere, 
since everything is present to Him immediately, without 
being removed from this centre. 

14. As regards the rational soul or mind, there is in it 
something more than in monads, or even in simple souls. 


It is not only a mirror of the universe of created things, but 
also an image of the Deity. The mind not only has a percep- 
tion of the works of God, but is even capable of producing 
something like them, though on a small scale. For, not to 
mention the wonders of dreams, in which we invent without 
effort (but also without will) things we could only discover 
after much thinking when awake, our soul is architectonic 
in its voluntary activities also, and, discovering the sciences 
in accordance with which God had regulated things (pondere, 
mensura, numero, 1 etc.), it imitates in its own sphere, and in 
the little world in which it is allowed to act, what God per- 
forms in the great world. 

15. For this reason all minds, whether of men or super- 
human spirits, entering as they do by virtue of reason and 
the eternal verities into a kind of society with God, are 
members of the City of God, that is to say of the most 
perfect state, formed and governed by the greatest and 
best of monarchs: where there is no crime without punish- 
ment, no good action without proportionate reward, and 
finally as much virtue and happiness as is possible; and this, 
not by any derangement of nature, as if what God has in 
store for the soul might disturb the laws of the body, but by 
the actual order of natural things, by virtue of the harmony 
pre-established from all time between the realms of nature 
and of grace, between God as Architect and God as Monarch, 
in such a way that nature itself leads to grace, and grace 
perfects nature in making use of it. 

16. Thus although reason cannot teach us the details of 
the great future, which are reserved for revelation, we can 
rest assured by this same reason that things are accomplished 
in a manner which exceeds our desires. Since, too, God is 
the most perfect and the most happy and consequently the 
most lovable of substances, and since pure true love consists 
in the state which causes pleasure to be felt in the perfections 

1 'by weight, measure, number', etc. 


and happiness of the beloved, this love ought to give us the 
greatest pleasure of which a man is capable, when God is 
the object of it. 

17. It is easy to love Him as we ought if we know Him as 
I have described. For although God is not sensible to our 
external senses, He is none the less very lovable and gives 
great pleasure. We see how much pleasure men derive from 
honours, although they do not consist of qualities that appear 
to the external senses. Martyrs and fanatics (although the 
affection of the latter is ill regulated) show of what the 
pleasure of the mind is capable: and what is more, even the 
pleasures of the senses are in the last resort intellectual 
pleasures, confusedly known. Music charms us although its 
beauty only consists in the harmony of numbers, and in the 
account which we do not notice, but which the soul none the 
less takes, of the beating or vibration of sounding bodies, 
which meet one another at certain intervals. The pleasures 
which the eye finds in proportions are of the same kind, and 
those caused by the other senses amount to much the same 
thing, although we may not be able to explain it so dis- 

18. It may even be affirmed that love of God gives us 
here and now a foretaste of future felicity. And although 
it is disinterested, it constitutes of itself our greatest good and 
interest, even though we may not seek them in it, and con- 
sider only the pleasure which it gives without regard to the 
utility it produces; for it gives us a perfect confidence in 
the goodness of our Author and Master, which produces a 
true tranquillity of mind, not as in the Stoics, who resolutely 
force themselves to patience, but by a present contentment, 
which further assures us a future happiness. And apart 
from the present pleasure, nothing could be more useful for 
the future, for the love of God also fulfils our hopes, and 
leads us in the way of supreme happiness, because in virtue 
of the perfect order established in the universe, everything 


is done in the best possible way, as much for the general 
good as also for the greatest particular good of those who 
believe in it, and who are satisfied by the Divine government: 
which cannot fail to be the case with those who know how to 
love the Source of all good. It is true that supreme happiness 
(with whatever beatific vision, or knowledge of God, it may 
be accompanied) can never be complete because God, being 
infinite, cannot be entirely known. Thus our happiness will 
never consist, and ought not to consist, in a complete enjoy- 
ment, in which there would be nothing left to desire, and 
which would make our mind stupid, but in a perpetual 
progress to new pleasures and new perfections. 


23 NOVEMBER 1697 

BESIDES the world or aggregate of finite things we find a 
certain Unity which is dominant, not only in the sense in 
which the soul is dominant in me, or rather in which the self 
or / is dominant in my body, but also in a much more exalted 
manner. For the dominant Unity of the universe not only 
rules the world, but also constructs or makes it; and it is 
higher than the world and, if I may so put it, extramundane; 
it is thus the ultimate reason of things. Now neither in any 
one single thing, nor in the whole aggregate and series of 
things, can there be found the sufficient reason of existence. 
Let us suppose the book of the elements of geometry to have 
been eternal, one copy always having been written down 
from an earlier one; it is evident that, even though a reason 
can be given for the present book out of a past one, never- 
theless out of any number of books taken in order going 
backwards we shall never come upon a full reason; though we 
might well always wonder why there should have been such 
books from all time why there were books at all, and why 
they were written in this manner. What is true of the books 
is true also of the different states of the world; for what 
follows is in some way copied from what precedes (even 
though there are certain laws of change). And so, however 
far you go back to earlier states, you will never find in those 
states a full reason why there should be any world rather 
than none, and why it should be such as it is. 

Indeed, even if you suppose the world eternal, as you will 
still be supposing nothing but a succession of states and will 
not in any of them find a sufficient reason, nor however many 



states you assume will you advance one step towards giving 
a reason, it is evident that the reason must be sought else- 
where. For in things which are eternal, though there may 
be no cause, nevertheless there must be known a reason; 
which reason in things that are permanent is necessity 
itself or essence, but in the series of changeable things (if 
this be supposed to be an eternal succession from an earlier 
to a later) it will be, as will be presently understood, the 
prevailing of inclinations, in a sphere where reasons do not 
necessitate (by an absolute or metaphysical necessity, in 
which the contrary implies a contradiction), but incline. 
From this it is evident that even by supposing the world 
to be eternal we cannot escape the ultimate, extra-mundane 
reason of things, or God. 

The reasons of the world then lie in something extra- 
mundane, different from the chain of states, or series of 
things, whose aggregate constitutes the world. And so we 
must pass from physical or hypothetical necessity, which 
determines the subsequent things of the world by the earlier, 
to something which is of absolute or metaphysical necessity, 
for which itself no reason can be given. For the present 
world is necessary physically or hypothetically, but not 
absolutely or metaphysically. In other words, when once it 
is determined that it shall be such and such, it follows that 
such and such things will come into being. Since then the 
ultimate root must be in something which is of metaphysical 
necessity, and since there is no reason of any existent thing 
except in an existent thing, it follows that there must exist 
some one Being of metaphysical necessity, that is, from whose 
essence existence springs; and so there must exist something 
different from the plurality of beings, that is the world, which, 
as we have allowed and have shown, is not of metaphysical 

Let me explain a little more distinctly how out of truths 
that are eternal or essential or metaphysical there arise 


truths that are temporal, contingent, or physical. First we 
must notice, from the very fact that something exists rather 
than nothing, that there is in things that are possible, or in 
possibility of essence itself, a certain need for existence, or 
(if I may so put it) a claim to exist; and, to put it bluntly, 
that essence in itself tends towards existence. From this it 
further follows that all things which are possible, or express 
essence or possible reality, tend by equal right towards 
existence in proportion to the quantity of essence or reality 
which they include, or in proportion to the stage of perfection 
which belongs to them; for perfection is nothing else than 
quantity of essence. 

Hence it is seen to be most evident that out of the infinite 
combination of possibles, and the infinite possible series, that 
one exists by whose means the greatest possible amount of 
essence or possibility is brought into existence. There is 
always, I take it, to be found in things a principle of de- 
termination which turns on considerations of greatest and 
least; namely, that the greatest effect should be produced 
with (if I may so put it) the least expenditure. And the 
time, the place, or (in a word) the receptivity or capacity of 
the world, may here be taken to be the expenditure or 
ground, on which a building is to be raised as fittingly as 
possible, while the variety of forms is in accordance with the 
fitness of the building and with the number and elegance 
of its rooms. It is very much like what happens in certain 
games, in which all the spaces on the board have to be filled 
in according to certain rules: unless you show some ingenuity 
you will find yourself at the end kept out of certain refractory 
spaces, and thereby compelled to leave empty more spaces 
than you need have done, and more than you wished. There 
is, however, a definite formula by which the greatest possible 
success in filling the spaces is easily obtained. For instance, 
if we suppose ourselves told to construct a triangle, there 
being no other principle of determination, the result is that 


we draw an equilateral triangle; and if we are required to go 
from one point to another, and nothing further is added to 
determine the way, we shall choose the path that is easiest or 
shortest. Similarly, once it has been granted that a being is 
better than a not-being, that is, that there is a reason why 
something should exist rather than nothing, or that transition 
from possibility to actuality is to take place, then, even if 
nothing further is determined, the consequence is that there 
exists as much as is possible in view of the capacity of time 
and place (or of the possible order of existing) in very much 
the same way as tiles are fitted together so as to put in as 
many as possible within the given area. 

From this it is now wonderfully clear how in the very 
origination of things a certain Divine mathematics or 
metaphysical mechanics is employed, and how the greatest 
quantity comes to be determined. It is on this principle that 
of all the angles the right angle is the determined angle in 
geometry, and that liquids when placed in heterogeneous 
media form themselves into the most capacious shape, that 
is, the spherical; but the best instance of all is that in com- 
mon mechanics itself, when several heavy bodies are operating 
against one another, the result is that movement which 
secures the greatest descent on the whole. For just as all 
things that are possible with equal right tend towards 
existence in proportion to their reality, so in the same way 
all weights with equal right tend towards descent in pro- 
portion to their gravity; and just as in the latter case there 
results a motion involving the greatest possible descent of 
the heavy bodies, so in the former case there results a world 
involving the greatest production of things that are possible. 

Thus we now have physical necessity based on metaphysical 
necessity. For although the world is not metaphysically 
necessary, so that its contrary would imply a contradiction 
or logical absurdity, nevertheless it is necessary physically, 
that is, determined in such a way that its contrary would 


imply imperfection or moral absurdity. And as possibility 
is the principle of essence, so perfection or degree of essence 
(which makes the largest number of things compossible) is 
the principle of existence. This makes it evident at the 
same time how there can be freedom in the Author of the 
world, although He does everything determinately, because 
He acts from the principle of wisdom or perfection. In- 
difference arises from ignorance, and the wiser a man is, the 
more is he determined to that action which is most perfect. 

But (you will say) this comparison of a certain metaphysical 
determining mechanism with the physical mechanism of 
heavy bodies, elegant though it may appear, has nevertheless 
this fault: there really exist heavy bodies acting against one 
another, but possibilities or essences prior to or beyond 
existence are imaginary or fictitious, and therefore it is of 
no use to seek in them the reason of existence. I answer, 
that neither the essences nor the truths about them which 
are known as eternal truths, are fictitious; they exist (if I may 
so put it) in a certain region of ideas, that is, in God Himself, 
the fount of all essence and of the existence of everything. 
That this is no merely arbitrary assertion is shown by the 
very existence of the actual series of things. For since in the 
series a reason cannot be found, as I have shown above, but 
must be sought in metaphysical necessities or eternal truths; 
since, too, existent things cannot come into being except 
from existent things, as I have explained previously; it 
follows that eternal truths must have their existence in some 
subject which is absolutely or metaphysically necessary, 
that is in God, through whom these truths, which would 
otherwise be imaginary, are (to use a barbarous but ex- 
pressive word) realized. 1 

And indeed in actual fact we find that everything in the 
world takes place in accordance with the laws of the eternal 
truths, not only geometrical but also metaphysical laws; 
1 The word realisentur is a barbarism in Latin. 


that is, not only according to material necessities, but also 
according to formal necessities. This is not only true 
in general, in regard to the reason (which I have just ex- 
plained) why the world should exist rather than not, and why 
it should exist just as it is rather than otherwise (this reason 
is certainly to be found in the tendency of what is possible 
towards existence); but more than this, if we come down to 
details, we see the marvellous way in which metaphysical 
laws hold sway in the whole of nature the laws of cause, of 
potency, of activity, and how they prevail even over the 
purely geometrical laws of matter themselves, as I found 
to my great wonder when I was giving an account of the 
laws of motion; so much so, indeed, that though from my 
early youth, when I was more of a materialist, I had defended 
the law of the geometric composition of forces, I was finally 
forced to abandon it, as I have explained at greater length 

Here then we have the ultimate reason of the reality both 
of essences and of existences in a Unity, which must certainly 
be greater, higher, and prior to the world itself, since through 
it alone not only the existent things, which the world contains, 
but also the things that are possible have their reality. It 
cannot be found except in one single source, because of the 
interconnection of all these things with one another. It is 
evident that from this source existent things are continually 
issuing and being produced, and have been produced, since 
it is not clear why one state of the world rather than another, 
yesterday's state rather than today's, should flow from the 
world itself. It is also evident how God acts not only 
physically but also freely; and how there lies in Him not only 
the efficient but also the final cause; and how from Him 
proceeds the reason not only of the greatness or potency 
that there is in the mechanism of the universe as now 
established, but also of the goodness or wisdom involved in 
the establishing of it. 


In case someone may think that moral perfection or good- 
ness is here being confused with metaphysical perfection or 
greatness, and may admit the latter while denying the 
former, it should be pointed out that it follows from what has 
been said not only that the world is the most perfect physic- 
ally, or, if you prefer it, metaphysically, or in other words 
that that series of things will be forthcoming which in actual 
fact affords the greatest quantity of reality, but also that 
the world should be the most perfect morally, because true 
moral perfection is physical perfection in minds themselves. 
Hence the world is not only the most wonderful machine, 
but also in regard to minds it is the best commonwealth, by 
whose means there is bestowed on minds the greatest possible 
amount of felicity or joyfulness; and it is in this that their 
physical perfection consists. 

But, you will say, we find in the world the very opposite 
of this. Often the worst of sufferings fall upon the best men; 
the innocent (I speak not only of the brutes, but of men also) 
are afflicted, and are slain even with tortures; indeed the 
world, especially if we look at the government of the human 
race, seems rather a confused chaos than an affair ordained 
by some supreme wisdom. So it appears at first sight, I 
allow: but on deeper examination it must be agreed that the 
opposite is the case. It is evident a priori from those very 
principles which I have adduced that without doubt there is 
secured in the world the highest perfection that there could 
possibly be of all things, and therefore of minds. 

And indeed it is unreasonable, as the lawyers say, to 
give a judgment without inspecting the whole law. We have 
knowledge of a tiny part of that eternity which stretches out 
immeasurably. For how small a thing is the memory of the 
few thousand years which history hands down to us! And 
yet out of so little experience we rashly make judgments 
about the immeasurable and the eternal; just as men who 
had been born and bred in prison or in the subterranean 


salt-mines of Sarmatia might think that there was no other 
light in the world than the treacherous flicker of torches, 
which was hardly sufficient to guide their footsteps. Look 
at the most lovely picture, and then cover it up, leaving 
uncovered only a tiny scrap of it. What else will you see 
there, even if you look as closely as possible, and the more so 
as you look from nearer and nearer at hand, but a kind of 
confused medley of colours, without selection, without art! 
And yet when you remove the covering, and look upon the 
whole picture from the proper place, you will see that what 
previously seemed to you to have been aimlessly smeared 
on the canvas was in fact accomplished with the highest 
art by the author of the work. What happens to the eyes in 
painting is equally experienced by the ears in music. The 
great composers frequently mingle discords with harmonious 
chords so that the listener may be stimulated and pricked as 
it were, and may become eager to know what is going to 
happen; presently when all is restored to order he feels so 
much the more content. In the same way we may take 
pleasure in small dangers, or in the experience of ills, from 
the very sense or proof they give us of our own power or 
felicity. Or again at the spectacle of rope-walking or sword- 
dancing we are delighted by the very element of fear that is 
involved, and we ourselves in play with children hold them 
as if we were going to throw them out of the window, and 
half let them go in very much the same way as the ape 
carried Christian, King of Denmark, when he was still an 
infant wrapped in long clothes, to the edge of the roof, and 
then, when everybody was in terror, turned it into jest and 
put him back into his cradle safe and sound. On the same 
principle it has an insipid effect if we always eat sweet things; 
sharp, acid, and even bitter things should be mixed in to 
stimulate the taste. He who has not tasted what is bitter 
has not earned what is sweet, nor will he appreciate it. This 
is the very law of enjoyment, that positive pleasure does not 


come from an even course; such things produce weariness, 
and make men dull, not joyful. 

What I have said, however, about the possibility of a part 
being disturbed without upsetting the harmony of the whole 
must not be interpreted to mean that no account is taken 
of the parts; or that it is sufficient for the whole world to be 
completed at all points, even though it should turn out that 
the human race was wretched, and that there was in the uni- 
verse no care for justice and no account was taken of us as is 
maintained by some people whose judgment about the sum of 
things is ill-grounded. For the truth is that, just as in a well 
regulated commonwealth care is taken that as far as possible 
things shall be to the interest of the individual, in the same 
way the universe would not be sufficiently perfect unless, as 
far as can be done without upsetting the universal harmony, 
the good of individual people is considered. Of this there 
could be established no better measure than the very law of 
justice itself, which dictates that each should have a part 
in the perfection of the universe and in his own happiness in 
proportion to his own virtue and to the extent to which his 
will is directed tgwards the common good ; by which is fulfilled 
what we call the charity and love of God, in which alone, 
according to the judgment of wise theologians also, stands the 
whole force and power of the Christian religion. Nor ought 
it to seem remarkable that all this deference should be paid to 
minds in the universe, since they bear the closest resemblance 
to the image of the supreme Author, and their relation to Him 
is not that of machines to their artificer (like the rest of the 
world) but rather that of citizens to their prince; moreover 
they will endure as long as the universe itself, and they, in some 
manner, express and concentrate the whole in themselves; so 
that it might be said that minds are whole parts. 

As for the afflictions of men, and especially of good men, 
we must hold ourselves assured that they contribute to the 
greater good of those who suffer them; and this is true not 


only theologically, but physically also, just as a grain of 
wheat cast into the earth must suffer before it bears fruit. 
And in general it is true to say that afflictions are for the 
time being evil, but in effect good, since they are short cuts 
to a greater perfection. Similarly in physics the liquids 
which ferment slowly are also more slowly purified, whereas 
those in which there is a more violent disturbance throw off 
the foreign parts with greater force and so more quickly 
become pure. You might fairly say that this is a case of 
taking a step back in order to make a stronger leap forward 
(reader pour mteux sauter). These things must be allowed 
to be not only pleasant and consoling, but also most true. 
Indeed in general I hold that there is nothing truer than 
happiness, and nothing happier and sweeter than truth. 

Further, we realize that there is a perpetual and a most 
free progress of the whole universe in fulfilment of the 
universal beauty and perfection of the works of God, so that 
it is always advancing towards a greater development. Thus, 
even now a great part of our earth has received cultivation, 
and will receive it more and more. And though it is true 
that there are times when some parts of it go back again to 
virgin forest, or are destroyed again and oppressed, this must 
be understood in the same sense as I just now interpreted 
the meaning of affliction, namely, that this very destruction 
and oppression contributes to achieve something greater, so 
that in some way we receive profit from our very loss. 

To the objection that may perhaps be offered that if this 
were so the world would long ago have become a paradise, 
the answer is at hand: although many substances have 
already come to great perfection, yet owing to the infinite 
divisibility of what is continuous, there always remain in 
the abyss of things parts that are asleep, and these need to 
be awakened and to be driven forward into something 
greater and better in a word, to a better development. 
Hence this progress does not ever come to an end. 




I AGREE with you that it is important to examine our pre- 
suppositions, thoroughly and once for all, in order to establish 
something solid. For I hold that it is only when we can prove 
all that we bring forward that we perfectly understand the 
thing under consideration. I know that the common herd 
take little pleasure in these researches, but I know also that 
the common herd take little pains thoroughly to understand 
things. Your scheme, as I understand it, is to examine the 
truths which assert that there is something outside us. In 
this you appear to be very just, for thus you grant us all the 
truths which are hypothetical, and which assert not that 
there is something outside us, but only what would happen 
if there were. Thus at the outset we save arithmetic, 
geometry and a great number of metaphysical, physical, and 
moral propositions, whose convenient expression depends on 
definitions arbitrarily chosen, and whose truth depends on 
axioms which I am accustomed to call identical; as for 
instance, that two contradictories cannot both exist, that a 
thing at one and the same time is what it is for instance, 
it is as big as it is, equal to itself, like itself, etc. 

Now although you do not enter ex professo* into the 
examination of hypothetical propositions, I am nevertheless 
of opinion that it should be done, and that none should be 
admitted that have not been absolutely proved and resolved 
into identicals. 

As regards those truths which deal with what is in fact 

1 Simon Foucher (1644-96), a Canon of Dijon, who professed 
philosophical scepticism. Cf. pp. 109-28. 

9 i.e. it is no part of your professed purpose to enter . . . 



outside us, this is the subject with which your inquiries are 
primarily concerned. Now in the first place it cannot be 
denied that the very truth of hypothetical propositions 
themselves is something which is outside us and which does 
not depend on us. For all these hypothetical propositions 
assert what would or would not be, granting something 
or its contrary; and consequently they assure us that the 
supposition at the same time of two things that agree, or 
that a thing is possible or impossible, necessary or unneces- 
sary, and also this possibility, impossibility, or necessity 
(for the necessity of one thing is the impossibility of its 
contrary), are none of them chimeras of our own making; 
since all we do is to recognize them in spite of ourselves and 
in a constant manner. Thus of all things which actually are, 
the possibility itself or impossibility of being is the first. 
Now this possibility or necessity forms or composes what are 
called essences or natures, and the truths which we are 
accustomed to call eternal; and we are right so to call them, 
for nothing is so eternal as what is necessary. Thus the 
nature of the circle with its properties is something which 
exists and is eternal: that is to say there is some constant 
cause outside us which makes all those who think about it 
carefully discover the same thing, and not merely that their 
thoughts agree with one another; this might be attributed 
simply to the nature of the human mind, but for the fact 
that phenomena or experiences confirm them whenever some 
appearance of a circle strikes our senses. And these phe- 
nomena necessarily have some cause outside us. 

But though the existence of necessities comes first of all in 
itself and in the order of nature, I agree none the less that 
it is not the first in the order of our knowledge. For you see 
that in order to prove its existence I have taken for granted 
that we think and that we have sensations. Here then are 
two absolute general truths, truths that is to say which 
treat of the actual existence of things: the one that we think, 


the other that there is a great variety in our thoughts. From 
the first it follows that we are, from the other it follows that 
there is something other than us; something other, that is to 
say, than that which thinks, which is the cause of the variety 
of our appearances. Now the one of these two truths is as 
incontestable and as independent as the other; and through 
fastening on the first only in the order of his meditations, M. 
Descartes failed to reach the perfection which he had aimed 
at. If he had exactly followed what I call thefilum medi- 
tandi, 1 I think that he would have brought to completion 
first philosophy? But the greatest genius in the world is 
unable to force matters, and we must of necessity enter by 
the gates provided by nature if we are not to go astray. 
Moreover, one man alone cannot do everything at the outset; 
and for my part when I consider all the fine things M. Des- 
cartes has said, and said by himself, I marvel rather at what 
he has done than that there is something that he failed to do. 
I admit that I have not yet been able to read his writings 
with all the care I intend to devote to them, and my friends 
are aware that it has so happened that I read almost all the 
recent philosophers before him. Bacon and Gassendi were 
the first to fall into my hands ; their familiar and easy style 
was more suited to a man desirous of reading everything. 
It is true that I often glanced at Galileo and Descartes, but 
as I have only recently become a geometrician, I was soon 
put off by their manner of writing, which necessitated 
serious thought. And personally, although I have always 
taken pleasure in meditations of my own, I have always 
found it difficult to read books which cannot be understood 
without much thought; for in following one's own meditations 
one follows a certain natural bent, and gains profit and 
pleasure at the same time, whereas one is terribly put out at 
having to follow the meditations of another. I always liked 

l lit. 'the thread of thinking', i.e. his actual train of thought. 

1 i.e. metaphysics. 


books which, while containing some fine thoughts, could be 
read straight through without stopping, for they gave rise 
in me to ideas which I followed at fancy, and pursued as the 
spirit moved me. This also prevented me from reading 
books on geometry, and I readily admit that I have not yet 
been able to make myself read Euclid in any different way 
from that in which one generally reads histories. I have 
learnt from experience that this method is in general a good 
one, but I have also learnt none the less that an exception 
must be made in the case of some authors, such as Plato and 
Aristotle among the ancient philosophers, and Galileo and M 
Descartes among those of our day. Still, such knowledge as I 
have of M. Descartes's metaphysical and physical meditations 
has been almost entirely derived from reading a number of 
books written in a rather more familiar style which expound 
his opinions. And it may be that I have not yet properly 
understood him. None the less, in so far as I myself have 
glanced at his work, I seem to myself at least to get a glimpse 
of what he has not done, nor attempted to do; and this is 
among other things, to resolve all our presuppositions. For 
this reason I am accustomed to commend all those who 
examined the least truth thoroughly; for I know that it is a 
great thing to understand a thing perfectly, however small 
and easy it may seem. This is the way to go well ahead 
and to set up finally the art of discovery which depends on 
a knowledge (though it must be distinct and perfect) of the 
easiest things. And for this reason I do not condemn the 
design of M. de Roberval, who wished to prove everything in 
geometry, even including certain axioms. I admit that we 
must not try to force others to be so exact, but I think it is 
well to force ourselves. 

I return to the truths which come first for our purpose 
among those which assure us that there is something outside 
us; that is to say, that we think, and that there is a great 
variety in our thoughts. Now this variety of thoughts 


cannot come from that which thinks, since one single thing 
cannot itself be the cause of the changes which are in it. 
For everything remains in the state in which it is if there is 
nothing to change it: and since it is not of itself determined 
to have certain changes rather than others, we could not 
begin to attribute to it any variety, without saying something 
for which we admit there is no reason, which is absurd. And 
even if we sought to maintain that there is no beginning to 
our thoughts, besides the fact that we should be obliged to 
assert that each of us has existed from all eternity, we should 
still not escape the difficulty; for we would still be obliged to 
admit that there is no reason for this variety which has 
existed in our thoughts from all eternity, since there is 
nothing in us which determines us to this thought rather 
than to another. Thus there must be some cause outside 
us for the variety of our thoughts. And as we agree that 
there are some subordinate causes of this variety, which 
nevertheless need a cause themselves, we have thereby 
established some particular beings or substances, whose 
actions we can recognize, that is to say, such that we conceive 
that from a change in them follows some change in us. And 
so we advance by great strides to the construction of what 
we call matter and body. 

But at this point you are right to hold us up a little, and to 
renew the pleas of the Academy of old. For at bottom, all 
our experiences assure us of two things only, namely that 
there is a connection in our appearances which gives us a 
means of successfully predicting future appearances; and 
secondly that this connection must have a constant cause. 
But from all this it does not strictly follow that there is 
matter or that there are bodies, but only that there is some- 
thing which presents us with appearances which follow 
properly on one another. For if an invisible power were to 
delight in giving us dreams properly connected with our 
preceding life, and in conformity with one another, could we 


distinguish them from realities except after awakening? Now 
what is it that prevents the course of our life being one long 
well-arranged dream, about which we could be undeceived in 
an instant ? And I do not see that this power would therefore 
be imperfect, as M. Descartes asserts, besides the fact that 
its imperfection is not under discussion. For it might 
be some subordinate power, or some superhuman spirit who 
was able to take a hand, I know not why, in our affairs, and 
who had at least as much power over someone, as that caliph 
who had a drunken man carried into his place, and there made 
him taste of the paradise of Mahomet when he was awakened, 
until he was once more drunk and in a condition to be taken 
back to the place from which he had been brought. When this 
man returned to his senses, he naturally took for a vision 
what seemed to him irreconcilable with the course of his life, 
and retailed to the people maxims and revelations which he 
believed he had learnt in this supposed paradise; and this 
was what the caliph desired. Now since a reality has passed 
for a vision, what prevents a vision from passing for a reality? 
It is true that the more we see a connection in what happens 
to us, the more we are confirmed in the opinion that there is 
reality in our appearances; and it is true also that the more 
nearly we examine appearances, the better connected we find 
them to be, as microscopes and other ways of making ex- 
periments show us. This perpetual agreement gives us great 
assurance; but after all it will be no more than a moral 
assurance until somebody discovers a priori the origin of the 
world which we see, and probes in the depths of its essence 
to find the reason why things are as they seem. When that 
is done, it will be proved that what appears to us is a reality, 
and that it is impossible that we should ever be disabused 
about it. But I think that this would be very like the 
beatific vision, and that it is difficult to pretend to such 
vision in the state in which we are. Still we learn from this 
how confused the knowledge which we commonly have of 


body and of matter must be, since we think that we are 
assured that they exist, and then find in the last analysis 
that we may be mistaken. 

And this confirms M. Descartes's beautiful thought con- 
cerning the proof of the distinction between body and soul, 
since it is possible to cast doubt on the one, without question- 
ing the other. For if there were nothing but appearances or 
dreams, we should be no less assured of the existence of that 
which thinks, as is very well said by M. Descartes; and I 
myself add that we could still prove just as well the existence 
of God, by methods different from those employed by M. 
Descartes, and which, in my view, take us further. For we 
have no need whatever to suppose a Being who will guarantee 
that we shall not be deceived, since it lies in our power to 
undeceive ourselves about many things, and at least about 
the most important. I hope, sir, that your meditations on 
this subject will have all the success you desire; but to that 
end it is a good thing to proceed in order and to establish 
propositions. This is the way to gain ground and to pro- 
gress with certainty. I think that you would oblige the 
public further by publishing from time to time chosen 
passages from the Academy, and especially from Plato; for 
I know that there are to be found in them some things that 
are more beautiful and sounder than is ordinarily thought. 

To Landgraf Ernst von Hessen-Reinfels. i/n Feb. 1686 

BEING recently at a place where for several days I had 
nothing to do, I composed a small Discourse on Metaphysics, 
about which I should be very glad to have the opinion of 
M. Arnauld. 1 For the questions of grace, of the relations of 
God with His creatures, of the nature of miracles, the cause 
of sin and the origin of evil, the immortality of the soul, 
ideas, etc., are touched upon in a manner which seems to 
provide new opportunities for throwing light on very great 
difficulties. I enclose herewith a summary of the articles 
contained in it, as I have not yet had time to make a fair 
copy. I beg Your Serene Highness to have this summary 
sent to him, and to ask him to consider it somewhat and 
express his opinion; for as he excels equally in theology and 
in philosophy, in learning and in the power of thought, I can 
think of no one more fitted than he to judge of it. I should 
very much appreciate having a critic as exact, as enlightened, 
and as reasonable as M. Arnauld, being myself as ready as 
any man in the world to yield to reason. Perhaps M. 
Arnauld will find this little matter not altogether unworthy 
of his consideration, especially as he has been much occupied 
in examining these questions. If he finds any obscurity, I 
will explain myself sincerely and frankly; and if he finds me 
worthy of his instruction, I will see to it that he has reason 
to be not ill satisfied with me. I beg Your Serene Highness 

1 Antoine Arnauld (1612-94), known as 'the great Arnauld'; 
a distinguished theologian, philosopher, and mathematician. 
He defended the Jansenists against the Jesuits. 



to attach this to the summary which I am sending for him, 
and to send both on to M. Arnauld. 


1. Of Divine perfection, and that God does everything in 
the most desirable manner. 

2. Against those who maintain that there is no goodness 
in the works of God; or rather that the rules of goodness and 
of beauty are arbitrary. 

3. Against those who think that God might have done 

4. That love of God demands that we should be com- 
pletely satisfied with and should acquiesce in all that He does. 

5. Wherein the rules of perfection of the Divine conduct 
consist, and that the simplicity of the means is exactly 
balanced by the richness of the effects. 

6. That God does nothing which is out of order, and that 
it is not even possible to imagine events which are not 

7. That miracles are in conformity with the general order, 
although they go against subordinate maxims. Concerning 
what God wills or permits, and concerning general and 
particular will. 

8. In order to distinguish God's activities from those of 
created beings, an explanation is offered of wherein consists 
the notion of an individual substance. 

9. That each single substance expresses the whole universe 
in its own way, and that in its notion are included all the 
events which will happen to it with all their circumstances, 
and the whole series of things outside it. 

10. That the theory regarding substantial forms has 
something in it, but that these forms do not change anything 
in phenomena, and must not be used to explain particular 


11. That the meditations of the theologians and of the 
philosophers known as Schoolmen are not wholly to be 
despised. 1 

12. That the notions which depend upon extension include 
an imaginary element, and cannot constitute the substance 
of body. 

13. As the individual notion of each person includes once 
and for all everything that will ever happen to him, in it can 
be seen the a priori proofs, or reasons of the truth of every 
event, or why one thing has happened rather than another. 
But these truths, although they are assured, are none the 
less contingent, since they are based on the free choice of 
God and of created beings. It is true that there are always 
reasons for their choice, but these reasons incline without 

14. God produces different substances, according to the 
different views which He has of the universe; and by the 
intervention of God the proper nature of each substance is 
such that what happens to one corresponds to what happens 
to all the others, without their acting immediately one upon 

15. The action of one finite substance upon another 
consists only in an increase of the degree of its expression 
together with a decrease of that of the other, inasmuch as 
God has so formed them in advance that they shall agree 

16. The extraordinary intervention of God is included in 
what is expressed by our essence; for this expression extends 
to everything. But it surpasses the forces of our nature or 
of our distinct expression, which is finite and follows certain 
subordinate maxims. 

17. An example of a subordinate maxim of the law of 

1 This section of the Discourse itself is purely general. Leibniz 
does not mention any instances of truths to be found in the 
Schoolmen. He mentions St. Thomas with special honour. 


nature, in which it is shown that God always regularly 
conserves the same force, but not the same quantity of 
motion, contrary to the teaching of the Cartesians and some 

18. The distinction between force and quantity of motion 
is important, among other things as snowing that it is 
necessary to have recourse to metaphysical considerations 
distinct from extension in order to explain the phenomena 
of bodies. 

19. The value of final causes in physics. 

20. A memorable passage from Socrates in Plato's Phaedo l 
against a too materialistic philosophy. 

21. If the laws of mechanics depended on geometry alone 
without metaphysics, phenomena would be quite other 
than they are. 

22. A reconciliation of two methods, one of which proceeds 
by final causes and the other by efficient causes; which will 
satisfy both those who explain nature mechanically and those 
who have recourse to incorporeal natures. 

23. Returning to immaterial substances, an explanation is 
offered how God acts on the understanding of minds, and 
whether we always have an idea of what we are thinking about. 

24. Of the nature of knowledge, clear or obscure, distinct or 
confused, adequate or inadequate, intuitive or supposititious; 
of nominal, real, causal, and essential definition. 

25. In what cases our knowledge goes always with the 
contemplation of the idea. 

26. We have within us all the ideas there are; and of 
Platonic reminiscence. 

27. Of how our soul may be compared to a tabula rasa, 2 
and of how our notions come from the senses. 

1 In this section of the Discourse itself a gap is left, into which 
Leibniz evidently intended to transcribe the passage from Plato. 

1 ' a blank tablet ', i.e. a wax writing tablet with no impressions 
on it, or (to use the language of Locke) a piece of white paper. 
Cf. p. 143. 


28. God is the sole immediate object of our perceptions, 
which exists outside of us, and He alone is our light. 

29. Nevertheless we think immediately by our own ideas, 
and not by those of God. 

30. How God inclines our soul without necessitating it; 
that we have no right to complain; that we must not ask 
why Judas sins, since that free action is included in his 
notion, but only why Judas the sinner is admitted into 
existence preferably to some other possible people. Of 
original imperfection or limitation before sin, and of the 
degrees of grace. 

31. Of the motives of elective choice, of faith foreseen, of 
mean science, 1 of absolute decree; and that everything is 
reduced to the reason why God chose to admit into existence 
such and such a possible person, whose notion includes the 
particular succession of acts of grace and of free actions. 
This at once puts an end to all difficulties. 

32. Value of these principles in matters of piety and religion. 

33. Explanation of the intercourse between the soul and 
the body, which has been regarded as inexplicable or as 
miraculous, and of the origin of confused perceptions. 

34. Of the difference between minds and other substances, 
souls or substantial forms. And that the immortality we 
desire requires memory. 

35. Excellence of minds: that God considers them above 
other created things; that minds express God rather than 
the world, and that other simple substances express the world 
rather than God. 

36. God is the Monarch of the most perfect commonwealth 
composed of all minds, and the happiness of the City of God 
is His chief design. 

1 Science moyenne. In the corresponding section of the 
Discourse itself there is no reference to it whatever. From the 
Theodicy it appears to refer to knowledge of ' conditional events ', 
which Leibniz regards as intermediate between knowledge of 
possibilities and knowledge of actual facts. 


37. Jesus Christ has revealed to mankind the mystery and 
the admirable laws of the Kingdom of Heaven and the 
greatness of the supreme happiness which God prepares for 
those who love Him. 

To Landgraf Ernst von Hessen-Rheinfels. 12 April 1686 

... I said in the thirteenth article of my Summary that 
the individual notion of each person includes once for all 
everything which will ever happen to him. He l draws from 
this the consequence that everything which happens to a 
person, and even to the whole human race, must happen by 
a more than fatalistic necessity as if notions or previsions 
rendered things necessary, and as if a free action could not be 
contained in the notion or perfect vision which God has of 
the person to whom it will belong. He adds that perhaps 
I shall find nothing to trouble me in the conclusion he draws. 
And yet I had expressly protested in the very same article 
that I did not admit such a conclusion. So either he must 
doubt my sincerity, for which I have given him no reason, 
or else he has not sufficiently examined the view he is re- 
jecting. Still I will not reproach him for this, as it seems I 
have a right to do, since I bear in mind that he was writing 
at a time when some indisposition did not allow him the 
free use of all his mind, as is witnessed by his letter itself. 2 

1 Arnauld. 

2 Arnauld had complained of a bad cold in the previous letter; 
and he had added, ' All that I can now do is to say in two words 
to Your Highness that I find in these meditations so many things 
which frighten me, and which, unless I am much mistaken, all 
mankind will find so shocking, that I do not see that any purpose 
would be served by a piece of writing which will manifestly be 
rejected by the whole world. . . . Would it not be better for him 
to abandon these metaphysical speculations, which can be of no 
value either to him or to any one else, and to apply himself 
earnestly to the matter which is of the greatest importance of 
all to him, namely to assure his own salvation by returning to 
the Church . . . ?' Arnauld afterwards sincerely apologized 
for this rather off-hand treatment of Leibniz. 


And I wish to have it known how much respect I feel for 

If that is the case, he says (namely that the individual 
notion of each person includes once for all everything which 
will ever happen to him), God was not free to create all that has 
happened to the human race and all that will ever happen by a 
more than fatalistic necessity (there is some fault in the copy 
but I think I have succeeded in restoring it as above). For 
the individual notion of Adam included his having so many 
children, and the individual notion of each of these children 
included everything that they would do and all the children they 
would have, and so on. God had, then, no more freedom in all 
this, supposing that He had once willed to create, than He had 
freedom not to create a being capable of thought^ These last 
words should strictly contain the proof of the consequence; 
but it is very clear that they confuse necessitatem ex hypothesi a 
with absolute necessity. A distinction has always been 
drawn between what God is absolutely free to do and what 
He is obliged to do by virtue of certain resolutions already 
taken (and He does not take any without previous regard to 
all). It is not worthy of God to conceive of Him (under 
pretext of vindicating His liberty), in the manner of some 
Socinians, as being like a human being who takes his resolu- 
tions in consideration of circumstances, and as now being no 
longer free to create what He considers good, if His earliest 
resolutions in regard to Adam or others already include a 
relation to everything already connected with their posterity. 
On the contrary every one is agreed that God has ordered 

1 Arnauld's own letter reads as follows: God had then no more 
freedom in all this, supposing He had once willed to create Adam 
than to argue that God was free, supposing He had once willed to create 
me, not to create a being capable of thought. (This sentence is some- 
what confused, but it sufficiently indicates the line of argument. 
It will be seen that the whole passage is loosely and confusedly 
written, as if Leibniz were in some difficulties to state his view.) 
1 i.e. that which necessarily follows from a given hypothesis. 


from all eternity the whole succession of the universe, without 
its diminishing His freedom in any way. 

It is evident also that this objection separates off from one 
another acts of will on the part of God, which are really 
connected together. We must not consider God's will to 
create a particular Adam as separated from all His other 
acts of will in regard to the children of Adam and all the 
human race; as if God first made the decision to create Adam 
without any relation to his posterity, and none the less by 
that decision, according to my view, deprived Himself of the 
freedom to create the posterity of Adam, as seemed to Him 
good. This would be a strange way of reasoning. Rather 
we should think of God as choosing, not just any Adam 
vaguely, but a particular Adam, of whom there exists among 
the possible beings in the ideas of God a perfect representa- 
tion, accompanied by certain individual circumstances, and 
possessing among other predicates that of having in the 
course of time certain posterity; we must think of God, I say, 
as choosing him with an eye to his posterity, and so as 
equally at the same time choosing the one and the other. I 
cannot see what harm there is in that. If He acted otherwise, 
He would not be acting like God. Let me suggest a com- 
parison. A wise prince, when he chooses a general whose 
connections he knows, in effect chooses at the same time a 
number of colonels and captains, whom he well knows the 
general will appoint, and whom he will not want to reject for 
reasons of prudence: yet they do not in any way destroy his 
absolute power, nor his freedom. The case is exactly the 
same with God for much stronger reasons. Therefore, to be 
exact, we must recognize in God a certain more general and 
comprehensive will, in which He has an eye to the whole 
order of the universe, since the universe is like a whole which 
God apprehends in a single view. This will virtually includes 
all the other acts of will about what is to come into this 
universe, and among the rest it includes that of creating a 


particular Adam, who is connected with the whole succession 
of his posterity, which God has also chosen as it is. We 
might even say that these particular acts of willing the 
details only differ from the willing of the whole general 
purpose in a simple respect, very much as the situation of a 
town considered from a particular point of view differs from 
its ground-plan. 1 For these particular acts of will all of 
them express the whole universe in the same way as each 
situation expresses the town. In fact the wiser a man is, 
the less does he have detached acts of will, and the more do 
his views and his acts of will become comprehensive and 
connected. And each particular act of will includes a relation 
to all the others, so that they are as well harmonized as 
possible. Far from finding in all this something shocking, I 
should have thought that the contrary would destroy the 
perfection of God. And in my opinion it must have been a 
matter of great difficulty, or else of great prejudice, to find in 
opinions so innocent, or rather so reasonable, an occasion for 
such strange exaggerations as those which were sent to Your 
Serene Highness. 

Moreover, some slight consideration of what I have said 
will show that it is evident ex ter minis? For by the individual 
notion of Adam I undoubtedly mean a perfect representation 
of a particular Adam, with given individual conditions and 
distinguished thereby from an infinity of other possible 
persons very much like him, but yet different from him 
(just as every ellipse is different from the circle, however 
closely it approaches to it). God preferred him to all these 
others, because it pleased Him to choose just this particular 
order of the universe; and all that follows from this decision 
of His is necessary only by a hypothetical necessity, and in 

1 Plan g&omltval: a plan drawn to scale, showing the true 
measurements in proportion, i.e. having no regard to perspective. 
Cf. p. 84. 

'from the terms themselves', i.e. from an analysis of the 
meaning of the terms. 


no way derogates from the freedom of God nor from that of 
created minds. There is one possible Adam whose posterity 
is such and such, and an infinity of others whose posterity 
would be different; is it not the case that these possible 
Adams (if I may so speak of them) are different from one 
another, and that God has chosen only one of them, who is 
exactly our Adam? There are so many reasons which prove 
the impossibility, not to say the absurdity and even impiety, 
of the contrary, that I think that at bottom all men are of 
the same opinion, when they give a little thought to what 
they say. Perhaps, too, if M. Arnauld had not held about 
me the prejudiced view with which he started, he would not 
have found my propositions so strange and would not have 
drawn from them the consequences which he did. ... 

To Landgraf Ernst von Hessen-Rheinfels. 12 April 1686 

. . . Every man who acts wisely considers all the circumstances 
and connections of the decision he is taking, and the more so 
in proportion to his capacity. Will God, who sees every- 
thing perfectly and with a single glance, fail to have taken 
His decision in conformity with everything He sees? Can 
He have chosen a particular Adam without considering 
and deciding as well everything which has any connection 
with him? Consequently it is ridiculous to say that this free 
decision of God's takes away His liberty. Otherwise, to be 
free it would be necessary to be for ever undecided. . . . 

Remarks on M. Arnauld' s letter about my proposition that the 
individual notion of each person includes once for all everything 
that will ever happen to him. May 1686 

... He admits in good faith that he understood my opinion 
to be that everything that happens to an individual can be 
deduced from his individual notion in the same way and with 
the same necessity as the properties of a sphere can be 


deduced from its specific notion or definition; and that he 
supposed I had been considering the notion of the individual 
in itself, without regarding the manner in which it exists in 
the understanding or will of God. For (he says) it appears to 
me that we are not accustomed to consider the specific notion of 
a sphere in relation to what is represented in the Divine under- 
standing, but in relation to what it is in itself, and I supposed 
it was the same with the individual notion of each person; 
but he adds that, now that he knows what my view is, that is 
enough to enable him to grant it sufficiently to try and find out 
whether it removes all the difficulties; a matter of which he is 
still in doubt. 

I see that M. Arnauld has not remembered, or at least has 
not concerned himself about, the opinion of the Cartesians, 
who hold that God establishes by His will the eternal truths, 
like those regarding the properties of the sphere. But as I 
am not of their opinion any more than M. Arnauld, I will 
simply explain why I hold that we must philosophize 
differently about the notion of an individual substance than 
we do about the specific notion of a sphere. This is because 
the notion of a species includes eternal or necessary truths 
only, whereas the notion of an individual includes sub 
ratione possibilitatis l what is fact, or what is related to the 
existence of things and to time; and consequently it depends 
on certain free decisions of God, considered as possible. 
For truths of fact or of existence depend upon God's decisions. 
Further, the notion of a sphere in general is incomplete or 
abstract; that is to say we only consider the essence of a 
sphere in general or in theory, without regard to individual 
circumstances. Consequently the notion does not include 
in any way what is required for the existence of a certain 
sphere. But the notion of the sphere which Archimedes 

1 'considered under the head of possibility'; i.e. that which is, 
as a matter of fact, an actual fact is considered, not as actual 
fact, but as possible. 


had placed upon his tomb is a fully worked out notion, and is 
bound to include everything which belongs to the object of 
that form. This is why in the case of individual considera- 
tions, or considerations of practice, quae versantur circa 
singularia, 1 besides the form of the sphere there enter in the 
matter of which it is made, the place, the time, and the other 
circumstances, which by a continual chain would in the end 
cover the whole series of the universe, if it were possible to 
follow out all that these notions include. For the notion of 
this piece of matter, of which the sphere is made, involves 
all the changes which have ever happened or will ever happen 
to it. According to my view, every individual substance 
always contains traces of all that has ever happened to it and 
marks of all that ever will ever happen to it for all time. 
What I have just said may suffice to explain my train of 

... As regards the objection that possibles are independent of 
the decisions of God, I grant that they are so of actual de- 
cisions (though the Cartesians do not agree with this); but 
I hold that possible individual notions include a number 
of possible free decisions. For example, if this world were 
possible only, the individual notion of any body in this world, 
which includes certain movements as possible, would include 
our laws of motion (which are free decisions of God), but it 
would include them as possible only. For as there is an 
infinity of possible worlds, there is also an infinity of laws, 
some proper to one world, others to another; and each 
possible individual of any world includes in its notion the 
laws of its world. 
The same thing can be said of miracles or the extraordinary 

1 ' which are concerned with individuals', what is individual 
being opposed to what is general. The point of introducing these 
Latin phrases is, of course, that Leibniz wishes to indicate that 
he is following orthodox logical doctrine of the Schools. 


operations of God, which none the less belong within the 
general order; they are in conformity with the principal 
designs of God, and consequently are included in the notion 
of this universe, which is a result of those designs. Just as 
the idea of a building results from the ends and designs of the 
builder, so the idea or notion of this world is a result of these 
designs of God, considered as possible. For everything must 
be explained by its cause; and the cause of the universe is the 
ends of God. Now each individual substance, according to 
my view, expresses the whole universe from a certain point 
of view, and consequently it also expresses the said miracles. 
All this must be understood of the general order, of the designs 
of God, of the series of the universe, of individual substance, 
and of miracles, whether they are taken in their actual state 
or are considered stib ratione posstbtlttatts. 1 For another 
possible world will have all those things too in their own 
manner, though the designs of our own world have been 

It will be seen too, from what I have just said about the 
designs of God and about the primary laws, that this uni- 
verse has a certain principal or primary notion, of which 
particular happenings are merely consequences without, 
however, eliminating freedom and contingency, to which 
certainty is in no way inimical, since the certainty of events 
is partly based on free actions. ... To speak exactly, it should 
be said that it is not so much because God decided to create 
this Adam that he decided on all the rest; the truth is rather 
that both His decision regarding Adam and His decision 
about other particular things are a consequence of His 
decision in regard to the whole universe and of the principal 
designs which determine its primary notion and establish in 
it this general inviolable order, with which everything is in 
conformity, without even excepting miracles, which are 
without doubt in conformity with the principal designs of 
1 i.e. not as facts, but as possibilities 


God, although they do not always observe the particular 
maxims which are called laws of nature. 

I said before that the supposition from which all human 
events can be deduced is not simply that of the creation of a 
vague Adam, but that of the creation of a particular Adam 
determined in all his circumstances and chosen from among 
an infinity of possible Adams. This has given M. Arnauld 
occasion to object, not without reason, that it is as impossible 
to conceive of several Adams, taking Adam as a unique 
nature, as it would be to conceive of several Is. I agree; 
but I must add that in speaking of several Adams, I was 
not taking Adam as a determined individual. I must 
explain myself; this is what I meant. When in considering 
Adam we consider a part of his predicates, as for instance 
that he is the first man, set in a pleasure garden, from out of 
whose side God took a woman, and similar things conceived 
stib ratione generalitatis l (i.e. without naming Eve, Paradise, 
or other circumstances which fix individuality), and we give 
the name Adam to the person to whom these predicates are 
attributed, all this is not sufficient to determine the indi- 
vidual; for there might be an infinity of Adams, that is to say 
of possible persons, different from one another, to whom all 
that is appropriate. Far from disagreeing with what M. 
Arnauld says against such a plurality of one and the same 
individual, I used the same argument myself to make it clear 
that the nature of an individual must be complete and deter- 
mined. I am indeed entirely persuaded of what St. Thomas 
had already taught in regard to intelligences, and which I hold 
to be of general application, namely that it is not possible 
that there should be two individuals entirely alike, or differing 
solo numero. 2 We must not then conceive of a vague Adam, 
that is to say a person to whom certain of Adam's attributes 

1 i.e. considered in general, as opposed to considered in respect 
of its unique, individual character 
fl numerically only.' 


belong, when it is a question of determining whether all 
human happenings follow from the supposition of him; we 
must attribute to him a notion so complete that everything 
that can be attributed to him can be deduced from it. Now 
there is no room for doubt but that God could form such a 
notion of him, or rather that He finds it ready made in the 
country of possibles, that is, in His understanding. 

It follows also that he would not have been our Adam, but 
another, if he had had different events; for nothing prevents 
us from saying that he would be another. Therefore he is 
another. It appears evident to us that this square of marble 
brought from Genoa would have been in all respects the 
same, if it had been left there, because our senses only make 
us judge superficially; but at bottom, because of the inter- 
connection of things, the whole universe with all its parts 
would be quite different, and would have been a quite 
different universe from the beginning, if the least thing 
went differently from the way it does go. It is not for this 
reason that .all that happens is necessary; it is because 
everything that happens is certain after God made choice 
of this possible universe, whose notion contains this series of 
things. I hope that what I am going to say will make even 
M. Arnauld agree with me. 

Let there be a straight line ABC representing a certain 
time. And let a certain individual substance, for instance 
myself, remain or exist throughout the given time. Let us 
first take the 1 which exists during the time AB, and then 
the / which exists during the time BC. Since then the pre- 
sumption is that it is the same individual substance enduring 
throughout, or rather that it is I who exist in the time AB, 
being then in Paris, and that it is still I who exist in the time 
BC, being then in Germany, it follows necessarily that there 
is a reason which makes us say truly that we endure, that is, 
that I who was in Paris am now in Germany. For if there is 
no reason, we should have as much right to say that it is 


another person. It is true that my internal experience 
convinces me a posteriori of this identicalness, but there must 
be a reason a priori. Now it is not possible to find any other 
except that both my attributes in the preceding time and 
state and my attributes in the later time and state are 
predicates of one and the same subject: insunt eidem sub- 
jecto. 1 Now what is meant by saying that a predicate is in a 
subject, except that the notion of the predicate is in some 
way included in the notion of the subject? And since from 
the time when I began to exist it was possible to say of me 
truly that this or that would happen to me, it must be 
acknowledged that these predicates were laws included in 
the subject, or in the complete notion of me which caused me 
to be called 7, which is the foundation of the interconnection 
of all my different states, and which was perfectly known to 
God from all eternity. 

After this I think that all doubts should disappear, for 
when I say that the individual notion of Adam includes 
everything that will ever happen to him, I do not mean 
anything other than what all the philosophers mean when 
they say praedicatum inesse subjecto verae propositions? 
It is true that the consequences of so evident a doctrine are 
paradoxical; but that is the fault of the philosophers, who 
do not follow up sufficiently the clearest notions. 

I think that M. Arnauld, being as penetrating and fair- 
minded as he is, will now no longer find my proposition so 
strange, even if he is not yet able to approve of it entirely 
(though I almost persuade myself that he will approve). I 
agree with what he says so judiciously about the circum- 
spection that is necessary in attempting to use the Divine 
knowledge 8 to find out what we ought to discover from the 

1 'they are included in the same subject'. 
1 ' in a true proposition the predicate is included in the subject', 
i.e. because God's knowledge is inaccessible to us as finite 
intelligences. We should not suppose that we can understand 


notions of things. But, rightly understood, what I have 
just said must be allowed, since God would only be brought 
in as much as is necessary. For we should not need to 
assert that God, in considering the Adam whom He is 
deciding to create, sees in him everything that will happen 
to him; it is enough that we can always prove that there must 
be a complete notion of this Adam which contains them. For 
all the predicates of Adam either depend upon other predi- 
cates of the same Adam, or they do not so depend. Putting 
on one side, then, those which do depend on others, we have 
only to take together the primary predicates in order to form 
the complete notion of Adam, which is sufficient to make it 
possible to deduce from it everything which must happen to 
him, as far as is necessary to give an explanation of it. It is 
evident that God can invent, and even does in fact conceive, 
such a notion, which is sufficient to account for all the 
phenomena which belong to Adam; but it is no less evident 
that it is possible in itself. It is true that we must not, unless 
it is necessary, involve ourselves in the investigation of 
Divine knowledge and Divine will because of the great 
difficulties therein; still, we can explain all of this which we 
need for our question without entering into the difficulties 
mentioned by M. Arnauld for example, whether the 
simplicity of God is reconcilable with the distinctions we 
are obliged to make with regard to Him. It is also extremely 
difficult to explain perfectly how God has a knowledge which 
He might not have had, namely the knowledge of vision 1 ; 
for if contingencies in the future did not exist, God would 
have no vision of them. It is true that He would have 
simple knowledge, which is vision, none the less, for having 
joined to it His will; so that this difficulty perhaps reduces 

God's knowledge, and infer from this the nature of particular 
things. We must start from the notions of things which we 
find in ourselves. 

1 vision in the sense in which the prophets had visions. 


itself to such difficulty as there is about His will, that is, how 
God is free to will. This is without doubt beyond us, but it 
is not so necessary to understand it in order to solve our 

As for the manner in which we conceive that God acts in 
choosing the best among several possibles, M. Arnauld is 
right in finding some obscurity there. Yet he seems to recog- 
nize that we are led to conceive that there is an infinity of 
possible first men, each with a great following of persons and 
events, and that God chose the one who together with his 
following pleased Him. All that is not as strange as it had 
first appeared to him. It is true that M. Arnauld testifies 
that he is very much inclined to think that substances that 
are purely possible are nothing but chimeras. About this I 
do not want to enter into dispute: but I hope that in spite of 
that he will grant me what I need. I agree that there is no 
other reality in pure possibilities but that which they have in 
the Divine understanding; and from this it can be seen that 
M. Arnauld himself will be obliged to fall back on the Divine 
knowledge to explain them, whereas he seemed to mean just 
now that they ought to be looked for in themselves. Since 
I should admit also the proposition, of which M. Arnauld is 
convinced and which I do not deny, namely that we do not 
conceive of any possibility except through ideas which are to 
be found in the things which God has created, this objection 
does not affect my argument. For when I speak of possi- 
bilities, I am quite satisfied that it should be possible to 
form true propositions about them. For example, if there 
were no perfect square in the world, we should still see that 
it does not involve any contradiction. And if we absolutely 
reject pure possibilities, this means that there is no con- 
tingency; for if nothing is possible except what God has in 
fact created, what God has created would be necessary, 
supposing He had once decided to create anything. 

Finally, I agree that in order to judge of the notion of 


an individual substance it is a good thing to consider that 
which I have of myself, just as it is necessary to consider 
the specific notion of a sphere in order to judge of its pro- 
perties. And yet there is a considerable difference; for the 
notion of me and of every other individual substance is 
infinitely more extended and more difficult to understand 
than a specific notion like that of a sphere, which is in- 
complete only. It is not enough that I feel myself a 
substance which thinks, it would be necessary to conceive 
distinctly what distinguishes me from all other minds; but 
of this I have only a confused experience. The result is 
that, though it is easy to determine that the number of 
feet in the diameter is not included in the notion of the 
sphere in general, it is not so easy to determine whether the 
journey which I intend to make is included in my notion; 
otherwise it would be as easy for us to be prophets as to 
be geometers. I am uncertain whether I shall go on the 
journey; but I am not uncertain that, whether I go or not, 
I shall still be the same I. It is an unreflective conviction, 1 
which must not be confused with a notion or distinct appre- 
hension. These things only seem to us to be undetermined 
because the foreshadowings or marks which are there in 
our substance are not recognizable by us. In the same 
way those who take no account of anything but the senses 
will treat with ridicule any one who says that the least 
movement communicates itself on and on as far as matter 
extends, because this could not be learnt from experience 
alone; but when we consider the nature of motion and of 
matter, we are convinced. It is the same here: when I 
consider the confused experience I have of the individual 
notion of me in particular, I take no care to perceive this 
connection of events; but when I consider the general, 
distinct notions which enter into the notion of me, I come 

1 Prevention. There is not, I think, a sufficiently exact English 
equivalent; and this cumbrous phrase seems to be unavoidable. 


upon that connection. In fact, in considering the notion 
that I have of every true proposition, I find that every 
predicate, necessary or contingent, past, present, or future, 
is contained in the notion of the subject; and I ask no more. 
Indeed, I think that this will open up to us a way of 
reconciliation; for I imagine that M. Arnauld felt a repug- 
nance against assenting to my proposition only because he 
took the connection, which I am maintaining, to be intrinsic 
and necessary at the same time, whereas I hold it to be 
intrinsic, but in no way necessary; and I have now suffi- 
ciently explained that it is founded on free decisions and 
actions. I do not mean any other connection between 
subject and predicate than that which is to be found in the 
most contingent truths; that is to say, there is always 
something to be conceived in the subject which provides 
the explanation why this predicate or this event belongs 
to it, or why a particular event happened rather than not. 
But the reasons of these contingent truths incline without 
necessitating. It is true then that I am not able to go 
on this journey, but it is certain that I shall go. This 
predicate or event is not certainly connected with my other 
predicates conceived incompletely or sub rattone generalitatis}- 
but it is connected certainly with my complete individual 
notion, since I suppose that this notion was expressly so 
constructed that it might be possible to deduce from it 
everything which happens to me. This notion is without 
doubt a parte rei\ 2 and it properly is the notion of me, who 
find myself in a number of different states, since it is this 
notion alone which is capable of including them all. . , . 

1 Cf. p. 65, note i. 

f 'from the side of the thing itself; i.e. the notion is of 
something really existing, and not of an imaginary or merely 
possible object. 


To Arnauld. Hanover, 14 July 1686 

... I agree that the connection of events, although it 
is certain, is not necessary, and that it is open to me to go 
or not to go on this journey; for although it is included in 
my notion that I shall go, it is also included that I shall 
go freely. And of all that in me which can be conceived 
sub ratione generalitatis seu essentiae seu notionis specificae 
sive tncompletae 1 there is nothing from which it can be 
inferred that I shall go necessarily; whereas from the fact 
that I am a man it can be concluded that I am capable of 
thinking. Consequently, if I do not go on this journey, it 
will not violate any eternal or necessary truth. Neverthe- 
less, since it is certain that I shall go, there is bound to be 
some connection between me, who am the subject, and the 
accomplishment of the journey, which is the predicate; 
semper enim notio praedicati inest stibjecto in propositione 
vera* Thus if I did not go there would be a falsity which 
would destroy my individual or complete notion, or that 
which God conceives of me, or did conceive even before he 
decided to create me. For this notion involves sub ratione 
possibilitatis* existences, or truths of fact, or decisions of 
God, on which facts depend. . . . 

. . . You approve, sir, the interconnections of God's 
decisions; you recognize as certain my principal proposi- 
tion, in the sense which I gave to it in my reply. You are 
simply in doubt whether I made the interconnection inde- 
pendent of the free decisions of God; and this quite rightly 
troubles you. But I have made it clear that according to 

1 ' in general terms, or in terms of its essence or of its specific 
or incomplete notion'. 

1 'for in a true proposition the notion of the predicate is always 
included in the subject'. 

r Cf. p. 64, note. 


my view it depends on these decisions, and that it is not 
necessary though it is intrinsic. You insisted on the diffi- 
culty that would be involved in saying that if I do not go 
on this journey as I am bound to do, I shall not be I; and 
I explained how it may be said or may not. Finally I gave 
a decisive reason, which in my opinion takes the place of 
demonstration; namely, that in every affirmative true pro- 
position, necessary or contingent, universal or singular, the 
notion of the predicate is contained in some way in that of 
the subject, praedicatum inest subjected Or else I do not 
know what truth is. 

Now I ask no more connection here than that which exists 
a parte rei a between the terms of a true proposition; and it 
is in this sense only that I say that the individual substance 
includes all its events and all its denominations, even those 
which are commonly called extrinsic (that is, they belong to 
it only by virtue of the general interconnection of things and 
because it expresses the whole universe in its own way), there 
must always be some foundation of the connection of the terms of a 
proposition, which foundation must lie in their notions. This 
is my chief principle, on which I hold that all philosophers 
ought to be agreed. And one of its corollaries is the common 
axiom that nothing happens without a reason, which can 
always be given to explain why the thing turned out thus 
rather than otherwise, though this reason often inclines 
without necessitating, a perfect indifference being a chi- 
merical or incomplete supposition. It will be seen that 
from the aforesaid principle I draw surprising consequences; 
but this is only because people are not accustomed to thinking 
out sufficiently the clearest apprehensions. . . . 

You may perhaps be surprised that I deny the action of one 
bodily substance on another, when it seems to be so evident. 

* 'the predicate is included in the subject*. 
1 Cf. p. 71, note 2. 


But besides the fact that others have denied it before me, 
we must bear in mind that it is rather a play of the imagina- 
tion than a distinct conception. If a body is a substance, 
and not a mere phenomenon like the rainbow, nor an entity 
united by accident or by aggregation like a heap of stones, it 
cannot consist of extension; and it must necessarily be con- 
ceived as something which is called substantial form, and 
which corresponds in some way to a soul. I became con- 
vinced of this in the end, as it were in spite of myself, after 
having held a very different opinion in earlier days. Still, 
approve as I may of the Schoolmen in this general and, if I 
may so put it, metaphysical explanation of theirs of the 
principles of bodies, I still subscribe fully to the corpuscular 
theory in the explanation of particular phenomena; in this 
sphere it is of no value to speak of forms or qualities. Nature 
must always be explained mathematically and mechanically, 
provided it is remembered that the very principles or laws of 
mechanics or of force do not depend on mathematical 
extension alone, but on certain metaphysical reasons. . . . 

To Arnauld. Hanover, 14 July 1686 

. . . Also I do not much approve of the behaviour of those 
who are always appealing to their ideas, when they are at 
the end of their proofs, and who misuse the principle that 
every clear and distinct conception is valid. 1 I hold that we 
must always look for some mark in a distinct apprehension; 
and as we often think without ideas, by using ciphers (in place 
of the ideas in question) whose signification we falsely suppose 
ourselves to know, and make up for ourselves impossible 
chimeras. I hold that the mark of a genuine idea is that its 
possibility can be proved, either a priori by conceiving its 
cause or reason, or a posteriori when experience teaches us 

1 lit. * good '. It will be seen that later in the same paragraph 
Leibniz speaks of ' a genuine idea ', and also of ' a true idea '. 


that it in fact exists in nature. For this reason definitions, 
in my view, are real when it is known that the thing defined is 
possible; otherwise they are nominal only, and should not be 
trusted, since if by chance the thing defined implied a con- 
tradiction, two contradictory consequences might be inferred 
from one and the same definition. Hence you were abso- 
lutely right to inform Fr. Malebranche and others that a 
distinction must be made between true and false ideas, and 
that too much rein must not be given to a man's imagination 
under pretext of its being a clear and distinct intellection. 

Draft of a letter to Arnauld. 28 November/ 8 December 1686 

. . . The action is attributed to that substance, whose ex- 
pression is more distinct, and which is called the cause. For 
instance, when a body is floating in water, an infinity of 
movements of the particles of the water are necessary so that 
the place which the body leaves may always be filled by the 
shortest way. Hence we say that the body is the cause of 
these movements; because by its means we can explain 
distinctly what happens. But if we examine what is physical 
and real in the motion, we can as well suppose that the body 
is at rest, and that everything else moves in conformity with 
this hypothesis, since the whole motion is in itself nothing but 
a relative thing, namely a change of situation, such that we 
cannot know to what to attribute it in mathematical pre- 
cision. Actually we attribute it to a body, by whose means 
everything is explained distinctly. . . . 

Thus in strict metaphysical precision, we have no more 
reason to say that the ship causes the water to produce this 
large number of circles which serve to fill up the place of the 
ship, than to say that the water is caused to produce all these 
circles and that it causes the ship to move accordingly. But 
short of saying that God has expressly willed to produce this 
large number of movements in this co-ordinated manner, we 


cannot give the reason for them; and as it is not reasonable to 
have recourse to God in matter of detail, we fall back on the 
ship, although as a matter of fact in the last analysis the 
agreement of all the phenomena of the different substances 
comes simply from the fact that they are all the products of 
one and the same cause, namely God, who arranges that each 
individual substance expresses the decision which God has 
taken in regard to the whole universe. 

I do not know whether the body, when the soul or sub- 
stantial form is put aside, can be called a substance. It 
might well be a machine, an aggregate of several substances, 
so that, if I am asked what I should say de forma cadaveris x 
or about a square of marble, my reply is that they are perhaps 
unities per aggregattonem a like a heap of stones, and are not 
substances. The same might be said of the sun, of the earth, 
of machines; and with the exception of man there is no body 
of which I can be assured that it is a substance rather than an 
aggregate of several substances, or perhaps a phenomenon. 
Nevertheless it seems to me certain that, if there are any 
corporeal substances, man is not the only one; and it appears 
probable that the brutes have souls, though they are without 

Finally, although I agree that the consideration of forms 
or souls is useless in particular physics, it is for all that of 
importance in metaphysics. In the same way geometers 
do not trouble themselves de compositione continui* and 
physicists do not concern themselves whether one ball 
impels another, or whether it is God. 

It would be unworthy of a philosopher to admit such souls 

1 'about the form of the physical, human body 1 , as dis- 
tinguished of course r om the whole living being. 

'by aggregation*. 

'about the composition of a continuum 1 ; i.e. how that which 
is continuous can have parts and yet be continuous, etc. 


or forms unless there were a reason for it; but without them 
the fact that bodies are substances is not intelligible. 

To Arnauld. Gottingen, 30 April 1687 

. . . You suppose that I will not say that a body can move 
itself; and so, since the soul is not the real cause of the 
movement of the arm, nor is the body, the cause will there- 
fore be God. But I am of a different opinion. I hold that 
all that is real in the state which is called motion proceeds 
as much from the corporeal substance as thought and will 
proceed from the mind. Everything happens in each 
substance in consequence of the first state which God gave 
to it in creating it, and, extraordinary intervention apart, 
His ordinary intervention consists simply in the conserva- 
tion of the same substance, in conformity with its precedent 
state and with the changes which it carries within it. Never- 
theless, it is quite right to say that one body impels another; 
that is to say that the fact is that one body never begins 
to have a given tendency except when another body which 
is touching it has a proportionate loss, in accordance with 
the constant laws which we observe in phenomena. And 
in fact, motions being real phenomena rather than entities, 
a movement as phenomenon is in my mind the immediate 
consequence or effect of another phenomenon, and similarly 
in the minds of others. But the state of a substance is 
not the immediate consequence of the state of another 
particular substance. . . . 

If my opinion that substance requires a true unity were 
founded on a definition that I had myself made up contrary 
to common usage, then the dispute would be simply one of 
words. But in the first place philosophers have understood 
this term in much the same manner, distinguendo uftum 
per se et unum per accidens, formamque substantialem et 
accidentalem, mixta imperfecta et perfecto, naturdia et 


artificialia. 1 In the second place, I approach the matter 
from a higher ground also, and, waiving the analysis of 
terms, / hold that where there are only entities by aggregation, 
there will not be any real entities. For every entity by aggre- 
gation presupposes entities endowed with a true unity, for 
it only takes its reality from the reality of those of which it 
is composed, so that it will not have any at all, if each 
entity of which it is composed is itself an entity by aggre- 
gation; or else it is necessary to look further for a different 
foundation of its reality, which, if it is at every stage neces- 
sary to go further in looking for it, can never be found. 
I agree, sir, that in all corporeal nature there are nothing 
but machines (which are often animated); but I do not agree 
that there are nothing but aggregates of substances \ and if 
there are aggregates there must also be some true substances 
of which the aggregates are made up. We must then come 
down to either the mathematical points, out of which some 
authors compound extension, or to the atoms of Epicurus 
and M. Cordemoy (which are things that you and I alike 
reject), or else we must acknowledge that no reality can be 
found in bodies; or finally we must recognize some substances 
as having a genuine unity. I have already said in another 
letter that a combination of the Grand Duke's diamond and 
the Great Mogul's diamond may be called a pair of diamonds, 
but that is only an entity of reason: when they are put 
side by side, that will be an entity of imagination or of 
perception, that is to say a phenomenon; for their contact, 
their common movement, and their co-ordination to carry 
out one and the same design, make no difference as regards 
substantial unity. It is true that there is sometimes more, 
sometimes less foundation for our supposition, when we 
suppose that several things are combining to make one 
1 'by distinguishing between that which is a unity of itself 
and that which is a unity adventitiously, between substantial and 
accidental form, and between imperfect and perfect, natural 
and artificial compounds'. 


single thing, according as the things have more or less 
connection; but this is only a way of abbreviating our 
thoughts and of picturing phenomena. 

It appears, too, that what constitutes the essence of an 
entity by aggregation is nothing but a manner of existence 
of the things of which it is composed; for example, what 
constitutes the essence of an army is simply a manner of 
existence of the men who compose it. This manner of 
existence, then, presupposes a substance, whose essence is 
not the manner of existence of a substance. Every machine, 
too, presupposes some substance in the pieces of which it is 
made; and there can be no plurality without true unities. 
To put it shortly, I maintain as axiomatic this identical 
proposition, whose differentiation can only be marked by 
the accentuation namely, that that which is not truly an 
entity cannot cither be truly an entity. It has always been 
held that unity and entity are reciprocal things. An entity 
is one thing, entities are quite another thing: but the plural 
presupposes the singular, and where there is no entity still 
less are there several entities. What could be more clearly 
stated? I therefore thought that I might be allowed to 
distinguish entities by aggregation from substances, since 
such entities have their unity in our mind only; which 
unity is based upon the relations or modes of genuine sub- 
stances. If a machine is a substance, a circle of men holding 
one another's hands will be a substance too; so will an 
army, and so will every plurality of substances. 

I do not mean that there is nothing substantial, or nothing 
but appearance, in the things which have no genuine unity; 
for I agree that they have always as much reality or sub- 
stantiality as there is genuine unity in that of which they 
are composed. 

You object, sir, that it may perhaps be of the essence of 


body not to have a true unity. But in that case it will be 
of the essence of body to be a phenomenon, deprived of all 
reality, like an ordered dream; for phenomena themselves, 
like a rainbow or a heap of stones, would be wholly imaginary, 
if they were not composed of entities with a genuine unity. 

You say that you do not see what leads me to admit that 
there are such substantial terms, or rather corporeal sub- 
stances, endowed with a genuine unity. It is because I do 
not conceive of any reality at all as without genuine unity. 
According to my view the notion of singular substance 
involves consequences which are incompatible with its being 
an entity by aggregation. I conceive of there being properties 
in substance which cannot be explained by extension, shape, 
and motion, besides the fact that there is no exact and fixed 
shape in bodies because of the actual subdivision of the con- 
tinuum ad infinitum. Moreover, motion inasmuch as it is 
only a modification of extension and a change of neighbour- 
hood, involves an imaginary element, so that it is not possible 
to determine to which of the subjects that change it belongs, 
unless we have recourse to the force in corporeal substance 
which is the cause of the motion. I admit that there is no 
need to mention these substances and qualities in order to 
explain particular phenomena, but neither is there any need 
to mention the intervention of God, the composition of the 
continuum, the plenum, and countless other things. We 
can explain mechanically, I fully admit, the particularities 
of nature; but my point is that after having accepted or 
assured the principles of mechanics themselves, we cannot 
establish them a priori except by metaphysical arguments; 
and even the difficulties de compositione continui l will never 
be resolved so long as extension is regarded as constituting 
the substance of bodies, and we go on embarrassing ourselves 
by our own chimeras. 

1 Cf. p. 76, note 3. 


I think, too, that to allow genuine unity or substance to 
man almost alone is to be as limited in metaphysics as those 
people were in physics who confined the world within a ball. 
And as genuine substances are so many expressions of the 
whole universe taken in a certain sense, and so many repro- 
ductions of Divine works, it is in agreement with the great- 
ness and beauty of these works of God, since these substances 
do not hinder one another from accomplishing as much in 
this universe as each of them can and as much as superior 
reasons allow. . . . 

I agree that there are degrees of accidental unity; that an 
ordered society has more unity than a confused mob, and 
that an organized body or a machine has more unity than a 
society that is to say there is more point in conceiving them 
as one single thing, because there is more relation between the 
constituent parts. But in the end all these unities only 
receive their existence from thoughts and appearances, like 
colours and all other phenomena, which for all that are called 
real. The tangibility of a heap of stones or of a block of 
marble does not any the more prove its substantial reality 
than the visibility of a rainbow proves the substantial 
reality of the rainbow; and as there is nothing so solid that it 
has not some degree of fluidity, perhaps this block of marble 
is only a heap made of an infinity of living bodies, or is like a 
lake full of fish, although these living creatures cannot 
ordinarily be distinguished by the eye except in the case of 
bodies that are half rotted. We may say then of these 
composites and of similar things what Democritus so well 
said of them, namely, csse opinione, lege, vofup. 1 Plato held 
the same view about everything which is purely material. 
Our mind notices or conceives a number of genuine sub- 
stances which have certain modes; these modes involve rela- 
tions to other substances, and so the mind takes occasion to 
1 ' they depend for their existence on opinion or custom*. 


join them together in thought and to give an inclusive name 
to all the things together. This is a convenience for reasoning ; 
but we must not allow ourselves to be misled into making of 
them so many substances or genuinely real entities. This only 
befits those people who go no further than appearances, or else 
those who make realities of all the abstractions of the mind, 
and who conceive of number, time, place, motion, figure, and 
sensible qualities as so many separate entities. Whereas I 
hold that philosophy cannot be better established, and 
reduced to some degree of precision, than by learning to 
recognize the only substances or complete entities, endowed 
as they are with a genuine unity in their different states 
following one another, all the rest being nothing but phe- 
nomena, abstractions, or relations. 

No kind of arrangement will ever be found which can make 
a genuine substance out of a number of entities by aggrega- 
tion. For example, if the parts which fit together into one 
and the same design are more competent to produce a 
genuine unity than are parts which are in contact, then all 
the officials of the Dutch East India Company will make a real 
substance far better than a heap of stones. But what else is 
a common design but a resemblance, or rather an ordered 
arrangement of actions and passions, which our mind notices 
in different things? If on the other hand we prefer the unity 
based on contact, we are faced by other difficulties. Hard 
bodies have perhaps nothing uniting their parts except the 
pressure of surrounding bodies and of themselves, and in 
their substance are no more united than a heap of sand, 
arena sine calce. 1 Or, consider a number of rings interlaced 
to make a chain: why should they compose a genuine sub- 
stance thus any more than if they had openings in them 
through which they could be separated? It may be that one 
of the parts of the chain does not touch another and even 

x 'sand without lime', i.e. without anything to bind it into 


does not enclose it, and yet they are so interlaced that 
unless they are taken in a certain manner they cannot be 
separated, as in the figure here given. Are we to sayjn that 
case that the substance of the com- 
pound of these things is as it were in 
suspense and depends on the future 
address of whoever may wish to dis- 
entangle them? These are all fictions 
of the mind; and so long as we do not 
distinguish what is genuinely a com- 
plete entity, or substance, we shall 
never have any fixed point at which we can stop; and such 
fixed point is the one and only means of establishing solid 
and real principles. 

In conclusion, nothing should be taken as certain without 
foundations; it is therefore for those who manufacture 
entities and substances without a genuine unity to prove 
that there is more reality than I have just said; and I am 
waiting for the notion of a substance, or of an entity, which 
successfully comprehends all these things; after which parts 
and perhaps even dreams will be able one day to lay claim 
to reality, unless very precise limits are set to this droit de 
bourgeoisie 1 which is to be accorded to entities formed by 

I have written at some length on these matters, so that 
you may be able to form some opinion not only of my views, 
but also of the reasons which have driven me to adopt 
them. . . . 

1 Leibniz seems to mean a kind of inferior citizenship. A 
bourgeois was originally a member of a small township who had 
certain rights akin to those of a citizen in a city. 


To Arnauld. 9 October 1687 

. . . You reply that you have no clear idea of what I 
mean by the word express. If I mean by it a thought, you 
say, you do not agree that the soul has any more thought 
and knowledge of the movement of the lymph in its lymphatic 
ducts than of the movements of the satellites of Saturn; if 
I mean something else, you do not know what I mean, and 
consequently (supposing that I cannot explain myself dis- 
tinctly) this term will be of no use to make clear how the 
soul can give itself the sensation of pain, since for that it 
would be necessary (so you say) for it to know beforehand 
that I am being stung, instead of learning of the sting by 
feeling the pain. In reply to your objection, I will first 
explain the term which you find obscure, and then apply it 
to the difficulty you raise. One thing expresses another (in 
my language) when there is a constant and ordered relation 
between what can be asserted of the one and what can be 
asserted of the other. In this sense a projection in perspective 
expresses its ground plan. 1 Expression is common to all forms, 
and is a genus of which natural perception, animal sensation, 
and intellectual knowledge are species. In natural percep- 
tion and in sensation it is sufficient that what is divisible 
and material, and is to be found dispersed in a number of 
entities, should be expressed or represented in a single 
indivisible entity, or in a substance possessing a genuine 
unity. There can be absolutely no doubt of the possibility 
of a good representation of several things in one single thing; 
for our soul presents us with an example. This representa- 
tion is accompanied by consciousness in a rational soul, and 
it is then that it is called thought. 

Now such expression is to be found on all sides, because 
every substance sympathizes with every other and receives 
1 son giomitYal. Cf . p. 60, note. 


some proportionate change, answering to the least change 
which occurs in the universe; though this change is more 
or less noticeable in proportion as the other bodies or their 
activities have more or less relation to ours. On this point 
I think M. Descartes himself would have agreed; for he 
would certainly grant that because of the continuity and 
divisibility of all matter the effect of the least movement is 
extended over all the neighbouring bodies, and consequently 
from body to body ad infinitum, though diminishing pro- 
portionately. Thus our body must be affected to some 
extent by the changes in all the others. 

Now to all the movements of our body there correspond 
certain perceptions or thoughts of our soul, more or less 
confused; so the soul in turn will have some thought of all 
the movements of the universe, and according to my opinion 
every other soul or substance will have some perception or 
expression of them. It is true that we do not perceive 
distinctly all the movements of our body, as for example 
the movement of the lymph; but (to make use of an example 
which I have employed previously) it is like this. It must 
be the case that I have some perception of the movement 
of each wave on the shore if I am to be able to apperceive 
that which results from the movements of all the waves 
put together, namely the mighty roar which we hear by 
the sea. Similarly we feel some confused result of all the 
movements which take place in us, but, being accustomed 
to this internal movement, we do not apperceive it distinctly 
and reflectively except when there is a considerable change for 
the worse, as at the beginning of an illness. And it would be 
an excellent thing if physicians devoted themselves to 
distinguishing more exactly these kinds of confused sensa- 
tions which we have of our bodies. Now since we do not 
apperceive the other bodies except by the relation which 
they bear to ours, I was quite right in saying that the soul 
expresses better what belongs to our body, and that we 


only know of the satellites of Saturn or of Jupiter in 
consequence of a movement occurring within our eyes. . . . 

With regard to minds, that is to say substances which 
think, and are capable of knowing God and of discovering 
eternal truths, I hold that God governs them by laws 
different from those by which He governs the rest of sub- 
stances. All forms of substances express the whole universe; 
but it may be said that brute substances express the world 
rather than God, while minds express God rather than the 
world. Moreover God governs brute substances by the 
material laws of force, or of the communication of motion, 
whereas He governs minds by the spiritual laws of justice, 
of which the other substances are incapable. It is for this 
reason that brute substances may be called material, because 
the economy which God observes in regard to them is that 
of a Workman or a Mechanician; whereas in regard to 
minds, God fulfils the function of Prince or Legislator, which 
is infinitely more exalted. And since God is nothing in 
regard to these material substances but that which He is 
in regard to everything, namely the general Author of all 
entities, He takes on, in regard to minds, a different char- 
acter, such that He must be conceived as invested with will 
and moral qualities; since He is Himself a mind, and as it 
were One among us, even to the point of entering with us 
into a social community of which He is the chief. It is 
this society or general Commonwealth of Minds under this 
sovereign Monarch which is the noblest part of the universe, 
composed of so many little gods under this great God. 
For created minds differ from God only as less from greater, 
as finite from infinite. And we may be truly assured that 
the whole universe was created only to contribute to the 
adornment and to the happiness of this City of God. This 
is why everything is so disposed that the laws of force, or 
purely material laws, conspire in all the universe to execute 


the laws of justice or of love, and that nothing can hurt the 
souls that are in the hand of God, and that all things must 
work together for the greatest good of those who love Him. 
This is why, since minds must keep their personality and 
their moral qualities, to the end that the City of God may 
not lose any person, it must be that in particular they should 
keep some manner of reminiscence or consciousness, or the 
power of knowing what they are; on this depends all their 
morality, punishments, and chastenings. Consequently it 
is necessary that every mind should be immune from those 
revolutions of the universe which would render it entirely 
unrecognizable to itself, and would make of it, morally 
speaking, a different person. Whereas for brute substances 
it is sufficient that each should simply remain the same 
individual in the strict metaphysical sense, even though it 
is subjected to all imaginable changes, since in any case it 
is without consciousness or reflection. . . . 



WHEN I gave myself the valuable pleasure of reading your 
Nouvelles de la Republique des Lettres, I found there my 
objection to the famous Cartesian principle regarding the 
Quantity of Motion, together with the Reply of a Cartesian 
scholar from Paris, by name M. 1'Abbe C. 2 I now send you 
my answer so that all the parts of the business may be 
collected together, if you consider that suitable. It is true 
that this is merely intended to clear up the matter, by 
following out rather than by justifying the objection I there 
raised; for M. 1'Abbe has in fact offered no opposition to it, 
but grants me more than I want. However, I am very 
much afraid that the other Cartesians may repudiate what 
he says. 

According to him, the Cartesian rule is limited in applica- 
tion, and is indeed a very small matter; he maintains that it is 
only a particular Principle regarding the five Common Machines 
and concerned with isochronic -powers, or movements recorded 
in equal times. I had shown that in a certain case (which 
was sufficiently ordinary), and in an infinite number of other 
similar ones, two bodies have the same force although they 
have not the same quantity of motion. He grants this, and 
I ask no more. But he adds that this is not surprising, 
because in the case referred to the two bodies acquired their 
forces in unequal times: as if the principle ought to be limited 
to forces acquired in equal times. This is to grant me my 
case, and indeed I do not ask so much. But as against the 

1 Pierre Bayle (1647-1706), author of the famous Historical 
and Critical Dictionary. Cf. pp. 118-40. 

a probably Jean de Catellan, Bishop of Vallence. 


Cartesians I should be wrong to try to take advantage of the 
fact that they are so feebly defended. For I do not believe 
that M. PAbbe C. would ever find one of them, at least among 
those who pass for geometricians, to approve of his restriction 
of the principle. You, sir, will be able to decide, and I have 
no doubt but that some clever Cartesians among your friends 
will admit it, if you think fit to consult them; which I should 
make bold to ask you to do, if I knew what your convenience 
allowed. The Cartesians claim in general that there is 
always maintained the same sum total of force, which they 
always estimate by the quantity of motion. And according 
to them, if some bodies transfer their force, or a part of their 
force, to others, there will be in all these bodies together the 
same quantity of motion as before, or the sum total of the 
products of the masses multiplied by their velocities will be 
the same. For example, if there is a body weighing 4 pounds, 
with a velocity of i degree, and we suppose that its whole 
force must now be transferred to a body weighing i pound, 
is it not true that the Cartesians assert that in this case 
the body must receive a velocity of 4 degrees for the same 
quantity of motion to be preserved? For mass 4 multiplied 
by velocity i produces the same result as mass i multiplied 
by velocity 4. According to my view, on the other hand, 
the body in question must only receive a velocity of 2 degrees 
(as I will prove below); so the difference between us is mani- 
fest enough. And in estimating in this way the force which 
the bodies have acquired, neither these gentlemen nor any 
others that I know of (with the exception of M. 1'Abbe C.) 
have worried themselves about whether they were gained 
in a long or short, an equal or an unequal time. Time, 
indeed, has nothing to do with this calculation. When we 
see a body of a given magnitude travelling at a given velocity, 
can we not estimate its force without knowing in what length 
of time and with what detours and delays it may have acquired 
that velocity? It seems to me that in this case we can judge 


of the present state without knowing the past. When there 
are two bodies, perfectly equal and similar, whose velocities 
are the same but acquired in the one case by a sudden shock, 
and in the other by a descent of observable duration, are we 
for that reason to say that their forces are different? This 
would be like saying that that man is richer whose money 
has taken longer to acquire. But, what is more, it is not 
even necessary that the two bodies in my suggested instance 
should fall from their different heights in unequal times, as 
is supposed by M. PAbbe C.; he did not see that the time 
taken over the descent may be changed at will, according as 
the line of descent is changed by being given a greater or less 
inclination, and that there are an infinite number of ways in 
which these two bodies may be made to descend from their 
different heights in equal times. For if we disregard the 
resistance of the air and similar hindrances we know that a 
body falling from the same height acquires the same velocity 
whether the descent be perpendicular and sudden, or sloping 
and not so fast. Consequently the distinction of times does 
not affect my objection. These things are so evident that I 
might perhaps return to M. PAbb6 C. the compliment of 
some of his expressions, but I think it is more fitting not to 
descend to these amusements. The fact is, I think, that my 
objection is so simple that its very simplicity operated to 
deceive him, since he could not believe that a comment which 
was so easy could have escaped the notice of so many able 
people. This is why, noticing the difference in the times, he 
leapt upon that, without giving himself leisure to reflect that 
it is only incidental. I have a sufficiently good opinion of 
his mind and of his sincerity to hope that he will now agree 
about this himself, and I think that what follows will help 
even more to make him see the truth of the matter. In 
order, too, to anticipate the doubts of those who may think 
it is a satisfactory answer to my objection to say that the 
insensible matter which presses heavy bodies downwards 


and causes their acceleration, has lost exactly the quantity 
of motion which it imparts to the bodies; I answer that I 
agree about this pressure which is the cause of weight, and 
that I hold that this Ether loses as much force (though not as 
much motion) as it imparts to the heavy bodies; but that all 
this does nothing to resolve my objection, even if I granted 
(contrary to the truth) that the Ether lost as much motion 
as it imparted. For my objection is expressly so stated that 
it does not matter how the force was acquired ; I left that 
out of account so as not to enter into any disputes on any 
hypothesis in that regard. I take the acquired force and 
the acquired velocity as they are, without bothering about 
whether they were imparted suddenly by a shock from another 
body or little by little by a continual acceleration from gravity 
or from a spring. It is sufficient for me that the body now 
has this given force or rather this given velocity. And under 
those circumstances I show that its force must not be esti- 
mated by the velocity or quantity of motion; and that the 
body can give its force to another body without giving it 
its quantity of motion, and that therefore when this trans- 
ference occurs, it may, and indeed it must, happen that the 
quantity of motion is diminished or increased in the bodies, 
while the same force remains. 

I shall now prove what I put forward above, namely, that 
if we suppose the whole force of one body, which weighs 4 
pounds and whose velocity (when it travels in a horizontal 
plane, in whatever manner it acquires its velocity) is i degree, 
is transferred to another body weighing i pound, then the latter 
body will receive a velocity, not of 4 degrees in accordance with 
the Cartesian principle, but of 2 degrees only] because in this 
way the bodies or weights would be in reciprocal ratio to 
the heights to which they could ascend by virtue of the 
velocities they possess. Now these heights are as the 
squares of their velocities. And if the body weighing 4 
pounds with its velocity in a horizontal plane of i degree, 


on meeting and becoming attached to the end of a pendulum 
or perpendicular line, climbs to a height of i foot, the body 
weighing i pound will have a velocity of 2 degrees, in order 
to be able, when similarly attached, to ascend to a height 
of 4 feet. For it requires the same force to raise 4 pounds 
i foot, as to raise i pound 4 feet. But if this body weighing 
i pound was bound to receive 4 degrees of velocity, as 
Descartes believed, it would be able to climb to a height 
of 16 feet. And consequently the same force which raised 
4 pounds i foot, would be able, if transferred to i pound, 
to raise it 16 feet. But this is impossible; for the effect is 
four times as great, which means that three times the force 
which was originally present has been acquired and derived 
from nothing. This is why I hold that in place of the 
Cartesian principle it is possible to set up another Law of 
Nature which I consider most universal and most inviolable, 
namely that there is always a perfect equation between the full 
cause and the entire effect. This principle does not assert 
merely that effects are proportional to causes, but more 
than this, that each complete effect is equivalent to its 
cause. And although this axiom is altogether metaphysical, 
it is none the less one of the most useful in physics, and 
provides a means of reducing forces to a geometrical calculus. 
But in order to show more clearly how it must be made 
use of, and why Descartes and others departed from it, 
let us consider his third rule of motion, as an example. 
Let us suppose that two bodies B and C, each weighing 
i pound, meet one another, B with a velocity of 100 degrees, 
and C with a velocity of i degree. Their total quantity of 
motion will be 101. But if C with its velocity can climb i 
inch, B with its velocity will be able to climb 10,000 inches. 
Thus the force of both together is capable of raising i pound 
io,ooi inches. Now according to the third Cartesian rule, 
after the shock they will travel together in company at a 
velocity of 50$, so that when multiplied by 2 (the number 


of pounds travelling together after the shock) there results 
the same quantity of motion, 101. But in that case these 
2 pounds will only be capable of ascending together to a 
height of 2,55<>i inches (i.e. the square of 50$), which is the 
same as if they had the force to raise i pound 5,iooJ inches, 
whereas before the shock there was force enough to raise 
i pound 10,001 inches. Thus nearly half the force will 
have been lost by virtue of this rule for no reason whatever, 
and without being used for anything. This is just as im- 
possible as what we showed above in another case, where 
by virtue of the same Cartesian general principle three times 
the force could be acquired for no reason. 

The famous author of the Recherche de la Verite 1 has 
indeed seen some errors of M. Descartes in these matters; 
but as he presupposed the maxim which I reject, he held 
that of the seven Cartesian rules numbers i, 2, 3, and 5 were 
true, whereas the only one which can be maintained is the 
first, which is self-evident. The same author of the Recherche, 
arguing on the supposition of bodies that are hard and 
without elasticity, maintains that they cannot spring back 
nor become separated after the shock, except when they 
meet one another with velocities in reciprocal relation to 
their magnitudes, and that in all other cases they will travel 
in company after the shock, preserving the original quantity 
of motion. But in this I find a serious difficulty. If body 
B, of magnitude 2 and velocity i, and body C, of magnitude 
i and velocity 2, move directly against one another, he grants 
that they will spring back at their own velocities. But if 
we suppose the velocity or the magnitude of one of the 
bodies, say B, to be increased by ever so little, he maintains 
that both will travel together in the direction in which 
B previously travelled alone, and this at a velocity of 
approximately , supposing that the change in B is so slight 
that in calculating the quantity of motion it is possible to 
1 Malebranche. 


retain the original numbers without any error worth men- 
tioning. But is it credible that simply because of the 
smallest conceivable change assumed in regard to the body 
B, there should arise so great a difference in the result that 
all springing back should cease, and that B, which had in 
the previous instance to turn back at a velocity of i, should 
now not only not have to travel backwards, but should even 
travel forwards at a velocity of approximately ^ which is 
all the more strange in that before the shock it only travelled 
forward at a velocity of i ? Thus the other body, instead 
of making this one recoil, or advance less, as a result of the 
shock of impact, makes it advance more, and as it were 
attracts it to itself which is beyond all probability. As 
it is the author of the Recherche de la Verite to whom we 
are indebted for the correction of a number of Cartesian 
prejudices of some importance, elsewhere as well as on this 
matter, it seemed to me fitting that I should explain here 
what else remained to be said. As I am assured that he 
is as honourable as he is penetrating, I have no fear that 
he may take it ill of me, but rather await his approbation. 

However, I think that M. Descartes, who in laying down 
his rules forgot to notice the cases where two unequal bodies 
move against one another with unequal velocities, would 
have been obliged in the case just mentioned to say the 
same as the author of the Recherche, so far as I can judge 
from his third rule, about which they are both agreed. 
But there will still occur the inequality of the effect and 
the cause, as it would be easy to show by calculation on the 
example of the third rule. This inequality is also to be 
found in what the author of the Recherche says in correction 
of M. Descartes's fourth, sixth, or seventh rules. In regard 
to the sixth rule, for example: let B be of weight i pound 
and velocity 4, and C of weight i pound and at rest. He 
maintains that they travel in company after the shock at 
a velocity of 2. Thus whereas previously there was a force 


capable of raising i pound 16 feet, there is now only a force 
capable of raising 2 pounds 4 feet, and half the force has been 
lost. According to M. Descartes, in this case B and C will 
travel in the same direction, and B's velocity will be 3, 
C's will be i; thus in all there will be a force capable of 
raising i pound 10 feet, and more than a third of the force 
will have been lost. 

What may have misled these worthy authors, and has 
caused most confusion in this matter, is that bodies whose 
velocities are reciprocally related to their extensions are 
observed to stop one another, both in a balance and outside. 
This is why their forces were believed to be equal, all the more 
because no account was taken in bodies of anything except 
velocity and extension. It is in this connection that it would 
have been of value to make use of the distinction between force 
and direction, or rather between the absolute force necessary 
to cause the existence of some effect (for example, to raise a 
certain weight to a certain height, or to compress a certain 
spring to a certain degree) and the force required to travel 
forward in a certain direction, or to maintain the direction. 
For although a body of magnitude 2 with velocity i and a 
body of magnitude i with velocity 2 stop one another or 
prevent one another from going forward, nevertheless if the 
first can raise a pound 2 feet, the second will be able to raise 
a pound 4 feet. This is paradoxical, but it cannot be doubted 
after what has just been said. It might be possible, however, 
to find some new interpretation of the principle of the 
quantity of motion, so that after such correction it might 
remain a universal principle; but it is not easy to see what it 
would be. 

I will add a remark of some consequence for metaphysics. I 
have shown that force must not be estimated by compounding 
the velocity and the magnitude, but by its future effect. Yet 
it seems that force or power is something real at the present 
moment, and the future effect is nott Whence it follows that 


it is necessary to admit in bodies something other than magnitude 
and velocity) unless we are willing to deny to bodies all power 
of action. I hold, moreover, that we have not a sufficiently 
perfect conception even of matter and extension. The 
author of the Recherche de la Verite has recognized the 
existence of such obscurity in regard to the soul and to 
thought, thereby differing from the Cartesians, but as 
regards matter and extension he appears to agree with 
them. . . . 



IT is now some years since I conceived this system, and 
entered into communication about it with several learned 
men, and in particular with one of the greatest theologians 
and philosophers of our time, 1 who had heard of some of my 
opinions from a personage of the highest rank, and found 
them highly paradoxical. But when he had received my 
explanations, he retracted in the most generous and edifying 
way imaginable, expressed his approval of a part of my 
propositions, and withdrew his censure of the others with 
which he still did not agree. Since that time I have con- 
tinued my meditations as opportunity offered, so as to give 
to the public well-considered opinions only: and I have tried 
also to satisfy the objections raised against my Essays on 
Dynamics, which have some connection with this. Some dis- 
tinguished people, moreover, have desired to see my opinions 
more clearly expressed, and so I venture to offer these medi- 
tations, although they are in no way popular, nor such as to 
be to the taste of all kinds of minds. My chief aim is to give 
myself the benefit of the judgment of those who are en- 
lightened in these matters, since it would be too difficult to 
seek out and call to my aid individually those who would 
be prepared to give me instruction which I shall always be 
very happy to receive, provided the love of truth appears 
therein, and not merely a passion for preconceived opinions. 
1 Arnauld. Cf. pp. 52-87. 


Although I am one of those who have done much work on 
mathematics, I have constantly meditated on philosophy 
from my youth up, for it has always seemed to me that in 
philosophy there was a way of establishing something solid 
by means of clear proofs. I had travelled far into the world 
of the Scholastics when mathematics and modern writers 
lured me out again, while still a young man. I was charmed 
with their beautiful way of explaining nature mechanically, 
and scorned, with justice, the method of those who only make 
use of forms or faculties, from which we learn nothing. But 
later, when I tried to get to the bottom of the actual principles 
of mechanics in order to give an explanation of the laws of 
nature which are known through experience, I became aware 
that the consideration of an extended mass is not of itself 
enough, and that use must also be made of the notion of 
force, which is fully intelligible, although it falls within the 
sphere of metaphysics. It seemed to me also that the opinion 
of those who transform or degrade the lower animals into 
mere machines, though it seems possible, is improbable, and 
even against the order of things. 

At first, when I had freed myself from the yoke of Aristotle, 
I had believed in the void and atoms, for it is this which 
best satisfies the imagination. But returning to this view 
after much meditation, I perceived that it is impossible to 
find the principles of a true unity in matter alone, or in what 
is merely passive, since everything in it is but a collection or 
accumulation of parts ad infinitum. Now a multiplicity can 
be real only if it is made up of true unities which come from 
elsewhere and are altogether different from mathematical 
points, which are nothing but extremities of the extended 
and modifications out of which it is certain that nothing 
continuous could be compounded. Therefore, to find these 
real unities, I was constrained to have recourse to what 
might be called a real and animated point or to an atom of 
substance which must embrace some element of form or of 


activity in order to make a complete being. It was thus 
necessary to recall and in a manner to rehabilitate substantial 
forms, which are so much decried to-day, but in a way which 
makes them intelligible and separates the use which must be 
made of them from their previous abuse. I found then that 
their nature consists of force and that from this there follows 
something analogous to feeling and to appetite; and that 
therefore it was necessary to form a conception of them 
resembling our ordinary notion of souls. But just as the 
soul must not be used to explain the detail of the economy of 
the animal's body, so I judged in the same way that these 
forms ought not to be used to explain the particular problems 
of nature, although they are necessary to establish true 
general principles. Aristotle calls them first entelechies ; I 
call them, more intelligibly perhaps, primary forces, which 
contain not only the act, or the fulfilment of possibility, but 
also an original activity. 

I saw that these forms and these souls must be indivisible 
like our mind ; and indeed I recollected that this had been the 
opinion held by St. Thomas concerning the souls of the lower 
animals. But this truth revived the great difficulties about 
the origin and duration of souls and forms. For since every 
simple substance which possesses a true unity can have its 
beginning and end by miracle alone, it follows that they 
could not begin except by creation, nor come to an end except 
by annihilation. Thus (with the exception of such souls as 
God still wills to create expressly) I was obliged to recognize 
that the constitutive forms of substance must have been 
created with the world and that they go on subsisting always. 
Moreover, some of the Scholastics, such as Albert the Great 
and John Bacho, had a notion of some part of the truth about 
their origin. Nor ought our view to appear extraordinary, 
since we are only attributing to forms duration, which was 
granted to their atoms by the followers of Gassendi. 

Nevertheless I deemed that we ought not to mix without 


distinction or to confuse with other forms or souls, minds or 
rational souls, which are of a superior order and have incom- 
parably more perfection than those forms embedded in matter 
which, on my view, are to be found everywhere, since in 
comparison with these others, minds or rational souls are 
little gods, made in the image of God, and having in them 
some glimmering of Divine light. This is why God governs 
minds as a prince governs his subjects, or as a father cares 
for his children; whereas He disposes of other substances as 
an engineer handles his machines. Thus minds have special 
laws which set them above the revolutions of matter, by the 
very order God has introduced into them; and it may truly 
be said that all the rest is made for them alone, the very 
revolutions being arranged for the felicity of the virtuous 
and the punishment of the wicked. 

But to return to ordinary forms or brute souls, the fact 
that duration must now be attributed to them instead of 
to atoms as previously, might give rise to the doubt whether 
they do not pass from one body to another; this would be 
metempsychosis, more or less as some philosophers have 
thought occurred in the transmission of movement and of 
character. But this fancy is very far removed from the 
nature of things. There is no such passing. It is here that 
the transformations of MM. Swammerdam, Malpighi, and 
Leeuwenhoek, who are among the best observers of our day, 
have come to my assistance and have made me admit more 
readily that the animal and every other organized substance 
does not begin when we think, but that its apparent genera- 
tion is only a development, a kind of increase. I have 
noticed, too, that the author of the Recherche de la Verite? 
M. Regis, M. Hartsoeker, and other clever men have not 
been very far removed from this opinion. 

But there still remained the more important question of 
what becomes of these souls or forms at the death of the 
1 Malebranche. 


animal, or at the destruction of the individual unit of 
organized substance. This question is the more awkward, 
inasmuch as it seems unreasonable that souls should remain 
useless in a chaos of confused matter. This ultimately 
made me decide that there was only one sensible thing to 
believe; that is to maintain the conservation not only of the 
soul but also of the animal itself and of its organic machine ; 
even though the destruction of its grosser parts has reduced 
it to such smallness that it evades our senses, just as it did 
before birth. Moreover, nobody can mark precisely the true 
time of death, which may for a long time pass for a mere 
suspension of observable actions, and fundamentally is never 
anything else but that in the case of simple animals; witness 
the resuscitations of flies which have been drowned and then 
buried under powdered chalk, and several similar instances, 
which make us realize that there might be other resuscita- 
tions, and in cases which were much further gone, if men 
were in a position to readjust the machine. And it looks 
as though it were something of this nature which was 
discussed by the great Democritus, thoroughgoing atomist 
though he was, although it was made fun of by Pliny. It 
is therefore natural that since the animal has always been 
living and organized (as some people of fine penetration are 
beginning to recognize), it should also always continue to 
be so. And since there is thus no first birth or entirely 
new generation of the animal, it follows that it will suffer 
no final extinction or complete death, in the strict meta- 
physical sense; and that consequently instead of a transmigra- 
tion of souls, there occurs only a transformation of one and 
the same animal, according as its organs are differently 
folded, and more or less developed. 

But rational souls obey much more exalted laws, and are 
immune from anything which could make them lose the 
status of citizens of the society of minds, since God has so 
well provided that no changes of matter could make them 


lose the moral qualities of their personality. And it may be 
said with truth that everything tends to the perfection not 
only of the universe in general, but also of these created 
beings in particular, who are destined for so high a degree 
of happiness that the universe becomes concerned in it by 
virtue of the divine goodness which is communicated to 
each created being, in so far as sovereign wisdom can permit. 

As regards the ordinary body of animals and other cor- 
poreal substances, which have hitherto been held to suffer 
complete extinction, and whose changes depend rather on 
mechanical rules than on moral laws, I was pleased to note 
that the ancient author of the book Of Regimen, which is 
attributed to Hippocrates, had some notion of the truth 
when he expressly says that animals neither are born nor 
die, and that the things which are thought to come into 
being and to perish merely appear and disappear. This 
was also the opinion of Parmenides and of Melissus in the 
pages of Aristotle. For these ancient thinkers are sounder 
than is supposed. 

I am as willing as any man to give the moderns their due; 
but I think they have carried reform too far, among other 
things in confusing the natural with the artificial, through 
not having had sufficiently exalted ideas of the majesty of 
Nature. They conceive that the difference between her 
machines and ours is but the difference between the great 
and the small. This recently led a very clever man 1 to 
remark that when looking at Nature from near at hand she 
appears less admirable than we thought, being no more than 
a workman's shop. I believe that this does not give a 
sufficiently just idea, or one sufficiently worthy of her, and 
there is no system except mine which properly exhibits 
the immense distance which really lies between the least 
productions and mechanisms of Divine wisdom and the 
greatest achievements of the skill of a limited mind. This 
1 Fontenelle. 


difference is one not merely of degree, but of kind also. It 
must be recognized that Nature's machines possess a truly 
infinite number of organs, and are so well protected and 
armed against all accidents, that it is not possible to destroy 
them. A natural machine still remains a machine in its 
least parts, and, what is more, it always remains the very 
same machine that it was, being merely transformed by the 
different foldings it receives, and being sometimes stretched, 
sometimes contracted and as it were concentrated, when 
we think that it is destroyed. 

Furthermore, by means of the soul or form, there is a true 
unity which corresponds to what is called the I in us; a thing 
which could not occur in artificial machines, nor in the simple 
mass of matter, however organized it may be. This can 
only be regarded as like an army or a flock, or like a pond full 
of fish, or a watch made up of springs and wheels. Yet if 
there were no true substantial unities, there would be nothing 
real or substantial in the collection. It was this that com- 
pelled M. Cordemoy to abandon Descartes, and to adopt 
Democritus's theory of atoms, in order to find a true unity. 
But atoms of matter are contrary to reason, besides the fact 
that they also are composed of parts, since the invincible 
attachment of one part to another (granted that this could 
be reasonably conceived or supposed) would not destroy their 
diversity. It is only atoms of substance, that is to say unities 
which are real and absolutely without parts, which can be 
the sources of actions, and the absolute first principles of 
the composition of things, and as it were the ultimate elements 
into which substantial things can be analysed. They might 
be called metaphysical points, there is about them something 
vital and a kind of perception, and mathematical points are 
their points of view for expressing the universe. But when 
corporeal substances are contracted all their organs consti- 
tute to us but a physical point. Thus physical points are 
indivisible in appearance only: mathematical points are 


exact, but they are nothing but modalities. It is only 
metaphysical points, or points of substance (constituted by 
forms or souls), which are both exact and real; and without 
them there would be nothing real, since without true unities 
there would be no plurality. 

Once I had established these things, I thought I had 
reached port; but when I set myself to reflect on the union 
of the soul with the body, I seemed to be cast back again into 
the open sea. For I could find no way of explaining how 
the body causes something to happen in the soul, or vice 
versa, nor how one created substance can communicate with 
another. M. Descartes left the field at this stage, as far as 
we can gather from his writings; but his disciples, realizing 
that the common opinion is inconceivable, maintained that 
we are aware of the qualities of bodies because God produces 
thoughts in the soul on the occasion of the movements of 
matter; and when our soul wishes to move the body in its 
turn, they deemed that it is God that moves it for the soul. 
And as the communication of motion seemed to them like- 
wise inconceivable, they maintained that God gives motion 
to a body on the occasion of the motion of another body. This 
is what they call the System of occasional causes, which has 
become very fashionable owing to the fine reflections of the 
author of the Recherche de la Vented 

It must be admitted that they have gone a great way in 
regard to this problem by showing what cannot possibly 
take place; but their explanation of what does in fact occur 
does not remove the difficulty. It is quite true that in the 
strict metaphysical sense there is no real influence exerted by 
one created substance on another, and that all things, with 
all their realities, are continually produced by the power of 
God: but to solve these problems it is not enough to make 
use of the general cause, and to drag in what is called the 
dens ex machina. For when this is done without giving any 
1 Malebranche. 


further explanation in terms of the order of secondary causes, 
this is properly speaking to fall back on miracle. In 
philosophy, we must attempt to give an account showing in 
what way things are brought about by the Divine wisdom, 
in conformity with the notion of the subject in question. 

Being thus constrained to grant that it is impossible for 
the soul or for any other true substance to receive anything 
from without, except by Divine omnipotence, I was in- 
sensibly led to adopt a view which surprises me, but which 
seems inevitable, and which does in fact possess very great 
advantages and considerable beauties. This view is that 
we must say that God first created the soul, and every other 
real unity, in such a way that everything in it must spring 
from within itself, by a perfect spontaneity with regard to 
itself, and yet in a perfect conformity with things outside. 
And thus, since our internal sensations (those, that is to say, 
which are in the soul itself and not in the brain or in the 
subtle parts of the body) are but phenomena dependent upon 
external entities, or rather are really appearances, and, as it 
were, well ordered dreams, these internal perceptions within 
the soul itself must arise in it from its own original constitu- 
tion, that is to say through the natural representative ability 
(capable of expressing entities outside itself in relation to 
its organs) with which it has been endowed since its creation, 
and which constitutes its individual character. It follows 
from this that, since each of these substances exactly repre- 
sents the whole universe in its own way and from a certain 
point of view, and since the perceptions or expressions of 
external things reach the soul at a determined point by 
virtue of its own laws and, as it were, in a world apart, as if 
nothing else existed but only God and itself (if I may make 
use of a way of speaking employed by a certain writer with 
a most exalted mind and famous for his holiness), there will 
be a perfect agreement between all these substances, pro- 
ducing the same effect as would occur if these communicated 


with one another by means of a transmission of species or 
qualities, as the common run of philosophers maintain. 
Furthermore, the organized mass, within which is the point 
of view of the soul, is itself more nearly expressed by it, and 
finds itself in its turn ready to act of itself according to 
the laws of the corporeal machine whenever the soul desires, 
without either disturbing the laws of the other, the animal 
spirits and the blood having precisely at the given moment 
the motions necessary to make them respond to the passions 
and perceptions of the soul; and it is this mutual relation, 
regulated in advance in every substance in the universe, which 
produces what we call their communication) and which alone 
constitutes the union of the soul and the body. And this makes 
it possible to understand how the soul has its seat in the body 
by an immediate presence, which could not be closer than 
it is, since it is present in the way in which the unity is present 
in that resultant of unities which is a plurality. 

This hypothesis is very possible. For why should not God 
be able in the first instance to give to substance a nature or 
internal force capable of producing for it in order (as if it 
were an automaton^ spiritual and formal, but free in the case 
of a substance which has a share of reason) everything that 
is going to happen to it, that is to say all the appearances and 
expressions it is going to have, and that without the assistance 
of any created thing? This is rendered all the more probable 
by the fact that the nature of substance necessarily requires 
and essentially involves a progress or change, without which 
it would have no force to act. And since it is the very nature 
of the soul to be representative of the universe in a very 
exact way (although with varying distinctness), the sequence 
of representations which the soul produces for itself will 
naturally correspond to the sequence of changes in the uni- 
verse itself: while on the other hand the body has also been 
adjusted to the soul, in regard to the experiences in which the 
latter is conceived as acting outside itself. This is all the 


more reasonable in that bodies are only made for those minds 
which are capable of entering into society with God, and of 
celebrating His glory. Thus once we recognize the possibility of 
this hypothesis of agreements, we recognize also that it is the most 
reasonable one, and that it gives a wonderful idea of the har- 
mony of the universe and of the perfection of the works of God. 

There is in it this great advantage also, that instead of 
saying that we are free only in appearance and in a manner 
adequate for practice, as several ingenious men have held, we 
must rather say that we are determined in appearance only; 
and that in strict metaphysical language we are perfectly 
independent as regards the influence of all other created 
things. This again shows up in a marvellously clear light 
the immortality of our soul, and the ever uniform conserva- 
tion of our individual self, which is perfectly well regulated 
of its own nature, and is beyond the reach of all accidents 
from outside, whatever the appearances to the contrary. 
No system has ever so clearly exhibited our exalted position. 
Since each mind is as it were a world apart, sufficient unto 
itself, independent of all other created things, including the 
infinite, expressing the universe, it is as lasting, as subsistent, 
and as absolute as the very universe of created things itself. 
We must therefore conclude that it must always play its 
part in the way most suited to contribute to the perfection 
of that society of all minds which constitutes their moral 
union in the City of God. Here, too, is a new and wonder- 
fully clear proof of the existence of God. For this perfect 
agreement of all these substances, which have no point of 
communication with one another, could only come from the 
one common cause. 

Besides the fact that this hypothesis is recommended by 
all these advantages, it may be added that it is something 
more than a hypothesis, since it seems hardly possible to 
explain things in any other intelligible way, and since 
several serious difficulties which have hitherto exercised 


men's minds seem to disappear of themselves when once it 
is properly understood. Ordinary ways of speaking can 
still be easily retained. For it may fairly be said that when 
the particular disposition of a given substance is the explana- 
tion of a change taking place in an intelligible manner, so 
that we can infer that it is to this substance that the others 
have been adjusted in this regard from the beginning, in 
accordance with the order of the decrees of God, then that 
substance ought to be conceived as in that respect acting 
upon the others. Further, the action of one substance on 
another is not a giving forth, or transplanting of an entity, 
as is commonly supposed; and it can reasonably be under- 
stood only in the way I have just described. It is true that 
we can easily conceive of matter both as giving out and as 
taking in parts; and it is in this way that we rightly explain 
in terms of mechanics all the phenomena of physics; but as 
the material mass is not a substance, it can be seen that 
action in regard to substance itself can only be such as 
I have just described. 

These considerations, metaphysical though they may 
appear, are yet wonderfully useful in physics, for establishing 
the laws of motion, as my Dynamics will be able to establish. 
For the truth is that in the shock of impact each body 
suffers only from its own reaction, caused by the motion 
which is already in it. And as for absolute motion, nothing 
can determine it mathematically, since everything termi- 
nates in relations. This means that there is always a perfect 
equivalence of hypotheses, as in astronomy; so that whatever 
number of bodies we take, we may at our own discretion 
assign rest, or any given degree of velocity, to any particular 
one of them we wish, without its being possible for us to be 
refuted by the phenomena of motion, whether in a straight 
line, circular, or composite. It is, however, reasonable to 
attribute to bodies true motions, in accordance with the 
supposition which explains phenomena in the most intelligible 


way; and this way of speaking is in conformity with the 
notion of activity which we have just established. 


... I recollect, sir, that I thought I was complying with 
your desire in imparting to you my philosophical hypothesis 
some years ago, though at the same time I pointed out that I 
had not yet decided to acknowledge it. In return I asked your 
opinion of it; but I do not remember receiving any objec- 
tions from you, otherwise with my usual docility I should 
certainly not have given you occasion to raise the same ones 
a second time. Yet they are still not too late, although they 
reach me after publication, for I am not one of those for 
whom the being committed to a view takes the place of 
sound reasoning, as you will find when you are able to say 
you have adduced some precise and pressing reason against 
my opinions which, it appears, is not your aim. You wish 
rather to speak as an able Academic, and thereby to provide 
an opportunity of going more deeply into the matter. 

1. It was my aim here to expound, not the principles of 
extension, but the principles of that which is in fact extended, 
or of bodily mass. These principles, according to me, are the 
real units, that is to say the substances that possess a true 

2. The unity of a clock, to which you refer, is on my 
view quite other than the unity of an animal; the latter 
may be a substance possessing a true unity, like that in us 
which is called the 7; whereas a clock is nothing but an 

1 A letter from Foucher to Leibniz was published in this copy 
of the Journal, giving a number of objections to the New System. 
For an earlier letter of Leibniz to Foucher, see pp. 45-51. 


3. It is not in the disposition of the organs that I find the 
principle of consciousness in animals; I agree that this 
disposition concerns nothing but the bodily mass. 

4. I mention these things to prevent misunderstandings 
and to show that what you say about them is not contrary 
to what I have propounded. It seems that you do not make 
me out to be wrong when I demand true unities, and when 
that makes me rehabilitate substantial forms. But when 
you appear to say that the souls of brutes must have some 
share of reason if they are allowed to have sensation, that is 
a conclusion the proof of which I do not see. 

5. You recognize with commendable sincerity that my 
hypothesis of harmony or concomitance is a possible one. 
But none the less you are still somewhat averse to it, no 
doubt because you believed that it was purely arbitrary, 
and did not realize that it follows from my view of unities, 
and that my whole contention stands or falls together. 

6. You therefore ask me, sir, what can be the purpose of 
all this artifice which I attribute to the Author of nature 
as if it were possible for too much artifice to be attributed 
to Him, and as if this exact correspondence of unities with 
one another through their own laws, which each received at 
the beginning, were not a thing admirably beautiful in itself 
and worthy of its Author. You further ask what advantage 
I find in this theory. 

7. I might refer to what I have already said about this. 
Still, I answer in the first place that when a thing cannot 
not be so, it is not necessary to ask what can be the purpose 
of it before admitting it. What is the purpose of the 
incommensurability of the side with the diagonal? 

8. In the second place I answer that this correspondence 
serves the purpose of explaining the communication of 
substances and the union of the soul with the body by means 
of the laws of nature established in advance, without having 
recourse either to a transmission of species, which is incon- 


ceivable, or to a fresh intervention of God, which does not 
appear admissible. For we must realize that as there are 
natural laws in matter, so there are also natural laws in 
souls or forms, and these laws mean what I have just stated. 

9. I am further asked how it happens that God is not 
content to produce all the thoughts and modifications of the 
soul, without these useless bodies which the soul (it is said) 
can neither move nor know. The answer is easy. It is that 
it was God's will that there should be a greater rather than 
a lesser number of substances, and He found it good that 
these modifications should correspond to something outside. 

10. There is no useless substance; they all have their 
contribution to make to God's design. 

n. Also I do not admit that the soul does not know bodies, 
though this knowledge arises without their influencing one 

12. I should have no objection even to saying that the 
soul moves the body; in the same way as a Copernican rightly 
speaks of the rising of the sun, a Platonist of the reality of 
matter, a Cartesian of the reality of sensible qualities, 
provided these statements are sanely understood, so I believe 
that it is very true to say that substances act upon one 
another, provided it is understood that the one is the cause 
of changes in the other in consequence of the laws of harmony. 

13. The objection touching the lethargy of bodies (namely 
that the bodies might be inactive even when the soul believed 
them to be in motion) cannot stand because of this same 
unfailing correspondence, established by Divine wisdom. 

14. I have no knowledge of these vain } useless, and inactive 
masses, to which reference is made. There is activity every- 
where; indeed, I maintain this more than the received 
philosophy, because I hold that there is no body without 
motion, nor substance without force. 

15. I do not understand the precise nature of the objection 
contained in the words: In truth, sir, can we not see that these 



views are formed with a set purpose, and that these systems, 
coming after the event, have only been manufactured to vindicate 
certain principles? All hypotheses are formed with a set 
purpose, and all systems come after the event to vindicate 
phenomena or appearances. But I do not see which are 
the principles in favour of which I am supposed to be pre- 
judiced, and which I want to vindicate. 

1 6. If this means that I am led to my hypothesis by a 
priori reasons also, or by fixed principles, as is in fact the 
case, this is rather a commendation of the hypothesis than 
an objection to it. It commonly suffices for a hypothesis 
to be proved a posteriori, because it satisfies the phenomena; 
but when we have other reasons as well, and those a priori, 
it is so much the better. 

17. But perhaps what is meant is that when I had invented 
a new view for myself, I was very glad to make use of it, 
more to assume airs on account of its novelty than because 
I recognized it to be useful. I do not know, sir, whether 
you have so poor an opinion of me as to attribute such 
thoughts to me. For you know that I love truth; and that 
if I had such a feeling for novelties, I should be in a greater 
hurry to produce them, especially those whose solidity is 
recognized. But in order that those who know me less 
well should not endow your words with a meaning which 
we should not like, suffice it to say that in my view it is 
impossible to explain transeunt activity in conformity with 
the laws of nature in any other way, and that I believed that 
the value of my hypothesis would be recognized in view of 
the difficulty which the ablest philosophers of our time have 
found in the communication of minds and bodies, and even of 
bodily substances one with another. I do not know whether 
you yourself have encountered any of these difficulties. 

1 8. It is true that there are, on my view, forces in all 
substances; but these forces are, strictly speaking, only in 
the substance itself; and what follows from them in the 


other substances is only by virtue of a pre-established har- 
mony, if I may use the word, and not by any real influence, 
or by the transmission of some species or quality. As I have 
explained the nature of activity and passivity, the nature 
of force and of resistance can readily be inferred. 

19. You say, sir, that you know that there are still many 
more questions to be put before we can decide those which we 
have been discussing. But perhaps you will find that I have 
already put them: I am not sure that your Academics have 
put into practice the valuable parts of their method more 
rigorously and effectively than I myself have done. I 
strongly approve of the attempt to prove truths from first 
principles; this is more useful than is commonly supposed, 
and I have often put this precept into practice. Thus I 
welcome what you say on this subject, and I hope your 
example will lead our philosophers to think about it as 
they should. 

20. I will add a further reflection which seems to me to 
be of considerable assistance towards the better understand- 
ing of the reality and value of my system. You know that 
M. Descartes believed that the same quantity of motion is 
conserved in bodies. It has been demonstrated that he was 
mistaken in this; but I have shown that it is always true 
that the same motive force instead of, as he thought, the 
same quantity of motion is conserved. Even so, the 
changes which take place in the body as a consequence of 
the modifications of the soul caused him embarrassment, 
because they seemed to violate this law. He thought there- 
fore that he had found a way out of the difficulty, which is 
certainly ingenious, by saying that we must distinguish 
between motion and direction of motion; and that the soul 
cannot increase or diminish the motive force, but that it 
changes the direction or determination of the course of the 
animal spirits, and it is in this way that voluntary motions 
take place. It is true that he made no attempt to explain 


how the soul sets about changing the course of bodies and 
in fact tliis seems as inconceivable as saying that it gives 
them motion, unless you have recourse, as I do, to pre- 
established harmony. But the truth is that there is another 
law of nature, which I have discovered and proved, and which 
M. Descartes did not know: namely, that there is conserved not 
only the same quantity of motive force, but also the same 
quantity of direction from whatever side in the world it be 
taken. That is to say: take any straight line you like, and 
take also any number of bodies, chosen as you please; you 
will find that, considering all these bodies together without 
leaving out any of those which act on any of those which 
you have taken, there will always be the same quantity of 
progression from the same side in all the lines parallel to the 
straight line you have chosen: provided care is taken that 
the sum total of progression is estimated by deducting that 
of the bodies which go in the opposite direction from that 
of those which go in the direction chosen. This law is as 
beautiful and as general as the other, and deserves as little 
to be violated: and this is so in my system, which conserves 
both force and direction, and, in a word, all the natural laws 
of bodies, notwithstanding the changes which occur in 
them as a result of those in the soul. 

P.S. Hanover, 3/13 January 1696. 

I see clearly from your reflections that I need to throw 
some light on that idea of mine which a friend caused to be 
inserted in the Journal de Paris. You say, sir, that you do 
not see how I could prove what I propounded concerning 
the communication or harmony of two substances as different 
as the soul and the body. It is true that I thought I had 
supplied the means of doing so. And I hope that what 
follows will satisfy you. 

Imagine two clocks or watches which are in perfect 


agreement. Now this agreement may come about in three 
ways. The first consists of a natural influence. This is what 
M. Huygens tried with a result that surprised him. He 
suspended two pendulums from the same piece of wood; 
the continual strokes of the pendulums communicated 
similar vibrations to the particles of the wood; but since 
these different vibrations could not well persist independently 
and without interfering with one another, unless the pen- 
dulums were in agreement, it happened by some sort of 
miracle that even when their strokes had been purposely 
disturbed, they soon went back to swinging together, rather 
like two strings l which are in unison. The second method 
of achieving the constant agreement of two clocks, albeit 
imperfect ones, would be to have them continually supervised 
by a skilful craftsman who should be constantly setting 
them right. The third method is to construct the two clocks 
so skilfully and accurately at the outset that one could be 
certain of their subsequent agreement. 

Now substitute the soul and the body for these two watches. 
Their agreement or sympathy will also arise in one of these 
three ways. The way of influence is that of ordinary philo- 
sophy; but as it is impossible to conceive of either material 
particles, or immaterial species or qualities, as capable of 
passing from one of these substances to the other, we are 
obliged to abandon this view. The way of assistance is that 
of the system of occasional causes. But I hold that this is 
bringing in the dens ex machina for a natural and ordinary 
thing, where reason requires it to intervene in the same way 
only as it contributes to all other things in nature. Thus 
there remains only my hypothesis, that it to say the way of 
pre-established harmony pre-established, that is, by a Divine 
anticipatory artifice, which so formed each of these substances 
from the beginning, that in merely following its own laws, 
which it received with its being, it is yet in accord with the 
1 i.e. strings of a musical instrument. 


other, just as if they mutually influenced one another, or as if, 
over and above His work of general co-ordination, God were 
for ever putting in His hand to set them right. After this 
I do not think there is anything for me to prove, unless I am 
desired to prove that God possesses the cleverness necessary 
for making use of this anticipatory artifice, of which we see 
samples among men, in proportion as they are clever people. 
And supposing that He can, it is clear that this is the finest 
way and the worthiest of Him. You had some suspicion 
that my explanation would be opposed to the rather different 
idea we have of mind and body. But now you see clearly, 
sir, that no one has better established their independence. 
For so long as it was necessary to explain their communica- 
tion by a kind of miracle, it was always left open to some 
people to fear that the distinction between them might not 
be what it was supposed to be, because it was necessary to 
go to such lengths to uphold it. Now all these scruples 
disappear. My Essays on Dynamics are connected with this ; 
in them I had to inquire more deeply into the notion of bodily 
substance, which on my view lies rather in the force of 
acting and resisting than in extension, which is but a repeti- 
tion or diffusion of something anterior, that is to say, of this 
force. And as these thoughts of mine, which to some have 
appeared paradoxical, have caused me to exchange letters 
with various well-known men, I could produce a Commercium 
Epistolicum on the subject, into which would come my 
correspondence with M. Arnauld, of which I spoke in my 
previous letter. It will contain a curious mixture of thoughts 
about philosophy and mathematics, which will perhaps 
sometimes have the charm of novelty. I leave you to judge, 
sir, whether the explanations I have just given are suitable 
for sounding the opinions of enlightened people through the 
intermediary of your journal. But do not give my name, as 
it was not given in the Journal de Paris either. 



. . . Let me say 4 a word on the subject of the dispute between 
two very clever people, the author of the Principles of Physics, 
published recently, and the author of the Objections (included 
in the Journal of i3th August and elsewhere), since my 
hypothesis serves to end these controversies. I do not 
understand how matter can be conceived as being extended, 
and yet as being without parts either actual or mental. If 
this be possible, I do not know what it is to be extended. 
I even hold that matter is essentially an aggregate, and 
consequently that it always has actual parts. Thus it is by 
reason, and not only by the senses, that we judge that it is 
divided, or rather that it is ultimately nothing but a plurality. 
I hold that it is true that matter (and even each part of 
matter) is divided into a greater number of parts than it is 
possible to imagine. It is this that makes me often say that 
each body, however small, is a world of created things infinite 
in number. Thus I do not believe that there are atoms, that 
is to say parts of matter which are perfectly hard, or in- 
vincibly solid; just as on the other hand I do not believe 
either that there exists matter which is perfectly fluid. My 

1 M. D. L. is a pseudonym of Leibniz. 

Nicolas Hartsoeker (1656-1725), a Dutch physicist, mainly 
concerned with the making of microscopes and telescopes. His 
correspondence with Leibniz about his philosophy of nature 
is extant. 

8 Foucher. Cf. p. 45, note. 

4 The first part of this letter repeats the illustration of the two 
clocks, given above; the second part deals with the solution of a 
purely mathematical problem; the third part is given here. 


view is that each body is fluid in comparison with more solid 
ones, and solid in comparison with more fluid ones. I am 
surprised that it should still be said that there is always 
conserved an equal quantity of motion in the Cartesian 
sense; for I have proved the opposite, and already excellent 
mathematicians have accepted my view. However, I do not 
consider the hardness or consistency of bodies as a primary 
quality, but as a consequence of motion, and I hope that 
my Dynamics will show wherein this consists; just as the 
understanding of my hypothesis will also serve to remove 
several difficulties which still exercise philosophers. Indeed, 
I believe I can answer intelligibly all the doubts to which the 
late M. Bernier devoted a whole book, and those who are 
ready to ponder what I have previously published will 
perhaps already find therein the means of doing so. 


I take the liberty, sir, of sending you this explanation of 
the difficulties which M. Bayle found in the hypothesis which 
I suggested to explain the union of the soul and the body. 
Nothing could be more accommodating than the manner in 
which he has treated me in regard to it; and I consider myself 
honoured by the objections which he included in his excellent 
Dictionary, under the article ' Rorarius '. Moreover, so great 
and profound a mind as his cannot make objections without 
being instructive, and I will try to take advantage of the light 
he has thrown on these questions, both here and in several other 
places in his work. He does not reject what I said about the 
conservation of the soul and even of the animal, 1 but he does 
not yet appear to be satisfied by the way in which I claimed 
to explain the union and intercourse between the soul and 
the body, in the Journal des Savans of 27th June and 4th 

H ft the whole animal nii1 anri hnriilv r>rea.nism. 


July 1695, and in the Histoire des Outrages des Savans of 
February 1696, pages 274 and 275. 

These are his words, and they seem to show where it was 
that he found difficulty: / am unable to understand (he says) 
that necessary connection between internal and spontaneous 
actions which would cause the soul of a dog to experience pain 
immediately after having experienced joy, even though it were 
alone in the universe. I answer, that when I said that the 
soul would experience everything it now experiences, though 
there were only God and itself in the world, I did but employ 
a fiction, that is, I postulated what could not happen naturally 
in order to make it clear that the feelings of the soul are 
nothing but a consequence of what is already present in it. 
I do not know whether M. Bayle means to demonstrate the 
incomprehensibility of the necessary connection only in what 
he says below, or whether he also intends to indicate it at 
once by giving this example of the spontaneous transition 
from joy to pain. Perhaps he wishes to give us to understand 
that this transition is opposed to the axiom which teaches 
that a thing remains always in the state in which it once is, 
if nothing supervenes to cause it to change; and that there- 
fore when an animal once feels joy, it will feel it always if 
it is alone, and there is nothing outside it to cause it to 
pass to pain. In any case, I remain in agreement with the 
axiom, and even claim that it is favourable to me, as indeed 
it is one of my fundamental principles. Is it not the case 
that from this axiom we conclude, not only that a body that 
is at rest will always remain at rest, but also that a body 
that is in motion will always retain this motion or change, 
that is to say the same velocity and the same direction, if 
nothing supervenes to prevent it? Thus it is not simply 
that in so far as depends upon itself a body remains in the 
state in which it is, but also when it is in a state of change it 
continues to change and this in accordance with the very 
same law. Now according to me, it is the nature of created 


substance to change continually following a certain order, 
by which it is led spontaneously (if I may be allowed to use 
this word) through all the states which are to happen to it, 
so that He who sees everything sees in its present state all 
its states both past and to come. And this law of order, 
which constitutes the individuality of each particular 
substance, has an exact relation to what occurs in every 
other substance, and in the whole universe. Possibly I am 
not making too bold a claim, if I say that I can prove all 
this; but at the moment it is only a question of upholding 
it as a possible hypothesis, and one fitted to explain the 
phenomena. Now in this way the law governing the 
changing of the substance of the animal bears him from joy 
to pain, at the moment when there occurs in his body an 
interruption of continuity, because the law of the indivisible 
substance of this animal is to represent what occurs in his 
body in the manner in which we experience it, and even to 
represent in some fashion and in relation to this body every- 
thing that occurs in the world; for the unities of substance 
are nothing else but different concentrations of the universe, 
represented according to the different points of view which 
distinguish them. 

M. Bayle continues: / understand why a dog passes im- 
mediately from pleasure to pain when, after being famished and 
eating bread, he is struck with a stick. I am not sure that 
this is sufficiently well understood. No one knows better 
than M. Bayle himself that just herein lies the great difficulty 
we find in explaining why what happens in the body causes 
a change in the soul ; and that it is just this which has driven 
those who uphold occasional causes to have recourse to the 
care that must be taken by God to see that all changes which 
occur in a body shall be continually represented to its soul: 
whereas I believe that it is its own nature, given it by God, 
to represent to itself, by virtue of its own laws, what occurs 
in its organs. He continues: 


But that his soul is so constructed that at the moment when 
he is struck he would feel pain even if he were not struck , but 
were to continue eating bread without let or hindrance, that is 
what I cannot understand. Neither do I recollect having 
said so; nor could it be said except by a metaphysical fiction, 
as when we suppose that God annihilates some body to 
create a void, both suppositions being equally contrary to the 
order of things. For since the nature of the soul was origin- 
ally made in a manner fitted to represent to itself in succes- 
sion the changes of matter, the supposed case could not 
arise in the natural order. God could have given to each 
substance its own phenomena independent of those of others, 
but in this way He would have made, as it were, as many 
unconnected worlds as there are substances; very much in 
the same way as we say that when a man dreams, he is in his 
own world apart, but that he enters the common world when 
he wakes. It is not that dreams themselves are unrelated 
to the organs and to the rest of the body, but that they are 
related in a less distinct manner. Let us continue with 
M. Bayle. 

Further } the spontaneity of this soul (he says) seems to me 
quite incompatible with feelings of pain, and in general, with 
all perceptions which are not pleasing to it. This incompati- 
bility would be certain if spontaneity and voluntariness 
were the same thing. Everything which is voluntary is 
spontaneous; but there are spontaneous actions which occur 
without choice, and which consequently are not voluntary. 
It does not rest with the soul to give itself always feelings 
which are pleasing to it; for the feelings which it is going 
to have are dependent on those which it has had. M. 
Bayle proceeds: 

Moreover, the reason why this gifted man does not fancy the 
Cartesian system appears to me a false supposition, for it 
cannot be said that the system of occasional causes makes the 
action of God intervene by miracle (deus ex machina) in the 


reciprocal dependence of the body and the soul: for as God does 
not intervene except in accordance with general laws, His action 
in this matter is not in any way out of the ordinary. It is not 
for this reason alone that I do not fancy the Cartesian system; 
and some slight consideration of my own doctrine will show 
that I find in it positive reasons for adopting it. Even if the 
hypothesis of occasional causes had no recourse to miracle, 
it appears to me that mine would none the less possess 
other advantages. I have said that three systems can be 
imagined which might explain the communion between the 
soul and the body; that is, (i) the system of the influence 
of the one on the other, which is that of the Schools, taken 
in the common sense this I agree with the Cartesians in 
believing to be impossible; (2) the system of a perpetual 
supervisor, who represents in the one what takes place in 
the other, very much as if a man were entrusted with the 
task of securing the agreement of two bad clocks, which 
would not of themselves be capable of agreeing this is the 
system of occasional causes; and (3) the system of the natural 
agreement of two substances, such as would arise with two 
very accurate clocks this system I hold to be as possible 
as the system of the supervisor, and more worthy of the 
Author of these substances, clocks, or automata. But now 
let us see whether the system of occasional causes does not 
in fact presuppose a perpetual miracle. M. Bayle says that 
it does not, because according to this system God would not 
act except through general laws. Granted, but on my view 
this is not enough to obviate the miracles; even were God 
to perform them continually, they would not cease to be 
miracles, if we take this word not in the popular sense of a 
rare and marvellous thing, but in the philosophical sense of 
that which is beyond the powers of created things. It is not 
enough to say that God made a general law; for besides the 
decree there must also be a natural means of carrying it out; 
that is to say, what occurs must be able to be explained by the 


nature with which things are endowed by God. The laws 
of nature are not so arbitrary or so indifferent as some 
people believe. If, for example, God decreed that all bodies 
should tend to move in circles, and that the radii of the 
circles should be proportionate to the size of the bodies, we 
should have either to say that there was a way of carrying 
this out by means of simpler laws, or else to admit that God 
brought it about miraculously, or at least by means of angels 
expressly entrusted with the task, something like the angels 
who in earlier times were supposed to be attached to the 
celestial spheres. The same would be true if someone main- 
tained that God had endowed bodies with natural and primary 
gravities, by means of which each tended to move towards 
the centre of its own sphere, without being impelled by other 
bodies ; in my opinion this system would require a perpetual 
miracle, or at least the assistance of angels. 

Does the internal and active power which is communicated 
to the forms of bodies know the sequence of actions which it will 
produce? By no means ; for we learn from experience that we 
do not know that we shall have such and such perceptions an 
hour hence. I reply that this power, or rather this soul or 
form itself, does not know them distinctly, but that it feels 
them confusedly. There are in every substance traces of 
everything that has happened to it and of everything that 
will happen to it. But the infinite multitude of these per- 
ceptions prevents us from distinguishing between them, in 
the same way as when I hear a loud and confused noise made 
by a crowd I am unable to distinguish one voice from another. 

// would thus be necessary for these forms to be directed by 
some external principle in the production of their actions; is not 
this the deus ex machina again just the same as in the system 
of occasional causes ? My foregoing answer shows that this 
conclusion does not follow. On the contrary, the present 
state of every substance is a natural consequence of its 
preceding state, but only an infinite intelligence can grasp 


this sequence for it involves the whole universe whether 
in souls or in any given portion of matter. 

M. Bayle concludes with these words: Finally, since he 
supposes, and rightly so, that all souls are simple and indivisible, 
it is impossible to understand how they can be compared to a 
pendulum, that it to say that by their original constitution they 
can vary their operations in utilizing the spontaneous activity 
received from their Creator. It is quite clear that a simple 
being will always act uniformly, if turned aside by no outside 
cause. If it were composed of several parts like a machine, its 
actions would show variety, because the particular activity of 
each part might at any moment change the course of the activity 
of the others ; but in a single substance, where will you find the 
cause of a change of operation ? This objection I consider to be 
worthy of M. Bayle : it is one of those which most deserve to 
be elucidated. But I also believe that if I had not previously 
provided for it, my system would not deserve to be examined. 
I compared the soul to a pendulum only in regard to the 
regulated exactitude of its changes, which is but imperfect 
in the best of clocks, though perfect in the works of God; and 
it may be said that the soul is an immaterial automaton of 
the most exact kind. When it is said that a simple being 
always acts uniformly, a distinction has to be made: if to 
act uniformly is to follow perpetually the same law of order, 
or of continuance, as in a given set or sequence of numbers, 
I admit that of itself every simple being, and even every 
compound being, acts uniformly; but if by uniformly is meant 
similarly, then I do not agree. Let me explain the difference 
of meaning by an example: a movement in a parabola is 
uniform in the first sense, but not in the second, for the parts 
of the parabola are not similar to one another, as are those 
of a straight line. . . , 1 

1 In the few lines here omitted Leibniz comments ' by the way ' 
on Bayle's statement that a simple body left to itself describes a 
straight line. He points out that this is true if we consider only 


We must also remember that the soul, simple though it is, 
has always a sensation which is composed of several percep- 
tions at once; and this serves the purpose for my theory as 
much as if it were composed of parts, like a machine. For 
each preceding perception has some influence on those which 
follow, in conformity with a law of order which is to be found 
in perceptions as well as in motions. Moreover, the majority 
of philosophers, for several centuries, who have endowed 
with thoughts both souls and angels (whom they hold to be 
destitute of all body), not to mention the intelligences of 
Aristotle, admit the occurrence of spontaneous change in a 
simple being. I add that, since the perceptions which exist 
together in the same soul at the same time include a truly 
infinite multitude of small feelings, indistinguishable from 
one another, which the future will develop, we must not be 
surprised at the infinite variety of what must result from 
them in the course of time. All this is but a consequence 
of the representative nature of the soul, which is bound to 
express everything that is occurring and even everything 
that is going to occur in its own body, and in some manner 
in all other bodies, owing to the connection or correspondence 
between all the parts of the world. It would perhaps have 
been enough to say that since God has made corporeal 
automata, He could easily likewise have made immaterial 
ones to represent them; but I thought it would be well to 
develop this matter a little further. 

For the rest, I have read with pleasure what M. Bayle says 
in the article 'Zeno*. Perhaps he will notice that what can 
be derived from it agrees better with my system than with 
any other; for whatever is real in extension and in motion 

the centre of the body; but in the case of a rotating body, a point 
in it distant from the centre describes a circle when the centre is 
stationary, and a more complicated curve (of which Leibniz 
gives the co-ordinates) when the centre is moving in a straight 
line. But he does not press this mathematical point into 
service for his general argument here. 


consists only in the foundation of the order and regulated 
sequence of phenomena and perceptions. The Academics 
and the Sceptics, no less than those who wished to reply to 
them, seem to have been in difficulties only because they 
sought a greater reality in the sensible things outside us than 
the reality of regulated phenomena. We conceive of ex- 
tension, by conceiving an order in co-existences; but we 
ought not to conceive of it, nor ought we to conceive of space 
after the manner of a substance. It is like time, which 
presents to the mind nothing but an order among changes. 
And as to motion, what is real in it is the force or power, 
that is to say, that which in the present state carries with 
it a change for the future. The rest is but phenomena 
and relations. 

The consideration of this system shows also that when we 
go deeply into things, we find more sound sense than we 
thought in the majority of philosophical sects. . . . 


i. My first comment * is that M. Leibniz exalts beyond any- 
thing that can be conceived the power and intelligence of Divine 
art. I agree that he exalts it beyond anything that can be 
understood, but not beyond anything that can be conceived. 

Imagine a ship having neither feeling nor knowledge, and with 
no being created or uncreated at the helm, to have the power to 
move itself of its own nature so skilfully that it always enjoys a 
favourable wind, avoids currents and shallows, and finds a 
haven just at the right moment. Suppose such a ship sailing 
thus for several years continuously, always turned in the very 
direction and situated in the very place required by the changes 
of atmosphere and the different situations of land and sea; 

1 Italics indicate quotations from Bayle's Dictionary. From 
this paper an extract only is given here. 


you will agree that the infinitude of God is not greater than 
is necessary to endow a ship with such a faculty, and you 
will even say that a ship's nature is not capable of receiving 
this power from God. Yet what M. Leibniz supposes regarding 
the machine of the human body is more wonderful and more 
surprising than all this. 

I will first reply to the question whether the supposition 
of such a ship is possible. And afterwards I will come to the 
comparison here made with the machine of the human body. 
In the first place I find it strange that M. Bayle should dare 
to decide the question in the negative, and to deny that this 
is possible to God, without adducing any reason, when he 
himself often agrees that anything which does not imply a con- 
tradiction or imperfection could be produced by the Divinity. 
I admit that M. Bayle would be right if God were being 
required to endow the ship with some faculty, perfection, or 
occult quality, by which it could of itself direct its own 
course, without any knowledge within itself and without any 
attraction or direction from without, like the Phaeacians* 
vessel in Homer's Odyssey. For such a supposition would be 
impossible, and would violate the principle of sufficient 
reason, since it would be impossible to give any explanation 
of such a perfection, and God would always have to be setting 
His hand to it by a perpetual miracle unless some occasion- 
alist thought it suitable to have recourse to his supposed 
general laws, since God might promulgate one in favour of 
this ship; nor could M. Bayle, who is anxious to divorce 
occasional causes from miracles, reasonably object to this. 
For myself, I reject these natural laws exemption from which 
is absolutely explicable by the nature of things. But while 
we reject this occult quality in the ship, we must admit that 
there is nothing to prevent there being a ship, born under a 
lucky star as it were, so that it always reaches port, without 
guidance by the winds and tides, through storms and shallows, 
simply by encountering favourable accidents, Certain it is 


that ships without men have sometimes reached their 
destined shore. Is there anything that makes it impossible 
for this to happen several times to the same ship, and con- 
sequently as many times as it puts to sea which will only 
happen a certain number of times? Since the number of 
accidents is not infinite, not only God but even an exceedingly 
excellent finite spirit would be able to foresee all the accidents 
to which the ship would be exposed, and could find out by 
solving a geometrico-mechanical problem the structure of the 
ship and the places, times, and methods of its putting to sea 
which would make it adjust itself in the best way to this 
finite number of accidents. Do we not know that men are 
sufficiently skilful to make automata capable of turning at 
a specified place at street corners, and of adjusting them- 
selves in this way to a certain number of accidents? And 
a Mind proportionally greater would provide against accidents 
in greater numbers. And if this excellent Mind did not find 
these accidents already given, but was free to make them 
arise or cease at His will, it would be incomparably easier 
still for Him to satisfy this demand, and to adjust in advance 
and by a pre-established harmony the ship to the accidents 
and the accidents to the ship. Thus it is the gravest mistake 
to doubt whether the infinity of God is great enough to be 
able to succeed in this. 

2. Let us apply to the person of Caesar the new system of the 
union of the soul and the body: according to this system we must 
say that the body of Julius Caesar exercised its motive power in 
such a way that from birth to death it followed a constant pro- 
gression of changes which corresponded in the last degree of 
exactness to the perpetual changes of a particular soul which 
the body did not know, and which made no impression on it. 

Bodies do not know what takes place in the soul, and the 
soul makes no physical impression on the body. M. Bayle 
agrees with this; but God has supplied this lack not by Him- 
self giving the body at intervals new impressions to make it 


obey the soul, but by making this automaton such in the 
first place that it will carry out what the soul commands 
punctually as to both time and place. 

We must say that the ride according to which this faculty of 
Caesar's body had to produce these actions was such that he 
would have gone to the Senate on such a day and at such an 
hour, that he would there have uttered such and such words , etc., 
even though it had pleased God to annihilate Caesar's soul the 
day after it was created. 

There is nothing strange in this when once we bear in mind 
that as great a craftsman as God can make an automaton 
which resembles a valet and is capable of performing his 
function, and of carrying out at a specified place whatever 
it was ordered to do over a long period of time. The body 
is an automaton of this kind in regard to the mind. 

We must say that this motive power punctually changed 
itself and modified itself in accordance with the volubility of the 
thoughts of that ambitious spirit, and that it assumed precisely 
such a particular state rather than any other, because the soul 
of Caesar passed from one particular thought to another. 

It seems that M. Bayle has let himself be deceived, for 
he has imagined that the ship of the man's body was endowed 
with some mysterious faculty or power capable of adjusting 
itself to the accidents or the thoughts without having any 
knowledge of them, and even without any intelligible reason. 
He is entirely justified in condemning such a faculty as 
impossible, but no one ever thought of such a thing. All that 
the automaton which played the valet would need would be 
a structure which would make it perform its functions by 
virtue of the rules of mechanics. It would not modify itself 
nor change itself to adjust itself to the thoughts of its master. 
It would follow its own course, and by that very means 
would exactly fall in with the will of him whom the craftsman 
who made it meant it to serve. 

Can a blind force so conveniently modify itself as the result 


of an impression conveyed 30 or 40 years previously ', and never 
since renewed, and which has moreover been left to itself without 
ever having any knowledge of its lesson ? Is this not much more 
incomprehensible than the navigation of which I spoke in the 
preceding paragraph ? 

It becomes clearer and clearer that M. Bayle has not 
properly grasped my view, which is that the body modifies 
itself in the required way not by some kind of impression 
or power it has received, but by its own structure, which is 
adjusted to that end. The automaton which plays the valet 
will again serve to remove the whole difficulty. The struc- 
ture with which it has been endowed suffices for all its 
functions, even if it is left to itself, even if its first impressions 
are not renewed, and even if it has no knowledge of the 
command or of the lesson given to it. And the difference 
between the body of Caesar and tfiis automaton is but the 
difference between the greater and the less. 1 

4. // is vain for upholders of the view that the brutes are 
nothing but automata to shelter themselves behind the power of 
God. It is vain to explain that God was able to construct 
machines, so artfully wrought that the voice of a man, the 
reflected light of an object, etc., strike them in precisely the right 
place so that they move in such and such a way. Every one, 
except a few of the Cartesians, rejects this siipposition. 

It is rejected not as impossible but as unlikely. 

And there is no Cartesian who would accept the view if it 
were extended to man, that is to say if it were maintained that 

1 Bayle points out (in 3, which is omitted here) that the 
changes which occur in the soul, corresponding to all the actions 
and interactions between the organs of the body and between 
the body and other bodies, are infinite in number, and urges 
that this infinity makes the theory of a pre-established harmony 
between spontaneous unities quite incredible. Leibniz replies 
that the fact that the variety of changes is infinite does nothing 
to increase the difficulty; it only gives ground for 'wondering 
still further at the Divine artifice '. 


God was able to make bodies which could perform mechanically 
all the things that we see other men do. 

The Cartesian will not deny that it is possible for God to 
make such an automaton; but he will not allow that other 
men are in fact inanimate automata of this kind. He will 
think, and rightly, that they are like himself. According to 
my view, all alike are automata, the bodies of men as well as 
those of brutes, but all of them are animated, the bodies of 
brutes as well as those of men. Thus pure materialists, such 
as the followers of Democritus, no less than formalists, such 
as the Platonists and Peripatetics, are right in some things, 
and wrong in others. There is a great deal of justification 
for the view of the followers of Democritus that the bodies of 
men as well as those of brutes are automata and perform all 
their actions mechanically; but they were wrong in thinking 
that these machines were not accompanied by an immaterial 
substance or form, and that matter was capable of perception. 
The Platonists and the Peripatetics held that brutes and men 
have animated bodies, but they were wrong in thinking that 
souls change the rules of the motion of bodies; thus they 
denied the automatism of the body of both brute and man. 
The Cartesians were right to reject this influence, but they 
were mistaken in denying automatism to man and sensation 
to brutes. I hold that we must allow both to both men and 
brutes, that we must follow Democritus in making all the 
actions of mechanical bodies independent of souls, and that 
we must also go further than the Platonists in holding that 
all the actions of souls are immaterial and independent of 
the machine. 

In denying this we do not claim to set limits to the power and 
knowledge of God. We simply mean that the nature of things 
requires that the powers given to the created being should 
necessarily have certain limitations. It is absolutely necessary 
that the activity of created things should be proportioned to their 
essential state , that it should be exercised in accordance with the 


character which is fitted to the given machine ; for according to 
the axioms of the philosophers everything which is received is 
proportioned to the capacity of the subject. 

M. Bayle keeps on reverting to this supposed power given 
to the body to enable it to accommodate itself to the soul. 
I do not require any such thing; I do not go outside the 
limitations of created things, nor of the state of bodies or 
machines. There is nothing in the artifice of the Divine 
machine which surpasses the knowledge and the power of 
God. Since He knows everything which can be known, and 
can do everything which can be done, He knows the number 
(which is limited) of the volitions of man: and He has the 
ability to make a machine capable of carrying them out. 

We may therefore reject as impossible M. Leibniz's hypothesis, 
since it involves greater difficulties than that of automatism. 

This argument would be good if the theory of automata 
had been convicted of impossibility, but since the contrary 
is manifest and has been sufficiently proved by the Cartesians, 
it is only a question of greater and less, which involves no 
difficulty when it is a question of a power and a wisdom which 
are infinite. Although man reasons about matters which 
are abstract and which surpass the imagination, he none the 
less has in his imagination signs which correspond to them, 
such as letters and characters. There is no understanding 
so pure as not to be accompanied by some imagination. 
Thus there is always in the body something mechanical which 
corresponds exactly to the sequence of thoughts present in a 
man's mind, in so far as that which can be imagined enters 
into the matter, and consequently the automaton of his body 
has no more need of the influence of the soul, or of the 
supernatural assistance of God, than has that of the brute's 

It maintains the existence of a continual harmony between 
two substances which do not act on one another. 

Why not? since they originate from one and the same 


Author who was willing and able to arrange that they should 
agree without acting on one another. 

But if the valets were machines, and punctually performed 
this and that whenever their master commanded, such a thing 
could only be if the master really acted on them : he would utter 
words and would make signs which would really affect the organs 
of the valets. 

But there are valets who are so well trained as not to need 
signs to be given to them. They anticipate them. Watches 
which strike, for instance, and alarm clocks are valets of this 
kind. Far from awaiting signs, they give them to us. The 
artificial valet, who imitates and counterfeits a real one, such 
as we have been speaking of above, does not even need to be 
wound or set by us, as do watches and alarm clocks. The Arti- 
ficer would have prepared him for us. Such a valet is our body. 

5. If we consider at this point the soul of Caesar, we shall 
find still more impossibilities. This soul was in the world 
without being exposed to the influence of any body or of any 
mind. The force it had received from God was the sole principle 
of the particular actions it produced at each moment ; and if 
these actions were different one from another, this was not due 
to the fact that some were produced with the co-operation of 
certain sources of action, which did not contribute to the pro- 
duction of the others ; for the soul of man is simple, indivisible, 
and immaterial. M. Leibniz agrees ; and if he did not agree, 
but on the contrary was at one with the majority of the philoso- 
phers and even with some of the greatest metaphysicians of our 
age (Mr. Locke for example) in supposing that a thing composed 
of several material parts arranged in a certain way is capable 
of thinking, I should in that case regard his hypothesis as 
absolutely impossible, 

(So M. Bayle does not yet regard it as impossible.) 
and many other ways of refuting it would present themselves, 
which are here no concern of mine, since he does recognize the 
immateriality of the soul, and builds upon it. 


To say that the force which the soul has received from 
God is the sole principle of its particular actions does not 
afford sufficient explanation of its actions. It is better 
to say that God has placed in every soul a concentration of 
the world, or the power of representing the universe from a 
point of view proper to that soul, and that it is this that 
is the principle of its actions, distinguishing them from one 
another and from the actions of another soul. For it follows 
that they will continually be undergoing changes representa- 
tive of the changes in the universe, and that the other souls 
will undergo other changes, but corresponding ones. 

Let us return to the soul of Caesar, and let us call it an im- 
material automaton, to use M. Leibniz's own expression ; and let 
us compare it with an Epicurean atom. I mean an atom which 
is surrounded by a void on all sides and which will never meet 
any other atom. The comparison is a very just one ; for on 
the one hand this atom has a natural faculty of moving itself, 
and exerts it without being helped by anything whatever, 
and without being checked or deflected by anything at all; and 
the soul of Caesar is a mind which has the power of giving 
itself thoughts, and which exerts it without being influenced by 
any other mind, or by any body. Nothing assists it, nothing 
deflects it. If you consult common notions and common ideas 
of order you will find that this atom must never stop, and that 
having moved in the preceding moment, it must move in the 
present moment and in all subsequent moments, and that the 
manner of its motion must always be the same. This is a 
consequence of an axiom approved by M. Leibniz. From the 
fact that a thing remains always in the state in which it once 
is, if nothing supervenes to cause it to change, we conclude (he 
says) not only that a body which is at rest will always remain 
at rest; but also that a body which is in motion will always 
retain this motion or change, that is to say the same velocity 
and the same direction, if nothing supervenes to prevent it. 
All the world knows clearly that this atom, whether it moves by 


an innate faculty, as Democritus and Epicurus assure us, or 
whether it moves by a faculty received from the Creator, always 
proceeds uniformly and equally in the same line without its ever 
happening to it to turn to right or to left or to turn back. Epicurus 
was made fun of when he invented the motion of atomic 'swerve'; 
he postulated it gratuitously to get himself out of the labyrinth 
of the fatal necessity of all things, and he could give us no reason 
for this new part of his hypothesis. It offended against the 
most obvious notions of our minds, for it is evident that if an 
atom which has pursued a straight line for two days is to turn 
aside from its route at the beginning of the third day it must 
either encounter some obstacle, or conceive some desire of leaving 
its path, or else contain some source of energy which becomes 
active at that moment. The first of these reasons does not arise 
in empty space, the second is impossible because an atom has 
not the power of thought; the third is likeioise impossible in a 
body which is absolutely one. 

Before proceeding, it is well to point out a great difference 
between matter and the soul. Matter is an incomplete 
being: it lacks the original source of actions. And when it 
receives an impression, that impression precisely, and what 
is in it at the moment, is all that the matter contains. It is 
for this reason that matter is not even capable of maintaining 
of itself a circular motion, for this motion is not sufficiently 
simple for it to be able to remember it, so to speak. It 
remembers only what happens to it in the last moment, or 
rather in ultimo signo rationis, 1 that is to say it remembers 
the direction straight along the tangent, without having the 
gift of remembering the instruction which would be given 
to it to turn aside from that tangent, to make it remain all 
the time on the circumference. This is why the body does 
not maintain its circular motion, even though it has begun 
such a motion, unless there is some reason compelling it to 
do so. This is why an atom can only learn to go simply 
1 'in the last stage in the order of reasoning*. 


in a straight line, such is its stupidity and imperfection. 
The case is quite different with a soul or mind. As it is a 
true substance or complete being, which is the original 
source of its own actions, it remembers as it were (confusedly, 
of course) all its preceding states, and is affected by them. 
It not only holds its direction, as does the atom, but it holds 
also the law of the changes of direction, or the law of curves, 
which the atom is incapable of doing; and whereas in the 
atom there is but a single change, there is an infinite number 
of changes in the modifications of the soul, each of which 
holds its own law; for the Epicurean atom, although endowed 
with parts, is a thing internally united, whereas the soul, 
although it has no parts, contains within itself a great 
number, or rather an infinite number, of varieties, owing to 
the multitude of the representations of external things, or 
rather owing to the representation of the universe, which the 
Creator placed in it. If M. Bayle had considered this dif- 
ference between the conatus of bodies and of souls, of which I 
had already some slight notion in my earliest youth, when I 
gave to the public my Physical Hypothesis (an idea which 
impressed the late M. Lantin of Dijon, as is proved by a 
letter he wrote me) he would not have brought up against me 
the comparison of an Epicurean atom with the human soul, 
as he does here. 

6. Let us make some use of all this. The soul of Caesar is 
a being to which the term unity is in the strictest sense applicable. 
The power of giving itself thoughts is a property of its nature, 
according to the system of M. Leibniz. It received it from 
Gody both as regards its possession and as regards its exercise. 
If the first sensation which it gives itself is a sensation of 

(I do not conceive that the soul gives itself first sensations. 
It received them from God with its being at the moment of 
creation, since it had some at the outset; and in its first 
sensations it received virtually all the rest.) 


it is not easy to see why the second thought also should not be 
a sensation of pleasure; for when the total cause of an effect 
remains the same, the effect cannot change. 

The total cause does not remain the same in this case. 
Present thoughts include a tendency to other thoughts. 
For the soul does not only have perception, but has appetite 
as well. But in tending towards new pleasures it sometimes 
encounters pains. 

Now this soul at the second moment of its existence does not 
receive a new power of thinking, it merely retains the power 
which it had in the first moment, and is as independent of the 
impact of every other cause in the second moment as in the 
first; it must therefore reproduce in the second moment the same 
thought that it has produced just before. 

Not at all; because it tends towards change in accordance 
with the laws of appetite, as body tends towards change in 
accordance with the laws of motion. 

If you object that it must be in a state of change, and that it 
would not be so in the case that I have supposed, I answer that 
its changing will be similar to the changing of the atom. For 
an atom which moves continually along the same line acquires 
at each moment a situation which is new but similar to its 
preceding situation. In order, therefore, that the soul may 
persist in its state of change, it is enough that it should produce 
a new thought similar to the preceding one. 

I have already explained above the great difference there 
is between the laws of change of a body, such as the atom, 
and those of the soul. And the very difference between the 
thought of the soul and the motion of the atom is evidence 
of this. Spontaneous motion consists in the tendency to 
move in a straight line; there is nothing which is so unified. 
But thought implies an actual material object, which is the 
human body; and this object is compound, and contains a 
very great number of modifications, whereby it is attached 
to the surrounding bodies, and by means of them in varying 


degree to all other bodies. And the tendencies of the soul 
towards new thoughts correspond to the tendency of the 
body towards new shapes and new motions. And as these 
new motions are capable of causing the object to pass from 
order to disorder, so their representations in the soul are 
capable of causing the soul to pass from pleasure to pain. 
Let us not press this point too rigidly; let us grant a metamor- 
phosis of thoughts. At the very least it would be necessary 
that the passage from one thought to another should include 
some ground of affinity. If I suppose that at a particular 
instant the soul of Caesar is looking at a tree which has flowers 
and leaves, I can conceive (if we assume that a created mind 
can give itself ideas, notwithstanding those reasons which 
prevent our understanding it) that his soul might immediately 
wish to see a tree which has only leaves and then another which 
has only flowers; and that thus it will produce for itself in 
succession several images which will arise one from another. 
But we cannot represent as possible changes from white to 
black, and from yes to no, nor the wild leaps from earth to shy 
which are common in the thought of man. We cannot believe 
that God was able to put into the soul of Julius Caesar the 
principle of what I am about to say. It no doubt happened 
to him on several occasions that when sucking he was pricked 
by a pin. It was therefore necessary (on the hypothesis we are 
here examining) for his soul to modify itself by a feeling of pain 
immediately after the pleasant perceptions of the sweetness 
of the milk 9 which it had experienced for two or three minutes 
in succession. By what source of energy was it forced to inter- 
rupt its pleasures, and to give itself suddenly a feeling of pain, 
when nothing had warned it to prepare for the change, and 
when nothing new had taken place in the substance? If you 
run through the life of this first Emperor you will find at every 
step material for a stronger objection than this one. 

Let us run through this statement. It is certainly true 
that the passage from one thought to another must include 


some link or reason, and this has been shown. If Caesar's 
soul had nothing but distinct thoughts, and gave them all to 
itself voluntarily, the passage from one thought to another 
might be like what M. Bayle suggests of the passage from one 
tree to another, for example. But besides the perceptions 
which the soul remembers, it has a heap of an infinite number 
of confused ones which it does not disentangle; and it is by 
these that it represents the bodies outside itself, and that it 
arrives at distinct thoughts dissimilar to the preceding ones 
because the bodies which it represents have passed suddenly 
to something which powerfully affects its own body. Thus 
the soul sometimes passes from white to black, or from yes 
to no, without knowing how, or at least in an involuntary 
manner. For what its confused thoughts and its sensations 
produce in it, is attributed to the bodies. It is not surprising, 
therefore, if a man who is eating jam and feels himself stung 
by an insect, passes immediately from pleasure to pain in 
spite of himself. For the insect was already affecting the 
man's body by getting near him before stinging, and the 
representation of this already affected his soul, albeit in- 
sensibly. Little by little, however, what is insensible 
becomes sensible, in the soul as in the body; this is how it 
happens that the soul modifies itself against its own inclina- 
tion, for it is the slave of its feelings and of its confused 
thoughts which arise in accordance with the states of its own 
body and of other bodies in relation to its own. Here then 
are the sources of energy by which pleasures are sometimes 
interrupted and succeeded by pains, without the soul always 
having warning or being prepared, as for example when the 
stinging insect approaches us noiselessly, or else, if for instance 
it is a wasp, some distraction prevents our noticing its buzzing 
as it approaches. Thus it must not be said that nothing new 
has taken place in the substance of the soul, to make it arrive 
at the feeling of the sting; it is the confused presentiments, 
or, to put it more strictly, the insensible dispositions of the 


soul which represent the dispositions to the sting in the 

7. We might understand something of all this if we suppose 
that the soul of man is not a mind but rather a legion of minds, 
each of which has its functions which begin and end precisely 
as required by the changes occurring in the human body. As 
a consequence of this we should have to say that something 
analogous to a great array of wheels and springs or of portions 
of matter in agitation, arranged in accordance with the vicis- 
situdes of our machine, awakened or put to sleep for such and 
such a time the activity of each of these minds; but in that 
case the soul of man would no longer be a substance, it would 
be an ens per aggregationem, an aggregate and a pile of 
substances, just like material things. What we are looking for 
here is one single thing which produces sometimes joy, sometimes 
pain, etc.; we are not looking for several things, of which one 
produces hope, another despair, and so on. 

M. Bayle is right to reject this view of the compound 
nature of the soul, for it would make it capable of destruction 
and dissipation since it would be an aggregate. But my 
theory does not require that the substance of the soul should 
be compound ; it is enough if its thoughts are compound and 
embrace a large number of objects and modifications which 
are known distinctly or confusedly; and this experience 
teaches us to be actually the case. For although the soul is 
a simple and single substance, it never has perceptions which 
are simple and single. It always has, at one and the same 
time, a number of distinct thoughts which it can remember, 
and attached to these an infinity of confused thoughts, whose 
ingredient parts it cannot distinguish. Since this complex 
of thoughts only has to produce other compound thoughts, 
it has no need of any legion of minds. Each partial modi- 
fication of the preceding state of the soul contributes to the 
subsequent total modification of the same soul, and gives it 
a new variation. 



SINCE the Essay on the Human Understanding, by a famous 
Englishman, 1 is one of the finest and most highly esteemed 
works of our time, I have resolved to make some remarks on 
it, because, having long meditated on the same subject and 
on the greater part of the matters therein considered, I 
thought this would be a good opportunity for publishing 
something under the title of New Essays on the Human 
Understanding, and for securing a favourable reception for 
my reflections by putting them in such good company. I 
further thought that I might profit by someone else's labour, 
not only to dimmish my own (since in fact it is less trouble 
to follow the thread of a good author than to work at every- 
thing afresh), but also to add something to what he has. 
given us, which is always an easier task than making a start;, 
for I think I have removed certain difficulties which he had 
left entirely on one side. Thus his reputation is of advantage- 
to me; and since I am moreover inclined to do justice to him x , 
and am very far from wishing to lessen the high opinion 
commonly entertained of his work, I shall increase his 

1 John Locke (1632-1704). When his Essay was published in 
1690 Leibniz sent him some short papers in criticism. Locke 
seems to have paid little attention to these. In 1700, Coste's 
translation of the Essay into French was published, and Leibniz 
set himself to write the New Essays, an elaborate work in which 
he examines and criticizes Locke's doctrines in a running com- 
mentary; he delayed publication, however, as a new edition of 
the French translation of the Essay was promised. Then in 
1704 Locke died; and the New Essays were not published until 
1 765, nearly fifty years after the death of Leibniz. 



reputation if my approval has any weight. It is true that 
1 am often of another opinion from him, but, far from denying 
the merit of famous writers, we bear witness to it by showing 
wherein and wherefore we differ from them, since we deem it 
necessary to prevent their authority from prevailing against 
reason in certain important points; besides the fact that, in 
convincing such excellent men, we make the truth more 
acceptable, and it is to be supposed that it is chiefly for 
truth's sake that they are labouring. 

In fact, although the author of the Essay says a thousand 
fine things of which I approve, our systems are very different. 
His bears more relation to Aristotle, mine to Plato ; although 
we both of us depart in many things from the doctrine of 
these two ancient philosophers. He is more popular, while 
I am sometimes compelled to be a little more acroamatic and 
abstract, which is not an advantage to me, especially when 
writing in a living language. But I think that by making 
two characters speak, of whom one expounds the views 
derived from our author's Essay* while the other gives my 
observations, I shall show the relation between us in a way 
that will be more to the reader's taste than dry remarks, the 
reading of which would have to be constantly interrupted by 
the necessity of referring to his book in order to understand 
mine. Nevertheless it will be well sometimes to compare our 
writings and to judge of his opinions by his own work only, 
although I have as a rule retained his expressions. It is true 

1 Philalethes gives Locke's views, and Theophilus those oJ 
Leibniz. The words of Philalethes are sometimes obviously a 
translation of Locke's own words, sometimes a paraphrase 01 
summary of a particular passage in Locke, and sometimes a 
free re-statement of Locke's doctrine. Where his words art 
obviously meant to be a translation, instead of retranslating 
them I have printed Locke's own words in italics, as it may be ol 
advantage to the reader to see at a glance what is the origina 
Locke, and what is Leibniz's summary or re-statement. Ir 
some places of course it is difficult to tell whether to treat the 
French as translation or as paraphrase; but as a general rule 
it is clear enough. 


that the necessity of having to follow the thread of another 
person's argument in making my remarks has meant that I 
have been unable to think of achieving the graces of which 
the dialogue form is capable: but I hope the matter will make 
up for this defect in the manner. 

Our differences are on subjects of some importance. The 
question at issue is whether the soul itself is entirely void, 
like a tablet whereon nothing has yet been written (tabula 
rasa), as is the view of Aristotle and the author of the Essay, 
and everything marked on it comes solely from the senses and 
from experience, or whether the soul contains originally the 
principles of various notions and doctrines, which external 
objects simply recall from time to time, as is my view and 
that of Plato, and even of the Schoolmen, and of all those 
who attribute this meaning to the passage from St. Paul 
(Rom. ii 15), where he says that the law of God is writ in 
men's hearts. The Stoics call these principles prolepses, that 
is to say assumptions which are fundamental or taken as 
agreed in advance. The mathematicians call them common 
notions (Koival eWoiac). Modern philosophers give them 
other fine names, and Julius Scaliger in particular called 
them semina aeternitatis 1 and again zopyra, meaning to say 
living fires, flashes of light, hidden within us, but caused 
to appear by the contact of the senses, like the sparks which 
the shock of the flint strikes from the steel. And it is not 
an unreasonable belief that these flashes are a sign of some- 
thing divine and eternal, which makes its appearance above 
all in necessary truths. From this arises another question, 
whether all truths depend on experience, that is to say on 
induction and on instances, or whether there are some which 
have another basis also. For if certain events can be fore- 
seen before we have made any trial of them, it is clear 
that we contribute in those cases something of our own. 
The senses, although they are necessary for all our actual 

1 ' seeds of eternity '. 


knowledge, are not sufficient to give us the whole of it, since 
the senses never give anything but instances, that is to say 
particular or individual truths. Now all the instances which 
confirm a general truth, however numerous they may be, are 
not sufficient to establish the universal necessity of this same 
truth, for it does not follow that what happened before will 
happen in the same way again. For example, the Greeks 
and the Romans, and all the other peoples of the earth known 
to the ancients, always observed that before the passage of 
twenty-four hours day changes to night and night to day. 
But they would have been wrong if they had believed that 
the same rule holds good everywhere, for since that time the 
contrary has been experienced during a visit to Nova Zembla. 
And any one who believed that in our zone at least this is a 
necessary and eternal truth which will last for ever, would 
likewise be wrong, since we must hold that the earth and 
even the sun do not exist of necessity, and that there may 
perhaps come a time when that beautiful star and its whole 
system will exist no longer, at least in its present form. 
From which it appears that necessary truths, such as we 
find in pure mathematics, and particularly in arithmetic 
and geometry, must have principles whose proof does not 
depend on instances, nor consequently on the testimony of 
the senses, although without the senses it would never have 
occurred to us to think of them. This is a distinction that 
should be carefully noted ; and it is one which Euclid under- 
stood so well that he often proves by reason what is evident 
enough through experience and sensible images. Logic also, 
together with metaphysics and morals, the one of which 
forms natural theology and the other natural jurisprudence, 
are full of such truths; and consequently proof of them can 
only arise from inner principles, which are called innate. It 
is true that we must not imagine that we can read in the soul 
these eternal laws of reason as in an open book, as the edict 
of the praetor can be read in his album without trouble or deep 


scrutiny. But it is enough that we can find them in ourselves 
by dint of attention, opportunities for which are afforded by 
the senses. The success of experiments serves also as a 
confirmation of reason, more or less as verifications serve in 
arithmetic to help us to avoid erroneous calculation when the 
reasoning is long. It is in this also that the knowledge of 
men differs from that of the brutes: the latter are purely 
empirical, and guide themselves solely by particular instances ; 
for, as far as we can judge, they never go so far as to form 
necessary propositions; whereas men are capable of the 
demonstrative sciences. This also is why the faculty the 
brutes have of making sequences of ideas is something inferior 
to the reason which is in man. The sequences of the brutes 
are just like those of the simple empiricists who claim that 
what has happened sometimes will happen again in a case 
where what strikes them is similar, without being capable 
of determining whether the same reasons hold good. It is 
because of this that it is so easy for men to catch animals, and 
so easy for pure empiricists to make mistakes. And people 
whom age and experience has rendered skilful are not 
exempt from this when they rely too much on their past 
experience, as some have done in civil and military affairs; 
they do not pay sufficient attention to the fact that the 
world changes, and that men become more skilful by dis- 
covering countless new contrivances, whereas the stags and 
hares of to-day are no more cunning than those of yesterday. 
The sequences of the brutes are but a shadow of reasoning, 
that is to say, they are but connections of imagination, 
transitions from one image to another; for in a fresh ex- 
perience which appears like the preceding one, there is the 
expectation that what was hitherto joined thereto will occur 
again, as though the things were connected in fact, because 
their images are connected in the memory. It is true that 
reason also teaches us to expect in the ordinary course of 
events to see occur in the future what conforms to a long 


experience of the past, but it is not therefore a necessary and 
infallible truth, and we may cease to be successful when we 
least expect it, when the reasons which have maintained it 
change. This is why the wisest people do not rely on it to the 
extent of not trying to discover, if it is possible, something 
of the reason of what happens, so as to judge when exceptions 
must be made. For reason alone is capable of setting up 
rules which are certain, and of supplying what is lacking to 
those which are not certain, by inserting the exceptions, and 
in short of finding connections which are certain in the force 
of necessary consequences. This often provides the means 
of foreseeing the event, without its being necessary to ex- 
perience the sensible connections between images which is 
all that the brutes can do; so that to vindicate the existence 
within us of the principles of necessary truths is also to 
distinguish man from the brutes. 

Perhaps our gifted author will not entirely dissociate 
himself from my opinion. For after having devoted the 
whole of his first book to the rejection of innate ideas, under- 
stood in a certain sense, he yet admits in the beginning of the 
second and in what follows that ideas whose origin is not in 
sensation arise from reflection. Now reflection is nothing 
but an attention to what is in us, and the senses do not give 
us what we already bring with us. This being so, can we 
deny that there is a great deal that is innate in our mind, 
since we are innate, so to speak, to ourselves, and since there 
is in ourselves being, unity, substance, duration, change, 
activity, perception, pleasure, and a thousand other objects 
of our intellectual ideas? And since these objects are im- 
mediate to our understanding and are always present (al- 
though they cannot always be apperceived on account of our 
distractions and our needs), why be surprised that we say that 
these ideas, and everything which depends on them, are 
innate in us? This is why I have taken as an illustration a 
block of veined marble, rather than a wholly uniform block 


or blank tablets, that is to say what is called tabula rasa in 
the language of the philosophers. For if the soul were like 
these blank tablets, truths would be in us in the same way as 
the figure of Hercules is in a block of marble, when the marble 
is completely indifferent whether it receives this or some other 
figure. But if there were veins in the stone which marked 
out the figure of Hercules rather than other figures, this 
stone would be more determined thereto, and Hercules 
would be as it were in some manner innate in it, although 
labour would be needed to uncover those veins, and to clear 
them by polishing, and by cutting away what prevents them 
from appearing. It is in this way that ideas and truths arc 
innate in us, like natural inclinations and dispositions, natural 
habits or potentialities, and not like activities, although these 
abilities are always accompanied by some activities which 
correspond to them, though they are often imperceptible. 
It seems that our gifted author claims that there is in us 
nothing potential, nor even anything which we do not always 
actually apperceive; but he cannot take this quite strictly, 
otherwise his opinion would be too paradoxical, since acquired 
habits also and the contents of our memory are not always 
apperceived, and do not even always come to our aid when 
needed, although we often easily recall them to mind on some 
trivial occasion which reminds us of them, in the same way 
as we only need the beginning of a song to make us remember 
the song. Moreover he limits his doctrine in other places by 
saying that there is nothing in us which we have not at least 
previously apperceived. But besides the fact that nobody 
can guarantee by reason alone how far our past apperceptions 
which may have been forgotten may have gone, especially in 
view of the Platonic doctrine of reminiscence, which, mythical 
though it is, is not incompatible, in part at least, with bare 
reason: besides this, I say, why should it be necessary that 
everything should be acquired by us by apperceptions of 
external things, and nothing be able to be unearthed in 


ourselves? Is our soul of itself alone so empty that apart 
from images borrowed from without it is nothing? This is 
not, I am convinced, an opinion that our judicious author 
could approve. And where are there to be found tablets 
which have not in themselves a certain amount of variety? 
We shall never see a perfectly level and uniform surface. 
Why, therefore, should we not also be able to provide some 
sort of thought from deep within ourselves, when we are 
willing to delve there? Thus I am led to believe that funda- 
mentally his opinion on this point does not differ from mine, 
or rather from the common opinion, inasmuch as he recognizes 
two sources of our knowledge, the senses and reflection. 

I am not sure that it will be so easy to reconcile him with 
us and with the Cartesians when he maintains that the mind 
does not always think, and in particular that it is without 
perception during dreamless sleep; and when he protests 
that since bodies can exist without motion, souls also might 
well exist without thought. But here I answer somewhat 
differently from what is usual; for I maintain that, naturally, 
a substance cannot exist without activity, and that there 
never even exists a body without motion. Experience is 
already in my favour on this point, and to be persuaded of it 
it is only necessary to consult the illustrious Mr. Boyle's 
book l against absolute rest. But I believe that reason also 
supports it, and this is one of the proofs which I use for 
refuting the theory of atoms. 

Besides, there are a thousand signs which make us think 
that there are at all times an infinite number of perceptions 
in us, though without apperception and without reflection; 
that is to say changes in the soul itself which we do not 
apperceive because their impressions are either too small and 
too numerous, or too unified, so that they have nothing 
sufficiently distinctive in themselves, though in combination 

l Of Absolute Rest in Bodies. Robert Boyle (1627-1691) was a 
famous chemist and physicist* 


with others they do not fail to have their effect and to make 
themselves felt, at least confusedly, in the mass. It is thus 
that habituation causes us not to notice the motion of a mill 
or waterfall, after we have lived near by for some time. It is 
not that the motion does not continue to affect our organs, 
and that something does not still take place in the soul to 
correspond to it, on account of the harmony of the soul and 
the body; it is that these impressions which are in the soul 
and in the body, when they are devoid of the attractions of 
novelty, are not strong enough to attract our attention and 
memory, when these are attached to more absorbing objects. 
For all attention demands some memory, and often when we 
are not admonished, so to speak, and warned to pay attention 
to certain of our present perceptions, we let them pass 
without reflection and even without observing them; but 
if someone draws attention to them immediately afterwards, 
and makes us notice, for example, some sound that has just 
been heard, we remember it, and we apperceive that we did 
have some sensation of it at the time. Thus there were 
perceptions which we did not immediately apperceive, 
apperception in this case only arising through our attention 
having been aroused after an interval, however small. In 
order the better to form an opinion of these minute percep- 
tions which we cannot distinguish in the crowd, I generally 
make use of the example of the roar or noise which strikes us 
when we are on the shore. To hear this noise as we do, we 
must surely hear the parts of which the whole is made up, 
that is to say the noises of each wave, although each of these 
little noises only makes itself heard in the confused combina- 
tion of all the others together, that is to say in the actual roar, 
and would not be noticed if the wave which makes it were 
the only one. For it is necessary that we should be slightly 
affected by the motion of this wave, and that we should have 
some perception of each of these noises, however small they 
may be; otherwise we should not have the perception of a 


hundred thousand waves, since a hundred thousand nothings 
cannot make a something. We never sleep so soundly but 
that we have some feeble and confused feeling, and we should 
never be awakened by the loudest noise in the world, if we 
had not some perception of its beginning, small as it is; just 
as we should never break a rope by the greatest exertion in 
the world, if it were not to some small extent strained and 
stretched by lesser efforts, although the slight extension they 
produce is not apparent. 

These minute perceptions are therefore more efficacious 
in their consequences than we think. They it is that con- 
stitute that indefinable something, those tastes, those images 
of the qualities of the senses, clear in the mass but confused 
in the parts, those impressions which surrounding bodies 
make on us, which include the infinite, that link which 
connects every being with all the rest of the universe. It 
may even be said that as a result of these minute perceptions 
the present is big with the future and laden with the past, 
that everything is in league together (OV^TTVOIO. TTCLVTO, as 
Hippocrates said), and that in the smallest substance eyes as 
piercing as those of God could read the whole sequence of 
things in the universe: 

Quae sint, quaefuerint, quae moxfutura trahantur. 1 
These insensible perceptions are also the signs and consti- 
tuents of personal identity: the individual is characterized 
by the traces or expressions of his previous states which 
these perceptions preserve by connecting them with his 
present state, and which can be known by a superior spirit, 
even though the individual himself may not be conscious of 
them, that is to say though he may no longer expressly 
recollect them. But they (these perceptions, I mean) also 
provide the means of rediscovering this recollection at need 
through periodic developments which may one day occur. 

1 ' The things that are, the things that have been, and those 
that are presently to come.' 


This is why, because of them, death can only be a sleep, and 
cannot even go on being that, since, in animals, the per- 
ceptions only cease to be sufficiently distinguished and become 
reduced to a state of confusion which suspends apperception, 
but which cannot last for ever not to speak here of man, 
who must in this have great privileges in order to retain his 

It is, moreover, these insensible perceptions which afford 
the explanation of that wonderful pre-established harmony 
of soul and body, and indeed of all monads or simple sub- 
stances, which takes the place of the untenable theory of the 
influence of the one on the other, and which in the opinion 
of the author of the greatest of dictionaries 1 exalts the 
grandeur of the Divine perfections beyond what has ever 
been conceived. After this I should be adding but little if I 
said that it is these minute perceptions which determine us in 
many experiences without our giving them a thought, and 
which deceive the common herd by giving the appearance of 
an indifference of equilibrium, as if we were entirely indifferent 
whether, for example, we turned to the right or to the left. 
Nor is it necessary that I should point out here, as I have done 
in the book itself, that they cause that uneasiness which, on 
my showing, consists in something which differs from pain 
only as the small from the great, and which yet often creates 
our desire and even our pleasure, giving it a kind of savour. 
It is moreover, these insensible parts of our sensible percep- 
tions which bring it about that there is a relation between 
those perceptions of colour, heat, and other sensible qualities 
and the motions in the bodies which correspond to them; 
whereas the Cartesians and our author, penetrating though 
he is, conceive of the perceptions which we have of these 
qualities as being arbitrary, that is to say, as if God had 
given them to the soul at His good pleasure without any 

1 i.e. Bayle. For the passage in Bayle's Dictionary referred 
to here, see p. 126. 


regard to any essential relation between perceptions and their 
objects: an opinion which surprises me, and which seems to 
me hardly worthy of the wisdom of the Author of things, 
who does nothing without harmony and without reason. 

In a word, the insensible perception is of as much use in 
pneumatics * as is the insensible corpuscle in physics; and it 
is equally unreasonable to reject the one or the other on the 
pretext that it is beyond the reach of our senses. Nothing 
takes place all at once, and it is one of my most important 
and best verified maxims that nature makes no leaps. This 
I called the law of continuity when I spoke of it in the first 
News of the Republic of Letters; and the use of this law in 
physics is very considerable : it means that the passage from 
the small to the great and back again always takes place 
through that which is intermediate, both in degrees and in 
parts, and that a motion never arises immediately from rest, 
nor is reduced to it except through a smaller motion, just as 
we never manage to traverse any given line or length without 
first traversing a shorter line although till now those who 
have exhibited the laws of motion have not observed this 
law, believing as they did that a body can receive in a moment 
a motion contrary to its preceding one. All this brings us 
to the conclusion that observable perceptions come by degrees 
from those which are too small to be observed. To think 
otherwise is to have but little knowledge of the immensely 
subtle composition of things, which always and everywhere 
include an actual infinity. 

I have also noticed that, by virtue of insensible variations, 
two individual things can never be perfectly alike, and that 
they must always differ more than numero. This at once 
puts out of court the blank tablets of the soul, a soul with- 
out thought, a substance without action, the void in space, 
atoms and even particles not actually divided in matter, 
absolute rest, complete uniformity in one part of time, place, 
1 An early name for the philosophy of mind or spirit. 


or matter, the perfect globes of the second element which 
are the offspring of the original perfect cubes, 1 and a thousand 
other fictions of the philosophers fictions arising from their 
incomplete notions, and not admitted by the nature of things, 
but merely allowed to pass because of our ignorance and of the 
slight attention we pay to the insensible; they can only be 
made tolerable by being limited to abstractions made by the 
mind, which protests that it is not denying any of the things 
which it considers irrelevant to the present inquiry but only 
setting them on one side. Otherwise, if we thought in good 
earnest that the things we do not apperceive are not there in 
the soul or in the body, we should fail in philosophy as in 
politics, by neglecting TO pucpov, 2 insensible progressions; 
whereas an abstraction is not an error, provided we know that 
what we are ignoring is really there. This is the use made 
of abstractions by mathematicians when they speak of the 
perfect lines they ask us to consider, and of uniform motions 
and other regular effects, although matter (that is to say the 
mixture of the effects of the surrounding infinite) is always 
making some exception. We proceed in this way so as to 
distinguish the various considerations from one another, and 
to reduce the effects to their reasons as far as is possible to us, 
and to foresee some consequences; for the more careful we are 
to neglect no consideration which we can regulate, the more 
does practice correspond to theory. But it belongs to the 
Supreme Reason, which misses nothing, distinctly to under- 
stand the whole infinite, and to see all the reasons and all the 
consequences. All that we can do in regard to infinities is to 
know them confusedly, and at least to have distinct knowledge 
that they exist. Otherwise we should have a very poor 
recognition of the beauty and grandeur of the universe; we 
should also be unable to have a sound physics to explain the 
nature of bodies in general, and still less a sound pneumatics 

1 The reference is to the vortex theory of Descartes. 
1 lit. ' the small ' ; i.e. by neglecting very small items. 


to include the knowledge of God, of souls, and of simple 
substances in general. 

This knowledge of insensible perceptions serves also to 
explain why and how two souls, whether human or of some 
other identical species, never come perfectly alike from the 
Creator's hands, but each has always from the beginning its 
own relation to the point of view it will have in the universe. 
But this follows from what I pointed out previously about 
two individuals, namely that their difference is always more 
than a numerical one. There is also another important point 
on which I am obliged to differ not only from the opinions 
of our author, but also from those of the greater part of the 
moderns; that is, that like most of the ancients I hold that all 
superhuman beings, all souls, all simple created substances, 
are always joined to a body, and that there never are entirely 
separate souls. I have a priori reasons for this, but there 
will be found to be this advantage also in my doctrine that it 
solves all the philosophical difficulties about the state of souls, 
their perpetual conservation, their immortality, and their 
operation: the difference between one state of the soul and 
another is never and has never been anything other than that 
between the more and the less sensible, the more and the less 
perfect, or the other way round, and so the past or future 
state of the soul is as explicable as its present state. The 
smallest reflection suffices to show that this is reasonable, 
and that a leap from one state to another infinitely different 
state could not be natural. I am surprised that the schools 
should have causelessly given up natural explanations, and 
should have been ready deliberately to plunge into very great 
difficulties and thus to provide occasion for the apparent 
triumphs of free-thinkers; all of whose reasons collapse at 
once on this explanation of things, in which there is no more 
difficulty in conceiving the conservation of souls (or rather 
on my view of the whole animal) than there is in the change 
from the caterpillar into the butterfly, and in the conserva- 


tion of thought during sleep sleep to which Jesus Christ 
with divine propriety likened death. I have already said 
that no sleep can last for ever, and it will have least duration, 
or almost none at all, in the case of rational souls, which are 
always destined to retain the personality which has been 
given to them in the City of God, and which consequently 
have memory, so that they may be more susceptible of 
punishments and rewards. I add further that in general no 
derangement of its visible organs is capable of carrying 
things to the point of complete confusion in the animal or of 
destroying all its organs, and of depriving the soul of the 
whole of its organic body and of the ineffaceable remains of 
all its preceding traces. But the ease with which the ancient 
doctrine that angels have subtle bodies * has been abandoned 
(a doctrine that has been confounded with the corporeality 
of the angels themselves), the introduction of supposed 
intelligences without bodies among created things (a view 
that has been much strengthened by Aristotle's doctrine 
that such intelligences make the heavens revolve), and 
finally the mistaken opinion that has existed that the con- 
servation of the souls of the brutes cannot be maintained 
without falling into metempsychosis and transferring them 
from body to body, and the perplexity some have felt through 
not knowing what to do with them all these things have, 
in my opinion, led to the neglect of the natural way of 
explaining the conservation of the soul. This has done much 
injury to natural religion, and has caused some people to 
believe that our immortality was but a miraculous grace of 
God. Our illustrious author also speaks of it with some 
doubt, as I shall subsequently point out. But it would be 
well if all those who are of this opinion had spoken of it as 
wisely and sincerely as he ; for it is to be feared that some who 

1 i.e. made of some more rarefied stuff than ordinary matter. 
Locke uses the word in this connection (to represent the Latin 
subtilis) in the correspondence with the Bishop of Worcester. 


speak of immortality through grace merely do so to preserve 
appearances, and at bottom are not very far from those 
Averroists and certain pernicious Quietists, who picture an 
absorption and reunion of the soul with the ocean of Divinity, 
a notion whose impossibility is perhaps shown up by my 
system alone. 

It appears, moreover, that we differ also in regard to 
matter, in that the author thinks that the existence of a 
void is necessary to motion, because he believes that the 
small parts of matter are rigid. 1 I admit that if matter were 
composed of such parts, motion in a plenum would be im- 
possible, just as if a room were filled with quantities of small 
pebbles without there being in it the least empty space. But 
I do not admit this supposition, for which, moreover, there 
does not appear to be any reason, although our gifted author 
goes so far as to hold that rigidity 1 or cohesion of parts 
is the essence of matter. Space should rather be conceived 
of as full of a matter originally fluid, susceptible of any 
division, and submitted indeed actually to divisions and 
subdivisions ad infinitum; with this difference, however, that 
it is divisible and divided unequally in different places on 
account of motions which are already helping to a greater 
or less degree to produce the divisions. This means that it 
has throughout a degree of rigidity as well as of fluidity, and 
that there does not exist any body which is absolutely hard 
or absolutely fluid; that is to say that it is impossible to find 
in any body any atom whose hardness is indefeasible, or any 
mass which is entirely indifferent to division. Besides, the 
order of nature, and particularly the law of continuity, make 
both equally impossible. 

1 Locke's own term is solid, and solidity. He says : That which 
hinders the approach of two bodies, when they are moved one 
towards another, I call solidity . . . but if any one think it better to 
call it impenetrability , he has my consent [Essay, Bk. II, ch. iv, i], 
But I do not think that Leibniz's word here (roide) can properly 
be translated by solid. The word hard is rejected by Locke on the 
ground that a hard body is no more solid than a soft one. 


I have also shown that cohesion, which could not of itself 
be the result of impulse or of motion, would cause a traction, 
strictly speaking. For if there were a body originally 
rigid, an Epicurean atom, for example, which contained a 
part projecting from it in the form of a hook (since we may 
imagine atoms of all kinds of shapes), this hook when impelled 
would draw with it the rest of the atom, that is to say the 
part which was not being impelled, and which did not fall 
in the line of impulse. Our gifted author, however, is 
himself opposed to these philosophic tractions, such as were 
formerly attributed to nature's abhorrence of a vacuum, and 
reduces them to impulses, maintaining in agreement with 
the moderns that one part of matter can only operate im- 
mediately on another by impelling it by contact; wherein I 
think they are right, because otherwise the operation is in 
no way intelligible. 

I must not, however, conceal the fact that I have observed 
a kind of recantation on this point on the part of our excellent 
author, whose modesty and sincerity in this I cannot too 
highly praise, just as on other occasions I have admired his 
penetrating insight. It is in the reply to the second letter 
of the late Bishop of Worcester, printed in 1699, page 408, 
where, in order to justify the view he had upheld against 
this learned prelate, namely that matter was capable of 
thought, he says among other things: 'It is true, 1 say 
"that bodies operate by impulse, and nothing else" (Essay, 
Bk. II, ch. viii, n). And so I thought when I writ it, and 
can yet conceive no other way of their operation. But I am 
since convinced by the judicious Mr. Newton's incomparable 
book, that it is too bold a presumption to limit God's power, in 
this point, by my narrow conceptions. The gravitation of 
matter towards matter, by ways inconceivable to me, is not only 
a demonstration that God can, if he pleases, put into bodies 
powers and ways of operation, above what can be derived from 
our idea of body or can be explained by what we know of matter, 


but also an unquestionable and everywhere visible instance, 
that he has done so. And therefore in the next edition of my 
book 1 shall take care to have that passage rectified. 11 I find 
that in the French translation of this book, which was no doubt 
taken from the latest editions, this n reads thus: 'It is 
evident, at least as far as we can conceive it? that bodies act 
upon one another by impulse and not otherwise; for it is 
impossible for us to understand that a body can act upon that 
which it does not touch, which is as much as to imagine that 
it can act where it is not.' 3 

I cannot but praise this modest piety on the part of our 
famous author, who recognizes that God can do things beyond 
what we can understand, and thus that there may be in- 
conceivable mysteries in the articles of faith: but I should 
not wish us to be obliged to have recourse to miracles in the 
ordinary course of nature, and to allow the existence of 
powers and operations which are absolutely inexplicable. 
Otherwise we should be granting too much licence to bad 
philosophers on the strength of what God can do. If we 
admit these centripetal faculties or immediate attractions from 
a distance without its being possible to make them in- 
telligible, I see nothing to prevent our Scholastics from 
saying that everything is done simply through their 'faculties' 
and from upholding their 'intentional species', which go 
from objects up to us, and find a way even of entering our 
souls. If this is true: 

Omnia jam fient, fieri quae posse negabam.* 
So that it seems to me that our author, judicious though he 

1 Italics indicate Locke's own exact words. 

* These italics are Leibniz's. 

1 In the English edition 1 1 runs as follows : The next thing to be 
considered is, how bodies produce ideas in us; and that is manifestly 
by impulse, the only way which we can conceive bodies to operate in. 

4 'Everything will now happen which I declared to be im- 


is, is in this going rather too much from one extreme to the 
other. He makes difficulties about the operations of souls, 
when it is only a question of admitting what is not sensible, 
and here we have him granting to bodies what is not even 
intelligible, in allowing them powers and activities beyond 
everything which, in my opinion, a created mind can do and 
understand, since he grants them attraction, even at great 
distance and without limiting himself to any stated sphere 
of activity, and that in order to uphold a view which seems 
no less inexplicable, to wit, the possibility of thinking in 
matter in the natural order. 

The question he is discussing with the celebrated prelate, 
who had attacked him, is whether matter can think, and as 
this is an important point, even for the present work, I 
cannot avoid going into the subject a little and taking some 
account of their dispute. I will set forth the substance of 
it as regards this subject, and will take the liberty of saying 
what I think about it. The late Bishop of Worcester, being 
apprehensive, though in my opinion without great cause, that 
our author's doctrine of ideas was liable to some abuses pre- 
judicial to the Christian faith, undertook to examine certain 
parts of it in his vindication of the doctrine of the Trinity. 
He first gives this excellent author his due by recognizing 
that he holds the existence of the mind as certain as that of 
the body, although one of these substances is as little known as 
the other; he then asks (page 241 seq.) how reflection could 
possibly assure us of the existence of mind, if God can give 
matter the faculty of thinking (as our author believes, Bk. V, 
ch. iii), since in this case the way of ideas, which is required 
to discriminate between the properties of soul and of body, 
would become useless; whereas it was said in Book II of the 
Essay on the Human Understanding (ch. xxiii, 15, 27, 28), 
that the operations of the soul provide us with the idea of 
mind, and the understanding together with the will makes 
this idea as intelligible to us as the nature of body is made 


intelligible to us by solidity and impulse. This is how our 
author replies in his first letter (page 65 seq.): '/ think it may 
be proved from my principles, and 1 think I have done it, that 
there is a spiritual substance in us . . . We experiment in ourselves 
thinking. The idea of this action, or mode of thinking, is in- 
consistent with the idea of self -subsistence, and therefore has a 
necessary connection with a support or subject of inhesion : the 
idea of that support is what we call substance . . . for the general 
idea of substance being the same everywhere, the modification of 
thinking, or the power of thinking, joined to it, makes it a spirit, 
without considering what other modifications it has, as whether 
it has the modification of solidity or not. As, on the other side, 
substance thzt has the modification of solidity, is matter, whether 
it has the modification of thinking or not. And therefore if your 
lordship means by a spiritual an immaterial substance, I grant 
I have not proved, nor upon my principles can it be proved, 
(your lordship meaning, as I think you do, demonstratively 
proved) that there is an immaterial substance in us that thinks. 
Though I presume, what I have said about the supposition of 
a system of matter thinking (Bk. IV, ch. x, 16) (which there 
demonstrates that God is immaterial) will prove it in the highest 
degree probable, that the thinking substance in us is immaterial. 
. . . Yet, / have shown [adds the author, page 68] that all the 
great ends of religion and morality are secured barely by the im- 
mortality of the soul, without a necessary supposition that the 
soul is immaterial. 

In his reply to this letter the learned bishop, to show that 
our author was of another opinion when he wrote the second 
book of his Essay, cites from it on page 51 this passage (taken 
from the same book, chapter xxiii, 15), where it is said that 
by the simple ideas we have taken from our own minds we are 
able to frame the complex idea of an immaterial spirit. And 
thus by putting together the ideas of thinking, perceiving, liberty, 
and power of moving themselves, and other things, we have as 
clear a perception and notion of immaterial substances as we 


have of material. He further cites other passages to show 
that the author opposed mind to body. He says (page 54) 
that the ends of religion and morality are best secured by 
proving that the soul is immortal by its very nature, that is to 
say immaterial. He further adduces (page 60) this passage, 
that all our ideas of the several sorts of substances are nothing but 
collections of simple ideas ; and that thus our author believed 
that the idea of thinking and willing gave a different substance 
from that given by the idea of solidity and impulse; and ( 17) 
regards these ideas as constituting body as opposed to mind. 

The Bishop of Worcester might have added that from the 
fact that the general idea of substance is in body and in mind, 
it does not follow that their differences are modifications of 
one and the same thing, as our author has just said in the 
passage I quoted from his first letter. It is necessary to 
distinguish properly between modifications and attributes. 
The faculties of having perception and of acting, extension, 
and solidity, are attributes of perpetual and principal predi- 
cates; but thinking, impetus, shapes, and motions are modifi- 
cations of these attributes. Further, we ought to distinguish 
between physical (or rather real) genus, and logical or ideal 
genus. Things which are of the same physical kind or which 
are homogeneous, are of the same matter so to speak, and can 
often be changed one into another by changing their modifi- 
cations, like circles and squares. But two heterogeneous 
things may have a common logical genus, and then their 
differences are not simple accidental modifications of one 
self-same subject or of one self-same metaphysical or physical 
matter. Thus time and space are quite heterogeneous things, 
and we should be wrong to imagine some kind of common real 
subject which had only continuous quantity in general and 
whose modifications resulted in time or space. People may 
laugh at these philosophical distinctions between two genera, 
the one only logical, the other real, and between two matters, 
one physical that of bodies the other only metaphysical 


or general, as if someone said that two parts of space are of 
the same matter or that two hours are also of the same matter 
as one another. Yet these distinctions are not a mere 
matter of terms, but are in the things themselves; and they 
seem to be particularly relevant here, where their confusion 
has given rise to a false conclusion. These two genera have 
a common notion, and the notion of real genus is common to 
both matters, so that their genealogy would be as follows: 

Logical merely, the 
variations consisting 
of simple differences. 

* Real, whose differ- ( Metaphysical merely , in which 

ences are modifica- 1 there is homogeneity, 

tions, that is to say 1 Physical, in which there is a 

matter. I solid homogeneous mass. 

I have not seen our author's second letter to the bishop, 
and the answer the latter makes to it hardly touches the point 
about the thinking of matter. But our author's reply to this 
second answer comes back to it. 'God (he says, nearly in 
these words, page 397), superadds to the essence of matter 
what qualities He pleases; to some parts simple motion, to 
plants vegetation, and to animals sense. Those who agree 
with me so far exclaim against me when I go a step further 
and say, God may give to matter thought, reason, and volition, 
as if that would destroy the essence of matter. To make good 
this assertion they say that thought and reason are not in- 
cluded in the essence of matter: which proves nothing, for 
motion and life are just as little included in it. They also 
urge that we cannot conceive how matter can think : but our 
conception is not the measure of God's omnipotency.' After 
this he quotes the example of the attraction of matter, page 
399 and particularly page 408, where he speaks of the gravita- 
tion of matter towards matter, attributed to Mr. Newton (in 
the words I have quoted above), admitting that we cannot 


conceive how the attraction takes place. This, in effect, is 
going back to qualities which are occult, or, what is more, in- 
explicable. He adds (page 401) that nothing is more likely to 
assist the sceptics than to deny what we do not understand, 
and (page 402) that we cannot conceive even how the soul 
thinks. He wants to maintain (page 403) that, since both 
substances, material and immaterial, can be conceived in their 
bare essence without any activity, it rests with God to give to 
the one or to the other the power of thinking. And he wants 
to take advantage of the admission of his opponent, who had 
granted sense in brutes, but would not grant them any 
immaterial substance. He claims that liberty and self- 
consciousness (page 408) and the power of making abstrac- 
tions (page 409) can be given to matter, not as matter, but as 
enriched by a divine power. Finally he reports (page 434) the 
observation of a traveller as important and judicious as M. de 
La Loubre that the pagans of the East know of the immor- 
tality of the soul without being able to understand its 

With regard to all this I may say, before coming to the 
explanation of my opinion, that it is certain that matter is 
as little capable of mechanically producing sensation as of 
producing reason, as our author agrees; that I fully recognize 
that it is not allowable to deny what we do not understand, 
but I add that we have the right to deny (in the order 
of nature at least) what is absolutely unintelligible and 
inexplicable. I maintain also that substances, whether 
material or immaterial, cannot be conceived in their bare 
essence without any activity, activity being of the essence 
of substance in general; and finally that the conception of 
created beings is not the measure of God's power, but that 
their conceptivity, or power of conceiving, is the measure 
of the power of nature; for everything which conforms with 
the order of nature can be conceived or understood by some 
created being. 


Those who understand my system will see that I cannot 
agree altogether with either of these excellent authors; their 
dispute, however, is very instructive. Let me explain myself 
distinctly: it must above all things be considered that the 
modifications which can attach to a subject naturally or 
without miracle, must come to it from the limitations or 
variations of a real genus, or of an original nature which 
is constant and absolute. This is how we distinguish in 
philosophy the modes of an absolute being from that being 
itself; for instance we know that size, shape, and motion are 
manifestly limitations and variations of corporeal nature. 
For it is clear how a limitation of extension gives figures, 
and that the change which therein takes place is nothing but 
motion. And every time we find some quality in a subject, 
we ought to think that if we understood the nature of this 
subject and of this quality, we should conceive how this 
quality could result from it. Thus, in the order of nature 
(miracles apart) God does not arbitrarily give to substances 
such and such qualities indifferently, and He never gives them 
any but those which are natural to them, that is to say 
qualities which can be derived from their nature as explicable 
modifications. Thus we see that matter does not naturally 
have the attraction mentioned above, and does not of itself 
go in a curve, because it is not possible to conceive how 
this takes place, that is to say, to explain it mechanically, 
whereas what is natural ought to be able to be rendered 
distinctly conceivable, if we were admitted into the secrets of 
things. This distinction between what is natural and ex- 
plicable and what is inexplicable and miraculous removes 
all the difficulties: in rejecting it we should be upholding 
something worse than occult qualities, and in so doing we 
should be renouncing philosophy and reason, and throwing 
open sanctuaries for ignorance and idleness, by a stupid 
system which admits not only that there are qualities which 
we do not understand (of which there are only too many), 


but also that there are some which the greatest mind, even 
if God provided him with every possible advantage, could 
not understand that is to say they would be either miracu- 
lous or without rhyme or reason. It would indeed be with- 
out rhyme or reason that God should perform miracles in the 
ordinary course; so that this do-nothing hypothesis would 
destroy equally our philosophy which searches for reasons, 
and the Divine reason which provides them. 

We can now turn to the question of thinking. It is certain 
that our author recognizes in more than one place that 
thinking cannot be an intelligible modification of matter, or 
one which could be understood and explained ; that is to say, 
a sentient or thinking being is not a mechanical thing like a 
watch or a windmill, so that we could conceive of sizes, 
shapes, and motions in such a mechanical conjunction that 
they could produce in a mass, in which there was nothing of 
the kind, something capable of thought and even of sensa- 
tion, which thinking and sensing would likewise stop if the 
mechanism got out of order. Thus it is not natural to matter 
to have sensation and to think, and there are only two ways 
in which it could do so; one of which is for God to join to 
it a substance to which thought is natural, and the other for 
God to endow it with thought miraculously. In this, then, 
I am entirely of the opinion of the Cartesians, except that I 
extend it to brutes also, and hold that they have sensation, 
and souls which are, properly speaking, immaterial, and as 
incapable of perishing as the atoms of Democritus or Gassendi; 
whereas the Cartesians, being needlessly embarrassed about 
the souls of brutes, and not knowing what to do with them 
if they were preserved (since it did not occur to them that the 
animal might be preserved in a minute form), were compelled 
to deny them even sensation, contrary to all appearances, 
and to the judgment of mankind. But if it is argued that 
God, at least, could add the faculty of thinking to such a 
mechanism, I would answer that if this occurred, and if 


God added this faculty to matter without at the same time 
endowing it with a substance of such a kind that this same 
faculty (as I conceive it) could be inherent in it, that is to say 
without adding an immaterial soul, then matter would have 
to be exalted miraculously so as to be able to receive a power 
of which it is not capable naturally: just as some Scholastics 
claim that God exalts fire to the point of giving it the power 
directly to burn spirits separated from matter which would 
be a miracle pure and simple. It is enough that we cannot 
maintain that matter thinks unless we attribute to it an 
imperishable soul, or rather a miracle, and that thus the 
immortality of our souls follows from what is natural: since 
we could not maintain that they are extinguished except by 
a miracle, whether by exalting matter, or by annihilating the 
soul. For we know, of course, that the power of God could 
render our souls mortal, even though they may be immaterial 
or immortal by nature, since He can annihilate them. 

Now this truth of the immateriality of the soul is un- 
doubtedly of consequence. For it is of infinitely more use 
in religion and morals, especially in our day (when many 
people have scant respect for revelation by itself or for 
miracles), to show that souls are naturally immortal, and that 
it would be a miracle if they were not, than to maintain that 
our souls must naturally die, and that it is by virtue of a 
miraculous grace, based solely on the promise of God, that 
they do not die. We have, moreover, known for a long time 
that those who wished to destroy natural religion, and 
reduce everything to revealed religion, as if reason taught us 
nothing about it, have been held suspect, and not always 
without reason. But our author is not of their number. He 
upholds the proof of the existence of God and attributes to 
the immateriality of the soul a probability of the highest 
degree, which may consequently pass for a moral certainty, 
so that I imagine that having as much sincerity as penetra- 
tion, he might quite well come to agree with the doctrine I 


have just expounded. This doctrine is fundamental in every 
reasonable philosophy, for otherwise I do not see how we can 
prevent ourselves from falling back into fanatical philosophy, 
such as the Mosaic philosophy of Fludd, which accounts for 
all phenomena by attributing them immediately and miracu- 
lously to God, or into a barbarous philosophy like that of 
certain philosophers and physicians of bygone days, who 
still savoured of the barbarism of their age, and who to-day 
are justly despised; these accounted for appearances by 
expressly fabricating suitable occult qualities or faculties, 
which were supposed to be like little demons or sprites able 
to do what was required of them out of hand just as if there 
were watches able to tell the time by some 'horodeictic 
faculty* without the need of wheels, or mills able to crush 
grain by a tractive faculty* without the need of anything 
in the nature of millstones. As to the difficulty many people 
find in conceiving an immaterial substance, that soon ceases 
to be felt (in part at least) when there is no longer any 
question of substances separated from matter; such sub- 
stances do not, I hold, ever naturally exist among created 



Whether there are any Innate Principles in the Human Min d 

2i. a PniLALETHES. 2 If the mind assents so promptly to 
certain truths, may this not come from the consideration 
of the nature of things, which does not suffer it to think 

1 The number of the section refers to the section in the corres- 
ponding chapter and book of Locke's Essay; i.e. in this case 
to Essay, Bk. I, ch. i, 21. It will be seen that Leibniz does not 
always follow the order of Locke's sections, but sometimes takes 
the points in an order that suits his own argument. A large part 
of the present chapter is omitted here. 

8 Cf. p. 142, note. 


otherwise, rather than because these propositions have been 
printed naturally in the mind ? 

THEOPIIILUS. Both these doctrines are true. The nature 
of things and the nature of the mind here agree. And since 
you oppose the consideration of the thing to the apperception 
of what is printed in the mind, your objection shows, sir, 
that those whose doctrines you are upholding understand 
by innate truths, only such as would be approved naturally, 
as if by instinct, and without apprehending them except 
confusedly. There are some of this nature, and I shall 
have occasion to speak of them. But what is called the 
natural light presupposes a distinct knowledge, and often 
enough the consideration of the nature of things is nothing 
else than the knowledge of the nature of our mind and of 
these innate ideas, for which there is no need to search outside. 
Thus I call innate those truths which have no need of such 
consideration for their verification . . . 

23. PH. . . . But what do you say, sir, to this challenge 
of one of my friends ? I would gladly have any one name, 1 he 
says, that proposition whose terms or ideas were either of 
them innate. 

TH. I should name the propositions of arithmetic and 
geometry, which are all of that nature; and as regards 
necessary truths, it is not possible to find any others. 

25. PH. Many people will find that very strange. Can 
it be said that the most difficult and profoundest sciences 
are innate ? 

TH. Actual knowledge of them is not innate, but rather 
what may be called virtual knowledge; just as the figure 
traced by the veins of the marble is in the marble, before 
they are uncovered by the workman. 

PH. But is it possible that children, when they receive 
notions which come to them from outside, and give to them 

1 In the speeches of Philalethes italics indicate Locke's own 
exact words ; in those of Theophilus the italics are Leibniz's. 


their assent, should still have no knowledge of those which 
are supposed to be innate and to form part of their mind, on 
which, it is said, they are imprinted in indelible characters to 
serve as a foundation? This would be to make nature take 
pains to no purpose; or at least, to write very ill, since its 
characters could not be read by those eyes which saw other things 
very well. 

TH. The apperception of what is in us depends upon the 
presence of attention and upon order. Now it is not only 
possible, it is also fitting, that children should pay more 
attention to the notions of sense, because attention is 
regulated by need. The event, however, makes it clear in 
the sequel that nature did not take pains to no purpose in 
printing in us innate knowledge, since without such know- 
ledge there would be no means of arriving at actual know- 
ledge of necessary truths in the demonstrative sciences, and 
at the reasons of facts; and so we should have nothing more 
than the brutes. 

5. PH. . . . But you will have rather more difficulty in 
answering what I am now going to propound to you, namely 
that if any one particular proposition can be said to be 
innate, then the same reasoning will enable it to be main- 
tained that all propositions that are reasonable, and that 
the mind is ever capable of regarding as such, are already 
imprinted in the soul. . . . Even supposing that there are 
truths which can be imprinted in the understanding, without 
the understanding perceiving them, I do not see how in 
respect of their original they can differ from the truths which 
it is simply capable of knowing. 

TH. The mind is not simply capable of knowing them, but 
also of finding them in itself. If it had only the simple 
capacity to receive knowledge, or the passive potency 
necessary for that, as much without determinations as that 
which the wax has to receive shapes and the tabula rasa to 


receive letters, then it would not be the source of necessary 
truths, as I have just proved that in fact it is. For it is in- 
contestable that the senses are not sufficient to make us see 
their necessity, and so the mind has the dispositions (as 
much active as passive) to draw them itself out of its own 
depths; though the senses are necessary to give to it the 
occasion and the attention required for this, and to lead it 
rather to the one sort than to the other. Thus you see, sir, 
that these people, clever as they are in other respects, who 
are of a different opinion, seem not to have reflected 
sufficiently about the consequences of the difference between 
truths which arc necessary or eternal and truths of experience, 
as I have already remarked and as our whole dispute makes 
clear. The original proof of necessary truths comes from the 
understanding alone, and all other truths come from ex- 
periences or from observations of the senses. Our mind is 
capable of knowing both the one sort and the other, but 
it is the source of the first; whatever number of particular 
experiences we may have of a universal truth, we cannot 
assure ourselves of it for always by induction, without 
apprehending its necessity by reason. 

PH. But is it not true that if these words, to be in the 
understanding) have any positive meaning they mean to be 
perceived and apprehended by the understanding? 

TH. To me they mean something quite different. It is 
sufficient if that which is in the understanding is capable of 
being found there, and if the original sources of proofs of the 
truths which are here in question are simply in the under- 
standing: the senses may suggest, justify, and confirm these 
truths, but they cannot demonstrate their infallible and 
perpetual certainty. 

18. TH. . . . Thoughts are actions, and apprehensions or 
truths, in so far as they are in us, even though we are 
not thinking of them, are habits or dispositions; and we 


have clear knowledge of things of which we hardly think 
at all. 

PH. It is very difficult to conceive how a truth can be in 
the mind, if the mind has never thought of that truth. 

Tn. To say that is like saying that it is difficult to con- 
ceive that there are veins in the marble before they are 
uncovered. It appears, too, that this objection comes very 
near to a petitio principii. All those who allow innate truths, 
without making them dependent on a Platonic reminiscence, 
allow some of which the mind has not yet thought. Besides, 
this reasoning proves too much. If truths are thoughts, it 
will deprive us, not only of truths of which we have never 
thought, but also of those of which we have thought but are 
not actually thinking now. If truths are not thoughts, but 
habits and aptitudes, natural or acquired, then there is 
nothing to prevent the existence in us of truths of which we 
have never thought, no, nor ever shall think. 



In which the author treats of ideas in general, and examines by 
the way whether the soul of man thinks always 

i. PH. Having now examined whether ideas are innate, 
let us consider their nature and their differences. Is it not 
true that an idea is the object of thinking? 

TH. I agree, provided that you add that it is an immediate 
internal object, and that this object is an expression of the 
nature or of the qualities of things. If an idea were the form 
of thinking, it would come into being and cease with the 
actual thoughts which correspond to it; but being the object 
of thought, it can exist anterior to and posterior to the 


thoughts. External sensible objects are only mediate, 
because they cannot act immediately on the soul. God 
alone is the immediate external object. It might be said that 
the soul itself is its own immediate internal object; but it is 
so only as containing ideas, or that which corresponds to 
things. For the soul is a little world, in which distinct ideas 
are a representation of God and confused ideas are a represen- 
tation of the universe. 

2. PH. Our friends, who supposed that at the beginning 
the soul is a blank tablet, void of all characters and without 
any ideas, ask themselves how it comes to receive ideas, and 
by what means it acquires such a vast store. To this they 
answer in one word: from experience. 

TH. This tabula rasa of which they talk so much, is nothing 
in my opinion but a fiction which nature does not admit, 
and which is founded only in the incomplete notions of the 
philosophers, like the void, atoms, rest (whether absolute 
rest or the relative rest of two parts of a whole in relation 
to one another), or like primary matter conceived as quite 
formless. Things which are uniform and contain no variety 
are never anything but abstractions, like time, space, and 
the other entities of pure mathematics. There is no body 
whose parts are at rest, and there is no substance which has 
not something to distinguish it from every other substance. 
Human souls differ not only from other souls, but also 
among themselves, although the difference is not of the 
nature of those which are called specific. And in accordance 
with the proofs which I think I can supply, every substantial 
thing, be it soul or body, has its relation to every other 
substantial thing, which is peculiar to itself; and one must 
always differ from another by intrinsic denominations. It 
need hardly be said that those who talk so much of this 
tabula rasa, after emptying it of all ideas, could not say 
what remains, just as the Schoolmen have nothing left for 
their primary matter. I shall be told, perhaps, that this 


tabula rasa of the philosophers means that the soul has 
naturally and originally nothing but bare faculties. But 
faculties without any activity, in a word the pure potencies 
of the Schools, these too are nothing but fictions, of which 
nature knows nothing, and which are obtained by making 
abstractions. For where in the world will you find a faculty 
which shuts itself up in a mere potency and never exercises 
any activity? There is always a particular disposition to 
action, and to one action rather than another. And besides 
the disposition there is always a tendency to action; indeed 
there is always an infinite number of them in every subject 
at any given time; and these tendencies are never without 
some effect. Experience is necessary, I allow, for the soul 
to be determined to such and such particular thoughts, and 
for it to take notice of the ideas which are in us. But by 
what means can experience and the senses provide ideas? 
Has the soul windows ? Does it resemble a tablet? Is it like 
wax? It is evident that all those who speak thus of the 
soul treat it at bottom as corporeal. I shall have brought 
against me the axiom, accepted among the philosophers, 
that there is nothing in the soul save that which comes from the 
senses. But we must except the soul itself and its affections. 
Nihil est in intellectu, quod non fuertt in sensu ; excipe, 
nisi ipse intellectus* Now the soul contains existence, 
substance, unity, identity, cause, perception, reasoning, and 
a quantity of other notions which the senses could not afford. 
This is in agreement with your friend the author of the 
Essay, who finds the source of a good part of our ideas in the 
reflection of the mind upon its own nature. 

PH. I hope, then, that you will agree with this able author 
that all our ideas come from sensation or from reflection, 
that is to say, from the observations we make either of 

1 ' There is nothing in the intellect which was not previously in 
the senses; provided we make the reservation, except the intellect 


external, sensible objects or of the internal operations of 
our soul. 

TH. To avoid a dispute over which we have delayed too 
long, I must make it quite clear at the outset, sir, that when 
you say that ideas come to us from the one or the other of 
these causes I understand you to speak of the actual per- 
ception of them, for I think I have shown that they are in us 
before they are apperceived in so far as they contain anything 
distinct. 1 


Of Perception 

i. PH. Let us now turn to the ideas of reflection in detail. 
Perception , as it is the first faculty of the mind exercised about 
our ideas, so it is the first and simplest idea we have from 
reflection. Thinking signifies that sort of operation of the 
mind about our ideas, wherein the mind is active ; where it, with 
some degree of voluntary attention, considers anything. For in 
bare naked perception, the mind is, for the most part, only 
passive ; and what it perceives, it cannot avoid perceiving. 

TH. We might perhaps add that brutes have perception, 
and that it is not necessary that they should have thought, that 
is to say, should have reflection or anything that can be the 
object of reflection. Moreover, we ourselves have minute 
perceptions which we do not apperceive in our present state. 
It is true that we could quite well apperceive them or reflect 
on them, if we were not deterred by their multitude, which 
distracts our mind, and if they were not effaced or rather 
obscured by greater ones. 

4. PH. I admit that whilst the mind is intently employed 
in the contemplation of some objects it takes no notice of im- 

1 In the remainder of this chapter Leibniz discusses Locke's 
contention that the mind thinks not always. 


pressions of sounding bodies made upon the organ of hearing. 
A sufficient impulse there may be on the organ ; but if not reaching 
the observation of the mind, there follows no perception. 

TH. I should prefer to distinguish between perception and 
apperceiving. The perception of the light or of the colour, for 
example, which we do apperceive, is composed of a number of 
minute perceptions, which we do not apperceive; and a noise 
of which we have perception, but of which we do not take 
notice, becomes apperceptible by a slight addition or increase. 
For if what precedes made no impression on the soul, 
neither would this little addition make any, and the whole 
would make none either. I have already touched on this 
point in ch. i of this book, u, 12, and 15. 

8. PH. We are further to consider concerning perception, 
that the ideas we receive by sensation are often in grown people 
altered by the judgment, without our taking notice of it. The 
idea imprinted on the mind by a globe of uniform colour is 
that of aflat circle variously shadowed and with several degrees 
of light and brightness coming to our eyes. But we have by use 
been accustomed to perceive what kind of appearance convex 
bodies are wont to make in us, what alterations are made in the 
reflections of light by the dijference of the sensible figures of 
bodies ; and so we put in the place of what appears to us the 
actual cause of the image, and confuse judgment with vision. 

TH. Nothing is more true, and this it is which provides 
the painter with the means of deceiving us by the artifice of 
a perspective which we can well understand. When bodies 
have flat surfaces, we can represent them without making 
use of shadows, by employing outlines only, and by simply 
making pictures in the fashion of the Chinese, only more 
in proportion than theirs. This is the usual way of drawing 
medals, so that the draughtsman may keep closer to the 
precise features of the originals. But there is no way by 
drawing, of exactly distinguishing the inside of a circle 
from the inside of a spherical surface bounded by that circle, 


without the assistance of shadows, since the insides have in 
neither case any distinct points or distinguishing features, 
although there is all the same a great difference which must be 
shown. This is why M. Des Argues laid down precepts about 
the effect of tints and shadows. When a painting deceives us 
there is a double error in our judgments; for in the first place 
we substitute the cause for the effect, and think we are seeing 
immediately that which is the cause of the image, rather like 
a dog who barks at a mirror. For, strictly speaking, we only 
see the image, and are affected by nothing but rays of light. 
And since these rays of light need time (however short), it is 
possible that the object might have been destroyed during 
this interval and no longer exist by the time the ray reaches 
the eye; and what no longer exists cannot be the present 
object of vision. In the second place we are mistaken in 
substituting one cause for another, and thinking that what 
only comes from a flat painting is derived from a body; so 
that in this case there is in our judgments at the same time 
both a metonymy and a metaphor; for the very figures of 
rhetoric become sophisms when they impose upon us. This 
confusion of the effect with the cause, whether real or alleged, 
often enters into our judgments in other places as well. It 
is involved when we feel our bodies, or what touches them, 
and when we move our arms, by an immediate physical 
influence, which we think constitutes the communion of the 
soul and the body; whereas the truth is that we feel and 
change in this way only what is within us. 

8. PH. I shall here insert a problem which was sent to 
the illustrious Mr. Locke by that very ingenious and studious 
promoter of real knowledge, the learned Mr. Molyneux. It 
was stated very much as follows : Suppose a man born blind, 
and now adult, and taught by his touch to distinguish between 
a cube and a sphere of the same metal, and nighly of the same 
bigness, so as to tell, when he felt one and the other, which is the 
cube, which the sphere. Suppose, then, the cube and sphere 


placed on a table, and the blind man be made to see: quaere, 
whether by his sight, before he touched them, he could now dis- 
tinguish and tell which is the globe, which the cube ? I beg you, 
sir, to tell me your opinion on this matter. 

TH. I should need time to think about this question, 
which seems to me a remarkable one; but since you urge me 
to reply on the spot, I venture to say, between ourselves, 
that I believe that if the blind man knew that the two 
figures lie was looking at were the cube and the globe, he would 
be able to distinguish them, and say without touching them: 
This is the globe, this the cube. 

PH. 1 fear that you must be numbered with the crowd of 
those who have wrongly answered Mr. Molyncux. For in the 
letter which contained this question, he stated that he had 
propounded it to various men of acute mind, apropos of Mr. 
Locke's Essay on the Human Understanding, and had found 
hardly one who began by giving him what he considered 
the right answer, although they became convinced of their 
mistake on hearing his reasons. This acute and judicious 
author answers: Not. For, though he (the blind man) has 
obtained the experience of how a globe, how a cube affects his 
touch, yet he has not obtained the experience, that what affects 
his touch so or so must affect his sight so or so ; or that a pro- 
tuberant angle in the cube, that pressed his hand unequally, 
shall appear to his eye as it does in the cube. The author of 
the Essay declares that he is altogether of the same opinion. 

TH. Perhaps Mr. Molyneux and the author of the Essay are 
not as far removed from my opinion as at first appears, and 
perhaps the reasons for their view, which were apparently 
contained in the letter of Mr. Molyneux, who had successfully 
made use of them to convince people of their mistake, were 
purposely suppressed by Mr. Locke so as further to exercise 
the minds of his readers. If you will closely consider my 
answer, you will find that I have included in it a condition 
which may be taken to be implied in the question, that is, 


that it is only a question of distinguishing; and that the 
blind man knows that the two shaped bodies which he has to 
distinguish are there, and therefore that each of the ap- 
pearances he sees is either that of the cube or that of the 
globe. In this case it seems to me certain that the blind 
man who has just ceased to be blind can distinguish them 
by the principles of reason, combined with what sensuous 
knowledge he has previously acquired by touch. I am not 
speaking of what he perhaps will do actually and on the spot; 
for he will be dazzled and confused by novelty, as well as 
little accustomed to drawing conclusions. The foundation 
of my opinion is, that in the globe there are no points dis- 
tinguished from the side of the globe itself, all of it being 
uniform and without angles, whereas in the cube there are 
eight points distinguished from all the others. If there were 
not this method of distinguishing figures, a blind man could 
not learn the rudiments of geometry by means of touch. Yet 
we see that men born blind are capable of learning geometry, 
and even have always some rudiments of a natural geometry; 
moreover geometry is most often learnt simply by sight, 
without the use of touch, as it could be, and indeed would have 
to be, learnt in the case of a paralytic or any other person 
who was more or less incapable of touch. And these two 
geometries, the geometry of the blind man and that of the 
paralytic, must meet and agree and even come back to the 
same ideas, although they have no common images. This 
shows again how necessary it is to distinguish images from 
exact ideaSy which consist of definitions. Indeed, it would be 
most interesting and even instructive thoroughly to examine 
the ideas of a man born blind, and to hear his descriptions of 
figures. For he can give such descriptions, and can even 
understand the doctrine of optics, in so far as it is dependent 
on ideas that are distinct and mathematical, although he 
cannot manage to conceive anything which is chiaroscuro, 
that is to say the image of light and colours. This is why a 


certain man, born blind, after listening to some lessons on 
optics, which he seemed to understand pretty well, when 
asked what he thought about light replied that he imagined 
it must be something pleasant like sugar. In the same way 
it would be very important to examine the ideas of a man 
born deaf and dumb about things without shapes, ideas 
which we ordinarily describe in words, and which he must 
acquire in a quite different way, although it may be equivalent 
to ours, as the writing of the Chinese has the same effect as 
our alphabet, although it is infinitely different from it, and 
might seem to have been invented by a deaf man. I have 
heard, through the courtesy of a great prince, of a man in 
Paris, born deaf and dumb, whose ears finally came to perform 
their proper office; this man has now learnt French (for it 
was from the French Court that he was summoned not long 
ago) and can tell many curious things about the conceptions 
he had in his former state, and about the change in his ideas, 
when his sense of hearing began to function. These people 
who are born deaf and dumb can go further than we think. 
There was one at Oldenburg in the time of the last count, 
who became a good painter, and showed himself very rational 
in other respects. A very learned man, Breton by nation- 
ality, told me that at Blainville, a place ten leagues from 
Nantes, belonging to the Duke of Rohan, there was about 
1690 a poor man living in a hut, near to the castle outside 
the town, who was born deaf and dumb, and who took letters 
and other things to the town, finding the houses by means of 
signs made him by the people who used to employ him. At 
last the poor man became blind too, and still did not give up 
performing services, and carrying letters to the town on the 
strength of what he was told by touch. He had in his hut a 
plank which went from the door to the place where his feet 
were, and which made him aware by its movement when 
any one came in. People are most negligent not to acquire 
exact knowledge of the ways of thinking of such persons. If 


he is no longer alive, there is likely to be someone in the 
vicinity who could still give us some information about him, 
and make us understand how he was shown the things he 
was to do. But to return to what the man born blind, 
who is beginning to see, will think about the globe and the 
cube, when he sees them without touching them, I answer 
that he will distinguish them in the way I have said, if 
someone informs him that one or the other of the appearances 
or perceptions he has of them belongs to the cube or to the 
globe; but without this preliminary instruction, I admit that 
it would not at first occur to him to think that these sorts 
of paintings which he received of them in the depths of his 
eyes, and which might arise from a flat painting on the table, 
represented bodies, until touch had convinced him of it, or 
until, by dint of reasoning about rays according to the laws 
of optics, he understood by the lights and the shadows that 
there was something there which arrested these rays, and that 
it was this which remained present to his sense of tcuch. He 
would arrive at this view finally, when he saw the globe and 
cube rolling along, and changing shadows and appearances 
as the result of their motion, or even when, the two bodies 
remaining at rest, the light which illuminated them changed 
its place, or his eyes changed their position. For these are 
more or less our methods of distinguishing at a distance 
between a picture or a perspective representing a body, and 
an actual body itself. 

n. PH. Let us return to perception in general. Percep- 
tion puts the difference between animals and inferior beings. 

TH. I am inclined to think that there is some perception 
and appetition in plants also, on account of the important 
analogy which exists between plants and animals; and if 
there is a vegetable soul, as is the common view, it must have 
perception. But I none the less attribute to mechanism all 
that takes place in the bodies of plants and animals, except 
their original formation. Thus I agree that the motion of 


the plant which is commonly called sensitive arises from 
mechanism, and I do not approve of having recourse to the 
soul for explaining the detail of the phenomena of plants 
and of animals. 

14. PH. It is true that I myself cannot but think that 
even in such kinds of animals, as oysters and cockles, 
there is some small dull perception : for would not quickness of 
sensation be an inconvenience to an animal that must lie still 
where chance has once placed it, and there receive the afflux of 
colder or warmer, clean or foul water, as it happens to come to it ? 

TH. Very true; and 1 hold that nearly as much could be 
said of plants ; but as to man, his perceptions arc accompanied 
by the power of reflection, which passes into action when 
need arises. But when he is reduced to a state like that of one 
who is in a lethargy, and is almost without sensation, reflec- 
tion and apperception cease, and there is no longer any thought 
of universal truths. Nevertheless, his faculties and dis- 
positions, innate and acquired, and even the impressions he 
has received in this state of confusion, do not for that reason 
cease, and are not wiped out, even though they are forgotten; 
they will even take their turn in contributing one day to some 
notable result. For nothing in nature is useless; every con- 
fusion is bound to be cleared up; the very animals, reduced to 
a state of stupidity, must one day return to more exalted 
perceptions; and since simple substances endure for ever, we 
must not judge of eternity by a few years. 



Of the degrees of our knowledge 

i . PH. Knowledge is intuitive when the mind perceives the 
agreement or disagreement of two ideas immediately by them- 
selves, without the intervention of any other. In this case the 
mind is at no pains of proving or examining the truth. As 


the eye sees the light, the mind sees that white is not black, 
that a circle is not a triangle, that three is two and one. 
This kind of knowledge is the clearest and most certain that 
human frailty is capable of; it acts in a manner that is irre- 
sistible, and it leaves no room in the mind for hesitation. It 
is to know that the idea in the mind is such as it is perceived 
to be. He that demands a greater certainty than this, demands 
he knows not what. 

TH. The primary truths which are known by intuition are 
of two kinds, like derivative truths. They are either truths of 
reason or truths of fact. Truths of reason are necessary, 
those of fact are contingent. The primary truths of reason 
are those which I call by the general name of identical, because 
it appears that they do nothing but repeat the same thing, 
without teaching us anything. They are affirmative or 
negative. . . , l 

Someone perhaps, after listening patiently to all that I 
have just said, will at last lose patience and say that I am 
amusing myself with frivolous enunciations, and that identical 
truths serve no purpose whatever. But such a judgment 
would be due to insufficient reflection on these matters. The 
consequences of logic, for example, are proved by principles 
which are identical; and geometry relies upon the principle 
of contradiction in those demonstrations which reduce ad 
impossibile. I will content myself here with showing the 
value of identical propositions in the demonstrations of the 
consequences of reasoning. I say then that the principle of 
contradiction alone is sufficient to demonstrate the second 
and third figures of the syllogism from the first. Take an 
example in the first figure, in Barbara : 

All B is C 

All A is B 

.'. all A is C. 

1 Here follows about a page of instances of identical proposi- 
tions, affirmative and negative, hypothetical, disjunctive, etc. 


Let us suppose that the conclusion is false (or that it is true 
that some A is not C), then the one or the other of the 
premises will be false also. Suppose the second is true: then 
the first, which asserts that all B is C, must be false. Then 
its contrary will be true ; that is to say, some B is not C. And 
this will be the conclusion of a new argument, drawn from 
the falsity of the conclusion and the truth of one of the 
premises of the preceding argument. Here is the new 

Some A is not C 

(which is opposite to the previous conclusion, supposed to 
be false). 

All A is B 

(this is the previous premise, supposed to be true). 
.'. some B is not C 

(this is the present conclusion, which is true, the opposite of 
the previous premise, which was false). 

This argument is in the mood Disamis of the third figure, 
which is thus demonstrated obviously and at a flash from the 
mood Barbara of the first figure, without involving anything 
but the principle of contradiction. And I observed in my 
youth, when I was criticizing these things, that all the moods 
of the second and third figures can be obtained from the 
first by this one method, if we suppose that the mood of the 
first is valid, and consequently that, the conclusion being 
falst' and its contrary being taken for true, and one of the 
premises being taken for true also, it follows that the contrary 
of the other premise must be true. It is true that in the 
Schools of logic they prefer to make use of conversions. 1 . . . 

1 The validity of conversions themselves, Leibniz says, must be 
demonstrated from the primary principle, that of contradiction ; 
it is therefore better to demonstrate the second and third figures 
direct, as above, and not to use conversion. 


Since the demonstration of conversions also shows the value 
of identical affirmative propositions, which some take to be 
utterly frivolous, it is all the more relevant to include it here. 
I will only mention conversions without contraposition, 
which are sufficient for my purpose here, and which are either 
simple or per accidens, as they are called. Simple conver- 
sions are of two kinds: the universal negative, like No 
square is obtuse-angled, therefore no obtuse-angled figure is 
square ; and the particular affirmative, such as Some triangles 
are obtuse-angled, therefore some obtuse-angled figures are 
triangles. But conversion per accidens, as it is called, 
concerns the universal affirmative, such as All squares are 
rectangles, therefore some rectangles are squares. By rectangle 
here is always understood a figure whose angles are right 
angles, and by square a regular quadrilateral. We have now 
to demonstrate these three kinds of conversions, which are: 

(1) No A is B, :. no B is A. 

(2) Some A is B, .*. some B is A. 

(3) All A is B, .'. some B is A. 

Demonstration of the first conversion in Cesare, which is of 
the second figure: 

No A is B 

All B is B 
.'. no B is A. 

Demonstration of the second conversion in Datisi, which is 
of the third figure: 

All A is A 

Some A is B 
/. some B is A. 

Demonstration of the third conversion in Darapti, which is 
of the third figure: 

All A is A 

All A is B 
:. some B is A. 


This shows that identical propositions which are most pure 
and appear to be most useless have considerable value in the 
abstract and in general. And that should teach us not to 
despise any truth. As regards the proposition that three is 
equal to two and one, which you adduce, Sir, as an example of 
intuitive knowledge, my comment is that it is simply the 
definition of the term three \ for the simplest definitions of 
numbers are formed in this manner two is one and one, 
three is two and one, Jour is three and one, and so on. It 
is true that there is hidden within these definitions an 
enunciation, which I have already mentioned, namely that 
these ideas are possible; and that is known in this case 
intuitively, so that we may say that there is intuitive know- 
ledge contained in definitions when their possibility first 
appears. And in this way all adequate definitions contain 
primary truths of reason, and consequently intuitive know- 
ledge. Finally, we may say in general that all primary 
truths of reason are immediate with an immediacy of ideas. 

As regards primary truths of fact, these are the immediate 
internal experiences of an immediacy of sensation. It is 
among these that is included the first truth of the Cartesians 
or of Saint Augustine : / think, therefore I am, that is to say, 
/ am a thing which thinks. But it is to be noted that the 
same is true of primary truths of fact as of identicals, that is 
to say that they can be either general or particular, and are 
as clear in the one case as in the other (since it is as clear to 
say that A is A as to say that a thing is what it is.) For not 
only is it clear to me immediately that I think, but it is just 
as clear to me that I have different thoughts, that now / think 
of A and now / think of B, etc. Thus the Cartesian principle 
is sound, but it is not the only one of its kind. So we see 
that all primary truths of reason or of fact have this in com-, 
mon that they cannot be proved by something more certain. 

2. PH. I am very much pleased, sir, that you have 
developed further my remarks, in which I did no more than 


touch upon intuitive knowledge. Now demonstrative know- 
ledge is simply a linking together of intuitive apprehensions 
in all the connections of the mediate ideas. For often the 
mind cannot join, compare, or apply its ideas to one another 
immediately, and so it is obliged to make use of other 
mediating ideas (one or more, as it happens) in order to 
discover the agreement or disagreement it is looking for; and 
this is called reasoning. For instance, in demonstrating that 
the three angles of a triangle are equal to two right angles, it 
finds out some other angles which it sees to be equal both to 
the three angles of the triangle and to two right angles. 
3. These intervening ideas are called proofs] and a quick- 
ness of the mind to find them is what is called sagacity. 4. 
Even when these ideas have been found, it is not without 
pains and attention, nor by a single transient view, that this 
knowledge can be acquired; there must be a progression of 
ideas by steps and degrees. 5. Before the demonstration 
there is a doubt. 6. It is less clear than intuitive know- 
ledge; just as a face reflected by several mirrors one to 
another grows weaker and weaker at each successive reflec- 
tion, and is not at first sight so knowable, especially to weak 
eyes. Thus it is with knowledge made out by a long train of 
proof. 7. And though in each step which reason makes in 
demonstrating there is an intuitive knowledge, or knowledge 
at sight, yet because in this long succession of proofs the 
memory does not retain so exactly this chain of ideas, men 
often embrace falsehoods for demonstrations. 

TH. Over and above sagacity, whether natural or acquired 
by exercise, there is an art of finding mediating ideas (the 
medium)] and this art is Analysis. Now it is well to con- 
sider here that it is sometimes a question of finding out the 
truth or falsity of a given proposition, that is, simply to 
answer the question whether ? that is to say, Is it or is it 
not? At other times it is a matter of answering a question 
which is much more difficult (ceteris paribus); for instance, 


where it is asked by what means ? or how ? and where there is 
more to be supplied. It is these questions only, which leave 
part of the proposition blank, which mathematicians call 
problems: for instance when we are asked to find a mirror 
which collects all the rays of the sun at a point ; that is to say 
we are asked its shape, or how it is made. As for the first 
kind of questions, where it is simply a matter of true and 
false, and where there is nothing to supply in the subject or 
predicate, here there is less invention; still there is some, and 
judgment alone is not sufficient. It is true that a man of 
judgment, that is to say, one who is capable of attention and 
restraint, and who has the necessary leisure and patience and 
is open-minded enough, can understand the most difficult 
demonstration if it is properly put to him. But the most 
judicious man in the world will not always be able to find 
the demonstration without assistance. Thus there is some 
invention in that too; and in geometry there used to be more 
in earlier times than there is now. For when the art of 
Analysis was less cultivated, it required more sagacity to 
arrive at it. ... It also happens that induction provides us 
with some truths about numbers and figures, for which the 
general reason has not yet been discovered. For we are 
far from having arrived at the perfection of Analysis in 
geometry and in numbers. . . . 

But it is much more difficult to find out important truths, 
and even more so to find out means of doing what is wanted, 
just when it is wanted, than it is to find out the demonstration 
of what someone else has discovered. Often beautiful truths 
are arrived at by Synthesis, by passing from the simple to the 
compound; but when it is a matter of finding out exactly the 
means for doing what is required, Synthesis is ordinarily not 
sufficient ; and often a man might as well try to drink up the 
sea as to make all the required combinations, even though it 
is often possible to gain some assistance from the method of 
exclusions, which cuts out a considerable number of useless 


combinations; and often the nature of the case does not 
admit of any other method. But there are not always 
available the means for properly following this method. So 
it is to Analysis that we must look for a thread in the laby- 
rinth, whenever it is possible; for there are cases where the 
very nature of the question requires that we should proceed 
by trial and error throughout, short cuts not always being 

8. PH. Now since demonstration always presupposes 
intuitive knowledge, it is this, I imagine, which gave occasion 
to the axiom that all reasoning is from things previously known 
and previously granted (ex praecogmtis et praeconcessis). But 
we shall have occasion to speak of the faults of this axiom, 
when we come to speak of the maxims which are mistakenly 
supposed to be the foundations of our reasonings. 

TH. I shall be curious to learn what fault you can find 
with an axiom which appears so reasonable. If it was 
necessary to reduce everything to intuitive apprehensions, 
demonstrations would often be of unbearable prolixity. . . . 
But there is another hindrance, namely that it is not easy to 
demonstrate all the axioms, and entirely to reduce demon- 
strations to intuitive apprehensions. And if attempts had 
been made to do this, perhaps ue should still be without the 
science of geometry. . . . 

14. PH. Besides intuition and demonstration) which are 
the two degrees of our knowledge, all the rest is faith or 
opinion, but not knowledge, at least in all general truths. There 
is, however, another perception of the mind employed about the 
particular existence of finite beings without us ; and this is 
called sensitive knowledge. . . . 

Sensitive knowledge, or the knowledge which establishes the 
existence of particular beings without us, goes beyond bare 
probability; but it does not possess all the certainty of the 
two degrees of knowledge of which we have been speaking. 
There can be nothing more certain than that the idea we receive 


from an external object is in our minds. But whether we can 
thence certainly infer the existence of anything without us which 
corresponds to that idea, is that whereof some men think there 
may be a question made ; because men may have such ideas in 
their minds when no such thing exists, no such object affects 
their senses. But yet here I think we are provided with an 
evidence which puts us past doubting. We are invincibly 
conscious of a different perception when we look on the sun 
by day and think on it by night; and the idea which is revived 
by the aid of memory is very different from the one which 
actually comes into our minds by our senses. If any one says 
a dream may do the same thing, I make him this answer: (i) 
That it is no great matter whether 1 remove this scruple or no: 
where all is but dream, reasoning and arguments are of no use, 
truth and knowledge nothing. (2) That I believe he will allow 
a very manifest difference between dreaming of being in the 
fire and being actually in it. And if he persists in appearing 
sceptical, I will tell him that it is enough that we certainly 
find that pleasure or pain follows upon the application of 
certain objects to us, whose existence we perceive, or dream that 
we perceive, by our senses: this certainty is as great as our 
happiness or misery ; beyond which we have no concernment to 
know or to be. So that I think we may reckon three degrees of 
knowledge ; viz., intuitive, demonstrative, and sensitive. 

TH. I believe you are right, and I even think that to these 
kinds of certainty or certain knowledge you might add know- 
ledge of the probable] thus there will be two sorts of knowledge 
as there are two sorts of proofs, of which the one produces 
certainty, while the other arrives at probability only. But let 
us turn to the quarrel between the Sceptics and the Dog- 
matists over the existence of things without us. We have 
already touched upon it, but we must return to it here. I have 
in the past had much argument about this both personally 
and by letter with the late M. PAbb6 Foucher, Canon of 
Dijon, a man both learned and subtle, but somewhat too 


much engrossed in the Academics, whose sect he would gladly 
have revived, just as M. Gassendi brought back upon the 
scene the sect of Epicurus. His criticism of the Recherche de 
la Verite, and other small treatises which he had printed 
subsequently, have brought their author some fame. He 
also published in the Journal des Savans some objections to 
my System of Pre-established Harmony, when I communi- 
cated it to the public, after meditating on it for some years; 
but death prevented him from answering my reply. He 
always preached that we ought to guard against prejudices 
and to insist on great exactitude; but not only did he not 
devote himself to practising what he preached, wherein he 
was excusable enough, but he also seemed to me not to heed 
whether others did so, foreseeing no doubt that no one ever 
would. Now I pointed out to him that the truth of sensible 
things only consisted in the connection of phenomena, for 
which there must be a reason, and which is the thing that 
distinguishes them from dreams; but that the truth of our 
existence and of the cause of phenomena is of another nature, 
because it establishes some substances. I urged that the 
Sceptics spoil what is good in their statements, by carrying 
them too far, even wishing to extend their doubts to im- 
mediate experiences, and even to geometrical truths (which, 
however, M. Foucher did not do), and to other truths of 
reason, which he did a little too much. But, to return to you, 
Sir, you are right in saying that there is a difference ordinarily 
between sensations and imaginings; but the Sceptics would 
say that a difference of more and less is not a difference 
of kind. Besides, though sensations are habitually more 
vivacious than imaginings, there are none the less cases where 
imaginative people are as much or perhaps more struck by 
their imaginings than others are by the truth of things; so 
that I hold that the true criterion regarding the objects of the 
senses is the connection between phenomena, that is to say 
the linking up of what occurs in different places and times, 


and in the experience of different men, who are themselves 
very important phenomena to one another in this regard. 
And the connection of phenomena, which guarantees truths 
of fact with regard to sensible things outside us, is verified by 
means of truths of reason-, as appearances in optics have light 
thrown upon them by geometry. Still it must be admitted 
that none of this certitude is of the highest order, as you have 
rightly recognized. For it is not impossible, metaphysically 
speaking, for there to be a dream which is consecutive and 
enduring like the life of a man; but it is a thing as contrary 
to reason as it would be for a book to be composed by chance 
through the type being jumbled up together anyhow. Besides 
it is also true, that provided phenomena are linked up, it 
matters not whether they are called dreams or not, since 
experience shows that we are not mistaken in the measures 
we take with phenomena, when they are taken in accordance 
with the truths of reason. 

15 PH. For the rest, knowledge is not always clear, where 
the ideas are so. A man that has as clear ideas of the angles of a 
triangle, and of equality to two right ones, as any mathematician 
in the world, may yet have but a very obscure perception of their 

TH. Usually, when ideas are fundamentally understood, 
their agreements and disagreements appear. Nevertheless, 
I admit that there are sometimes ideas so compounded that 
much care is needed to develop what is hidden in them; and 
considering this, some agreements and disagreements may 
still remain obscure. As to your example, my comment is that 
the fact that we have the angles of a triangle in the imagina- 
tion does not mean that we therefore have clear ideas of them. 
Imagination is incapable of providing us with an image 
common to acute-angled and obtuse-angled triangles, and 
yet the idea of triangle is common to both. Thus this idea does 
not consist in the images, and it is not as easy as one might 
think fundamentally to understand the angles of a triangle. 


(Extract from a letter written in 'November 1715) 

IT appears that even natural religion is growing very much 
weaker. Many hold that souls are corporeal ; others hold that 
God Himself is corporeal. Mr. Locke and his followers are 
at any rate doubtful whether souls are not material and 
naturally perishable. Mr. Newton says that space is the 
organ which God makes use of to perceive things by. But 
if He stands in need of any medium whereby to perceive them, 
they do not then depend entirely on Him, and were not 
produced by Him. Mr. Newton and his followers have also 
an extremely odd opinion of the work of God. According 
to them God has to wind up His watch from time to time. 3 
Otherwise it would cease to go. He lacked sufficient fore- 
sight to make it a perpetual motion. This machine of God's 
is even, on their view, so imperfect that He is obliged from 
time to time to come to its assistance especially out of the 

1 Samuel Clarke (1675-1729), English philosopher and divine; 
the most celebrated disciple of Newton. 

* This paper by Leibniz begins the correspondence. It is 
given here complete. 

Clarke thinks that the passage to which Leibniz is referring 
is the following, from Newton's Optics: ' Whilst the comets move 
in orbs very eccentrical, with all variety of directions towards 
every part of the heavens; 'tis not possible it should have been 
caused by blind fate, that the planets all move with one similar 
direction in concentrick orbs; excepting only some very small 
irregularities, which may have arisen from the mutual actions of 
the planets and comets upon one another; and which 'tis 
probably will in length of time increase more and more, till the 
present system of nature shall want to be anew put in order by 
its Author.' (The translation from Newton's Latin is Clarke's.) 



ordinary course, and clean it, and even to mend it, as a clock- 
maker might his handiwork; and the less skilful the workman 
is, the more often is he obliged to rehandle and correct his 
work. According to my view, the same force and vigour 
goes on existing in the world always, and simply passes from 
one matter to another, according to the laws of nature and to 
the beautiful pre-established order. And I hold that, when 
God performs miracles, it is not to uphold the needs of nature, 
but for those of grace. To think otherwise would be to 
have a very low opinion of the wisdom and power of God. 


It is rightly said in the Paper which was sent to the Princess 
of Wales, and which Her Royal Highness did me the honour 
of sending me, that next to vicious passions the principles of 
the Materialists contribute much to support impiety. But I 
do not think the author was justified in adding that the 
Mathematical Principles of philosophy are opposed to those of 
the Materialists. On the contrary, they are the same except 
that Materialists follow the example of Democritus, Epicurus, 
and Hobbes, and restrict themselves to mathematical prin- 
ciples alone and admit nothing but bodies; while the Christian 
Mathematicians admit immaterial substances also. Thus 
it is not Mathematical Principles (in the ordinary sense of the 
term) but Metaphysical Principles which must be opposed 
to those of the Materialists. Pythagoras, Plato, and to some 
extent Aristotle had some knowledge of these, but it is my 
claim to have established them demonstratively, although 
I was giving a popular exposition, in my Theodicy. The 
great foundation of mathematics is the principle of contra- 
diction or of identity, that is to say, that a statement cannot 
be true and false at the same time and that thus A is A, and 

1 This Second Paper was written in answer to Clarke's reply to 
Leibniz's First Paper. It is given here complete. 


cannot be not A. And this single principle is enough to 
prove the whole of arithmetic and the whole of geometry, 
that is to say all mathematical principles. But in order to 
proceed from mathematics to physics another principle is 
necessary, as I have observed in my Theodicy, that is, the 
principle of a sufficient reason, that nothing happens 
without there being a reason why it should be thus rather 
than otherwise. This is why Archimedes, wishing to proceed 
from mathematics to physics in his book On Equilibrium, was 
compelled to make use of a particular case of the great 
principle of sufficient reason; he takes it for granted that if 
there is a balance in which everything is the same on both 
sides, and if, further, two equal weights be hung on the two 
ends of the balance, the whole will remain at rest. This is 
because there is no reason why one side should go down 
rather than the other. Now by this principle alone, to wit, that 
there must be a sufficient reason why things are thus rather 
than otherwise, is proved Divinity, and all the rest of meta- 
physics and natural theology, and even in some manner 
those physical principles which are independent of mathe- 
matics, that is to say, the principles of dynamics or of 

Our author goes on to say that according to the mathe- 
matical principles, that is to say according to the philosophy 
of Mr. Newton (for mathematical principles here prove 
nothing one way or the other), matter is the least considerable 
part of the universe. This is because he holds that besides 
matter there is empty space, and because according to him 
matter only occupies a very small part of space. But 
Democritus and Epicurus maintained the same thing, except 
that in this they differed from Mr. Newton on the point of 
quantity; according to them there was perhaps more matter 
in the world than according to Mr. Newton. Wherein I 
think their view is preferable; for the more matter there is, 
the more opportunity is there for God to exercise His wisdom 


and His power; and it is for this, among other reasons, that I 
hold that there is no void at all. 

It is said expressly in the Appendix to Mr. Newton's 
Optics that space is God's sensorium. 1 Now the word 
sensorium has always meant the organ of sensation. Let him 
and his friends now give a quite different explanation of their 
meaning: I shall not object. 

Our author supposes that the presence of the soul is enough 
to enable it to perceive what is going on in the brain. But 
this is exactly what Malebranche and the whole Cartesian 
School deny, and rightly deny. Something quite other than 
mere presence is needed for one thing to represent what takes 
place in another. For this some explicable communication 
is necessary, some kind of influence either of the things upon 
one another or of a common cause. Space, according to Mr. 
Newton, is intimately present to the body which it contains 
and which is commensurate with it. Does it therefore 
follow that space perceives what takes place in the body, and 
remembers it after the body has left it? Besides, since the 
soul is indivisible and its immediate presence in the body 
could therefore be conceived to be at a point only, how could 
it then perceive what took place outside this point ? I claim 
to be the first to have shown how the soul perceives what 
takes place in the body. 

The reason why God perceives everything is not His 
simple presence, but His operation also; it is because He 
preserves things by an activity which continually produces 
all that there is in them of goodness and perfection. But 
since souls have no immediate influence on bodies, nor bodies 
on souls, their mutual correspondence cannot be explained 
by presence. 

The real reason which chiefly causes us to praise a 

1 Clarke had objected to Leibniz's statement in his First Paper 
that ' Mr. Newton says that space is the organ which God makes 
use of to perceive things by '. Cf . p. 192. 


machine, is derived rather from the effect of the machine 
than from its cause. We seek information less regarding 
the power of the mechanician than regarding his in- 
vention. Thus the reason alleged for praising God's 
machine that He made it entirely without borrowing any 
matter from outside is not enough. It is a shift to which 
the author has been compelled to resort. The reason why 
God is to be preferred above another mechanician is not 
only because He makes the whole, whereas the artisan has 
to seek for his material. This superiority would arise from 
power only. But there is another reason for the excellence 
of God, which arises from wisdom. This reason is that His 
machine also lasts longer and goes more correctly than that 
of any other mechanician whatever. The buyer of the watch 
does not trouble himself whether the workman made the 
whole of it, or whether he had the pieces of it made by other 
workmen and merely adjusted them himself, provided that 
it goes properly. And if the workman had received from God 
the gift of creating as well the material for the wheels, the 
buyer would not be satisfied if he had not also received the 
gift of adjusting them properly. And in the same way the 
man who wants to be satisfied with God's handiwork will 
not become so merely for the reason alleged here. 

Thus it is needful that God's invention should not be 
inferior to that of a workman; it must even go infinitely 
beyond it. The mere production of everything would indeed 
exemplify the power of God, but it would not sufficiently 
show His wisdom. Those who maintain the opposite fall 
exactly into the error of the Materialists and of Spinoza, 
from whom they protest they differ. They recognize power, 
but not sufficient wisdom in the principle of things. 

I do not say that the corporeal world is a machine or watch 
which goes without God's interposition, 1 and I am insistent 

1 Clarke had made the (usual) objection to Leibniz : ' The notion 
of the world's being a great machine, going on without the inter- 


enough that created things stand in need of His continual 
influence. But 1 do maintain that it is a watch which goes 
without needing His correction: otherwise we should have to 
admit that God keeps improving upon His own work. God 
has foreseen everything, He has provided a remedy for every- 
thing in advance. There is in His works an already pre- 
established harmony and beauty. 

This view does not exclude the providence or the govern- 
ment of God: on the contrary it makes it perfect. A true 
providence in God requires a perfect foresight, but moreover 
it further requires not only that He should have foreseen 
everything but also that He should have provided for every- 
thing by means of suitable preordained remedies: otherwise 
He would lack either wisdom to foresee things or power to 
provide for them. He would be like the God of the Socinians, 
who lives from day to day, as M. Jurieu said. It is true that 
God, according to the Socinians, fails even to foresee defects, 
whereas, according to these gentlemen who force Him to 
correct Himself, He fails to provide for them. But this 
seems to me to be still a very great lack; He would have to 
lack either power or good will. 

I do not think I can be justly rebuked for having said 
that God is Intelligentia Supramundana. Will those who dis- 
approve of it say He is Intelligentia Mundana, that is to say 
the Soul of the World? I hope not. However, they would 
do well to take care not to slip into this unintentionally. 

The comparison with a king in whose kingdom everything 
went on without his interference is not to the point, since 
God preserves things continually, and since they cannot 
subsist without Him: thus His Kingdom is not a nominal one. 
To say this would be like saying that a king who had his 

position of God, as a clock continues to go without the assistance 
of a clockmaker, is the notion of Materialism and Fate, and tends 
(under pretence of making God a Supra - mundane Intelligence) 
to exclude Providence and God's government in reality out of 
the world*. 


subjects so well educated, and by his care in providing for 
their subsistence, preserved them so well in their fitness for 
their several stations and in their good affection towards 
him, that he had no occasion ever to be amending anything 
amongst them, was only a nominal king. 

Finally, if God is obliged to correct natural things from 
time to time, this must occur either supernaturally or 
naturally. If it occurs supernaturally, recourse is had to 
miracles to explain natural things; which is in effect a 
reductio ad absurdum of a hypothesis. For by miracles, 
anything can easily be accounted for. But if it occurs 
naturally, God will not be Intelligentia Supramundana, He 
will be included in the nature of things, that is to say, He 
will be the Soul of the World. 


1. According to the usual way of speaking, mathematical 
principles 2 are those which consist in pure mathematics, 
for instance numbers, figures, arithmetic, geometry. But 
metaphysical principles concern more general notions, as for 
example cause and effect. 

2. I am granted this important principle, that nothing 
happens without a sufficient reason why it should be thus rather 
than otherwise. But it is granted me in words and refused 
me in fact; which shows that the full force of it has not been 
properly understood ; and in this connection the author makes 

1 Written in answer to Clarke's reply to the Second Paper. It 
is given here complete. 

'Clarke had argued that the Mathematical Principles of 
Philosophy (i.e. Newton's philosophical doctrines) are opposed to 
Materialism because they demonstrate that the existing state of 
things can only have arisen from an Intelligent and Free Cause. 
As regards the propriety of the name ; he says : ' So far as meta- 
physical consequences follow demonstratively from mathe- 
matical principles, so far the mathematical principles may 
(if it be thought fit) be called metaphysical principles '. 


use of an example which exactly falls in with one of my 
demonstrations against real absolute space, the idol of some 
modern Englishmen. I call it 'idol* not in a theological 
sense, but in the philosophical sense in which Chancellor 
Bacon used the word when he said, a long time ago, that 
there are idola tribus, idola specus. 1 

3. These gentlemen maintain, then, that space is a real 
absolute being; but this leads them into great difficulties. 
For it appears that this being must be eternal and infinite. 
This is why there have been some who believed that it was 
God Himself, or else His attribute, His immensity. But as 
it has parts, it is not a thing which can be appropriate 
to God. 

4. As for me, I have more than once stated that I held 
space to be something purely relative, like time; space being 
an order of co-existences as time is an order of successions. 
For space denotes in terms of possibility an order of things 
which exist at the same time, in so far as they exist together, 
and is not concerned with their particular ways of existing: 
and when we see several things together we perceive this 
order of things among themselves. 

5. I have several proofs for refuting the conception of 
those who take space to be a substance, or at least an absolute 
being of some kind. But here I only wish to make use of 
the one which the present occasion requires. I say then 
that if space were an absolute being, there would happen 
something for which it would be impossible that there should 
be a sufficient reason, and this is contrary to our axiom. This 
is how I prove it. Space is something absolutely uniform, 
and without the things situated in it one point of space 
absolutely does not differ in any respect from another point 
of space. Now from this it follows that if we suppose that 
space is something in itself, other than the order of bodies 
among themselves, it is impossible that there should be a 

1 'idols of the tribe, idols of the cave.' 


reason why God, preserving the same positions for bodies 
among themselves, should have arranged bodies in space 
thus and not otherwise, and why everything was not put 
the other way round (for instance) by changing east and west. 
But if space is nothing other than this order or relation, and 
is nothing whatever without bodies but the possibility of 
placing them in it, these two conditions, the one as things are, 
the other supposed the other way round, would not differ 
from one another: their difference exists only in our chimerical 
supposition of the reality of space in itself. But in truth the 
one would be just the same as the other, as they are abso- 
lutely indiscernible; and consequently there is no occasion 
to search after a reason for the preference of the one to the 

6. The same is true of time. Suppose someone asks why 
God did not create everything a year sooner; and that the 
same person wants to infer from that that God did something 
for which He cannot possibly have had a reason why He did 
it thus rather than otherwise, we should reply that his 
inference would be true if time were something apart from 
temporal things, for it would be impossible that there should 
be reasons why things should have been applied to certain 
instants rather than to others, when their succession remained 
the same. But this itself proves that instants apart from 
things are nothing, and that they only consist in the succes- 
sive order of things; and if this remains the same, the one 
of the two states (for instance that in which the creation was 
imagined to have occurred a year earlier) would be nowise 
different and could not be distinguished from the other which 
now exists. 

7. It will be seen from everything I have said that my 
axiom has not been fully understood, and that the author, 
while appearing to grant it, has really denied it. // is true, 
he says, that nothing exists without a sufficient reason why it is 
thus rather than otherwise, but he adds that this sufficient 


reason is often the simple or mere will of God, as when it is 
asked why matter was not differently arranged in space, 
the positions as between bodies being preserved. But this 
is simply maintaining that God wills something without there 
being a sufficient reason for His will, contrary to the axiom 
or general rule governing everything which happens. This 
is to relapse into the loose indifference which I have amply 
refuted, and which I have shown to be absolutely chimerical, 
even in created beings, and contrary to the wisdom of God, 
as if He could operate without acting reasonably. 

8. I am met with the objection that not to admit this 
simple and mere will would be to remove from God the power 
of choice, and that this would be to fall into fatalism. But 
quite the reverse is true. I maintain that God has the power 
of choice, since I base it on the reason for the choice which is 
in conformity with His wisdom. And it is not this fatalism 
(which is nothing but the order of the highest wisdom or of 
providence) but a brute fatalism or necessity, in which there 
is neither wisdom nor choice, that we ought to avoid. 

9. I had observed that if we diminish the quantity of 
matter, the quantity of objects on which God can exercise 
His goodness is diminished. The author answers that in- 
stead of matter there are other things in the void on which 
He does not fail to exercise it. Be it so; though I do not 
agree, for I hold that all created substance is accompanied 
by matter. But be it so. I answer that more matter was 
compatible with those same things, and consequently the said 
object will still be lessened. The example of a greater 
number of men or animals is not to the purpose, for they 
would occupy the room of other things. 

10. It will be difficult to make me believe that, in its 
ordinary use, sensorium does not mean the organ of sensation. 
Here are the words of Rudolphus Gocleniiu, in his Philoso- 
phical Dictionary: Sensiterium: barbarum Scholasticorum 
(he says) qui interdum sunt simiae Graecorum. Hi dicunt 


ex quo illi fecerunt Sensiterium pro Sensorio, id 
estj organo sensationis. 1 

11. The simple presence of a substance, even an animated 
one, is not enough for perception: a blind man does not see, 
nor even does an absent-minded one. It is necessary to 
explain how the soul perceives what is outside itself. 

12. God is not present in things by situation but by 
essence; His presence is manifested by His immediate 
operation. The presence of the soul is of quite another 
nature. To say that it is diffused throughout the body is to 
make it extended and divisible; to say that the whole of it 
exists in each part of each body is to make it divisible from 
itself. To attach it to one point, to spread it over several 
points are only improper expressions, idola tribus? 

13. If active force were lost in the universe by the natural 
laws which God has established in it, so that He needed a 
new impression to restore this force, like a workman setting 
right the imperfection of his machine, the disorder would 
occur not only with regard to us, but with regard to God 
Himself. He could have prevented it and have taken better 
steps to avoid such an untoward occurrence. Actually, 
indeed, He has done so. 

14. When I said that God has prepared actual remedies 
against these disorders in advance, I do not mean that God 
lets the disorders come and then the remedies for them; but 
that He has found means in advance to prevent disorders 
from happening. 

15. Our author attempts without success to criticize my 
expression, that God is Intelligentia Supramundana. To say 
that He is above the world is not to deny that He is in the 

1 ' Sensiterium: a barbarism of the Scholastics, who sometimes 
ape the Greeks. The latter say alcrQifT-fipior , from which the 
former have manufactured the word sensitenum in place of 
sensorium, i.e. the organ of sensation/ 

1 Cf note, p. 199. 


16. I have never given occasion for doubt whether God's 
conservation is an actual preservation and continuation of 
beings, powers, orders, dispositions, and motions; and I 
think I have perhaps explained it better than many others. 
But, says our author, this is all that I contended Jor : herein 
consists the whole dispute. To this I answer: Your most 
humble servant. Our dispute consists in quite different 
things. The question is whether God does not act in the 
most regular and perfect manner; whether His machine is 
liable to disorders which He will be obliged to set right by 
extraordinary means; whether the will of God is capable 
of acting without reason; whether space is an absolute 
being; wherein consists the nature of miracles: and many 
similar questions which set a great gulf between us. 

17. Theologians will not agree with the thesis advanced 
against me, that there is no difference in relation to God 
between the natural and the supernatural. The majority of 
philosophers will approve it even less. There is an infinite 
difference, but it certainly seems not to have been given 
proper consideration. The supernatural surpasses all the 
powers of created things. We must take an example. Here 
is one which I have often made use of with success. If God 
wished to cause a free body to circle in the ether round about 
a given fixed centre, without any other created thing acting 
on it, this, I say, could only occur by miracle, not being 
explicable by the nature of bodies. For a free body natur- 
ally departs from a curve along the tangent. It is in this 
sense that I maintain that the attraction of bodies, properly 
so called, is a miraculous thing, since it cannot be explained 
by their nature. 


i. In things which are absolutely indifferent there can be 

1 Written in answer to Clarke's reply to the Third Paper. As 
will be seen, some paragraphs have been omitted here. 


no choice and consequently no election or will, since choice 
must have some reason or principle. 

2. A simple will without any motive (a mere will) is a 
fiction which is not only contrary to the perfection of God, 
but also chimerical and contradictory, incompatible with the 
definition of will and sufficiently refuted in my Theodicy. 

3. It is indifferent whether three bodies which are equal 
and alike in every respect be placed in any order whatsoever, 
and consequently they never would be placed in order by 
Him who does nothing without wisdom. But also, being the 
Author of things, He will not produce any such; and conse- 
quently there are none in nature. 

4. There are no two individuals indiscernible from one 
another. A clever gentleman, a friend of mine, when con- 
versing with me in the presence of Her Electoral Highness 1 
in the garden at Herrenhausen, thought he would cer- 
tainly find two leaves exactly alike. Her Electoral Highness 
challenged him to do so, and he spent a long time running 
about looking for them, but in vain. Two drops of water or 
milk looked at under the microscope will be found to be 
discernible. This is an argument against atoms, which, like 
the void, are opposed to the principles of a true metaphysic. 

5. These great principles of a Sufficient Reason and of the 
Identity of Indiscernibles change the state of metaphysics, 
which by their means becomes real and demonstrative; 
whereas formerly it practically consisted of nothing but 
empty terms. 

6. To suppose two things indiscernible is to suppose the 
same thing under two names. Thus the hypothesis that the 
universe should have originally had another position in time 
and place from that which it actually had, and yet all the 
parts of the universe should have had the same position with 
regard to one another as that which they have in fact re- 
ceived, is an impossible fiction. 

1 Sophia, Electress of Hanover, mother of George I of England. 


7. The same reason which shows that space outside the 
world is imaginary proves that all empty space is something 
imaginary; for they differ only as the great from the small. 

8. If space is a property or an attribute, it must be 
the property of some substance. Of what substance is the 
bounded empty space, which the supporters of this view 
suppose to exist between two bodies, the property or affection ? 

9. If infinite space is immensity, finite space will be the 
opposite of immensity, that is to say mensurability or 
bounded extension. Now extension must be the affection 
of something extended. But if this space is empty, it will 
be an attribute without a subject, an extension of no extended 
thing. This is why in making space a property the author 
is accepting my position, according to which it is an order of 
things and not something absolute. 

10. If space is an absolute reality, far from being a property 
or accident opposed to substance, it will have more sub- 
sistence than substances; God will be unable to destroy it, 
or even to change it in any respect. It will be not only 
immense in the whole, but also immutable and eternal in 
each of its parts. There will be an infinity of eternal things 
besides God. 

11. To say that infinite space is without parts, is to say 
that it is not made up of finite spaces, and that infinite space 
might continue to exist though all finite spaces were reduced 
to nothing. It would be as if we were to say, on the Cartesian 
supposition of a corporeal extended universe without limits, 
that this universe might continue to exist though all the 
bodies which make it up were reduced to nothing. 

13. To say that God could move the universe forward in a 
straight line or otherwise without changing it in any other 
way is another chimerical supposition. For two indiscernible 
states are the same state, and consequently it is a change 
which changes nothing. Further, there is no rhyme nor 


reason in it. Now God does nothing without a reason, and 
it is impossible that there should be one here. Besides, it 
would be agenda nihil agere, 1 as I have just said, because of 
the indiscernibility. 

14. These are idola tribus, 2 the purest chimeras and super- 
ficial imaginings. It is all founded merely on the supposition 
that imaginary space is real. 

15. It is a similar, that is to say an impossible, fiction to 
suppose that God had created the world several million years 
sooner. Those who incline towards such kinds of fiction 
will be unable to reply to those who argue in favour of the 
eternity of the world. For since God does nothing without a 
reason, and since there is no reason assignable why He did not 
create the world sooner, it will follow either that He created 
nothing at all, or that He produced the world before any 
assignable time, which is to say that the world is eternal. 
But when we show that the beginning, whatever it was, 
is always the same thing, the question why it was not other 
wise ceases to arise. 

16. If space and time were something absolute, that is to 
say if they were something other than certain orders of 
things, what I am saying would be a contradiction. But 
since this is not the case, the hypothesis is contradictory, 
that is to say it is an impossible fiction. 

17. It is very like what happens in geometry where, by 
the very supposition that a figure is greater, we sometimes 
prove that in fact it is not greater. It is a contradiction; 
but the contradiction is in the hypothesis, which for this 
very reason is shown to be false. 

18. The uniformity of space means that there is neither 
internal nor external reason for discerning its parts, and 
for choosing between them. For such external reason for 
discerning could only be founded in the internal one; other- 

1 'acting without doing anything'. 
1 Cf. p. 199, note. 


wise it would be discerning the indiscernible, or choosing 
without discerning. Will without reason would be the 
'chance' of the Epicureans. A God who acted by such a 
will would be a God only in name. The source of these 
errors is want of care to avoid what is derogatory to the 
Divine perfections. 

19. When two incompatible things are equally good, and 
when one has no advantage over the other either in itself 
or in its combination with others, God will produce neither. 

20. God is never determined by external things, but always 
by what is in Himself, that is to say by His knowledge, before 
anything exists outside Him. 

21. There is no possible reason which could limit the 
quantity of matter. Therefore there cannot in fact be any 
such limitation. 

22. And suppose such an arbitrary limitation did exist, it 
would always be possible to add something without dero- 
gating from the perfection of those things which already 
exist: and consequently it would always be necessary to 
add something, in order to accord with the principle of the 
perfection of Divine operations. 

23. Thus it cannot be said that the present quantity of 
matter is the most fitting for the present constitution of 
things. And even if this were the case, it would follow that 
this present constitution of things would not be the most 
fitting absolutely, if it prevents the employment of more 
matter; it would therefore be necessary to choose another 
constitution of things, capable of something more. 

29. God perceives things in Himself. Space is the place of 
things, and not the place of the ideas of God: unless we 
consider space as something which causes the union of 
God and things, in imitation of the imagined union of 
the soul and the body; which would still make God the 
Soul of the World. 


32. Those who imagine that souls can give a new force to 
bodies, and that God does the same in the world so as to 
correct the imperfections of His machine, make God too like 
the soul, by attributing too much to the soul and too little 
to God. 

33. For it is only God that can give nature new forces, and 
He does it supernaturally only. If He needed to do it in the 
natural course of things He would have made a very im- 
perfect work. He would be, in the world, like what the 
soul is commonly held to be in the body. 

38. Those who imagine that active forces 1 diminish of 
themselves in the world, do not properly understand the 
principal laws of nature, and the beauty of the works of 

41. The author says that space does not depend on the 
situation of bodies. I answer that it is true that it does not 
depend on such and such a particular situation of bodies; but 
it is the order which makes bodies capable of having situation, 
and through which they have a situation with regard to one 
another when existing together; just as time is this order in 
relation to their successive position. But if there were no 
created beings space and time would only exist in the ideas 
of God. 2 

1 Clarke says that when he spoke of active forces diminishing, 
he meant by active force ' nothing but motion, and the impetus 
or relative impulsive force of bodies, arising from and being 
proportional to their motion '. He quotes from Newton's Optics : 
' Since therefore all the various motions that are in the world are 
perpetually decreasing, 'tis absolutely necessary, in order to 
preserve and renew those motions, that we have recourse to some 
active principles 1 . (The translation from Newton's Latin is 
by Clarke.) 

* Several sections containing a further discussion of the nature 
of miracles are omitted here. 



All those who believe in the void allow themselves to be 
guided more by imagination than by reason. When I was 
a young man, I also was inclined to believe in the void and 
in atoms; but reason brought me back. Imagination was 
utterly contented. On this theory a limit is set to our 
researches; reflection is fixed and as it were pinned down; 
we suppose ourselves to have found the first elements a non 
plus ultra. We should like nature to go no further; 
we should like it to be finite, like our mind; but this is 
to ignore the greatness and majesty of the Author of 
things. Actually the least corpuscle is subdivided ad 
infinitum and contains a world of new created things, which 
the universe would lack if this corpuscle were an atom, that 
is a body all of a piece and not subdivided. All the same, to 
want to put a void in nature is to attribute to God a very 
imperfect production; it is to violate the great principle of 
the necessity of a sufficient reason, of which many people 
speak with their lips without at all recognizing its force, as I 
showed recently when I made it clear by means of this 
principle that space is only an order of things, like time, and 
in no sense an absolute being. Not to mention many other 
reasons against the void and atoms, here are those which I 
derive from the perfection of God and from sufficient reason. 
I assume that any perfection which God could put in things 
without derogating from the other perfections in them, has 
been put there. Now let us imagine a space entirely empty; 
God could put in it some matter without in any way dero- 
gating from anything else whatever; therefore He did put 
some matter therein; therefore there is no space entirely 
empty; therefore everything is full. The same argument 
proves that there is no corpuscle which is not subdivided. 
Here also is the reason taken from the necessity of a 
sufficient reason. It is not possible that there should be a 


principle determining the proportion of matter, or what is 
filled, to the void, or of the void to the plenum. It will 
perhaps be said that one must be equal to the other; but as 
matter has more perfection than empty space, reason demands 
that geometrical proportion be observed, and that there 
should be more plenum in proportion as it is worthy of 
preference. But then there would be no void at all, for the 
perfection of matter is to the perfection of the void as some- 
thing is to nothing. The same argument applies to atoms. 
What reason can be assigned for limiting nature in the process 
of subdivision? Purely arbitrary fictions, and unworthy of 
true philosophy. The reasons alleged in favour of the void 
are but sophisms. 


8. 8 But the good, whether true or apparent, in a word the 
motive, inclines without necessitating, that is to say without 
imposing an absolute necessity. For when God (for instance) 
chooses the best, that which He does not choose and which is 
inferior in perfection is none the less possible. If what God 
chooses were necessary, everything else would be impossible, 
which would be contrary to our hypothesis, for God chooses 
between possibles, that is to say between several things, not 
one of which implies a contradiction. 

9. To say that God can only choose the best, and to infer 
from this that what He does not choose is impossible, is to 
confuse terms: namely, power and will, metaphysical neces- 
sity and moral necessity, essences and existences. For what 
is necessary is so by its essence, because the opposite implies 
a contradiction; but the contingent which exists owes its 
existence to the principle of what is best, the sufficient 

1 Written in answer to Clarke's reply to the Fourth Paper. 
Here Leibniz takes up the points at much greater length. It 
will be seen that much of this paper has been omitted here. 

1 1-7 contain further answers to the charge of fatalism. Cf. 
p. 197- 


reason for things. And this is why I say that motives incline 
without necessitating; and that there is a certainty and 
infallibility, but not an absolute necessity, in contingent 

10. And I have sufficiently shown in my Theodicy that 
this moral necessity is good, and in conformity with Divine 
perfection, and in conformity with the great principle of 
existences, which is that of the need of a sufficient reason; 
whereas absolute metaphysical necessity depends on the 
other great principle of our reasonings, the principle of 
essences, that is to say that of identity or contradiction: for 
what is absolutely necessary is the only possible course, and 
its contrary implies a contradiction. 

11, I have shown also that our will does not always 
precisely follow the practical understanding, because it may 
have or find reasons for suspending its resolution until a 
further discussion. 

14. ... I now come to the objection made against my 
comparison between the weights of a balance and the motives 
of the will. The author objects that the balance is purely pas- 
sive and weighed down by the weights, whereas agents which 
are intelligent and endowed with will are active. To this I 
reply, that the principle of the necessity of a sufficient reason 
is common both to active and to passive things. They need 
a sufficient reason for their activity as well as for their 
passivity. Not only does the balance not act when it is 
weighed down equally on both sides, but equal weights do 
not act either, when they are in equilibrium in such a way 
that one cannot go down without the other going up to the 
same extent. 

15. It must also be considered that, strictly speaking, 
motives do not act on the mind like weights on a balance; it is 
rather the mind which acts by virtue of the motives, which 
are its dispositions to act. Thus to maintain, as it is here 


maintained, that the mind sometimes prefers weak motives 
above stronger ones, and even sometimes what is indifferent 
above motives, is to separate the mind from its motives, as 
if they were outside of it, as the weight is distinct from the 
balance; and as if there were in the mind other dispositions 
to action besides motives, by virtue of which the mind 
rejected or accepted the motives. Whereas the truth is that 
motives comprise all the dispositions which the mind can 
have to act voluntarily, for they comprise not only reasons 
but also inclinations, which come from the passions or from 
other preceding impressions. Thus if the mind preferred a 
weak above a strong inclination it would be acting against 
itself and otherwise than it is disposed to act. This shows 
that notions which differ on this point from mine are super- 
ficial and turn out to have nothing in them, when they are 
properly considered. 

1 6. To say also that the mind may have good reasons for 
acting when it has no motives, and when things are absolutely 
indifferent, as is explained here, is a manifest contradiction. 
For if there are good reasons for the course it adopts, the 
things are not indifferent to it. 

17. And to say that a man will act when he has reasons for 
acting, even though the ways of acting may be absolutely in- 
different, is again to speak most superficially, and in a very 
unjustifiable manner. For in this case there is no sufficient 
reason for acting when there is not a sufficient reason for 
acting in a particular manner, since every action is individual, 
and not general or abstracted from its circumstances, and 
it needs some way of being carried out. Thus when there is 
a sufficient reason for doing a particular action, there is a 
sufficient reason also for acting in a particular way, and 
consequently the ways of acting are not indifferent. On 
every occasion that a man has sufficient reasons for a given 
particular action, he has sufficient reasons also for doing 
everything which is requisite for that action. 


21. It must be admitted that this great principle, 1 although 
it has been recognized, has not been sufficiently made use of. 
And this is to a great extent why First Philosophy 2 has been 
so little productive and demonstrative hitherto. I infer from 
this principle, among other consequences, that there are not 
in nature two real absolute beings which are indiscernible 
from one another; because if there were, God and nature 
would be acting without reason in treating one differently 
from the other; and thus that God does not produce two 
portions of matter which are perfectly equal and alike. The 
author replies to this conclusion without refuting the reason 
for it, and he replies by a very feeble objection. That 
argument, he says, if it was good would prove that it would be 
impossible for God to create any matter at all. For the perfectly 
solid parts of matter, if we take them of equal figure and di- 
mensions (which is always possible in supposition) would be 
exactly alike. But it is an obvious petitio principii to suppose 
this perfect agreement which, on my view, cannot be ad- 
mitted. This supposition of two indiscernibles, as of two 
portions of matter which perfectly agree with one another, 
seems possible in the abstract, but it is not compatible with 
the order of things, nor with Divine wisdom, by which 
nothing is admitted without a reason. The vulgar imagine 
such things because they are satisfied with incomplete notions. 
And this is one of the faults of the Atomists. 

22. Besides, I do not allow that there are in matter parts 
which are perfectly solid, or which are all of a piece, without 
any variety or particular motion in their parts, as the pre- 
tended atoms are conceived to be. To suppose that there 
are such bodies is another popular and ill-founded opinion. 
According to my demonstrations, each portion of matter is 
actually subdivided into parts differently affected, and no 
one altogether resembles another. 

1 i.e. the principle of sufficient reason, 
"i.e. metaphysics. 


23. I had maintained that two indiscernibles can never be 
found among sensible things, and that, for example, we should 
never find two leaves in a garden, nor two drops of water, 
which were perfectly alike. The author admits this with 
regard to leaves and 'perhaps* with regard to drops of water. 
But it might be admitted without question, or without the 
'perhaps', of the drops of water too. 

24. I hold that these general observations which apply to 
sensible things apply also in proportion to insensible things. 
And that in this respect it may be said, as Harlequin says in 
the Emperor of the Moon, ' 'tis there as 'tis here'. And it is a 
great argument against indiscernibles that no instance of 
them can be found. But the author objects to this conse- 
quence on the ground that sensible bodies are compounded, 
whereas there are alleged to be insensible bodies which are 
simple. I answer again that I do not admit of any. Accord- 
ing to me, there is nothing simple except true monads, which 
have no parts and no extension. Simple bodies and even 
perfectly similar ones are a consequence of the false doctrine 
of a void and of atoms, or else of lazy philosophy, which does 
not press far enough the analysis of things, and thinks it can 
arrive at the primary corporeal elements of nature, since they 
would satisfy our imagination. 

25. When I deny that there are two drops of water perfectly 
alike, or two other bodies indiscernible from one another, I 
do not mean that it is absolutely impossible to suppose them, 
but that it is a thing contrary to Divine wisdom and conse- 
quently that it does not exist. 

26. I admit that if two perfectly indiscernible things did 
exist, they would be two. But the supposition is false, 
and contrary to the great principle of reason. The vulgar 
philosophers were mistaken when they thought that there 
existed things which differed solo numero, 1 or only because 
they were tivo: and it is from this error that their perplexities 

1 'numerically only*. 


about what they called the principle of individuation arose. 
Metaphysics has ordinarily been treated as a mere doctrine 
of terms, like a philosophical dictionary, without ever coming 
to a discussion of things. Superficial philosophy , like that of 
the Atomists and Vacuists, fabricates for itself things which 
higher reasons render inadmissible. I hope that my proofs 
will change the face of philosophy, in spite of feeble contra- 
dictions such as I meet with here. 

27. The parts of time and of place, taken in themselves, 
are ideal things: thus they are perfectly alike, like two 
abstract units. But this is not the case with two concrete 
unities, nor with two actual times, nor with two occupied, 
that is to say truly actual, spaces. 

28. I do not say that two points of space are one and the 
same point, nor that two instants of time are one and the 
same instant, as seems to be imputed to me. But it may be 
imagined through lack of knowledge that there are two 
different instants when there is one only, as I observed in 
17 of my foregoing reply that often in geometry we suppose 
there to be two, so as to show up an opponent's error, and 
find but one. If someone supposed that one straight line 
cut another at two points he would ultimately find out that 
these two pretended points must coincide and can only make 
one. This also happens when a straight line, which in all 
other instances cuts a given curve, becomes a tangent. 

29. I have proved that space is nothing other than an 
order of the existence of things, which is observed when they 
exist simultaneously. Thus the fiction of a finite material 
universe, the whole of which moves about in an infinite empty 
space, cannot be admitted. It is altogether unreasonable 
and impracticable. For besides the fact that there is no 
real space outside the material universe, such an action 
would be without purpose; it would be working without doing 
anything, agenda nihil agere. No change which could be 
observed by any one whatever would be occurring. Such 


things are the imaginings of philosophers with incomplete 
notions, who make of space an absolute reality. Mere 
mathematicians who do but concern themselves with the 
play of the imagination are capable of fabricating to them- 
selves such notions; but they are destroyed by higher reasons. 

30. Absolutely speaking, it appears that God is able to 
make the material universe finite in extension; but the 
contrary seems better to conform with His wisdom. 

31. I do not allow that everything finite is mobile. Indeed, 
according to the hypothesis of my opponents, a part of space, 
though finite, is not mobile. What is mobile must be able to 
change its position in relation to something else, and it must 
be possible for a new state discernible from the first state 
to arise: otherwise the change is a fiction. Thus a mobile 
finite thing must be part of some other finite thing, so that a 
change that can be observed can take place. 

32. Descartes maintained that matter has no limits, and I 
do not think he has been sufficiently refuted. And even if 
this is granted him, 1 it does not follow that matter would be 
necessary, nor that it should have existed from all eternity, 
since the unlimited diffusion of matter would but be an effect 
of the choice of God, who held it to be better so. 

33. Since space is itself a thing ideal, like time, space 
outside the world must certainly be imaginary, as the 
Schoolmen themselves recognized well enough. The same 
is true of empty space in the world, which I also hold to be 
imaginary for the reasons I have given. 

34. The author brings forward as an objection against me 
the vacuum discovered by M. Guericke of Magdeburg: this 
was made by pumping the air out of a container. It is 
claimed that there genuinely is a perfect void, or space empty 

1 Clarke had said : ' To say that God could not have altered the 
time or place of the existence of matter, is making it to be 
necessarily infinite and eternal, and reducing all things to Necessity 
and Fate '. 


of matter, in part at least, in the container. The Aristote- 
lians and the Cartesians, who do not admit the existence of a 
true void, replied to this experiment of M. Guericke's as well 
as to the experiment made by M. Torricelli of Florence (who 
emptied the air out of a glass tube by means of mercury), by 
saying that there is no vacuum at all in the tube or in the 
container since the glass has subtle pores, through which 
rays of light, magnetic rays, and other very fine things can 
pass. And I am of their opinion. For I hold that the con- 
tainer may be compared to a box full of holes placed in 
water, in which there are fish or other gross bodies, which 
being removed, their room would not fail to be filled with 
water. There is this difference only, that water, though it is 
fluid and more amenable than these gross bodies, is yet as 
heavy and as massive as they are, or even more so; whereas 
the matter which enters the container in the room of the air 
is much finer. The new supporters of the void reply in this 
instance that it is not the grossness of matter, but simply its 
quantity, which produces resistance, and that consequently 
there is necessarily more void where there is less resistance. 
They add that subtlety has nothing to do with it, and that 
the parts of quicksilver are as subtle and as fine as those of 
water, and that yet quicksilver has more than ten times the 
resistance. To this I answer, that it is not so much the 
quantity of matter as the difficulties it makes in giving way 
which causes the resistance. For example, floating timber 
contains less weight of matter than water of equal volume, 
and yet it resists a boat more than the water does. 

35. And as to quicksilver, it contains in truth about 
fourteen times as much weight of matter as an equal volume 
of water; but it does not follow that it contains fourteen times 
more matter absolutely. On the contrary, water contains as 
much, if we take together both its own matter which has 
weight and a foreign matter of no weight which passes through 
its pores. For both quicksilver and water are masses of heavy 


matter pierced with holes, through which there passes a great 
deal of matter which has no weight and which does not resist 
sensibly. Such, it appears, is the matter which composes 
rays of light, and other insensible fluids ; such above all is that 
fluid which itself causes the weight or gravity of gross bodies, 
by withdrawing itself from the centre where it forces them 
to go. For it is a strange fiction to regard all matter as having 
weight or gravity, and even to regard it as gravitating 
towards all other matter, as if every body had an equal 
attraction for every other body in proportion to mass and 
distance ; and this, by means of attraction properly so called, 
and not derived from an occult impulsion of the bodies. 
Whereas in truth the gravitation of sensible bodies towards 
the centre of the earth must be produced by the movement 
of some fluid. And the same is true of other gravitations 
such as those of the planets towards the sun or towards one 
another. A body is never moved naturally except by 
another body which impels it by touching it; and after this 
it goes on until it is hindered by another body touching it. 
Any other operation on bodies is either miraculous or 

36. As I objected that space, taken as something real and 
absolute without bodies, would be a thing eternal, impassive, 
and independent of God, our author has tried to elude this 
difficulty by saying that space is a property of God. In my 
previous paper I opposed this by saying that the property of 
God is immensity; but that space, which is often commen- 
surate with bodies, and the immensity of God are not the 
same thing. 

37. I further objected that if space is a property, and if 
infinite space is the immensity of God, then finite space will 
be the extension or mensurability of something finite. Thus 
the space occupied by a body will be the extension of that 
body: an absurd thing, since a body can change space, but 
cannot leave its extension. 


38. I also asked: If space is a property, of what thing will 
a limited empty space, such as is imagined in the container 
emptied of air, be the property? It does not seem reasonable 
to say that this round or square empty space is a property 
of God. Is it perhaps the property of some immaterial, 
extended, imaginary substance which (it seems) our author 
pictures to himself in the imaginary spaces ? 

39. If space is the property or affection of the substance 
which is in space, the same space would be the affection now 
of one body, now of another body, now of an immaterial 
substance, now perhaps of God, when it is empty of any other 
substance, material or immaterial. But it must be a very 
strange property or affection to pass like this from subject to 
subject. Subjects would thus put off their accidents like 
garments, so that other subjects could put them on. After 
that, how would one distinguish accidents and substances? 

40. If limited spaces are the affections of limited substances 
which are in them, and if infinite space is the property of God, 
it must follow (strange though it may seem) that the property 
of God is composed of the affections of created things ; for all 
the finite spaces, taken together, make up infinite space. 

41. If it is denied that limited space is an affection of 
limited things, it will not be reasonable either for infinite 
space to be the affection or property of an infinite thing. I 
have touched on all these difficulties in my previous paper, 
but it does not look as though any attempt has been made to 
answer them. 

42. I have yet other reasons against this strange fancy that 
space is a property of God. If it is, space enters into the 
essence of God. Now space has parts, so there would be 
parts in the essence of God. Spectatum admtsst. 1 

43. Moreover, spaces are sometimes empty, sometimes 
full: thus there would be in the essence of God parts which 

1 Spectatum admissi risum teneatis, amid ? * If you saw such a 
thing, my friends, could you restrain your laughter? ' 


are sometimes empty, sometimes full, and consequently 
subject to a perpetual change. The bodies which fill space 
would fill a part of the essence of God, and would be com- 
mensurate with it; and, on the supposition of a vacuum, a 
part of the essence of God would be in the container. This 
God with parts will be very like the Stoic God, who was the 
whole universe, considered as a divine animal. 

44. If infinite space is God's immensity, infinite time will 
be God's eternity. We must say, then, that what is in space 
is in God's immensity, and consequently in His essence; and 
that what is in time is in the essence of God also. Strange 
phrases, which plainly show that our author is misusing terms. 

45. Here is another instance: God's immensity makes 
Him present in all spaces. But if God is in space, how can 
it be said that space is in God, or that it is His property? We 
have heard of the property being in the subject, but never 
of the subject being in its property. In the same way God 
exists in every time; how then is time in God, and how can 
it be a property of God ? These are perpetual dAAoyAcorrtou. 1 

46. It looks as though the immensity or extension of things 
were being confused with the space according to which that 
extension is taken. Infinite space is not the immensity of 
God, finite space is not the extension of bodies, just as time 
is not their duration. Things keep their extension, but they 
do not always keep their space. Each thing has its own 
extension, its own duration; but it does not have its own 
time, and it does not keep its own space. 

47. This is how men come to form the notion of space. 
They consider that several things exist at the same time, and 
they find in them a certain order of co-existence, in accordance 
with which the relation of one thing to another is more or 
less simple. This is their situation or distance. When it 
happens that one of these co-existent things changes its 
relation to a number of others without their changing with 

1 'misuses of words'. 


regard to one another, and when another thing makes its 
appearance and acquires the same relation to the others as 
the first one had, we say that it has taken its place, and we 
call this change a motion in that body wherein is the im- 
mediate cause of the change. And when several or even all 
of these co-existent things change in accordance with certain 
known rules of direction and velocity, we can always deter- 
mine the relation of situation which any given body acquires 
with regard to every other: and even the relation which any 
other would have, or which the given body would have to 
any other, if it had not changed, or if it had changed in a 
different way. If we suppose or pretend that among these 
co-existents there were a sufficient number which suffered 
no change in themselves, we should say that those which 
have the same relation to these fixed existents as others had 
before, occupy the same place as those others occupied. That 
which includes all these places is called space. This shows 
that in order to have the idea of place, and consequently of 
space, it is enough to consider these relations and the rules 
of their changes, without needing to picture any absolute 
reality beyond the things whose situation is being considered. 
To give a kind of definition : Place is that which is said to be 
the same for A and for B, when the relation of co-existence 
between B and C, E, F, G, etc., entirely agrees with the 
relation of co-existence which A previously had with those 
bodies, supposing there has been no cause of change in 
C, E, F, G, etc. It may also be said (without K0ais l ) that 
place is that which is the same at different moments for certain 
entities when they, although different, have relations of co- 
existence with other entities (these latter being supposed to 
be fixed from the one of these moments to the other) which 
agree entirely. And fixed entities are those in which there 
has been no cause for a change of the order of co-existence 
with others, or (which is the same thing) in which there has 
1 i.e. without particular enunciation. 


been no motion. Lastly, space is that which results from 
places taken together. And it is well here to consider the 
difference between the place and the relation of situation of 
the body which occupies the place. For the place of A and 
B is the same, whereas the relation of A to the fixed bodies 
is not precisely and individually the same as the relation 
that B (which is to take its place) will have to the same 
fixed bodies; these relations only agree. For two different 
subjects, such as A and B, cannot have exactly the same 
individual affection, since one and the same individual 
accident cannot occur in two subjects, nor pass from one 
subject to another. But the mind, not content with agree- 
ment, seeks an identity, a thing which is truly the same, and 
conceives it as outside these subjects; and this is what is 
here called place and space. This, however, can only be ideal, 
comprising a certain order wherein the mind conceives the 
application of the relations: just as the mind can imagine an 
order consisting of genealogical lines, whose length would 
consist only in the number of generations, in which each 
person would have his place. And if we added the fiction of 
metempsychosis, and made the same human souls come in 
again, the persons might change their places in these lines, 
He who had been father or grandfather might become son or 
grandson, etc. And yet those genealogical places, lines, and 
spaces, although they expressed real truths, would only be 
ideal things. I will give another example of the mind's 
habit of creating for itself, upon occasion of accidents 
existing in subjects, something which corresponds to those 
accidents outside the subjects. The ratio or proportion of 
two lines L and M can be conceived in three ways : as a ratio 
of the greater L to the smaller M, as a ratio of the smaller M to 
the greater L, and lastly as something abstracted from both 
of them, that is to say as the ratio between L and M , without 
considering which is the anterior and which the posterior, 
which the subject and which the object. It is in this way 


that proportions are considered in music. In the first way 
of considering them, L the greater is the subject ; in the second, 
M the smaller is the subject of this accident which philosophers 
call relation. But which will be the subject in the third way 
of considering them ? We cannot say that the two, L and M 
together, are the subject of such an accident, for in that case 
we should have an accident in two subjects, with one leg in 
one and the other leg in the other, which is contrary to the 
notion of accidents. Thus we are bound to say that the 
relation in this third way of considering it is indeed outside 
the subjects; but that being neither substance nor accident, 
it must be a purely ideal thing, the consideration of which is 
none the less useful. For the rest, I have acted rather like 
Euclid, who, when he could not make it absolutely under- 
stood what is meant by ratio, in the geometricians' sense, 
defined properly what is meant by the same ratios. In the 
same way, in order to explain what place is, I have tried to 
define the same place. Finally I remark that the traces 
which mobile things sometimes leave on the immobile things 
on which they exercise their motion, have afforded to men's 
imagination occasion to form this idea, as if there still 
remained some trace even when there is nothing immobile: 
but this is ideal merely, and only means that if there were 
something immobile actually there, the trace might be pointed out 
on it. And it is this analogy which causes us to imagine 
places, traces, and spaces, although these things only consist 
in the truth of relations, and nowise in any absolute reality. 

49. We cannot say that a certain duration is eternal, but 
we can say that the things which last for ever are eternal, 
because they are always acquiring a new duration. What- 
ever of time and of duration does exist, since it is successive, 
continually perishes. And how could a thing exist eternally 
which properly speaking never exists? And how could a 
thing exist, no part of which ever exists? In the case of time 


nothing exists but instants, and an instant is not even a 
part of time. Whoever gives proper consideration to these 
observations will easily understand that time can only be an 
ideal thing. And the analogy of time and space will indeed 
make us judge that the one is as ideal as the other. Still, if, 
when it is said that the duration of a thing is eternal, this 
only means that the thing endures eternally, I have nothing 
further to say. 

52. In order to prove that space without bodies is an 
absolute reality, the author raised it as an objection to my 
view that a finite material universe might move about in 
space. I answered, that it does not seem reasonable that the 
material universe should be finite; and even if it were supposed 
to be so, it is unreasonable that it should have any movement 
except in so far as its parts change their situation among 
themselves : because a movement of this kind would produce 
no observable change and would be without purpose. It is a 
different thing when its parts change their situation among 
themselves, for then we recognize a movement in space; but 
it consists in the order of the relations, which are changed. 
The author now answers that the truth of the movement is 
independent of its being observed, and that a ship can go 
forward without a man who is in it perceiving the motion. 
I answer that motion is independent of being observed, but it 
is not independent of being observable. There is no motion 
when there is no observable change. Moreover, when there is 
no observable change, there is no change at all. The contrary 
view is based on the supposition of a real absolute space, 
which I demonstratively refuted by the principle of the 
necessity of a sufficient reason of things. 

53. I find nothing in the eighth definition of the Mathe- 
matical Principles of Nature, nor in the Scholium of this 
definition, which proves, or can prove the reality of space in 
itself. But I grant that there is a difference between a 


genuine absolute movement of a body and a simple relative 
change of its situation with respect to another body. For 
when the immediate cause of the change is in the body, it is 
genuinely in motion and then the situation of the rest with 
respect to it will be changed in consequence, although the 
cause of this change is not in them. It is true that, to speak 
exactly, there is no body which is perfectly and entirely at 
rest; it is an abstraction which we make when we consider 
the thing mathematically. Thus I have left unanswered 
nothing of all the arguments alleged in favour of the absolute 
reality of space. And I have proved the falsity of this 
reality by one of the most reasonable and well founded of 
fundamental principles, against which no exception nor 
example can be brought. For the rest, it may be seen from 
all that I have just said, that I cannot admit a movable 
universe, nor any place outside the material universe. 

54. I know of no objection which I do not think I have 
adequately answered. And as to this objection that space 
and time are quantities, or rather things having quantity, 
and that situation and order are not such, I reply that order 
also has its quantity: there is that which precedes and that 
which follows, there is distance or interval. Relative things 
have their quantity as well as absolutes: for example, ratios 
or proportions in mathematics have their quantity and are 
measured by logarithms, and yet they are relations. Thus 
although time and space consist in relations, they have their 
quantity none the less. 

57. This enables us to see how to interpret the truth that 
God created things at the time which was pleasing to Him, 
for the time depends on the things which He resolves to 
create. Once the things have been resolved upon with their 
relations, there remains no further choice of time or place; 
for these considered apart have nothing real in them, nothing 
to determine them, and indeed nothing that is discernible. 


58. So it cannot be said, as is said here, that the wisdom of 
God may have good reasons for creating this world at a given 
particular time; for this particular time, taken apart from 
things, is an impossible fiction, and there can be no good 
reasons for a choice there where everything is indiscernible. 

60. It should not then be said, as is said here, that God 
created things in a particular space, or at a particular time, 
which was pleasing to Him, for since all times and all spaces 
are in themselves perfectly uniform and indiscernible, one 
cannot please more than another. 

63. But it nowise follows that matter is eternal and neces- 
sary, unless we suppose that space is eternal and necessary: 
an altogether ill-founded supposition. 

67. The parts of space are determined and distinguished 
only by the things which are in them, and the diversity of the 
things in space determines God to act differently on different 
parts of space. But space, taken apart from things, has 
nothing in itself to determine it, and indeed it has nothing 
actual about it. 

68. If God has decided to place a certain cube of matter, 
He thereby also becomes determined on the place of the cube: 
but this is with respect to other particles of matter, and not 
with respect to detached space which has nothing in it to 
distinguish it. 

93. I do not admit that every action gives a new force 
to the thing acted upon. It often happens at the meeting of 
bodies that each keeps its force, as when two hard bodies of 
equal size meet directly. Then the direction alone is changed, 
without there being any change in the force, each body taking 
the direction of the other, and turning back with the same 
velocity it had before. 


94. I am, however, careful not to say that it is supernatural 
to give a body a new force, for I recognize that one body often 
receives a new force from another body, which loses as much 
of its own. But I say merely that it is supernatural for the 
whole universe of bodies to receive a new force; and thus that 
one body should gain force without others losing the same 
amount. This is why I say also that it cannot be maintained 
that the soul gives force to the body; for then the whole 
universe of bodies would receive a new force. 

99. I do not here undertake to establish my Dynamics, or 
my doctrine of forces. This would not be the proper place. 
But I can reply very well to the objection raised here. I had 
maintained that active forces are preserved in the world. 
The objection is that two soft non-elastic bodies meeting to- 
gether lose their force. I answer that this is not so. It is true 
that the wholes lose it in relation to their total movement, 
but the parts receive it, being internally agitated by the 
force of the meeting or shock. Thus this loss occurs in 
appearance only. The forces are not destroyed, but dissi- 
pated among the small parts. There is here no loss of forces, 
but the same thing happens as takes place when big money 
is turned into small change. I agree, however, that the 
quantity of motion does not remain the same, and in this 
matter I approve what is said on page 341 of Mr. Newton's 
Optics which the author here quotes. But I have shown 
elsewhere that there is a difference between the quantity of 
motion and the quantity of force. 

104. I do not say that space is an order or situation which 
makes things situable. That would be talking nonsense. It 
is only necessary to consider my own words and to join them 
with what I have said above ( 47), to show how the mind 
comes to form the idea of space, without its being necessary 
for there to be a real and absolute being, corresponding to 


that idea, outside of the mind and outside of relations. I 
do not say then that space is an order or situation, but an 
order of situations, or an order according to which situations 
are arranged ; and that abstract space is this order of situations 
which are conceived as possible. Thus it is something ideal, 
but the author appears not to want to understand me. I 
have already replied ( 54) to the objection that an order is 
not capable of quantity. 

105. The author objects that time could not be an order of 
successive things, because the quantity of time can become 
greater or smaller, while the order of successions remains the 
same. I answer that this is not so ; for if the time is greater 
there will be more similar successive states interposed, and if 
it is less there will be fewer, because there is no void nor 
condensation nor penetration (so to speak) in times any more 
than in places. 

106. I maintain that if there were no created things, the 
immensity and eternity of God would none the less subsist, 
but without any dependence on times or places. If there 
were no created things there would be no time or place, and 
consequently no actual space. The immensity of God is 
independent of space, as the eternity of God is independent 
of time. They only signify with regard to these two orders 
of things that God would be present and co-existent with 
everything which existed. Thus I do not admit what is 
here advanced, that if God alone existed time and space 
would exist as at present. On the contrary, on my view, 
they would exist in ideas only, like mere possibilities. The 
immensity and eternity of God are something more eminent 
than the duration and extension of created beings, not only in 
relation to the greatness, but also to the nature of the thing. 
These Divine attributes are not dependent upon things 
outside God, as are actual places and times. These truths 
have been sufficiently recognized by theologians and 


124. The natural forces of bodies are all subject to 
mechanical laws; and the natural forces of minds are all 
subject to moral laws. The former follow the order of 
efficient causes; and the latter follow the order of final causes. 
The former operate without liberty, like a watch; the latter 
are exercised with liberty, although they agree exactly with 
that kind of watch which another, superior, free cause has 
set beforehand to fit in with them. I have already spoken 
of this in the present paper ( 92). 



From a letter to Landgraf Ernst von Hessen Rheinfels 
November 1686 

I TAKE the liberty, Sire, once more to entreat Your Serene 
Highness to be good enough to have the enclosed papers 
given to M. Arnauld, and since they treat of matters removed 
from the outer senses and dependent on pure intellection, 
matters which are not pleasing to, and are most often despised 
by, those who are most alive and most excellent in the 
affairs of the world, I will here say something in favour of 
these meditations. It is not that I am so ridiculous as to 
desire that Your Serene Highness should amuse himself 
therewith (this would be as unreasonable as to want the general 
of an army to apply himself to algebra, although this science 
is very useful for anything which has any connection with 
mathematics). My aim is rather that Your Serene Highness 
may better be able to form a judgment of the purpose and 
value of such reflections, which might seem but little worthy 
to occupy, even for a moment, a man to whom all moments 
must be precious. In truth, in the way in which these things 
are ordinarily treated by the Scholastics, they are but disputes, 
distinctions, a play upon words. Yet there are veins of gold 
among these barren rocks. I take it to be a fact that thought 
is the principal and perpetual function of our soul. We 
shall always think, but we shall not always live here. This 
is why whatever renders us more capable of reflecting on 
more perfect objects and in a more perfect manner, also 
makes us naturally perfect. But the present condition of 
our life forces us to have a great number of confused thoughts 
which do not make us more perfect. Such is the knowledge 
of customs, genealogies, and languages, and indeed all 
historical knowledge of facts both civil and natural. This is 



useful to us for avoiding dangers and for handling the bodies 
and men around us, but it does not enlighten the mind. The 
knowledge of routes is useful to a traveller on his journey; 
but that knowledge which has more relation to the functions 
to which he is destined in patria l is more important to him. 
Now we are destined one day to live a spiritual life, where 
substances separated from matter will occupy us much more 
than bodies. But in order to distinguish better between 
knowledge that enlightens the mind and that which merely 
leads it blindfold, consider these examples taken from the 
arts. If a workman knows, by experience or from tradition, 
that if the diameter is 7 feet the circumference of the circle 
is a little less than 22 feet; or if a gunner knows by hearsay, 
or because he has frequently measured it, that bodies carry 
furthest when thrown at an angle of 45 degrees, theirs is a 
confused knowledge, the knowledge of an artisan who will 
make very good use of it to earn his living and in the service 
of others. But the knowledge which enlightens our mind, is 
that which is distinct, that is to say, which contains the causes 
or reasons, as when Archimedes gave the proof of the first 
law, and Galileo that of the second. In a word, the only 
knowledge which can make us perfect is the knowledge of 
reasons in themselves, or of eternal and necessary truths, 
especially those truths which are most comprehensive and 
which bear most relation to the Sovereign Being. This 
knowledge alone is good in itself; all the rest is mercenary, 
and we should only learn it through necessity, by reason of 
the needs of this life, and so that we may be the better able 
to make room afterwards for the perfection of the mind, 
when we have put in order all that which concerns our 
subsistence. Yet the disorderliness of mankind, and what is 
called the care de pane lucrando? and often vanity also, 

x * in his fatherland', i.e. when he is at home in his own 
country, and not travelling. 
* ' of earning daily bread'. 


causes us to forget the master for the valet and the end for 
the means. This, as the poet says, is exactly propter vitam 
vivendi perdere causas. 1 It is very much like a miser pre- 
ferring gold to health, whereas gold exists but to serve the 
conveniences of living. Now since what perfects our mind 
(if we leave on one side the illumination of grace) is the 
demonstrative knowledge of the greatest truths by their 
causes or reasons, it must be admitted that metaphysics or 
natural theology, which treats of immaterial substances, and 
particularly of God and the soul, is the most important of all. 
And it is impossible to make progress in this without knowing 
the genuine notion of substance, which I explained in such a 
way in my last letter to M. Arnauld that he himself, who is 
so exact, and who had been shocked by it at the outset, gave 
to it his acceptance. 

Finally, these meditations provide us with conclusions 
which are surprising but of marvellous utility for delivering 
us from the greatest scruples regarding God's care for His 
creatures, His prescience and preordination, the union of 
soul and body, the origin of evil, and other things of this kind. 
I will not here say anything of the great value of these 
principles in the human sciences; but at least I can say that 
nothing is more instrumental in raising our mind to the 
knowledge and love of God, so far as nature helps us. I 
admit that all this is of no use without grace, and that God 
gives grace to some people who have never dreamt of these 
meditations. But God desires also that we should omit 
nothing on our side, and that we should use the perfections 
which He has given to human nature, as opportunity offers, 
each of us according to his vocation; as His sole purpose in 
making us was that we should know and love Him, we 
cannot work for it too much, nor make a better use of our 
time and energies, unless we are otherwise engaged for the 
public and for the welfare of others. 

1 ' for the sake of life to lose the causes of living*. 


From the Discourse of Metaphysic. 1686 

. . . Suppose, for example, that someone marks a number of 
points on a sheet of paper entirely at random, in the manner 
of those who practise the ridiculous art of geomancy. I say 
that it is possible to find a geometrical line whose motion is 
constant and uniform in accordance with a certain rule, such 
that this line shall pass through all the points, and in the same 
order in which they were marked by the pen. . . . Nor is there 
any instance of a face whose contour does not form part of a 
geometrical line, and which cannot be traced at one stroke 
by a given regulated movement. But when a rule is very 
complicated, that which conforms to it passes for being 
irregular. . . . 

From the same work 

The ancient philosophers had very little knowledge of 
these important truths. Jesus Christ alone has expressed 
them divinely well, and in a manner so clear and so familiar 
that the dullest minds have been able to understand them: 
that is why His Gospel has completely changed the face of 
human affairs. He has made known to us the Kingdom of 
Heaven or that perfect commonwealth of minds which 
deserves to be called the City of God, whose admirable laws 
He has revealed to us. He alone has made us see the extent 
of God's love for us, and with what accuracy He has provided 
for all that concerns us. He has shown us that He who 
cares for the sparrows will not neglect the rational creatures 
who are infinitely dearer to Him; that all the hairs of our 
head are numbered; that heaven and earth shall pass 
away rather than that the word of God, and all that belongs 
to the economy of our salvation, shall be changed ; that God 
has more care for the least among intelligent souls than for 
the whole machine of the world; that we ought not to fear 


those who have power to destroy the body, but cannot hurt 
the soul, which God alone can make happy or miserable; 
and that the souls of the just are in His hand, safe from all the 
revolutions of the universe, since nothing can act upon them 
save God alone; that not one of our actions is forgotten, but 
everything is included in the final reckoning, even idle words 
and the least spoonful of water that has been put to a good 
use; finally that everything must work for the greatest good 
of the righteous; that the just will be like suns, and that 
neither our senses nor our minds have ever tasted anything 
approaching the happiness which God prepares for those 
who love Him. 

From a paper without superscription precepts for advancing 
the sciences. (Date unknown) 

The human race, considered in relation to the sciences 
which minister to our happiness, appears to me like a 
disorderly rabble marching in the darkness, having neither 
leader nor order, without password or other signals to 
regulate their march, or by which to know themselves. 
Instead of holding one another by the hand so as to guide 
one another and make sure of our way, we run about at 
random and to and fro, and even hurl ourselves one against 
another, far from helping and supporting each other. This 
means that we advance but little, or else that we know not 
where we are. We even plunge into morasses and shifting 
sands of doubts without end, wherein is nothing solid nor 
firm, or else we drag ourselves into the principles of very 
dangerous errors. Talibus in tenebris vitae tantisque peridisf 
it is given to no mortal to light a torch capable of dispersing 
this obscurity. Sects and leaders of sects serve merely to 
seduce us like the false lights of marsh fires; and it is left 
to the sun of our souls to enlighten us utterly, but in another 
1 ' In such darkness of life and in so great dangers'. 


life. Nevertheless, what we can do here is to march together 
and in order, to share our journeyings, to make known the 
roads and to repair them: and finally to travel slowly, but 
with a firm unwavering tread, by the side of that pure and 
living stream of clear and simple knowledge, which has its 
source among us, which can serve as a comfort on our painful 
march, and as a thread in the labyrinth of these vast over- 
grown territories, a thread which grows gradually larger and 
increases our knowledge, until at last it leads us, albeit by a 
roundabout way, to a delightful plain I mean the most 
important practical truths which serve to content the mind 
and to preserve the health of the body, as far as this can be 
done by reason. 

We see then that what would help us most would be to 
unite our labours, to share them advantageously and to 
regulate them in an orderly way. But at the present, men 
barely touch what is difficult and has not yet been attempted ; 
but all run in crowds to what others have already done, 
where they cease not from copying and even from striving 
with one another. What one has built is first overthrown 
by another, who claims to found his reputation on the ruin of 
someone else's ; but his own reign is no better established nor 
of longer duration. The fact is that they seek glory much 
more than truth, and seek rather to dazzle others than to 
enlighten themselves. To escape from this unhappy position, 
we must abandon the spirit of sect, and the affectation of 
novelty. We must imitate the geometers, who are not 
Euclideans nor Archimedeans. They are all for Euclid and 
all for Archimedes, because they are all for their common 
master, that is, divine truth. . . . 

. . . We are responsible for our talent to God, and to the 
commonwealth. There are so many men of ability of whom 
much might be expected, if they would combine what is 
serious with what is pleasant. It is not always a question of 
writing great works; if each one contributed only a single 


discovery, we should gain a great deal in a short time. A 
single remark or demonstration of consequence is enough to 
gain a man immortality. . . . 

. . . What century could be more suited to this task than ours, 
which will perhaps one day be known as the century of 
inventions and wonders? And the greatest wonder that will 
be noted in it will perhaps be that great prince, 1 who is the 
acknowledged glory of our time, and for whom succeeding 
ages will long in vain. I do not mention here his merits as a 
statesman and in war, which belong neither to this place nor 
to this pen. What he has done for the sciences would alone 
be enough to immortalize him. There is no need to describe 
him in more detail, he is too unique and too easily recognized 
on all hands. Why then seek in the uncertain idea of future 
things what exists amongst us in reality, and is even beyond 
what an ordinary mind is capable of conceiving? Perhaps 
among the great numbers of men of ability in his flourishing 
kingdom, and especially among those at his court, which is 
an assembly of remarkable persons, there is someone who has 
long since drawn up, at his command, a general plan for the 
advancement of the sciences, worthy of the sciences and of 
the king, and far beyond anything that I should be able to do. 

From a draft of a letter to Malebranche. June 1679 

. . . The value and even the mark of true science consists 
in my opinion in the useful inventions which can be derived 
from it. But I have not yet seen that any Cartesian has 
found anything useful by means of the philosophy of his 
master; whereas we owe at least the beginnings of pendulums 
and alleged experiments with a vacuum to the meditations of 
Galileo. It seems that the harvest of Descartes' philosophy 
is finished, or else that the promise of it was destroyed while 
it was still growing by the death of its author. For the 
majority of Cartesians are but commentators, and I could 
1 Louis XIV. 


wish that some one of them was capable of adding as much 
to physics as you have contributed to metaphysics. What is 
more, even if all Descartes' physics were granted, this would 
not take us very far. For, after all, the first and second 
elements are difficult things to handle. Are we ever likely 
to succeed in discovering and executing a formula to compare 
with this? Recipe libram unam secundi elementi, unciarn 
semis carports ramosi, drachmam materiae subtilis, misce, 
fiat aurum. 1 I think we should perhaps need a book as big 
as this terrestrial globe to explain the relation between any 
given sensible body and the first elements, even supposing 
these are genuine and are known. This can be seen from 
experiments with the microscope. For there are perhaps as 
many as 800,000 tiny animals visible in a drop of water, and 
each of these animals is still about as far from the first 
elements as we are, since it still has a body which bears 
a considerable relation to ordinary animals. There is even 
cause to fear that there may not be any elements, everything 
in organic bodies being actually divided up ad infinitum. For 
if these microscopical animals were again composed of 
heterogeneous animals or plants or bodies ad infinitum, it is 
obvious that there would be no elements. 

Notwithstanding all these considerations I still have a high 
opinion of M. Descartes, and perhaps few people recognize 
as well as I do the greatness of his mind. In truth, of all the 
authors who preceded him and whose works we possess only 
Archimedes and Galileo can enter the lists with him. It is 
true that few of Archimedes's meditations remain to us; 
and although I hold that Galileo invariably makes some fine 
comment whenever he is obliged to treat of any matter, 
whatever it is, so that it would have been a good thing if 
he had had the opportunity to write more, nevertheless I 

1 ' Take one pound of the second element, an ounce and a half 
of a ramous body, a drachm of subtle matter : mix well. Result : 
gold.' The term ' ramous ' was applied (following ancient physics) 
to the particles of viscous or rigid bodies. 


admit that he certainly has not so vast a genius as M. 
Descartes. But to make up for this he devoted himself 
more to what was solid and useful; whereas M. Descartes, 
through his ambition to establish a school, allowed himself 
to say a number of things, which were extremely ingenious, 
but often uncertain and sterile. All the same, I should 
always advise a lover of truth to study his system thoroughly; 
for there is to be found in it a wonderful mental dexterity; 
and his physics, uncertain as it is, may serve as a model for 
the true one, which must at least be as clear and as well 
co-ordinated as his. For a romance may be fine enough to 
be worthy of imitation by a historian. In short, Galileo 
excels in the art of reducing mechanics to science; Descartes 
is admirable at explaining by beautiful guesses the reasons 
for the effects of nature; and it would have been a good 
thing if he had been able to apply himself more to medicine, 
which is altogether conjectural, and yet necessary. But 
Archimedes, if we can trust the histories, had a talent lacking 
in both the others: that is, he had a marvellous mind for the 
invention of machines that are useful for the purposes of 

Fragment without superscription. 1 (Date unknown) 

The best apologia that could be made for M. Descartes 
would be to complete his hyperbolic spectacles, which are 
the only useful things he discovered if it were practicable 
to do so; and I could wish that Fr. Malebranche and others, 
who assume the task of defending everything he said, were 
obliged to do it. 

From a letter to Basnage. 16/26 July 1695 

The death of the illustrious M. Huygens is an inestimable 
loss. Few know this as well as I do. He equalled, in my 

1 Taken from Bodeman's Catalogue of the Leibniz M 55. in the 
Royal Public Library at Hanover (1895). 


opinion, the reputation of Galileo and Descartes, and, with 
the help of what they had done, he surpassed their discoveries. 
In a word, he was one of the chief ornaments of our time. I 
often exhorted him to give us his reflections, even if it were 
only in scraps and in an informal manner. I hope that his 
book on the system of the world and the internal constitution 
of the planets has been finished. But as he was accustomed 
to putting his reflections in writing in pretty good order, I 
have hopes that a great treasure may be found among 
his papers. 

From the l Theodicy 9 (Preliminary Discourse). 1710 

87. ... It is to be hoped that M. Bayle now finds himself 
surrounded by that illumination which we lack here below, 
since there is every ground to suppose that he was never 
lacking in good will. 

From the same work 

if 2. ... This view that has been held regarding Mr. Hobbes, 
that he taught an absolute necessity of all things, has seriously 
injured his reputation, and would have done him harm, even 
had it been his only error. 

173. Spinoza went further; he appears to have expressly 
taught that there is a blind necessity, having denied the 
Author of things understanding and will, and imagining that 
the good and perfection have relation only to us and not to 
Him. It is true that Spinoza's opinion on this point is not 
without obscurity, for he attributes thought to God after 
having deprived Him of understanding: cogitationem, non 
intellectum concedit Deo. There are even passages in which 
he relents a little on the question of necessity. However, 
as far as I can understand him, he does not recognize any 
goodness in God, properly speaking, and teaches that all 
things exist by the necessity of the Divine nature, without 


any choice on the part of God. We will not amuse ourselves 
here in refuting so bad, and indeed so inexplicable, an opinion. 

From a letter to des Bosses. 15 March 1715 

We rightly regard bodies as being things, for even phe- 
nomena are real. But if any one seeks to regard bodies as 
being substances he will surely need some new principle of 
real unity. The man in Ireland l who impugns the reality of 
bodies seems neither to give adequate reasons nor to explain 
sufficiently what is in his mind. I suspect that he is one 
of those people who seek to become famous by their paradoxes. 

From a letter to Thomas Burnett. 8/18 May 1697 

... I find that it is not possible to regulate currency without 
regulating at the same time the price of merchandise and 
commerce, at any rate in part, since silver is itself a piece of 
merchandise. And I find that it involves a logical circle 
if we seek to estimate the value of a piece of silver by money, 
and thus that what our lawyers are accustomed to call 
bonitas extrinseca? when they say for example that an ecu 
is worth so many gray, 3 is at bottom a chimera. As Mr. 
Newton holds a position of responsibility in regard to matters 
of currency, I should place great reliance on his judgment on 
this point, as well as on every other question ; as also on the 
opinion of Mr. Locke, since he has made a profound study of 
commerce. ... I would not have it thought in the world that 
I am the kind of man to set Mr. Newton problems of mere 
curiosity. If I wished to set him problems, I should choose 
more useful ones though I recognize that M. Bernoulli's 
problems are good ones. But more important things are 

1 Berkeley. 

1 i.e. extrinsic valuation, as opposed to intrinsic weight or 

An ecu was a French standard silver coin; a gros was a Dutch 
copper coin of small value. 


needed to occupy such a man as Mr. Newton. ... I beg you to 
present my compliments to Mr. Newton and to assure him 
that I hold him ever in the highest esteem, and that I do not 
accept the excuses he gives for not yet having given to the 
public his meditations on colours and other matters. A man 
of his power should prefer the public good to all other con- 
siderations; and everything which comes from his pen is so 
generally esteemed that he has no ground for complaining 
of the ingratitude of his readers. I beg you to stir up Mr. 
Newton's friends to put pressure on him and to give him 
no quarter. . . . 

From a letter to Hartsoeker. 10 March 1707 

. . . You say, sir, that homogeneous rays change colour when 
they penetrate bodies of another colour. Yet you yourself 
adduce in your book an experiment which supports Mr. 
Newton's opinion as opposed to yours. For you follow him 
in stating that bodies which otherwise are blue appear red, 
when they are exposed to a homogeneous red light: and the 
same with the others. For the rest, it is possible that a white 
body absorbs or at least diverts elsewhere as many rays as a 
coloured body, if we suppose, for instance, that this white 
is composed of red and blue parts, or, to speak more exactly, 
of parts some of which are fitted to reflect red rays and 
others blue rays, and in this way the blue parts will cause 
the loss of many red rays, and vice versa. And if we conceive 
what is ordinarily white as composed of little mirrors, it is 
clear that a good part of the mirror is black and diverts the 
rays elsewhere. Thus from the fact that a yellow colour 
sometimes seems as vivid as a white colour, it does not follow 
that rays other than the yellow ones are sent to us to make 
the body appear yellow: this would be changing homogeneous 
rays which are not yellow into yellow. Mr. Newton mentions 
at the end of his work a number of points which he leaves for 


others to investigate. They are worthy of your attention, 
as you have applied yourself to this matter. 

From a letter to Bourget. 5 August 1715 

I cannot say anything about the details of the generation 
of animals. All that I think I can affirm is that the soul of 
every animal has pre-existed, and has been in an organic 
body which at last, by many changes, involutions and 
evolutions, has become the present animal. Your conjecture 
that every animal in the human seed will ultimately achieve 
rationality is ingenious and might be true, but I do not see 
that it is necessary. If there were a good number of them 
which remained mere animals, there would be no harm done. 
I would not dare to affirm that the animals which M. Leeu- 
wenhoek has rendered visible in the seed are exactly those 
which I have in mind; but neither would I dare to affirm that 
they are not so; and I am waiting impatiently to see what M. 
Vallisnieri is going to give us in refutation of them. In the 
meantime I should not wish to speak as decisively as you do, 
Sir, when you say that M. Leeuwenhoek's opinion is one of the 
emptiest of fables. M. Huygens, who was one of the most 
penetrating men of his time, did not think so. The prodigious 
quantity of these animals (which constitutes your first objec- 
tion) is in no way against it. A similar abundance may be 
found in the seeds of some plants. There are some, for 
example, whose grain consists of a very fine dust. Also, I 
do not see that there is any difficulty in the introduction into 
the egg of one of these animals to the exclusion of the other 
(your second objection). A great many appear to be intro- 
duced, because they are so small, but there appears to be 
only one place, a punctum saliens * so to speak, which can 
receive them with effect. And this also satisfies your third 
objection, which is that their extreme smallness is out of 

x * salient point'; in old medical usage, the heart as it first 
appears in an embryo. 


proportion to the egg. The case is the same as when a fruit 
is very large, but its seminal part is very small and insensible. 
The fourth objection is that the egg and the foetus are the 
same animal; but this proposition is not proved; it might be 
that the egg was only a receptacle suited for giving growth 
and for assisting transformation. The fifth objection is that 
according to modern zoologists, and particularly according 
to M. Vallisnieri, the animals which are found in the sperms 
must be animals of their species which propagate and per- 
petuate themselves, exactly in the same way as occurs with 
the other animals which are known to us. With this I am 
in entire agreement: but in my opinion, even if these animals 
were the true seminal animals, they would none the less be a 
particular species of living things, of whom some individuals 
would be raised to a higher stage by a transformation. 

However, I would not venture to assert that your view is 
false, namely that the animal to be transformed is already 
present in the egg when conception takes place. But the 
view that it enters it by the conception seems more likely. 
Do not then let us decide anything with too much assurance, 
and above all let us not treat ill a man like M. Leeuwenhoek, 
to whom the public owes thanks for the pains he has taken 
in his researches. It is, of course, most permissible to oppose 
his view, and I am very glad that it should be done, but it is 
not just to despise him. There is one difficulty which seems 
to me to be common to all the hypotheses, and on which I 
should like to have M. Vallisnieri's opinion; namely, why in 
the copulation of certain species of animals a single egg is 
generally fertilized, and why, in these species, twins are 
comparatively rare. 

From the same letter 

. . . Two hypotheses are possible: one that nature is always 
equally perfect, the other that it is always growing in per- 


fection. If it is always equally perfect, but variable, it is 
more probable that there is no beginning. But if it is always 
growing in perfection (supposing that it is not possible to give 
it the whole of perfection all at the same time), the matter 
could still be explained in two ways, that is to say by 
the ordinates of the hyperbola Z?, or by the triangle C. 
On the hypothesis of the hyperbola, there would be no be- 
ginning, and the instants or states of the world would have 

B A c 

i i 


been growing in perfection from all eternity; but following 
the hypothesis of the triangle, there would have been a 
beginning. The hypothesis of equal perfection would be that 
of the rectangle A. I do not yet see the way to show 
demonstratively which we ought to choose by pure reason. 
However, although on the hypothesis of growth the state of 
the world could never be perfect absolutely, taken at any 
given instant, yet the actual sequence would none the less 
be the most perfect of all possible sequences, for the reason 
that God always chooses the best possible. . . . 


Fragment without superscription. 1 (Date unknown) 

Goodness is in the will, wisdom is in the understanding. 
Wherein is power? Someone will say it is in body or matter. 
But body is not a substance unless it be taken to be a unity; 
and moreover there is power in God who is without matter. 
It is true, however, that power is in what corresponds ana- 
logically to matter, that is to say, in the common subject of 
goodness and wisdom, which is the source of changes or 
actions. This subject may be called matter in created 

Fragment without superscription. 2 (Date unknown) 

I have learnt by experience that nothing defeats courage 
and removes the taste for beautiful things more than the 
importunate reflections we make on human misery, and on 
the vanity of our undertakings. It is the sole stumbling- 
block of noble minds, on which it is all the easier to fail the 
more exalted one's genius. For ordinary minds do not pause 
over this great consideration about the future which in some 
sort includes the whole universe: but in compensation they 
are happier, for they taste apparent goods, without its occur- 
ring to them to destroy the pleasure by too exact a reflection. 
And since a happy folly is better than a bitter prudence, I 
think we should do well to turn deaf ears to reason and give 
ourselves up to custom, or else to reason for our diversion 
only, if there be no means of reconciling wisdom with con- 
tentment. But, God be praised, we are not so unfortunate, 
and Nature would be a stepmother, if that which makes our 
perfection were the cause of our wretchedness. 

1 Taken -from Bodeman's Catalogue (cf. p. 241, note). 
1 Ibid. 


Comment on a book entitled: 'Reflections on Great Men 
who have died jesting*. l (Date unknown) 

This little book is written with wit and learning, but there 
are signs in it of some moral laxity. I strongly approve that 
one should die joyfully, and consider that the Italian lawyer 
who gave orders that his funeral should be celebrated with 
rejoicings performed the action of a wise man, although it 
has been contested. But I should not wish an event which 
merits all our attention to be treated as of no account. This 
could be approved only by those who are ignorant of the 
dignity of man, and do not know that Providence put him at 
his post to render account of his movements; of which one 
of the most important is the manner of leaving it. Our 
author very rightly remarks that death is more to be desired 
than feared, but he adduces a bad reason for this when he 
says that man is not born to be happy. This is humorous, 
indeed. These gentlemen want to be unhappy by force, 
while charitable Nature has granted them almost everything 
necessary for their good. It is most untrue that there is 
ordinarily more unhappiness than happiness in life. The 
wretched thoughts and complaints against Nature of some 
persons are very unjust. It seems to me that the author 
rails in comfort against evils which he does not feel. Reason, 
which can make death pleasant to us, is not the misfortune of 
this life, but the greatest happiness of another. The author 
himself defends troubles on the ground that they make for 
vivacity. He is sure that a state which left nothing to be 
desired, would make us stupid. But I am not of his opinion 
when he holds that the verses which Ovid wrote in exile are 
better than those he wrote when in love. He does not seem 
to me to have rightly reported the words of M. Gassendi, 
when he was in danger of dying. M. Guy Patin, who was not 

1 Taken from Bodeman's Catalogue (cf. p. 241, note). 


too much of a preacher, kept on telling him that he must 
think of death. M. Gassendi replied with this line from 

Omnia praecepi atque animo mecum ante peregi. 1 

M. de Meaux 2 and Madame de Maintenon have assured me 
that death came upon M. Pellisson by surprise, and that he 
did not by any means scorn the rites of the Church. I prefer 
to believe them rather than the author of this book, who 
attributes an unworthy avowal to a person who showed me 
friendship, and whom I, like most others, held in esteem. 

From a letter without address or date 3 

I realized, sir, from the little talk I had the honour to have 
with you, that you meditate deeply on the nature of human 
freedom. And this it is which drives me to expound to you 
more clearly what I referred to in conversation, so that I may 
profit by your opinion of it. I hold that it is in the interests 
of piety and faith to reconcile the way in which our will acts 
not only with the dogmas of faith, but also with the great 
principles of reason, which hold sway everywhere else, and 
are the foundations of our knowledge. Otherwise we seem 
to be yielding the victory to impious men and atheists, or at 
the least to be confirming and strengthening them in their 
errors. This is why I never could fancy the opinion of those, 
who maintain that the principle of contradiction does not 
apply in Divinis, and that we do in fact find an exception to 
it in the case of the Trinity of the Divine Persons, as is 
admitted to some extent by those who introduce certain 
virtual distinctions. Now it is the same reason which 

1 ' I have imagined it all and have gone over it all beforehand 
in my mind. ' 
1 Bossuet. 
1 Taken from Bodeman's Catalogue (cf. p. 241, note). 


makes me doubt whether it is fitting to say that another 
principle, which is of hardly less general application than the 
principle of contradiction, does not apply with regard to 
freedom the principle, namely, that nothing ever takes 
place without its being possible for one who knew everything 
to give some reason why it should have happened rather than 
not. All the more so, because it seems to me that this 
principle is of just the same use to us in matters of contin- 
gency, as is the principle of contradiction in matters of 
necessity. It is for this reason that the laws of motion 
depend on it, because they are not of geometrical necessity, 
since they originate from the will of God, regulated by 
wisdom. Now since the principle of contradiction is the 
principle of necessity, and the principle that a reason must 
be given is the principle of contingency, it seems to me that 
we must not except freedom from them. Archimedes takes 
it for granted that a balance will not tip more in one direction 
than in the other, when everything is equal on both sides, 
and in the same way all those who reason about morals and 
politics, with a view to discovering about human actions, 
tacitly make use of this same foundation, that there is always 
a reason or cause which inclines the will. We shall, more- 
over, never find a contrary instance, and no one but a Scholas- 
tic, buried in abstractions, thinks otherwise. To show that 
the will ought to be excepted it would be necessary to have a 
means of determining the limitation of this principle a 
priori. This we can never find; and any foundation which 
might be adduced for such a distinction will always go further 
than we wish. It therefore seems to me that we do not need 
to seek even this exception, and that free choice is not 
incompatible with the general principle I have just estab- 
lished. To explain myself more clearly: I say that Adam 
sinned without necessity, although He who knows every- 
thing could give a reason why he rather let himself sin than 
remain in innocence. Even Holy Writ, in the account it 


gives of the method adopted by the serpent to betray Eve, 
also seems to hint that there was some reason or inclination 
which prevailed over the will of Eve. It looks as though the 
soul is never in that state of complete indifference, in which 
nothing matters whether within or without. There is always 
a reason, that is to say a greater inclination, for what has in 
fact been chosen, which may come not only from arguments 
good or bad, but also from passions, habits, dispositions of 
the organs of the mind, external impressions, greater or less 
attention, etc. But this inclination does not master freedom, 
although it inclines it. There is a great deal of difference be- 
tween a necessary cause and a certain concomitant. It is my 
view also that if we established the opposite, and claimed 
that the perpetual accompaniment of a stronger reason for 
choice destroys freedom, it would follow that inclination or 
the strongest reason would destroy freedom on every occasion 
that it accompanied it. From which it would follow further 
that we should almost never be free, since the cases when we 
are completely indifferent, or have a metaphysical freedom 
of choice, are at the least extremely rare, if they ever occur. 
Thus when we choose what is best, because it is best, it would 
be from necessity. Consequently the most perfect actions 
would be the least free and the least praiseworthy, since it is 
in freedom that we seek the reason for praise and blame, or 
rewards and punishments. The more perfect and the more 
inclined towards good a man was, the less free and praise- 
worthy he would be. Thus man would have to be reduced 
to a complete nudity, and despoiled of good qualities and 
graces, if he were to be allowed any merit. This is a vision 
favoured by some of our moderns, who seek the notion of 
freedom in indifference; which is as far removed from good 
sense as are their doctrines about probability and about 
knowledge of the badness of the action being necessary for 
sin. Whence has recently arisen that extraordinary dis- 
tinction between philosophical and theological sin, which is 


upheld by certain authors who maintain that an assassination 
or an adultery is not a mortal sin, when the man who com- 
mits it does not actually reflect that he is offending God; 
because they imagine that otherwise the action is not suffi- 
ciently voluntary, that is to say, according to them, suffi- 
ciently indifferent, when the man does not give sufficient 
thought to everything which might dissuade him from it. 

Leibniz 9 s Philosophical Dream. 1 (Date unknown) 

I was happy to be among men, but not happy about human 
nature. Often I thought with sorrow of the evils to which 
we are subjected, of the short duration of our life, the vanity 
of glory, the inconveniences which spring from pleasure, the 
illnesses which crush our very spirit; finally the annihilation 
of all our glories and all our perfections in the moment of 
death, which seems to reduce to nothing the fruits of our 
labours. These meditations made me melancholy. I had a 
natural love of doing good and knowing the truth. Yet it 
looked as though I were taking pains to no purpose, and as 
though a fortunate crime were better than an oppressed 
virtue, and the folly which satisfies preferable to the reason 
which gives pain. But I resisted these objections, and the 
better part triumphed in my mind through the consideration 
of the Divinity, who must have ordered everything properly, 
and who kept up my hopes by the expectation of a future 
capable of making up for everything. The struggle in me 
was renewed at the sight of any great disorder, either among 
men, when I beheld injustice triumphant and innocence 
afflicted, or in nature, when tempests or earthquakes made 
havoc of towns and provinces, and caused the death of 
thousands without distinction between the righteous and 
the wicked, as if nature took no more account of us than we 

1 Taken from Bodeman's Catalogue (cf. p. 241, note). The 
superscription is in the hand of a librarian. 


take of the ants and worms we come across on our path. 
I was greatly moved by these spectacles, and could not 
prevent myself from pitying the condition of mortal men. 

One day, wearied by these thoughts, I fell asleep, and 
found myself in a dark place, which was like a subterranean 
cave, very large and very deep, and swarming with men, who 
with strange haste pursued in this darkness wandering fires 
which they called honours, or tiny shining flies under the 
name of riches; many there were who searched on the ground 
to find shining pieces of rotten wood, which were called 
pleasures. These unlovely lights had each its followers; 
there were some who changed their course, and some who 
abandoned the pursuit altogether, through tiredness or 
through despair. Many of those who were running blindly 
about, and who often thought they had attained their goal, 
fell over precipices, whence naught was heard but their 
groans; some were stung by scorpions and other venomous 
creatures, which made them wretched and often mad with rage. 
But neither these examples, nor the arguments of some better 
informed persons, prevented the others from running the 
same risks, or from fighting in order to forestall others, or to 
prevent themselves from being forestalled. In the vault of this 
great cave, there were little chinks and barely perceptible 
cracks through which filtered some traces of the light of day, 
but it was so weak that much attention was required for it 
to be noticed. Often there were heard voices which said: 
'Hold, mortals; whither go ye, wretched that ye are?' Others 
cried, 'Lift up your eyes to heaven'; but they did not stop, 
and only lifted their eyes to pursue these dangerous trifles. 
I was one of those who was extraordinarily struck by these 
voices. I kept on looking up, and at last I saw the little 
light which required so much attention. It seemed to me to 
grow in proportion as I looked fixedly at it. My eyes 
became as it were imbued with its rays, and when I used 
them immediately afterwards to see where I was and whither 


I was going, I was able to discern what was around me, 
which was enough to save me from the dangers. A venerable 
old man, who had long been wandering in the grotto, and 
whose thoughts were not unlike mine, told me that this light 
was what in our world is called good sense and reason. I 
often changed my position to examine the different chinks 
in the vault through which this little light came, and when I 
was stationed in one place, where several lights could be 
perceived at the same time from their true point of view, I 
found an assemblage of rays which greatly enlightened me. 
This occupation was of great benefit to me, and made me more 
capable of acting in this obscurity. Finally, after having 
attempted several views, I was led by my good star to a 
place which was the sole and most advantageous spot in 
the grotto destined for those whom the Divinity wished to 
withdraw altogether from these dark regions. Barely had I 
begun to look up when I was surrounded by a great light 
gathered from all sides, and the whole grotto and its horrors 
were fully revealed to my eyes. But a moment afterwards 
a dazzling brightness took me by surprise. Presently it took 
shape, and I saw before me the appearance of a young man 
whose beauty charmed my senses. His mien had a majesty 
which inspired me with veneration mingled with awe, but the 
gentleness of his glances reassured me. But I began to feel 
a weakness overcoming me, and was about to faint, when I 
felt myself touched by a branch imbued with a marvellous 
liquid which I cannot compare with anything I have ever 
felt, which gave me the strength necessary to bear the 
presence of this celestial messenger. He called me by my 
name, and said in gracious tones: 'Give thanks to the Divine 
goodness which withdraws you from this mob'. At the same 
time he touched me a second time, and at that moment I felt 
myself raised up. I was no longer in the cave, I no longer 
saw a vault above me, and I found myself on a high mountain 
which revealed to me the face of the earth. I saw in the 


distance anything that I wished to look at only in a general 
way; but when I considered a particular place fixedly, im- 
mediately it grew, and in order to see it as if close at hand, 
I needed no other telescope than my attention. This gave 
me a wondrous pleasure, and emboldened me to say to my 
guide: 'Powerful spirit, for I cannot doubt but that you are 
one of the celestial angels, who pay court from near at hand 
to the Sovereign of the Universe, since you have been ready 
to enlighten my eyes, do as much for my mind'. He seemed 
to me to smile, and to take pleasure in hearing my wish. 
'Your desires are granted/ he said, 'since you desire wisdom 
rather than the pleasures of the vain spectacles which the 
world offers to your gaze. But you will lose nothing of what 
is solid in these same spectacles. You will see them with 
eyes quite differently enlightened. Your understanding, 
being fortified from on high, will discover everywhere the 
brilliant enlightenments of the Divine Author of things; you 
will observe only wisdom and happiness where men cus- 
tomarily find nothing but vanity and bitterness. You will 
be satisfied by your Creator; you will be enchanted by the 
sight of His works. Your admiration will not be the result of 
ignorance, as is that of the common herd. It will be the 
fruit of the knowledge of the glories and wonders of God. 
Whereas among men secrets are despised when they are 
discovered, though they were previously regarded with 
astonishment; you will find that when you are admitted into 
the heart of nature, the further you go the greater will be 
your delights, because you will be only at the beginning of a 
chain which goes on to infinity. The pleasures which charm 
your senses, and that fabled Circe who changes men into 
beasts, will have no power over you, if you bind yourself to 
the beauties of souls which never perish and never cause 
displeasure. You will be of our company, and will go with us 
from world to world, from discovery to discovery, from per- 
fection to perfection. You will pay court with us to the 


Supreme Substance, which is beyond all worlds and which 
fills them without dividing Itself in doing so. You will be at 
one and the same time before His throne and among those 
who are distant from it. For God will establish His seat 
in your heart, and the heavens follow Him everywhere. Go 
then and lift up your mind above whatever is mortal, and 
whatever perishes, and bind yourself only to the eternal 
verities of the light of God. You will not always live here 
below this mortal life, so like that of the brutes; a time will 
come when you will be wholly freed from the chains of this 
body. Make good use, therefore, of the time which Providence 
grants you here, and know that your perfections to come will be 
proportioned to the care you take here below to attain them/ 

From the ' Theodicy ' . 1710 

405. I had intended to stop at this point, having answered 
(so it seemed to me) all M. Bayle's objections on this subject, 
which I could find in his works. But recalling Laurentius 
Valla's dialogue Of Free-will, which was written against 
Boethius and which I have mentioned before, I thought it 
would be fitting to give a summary of it here, keeping the 
dialogue form, and then to go on from the point at which he 
stops, continuing the story which he begins. My aim is not 
so much to brighten up the subject-matter, but rather to 
explain myself at the end of my discourse in the clearest and 
most popular manner that is open to me. . . . 

ANTONY. I know that you can give me wings, like a 
second Daedalus, to escape from the prison of ignorance, and 
to soar to the region of truth which is the dwelling-place of 
souls. I have derived no satisfaction from the books I have 
read, no, not even from the celebrated Boethius, who has 
won general approbation. I know not whether he himself 
has rightly understood what he says about God's under- 
standing, and about eternity which transcends time. I beg 


you to give me your opinion about the way of reconciling 
foreknowledge with freedom. 

LAURENTIUS. I fear that I shall shock many people if I 
refute this great man. I will, however, subordinate this 
fear to my regard to the entreaties of a friend, on condition 
that you promise me 

ANT. What? 

LAUR. That after you have dined with me you will not ask 
for supper also. By this I mean that you will be satisfied 
with the solution of the question you have put me, without 
asking me another. 

ANT. I promise. Here is the heart of the difficulty. If 
God foresaw the treachery of Judas, it was necessary that 
Judas should betray; it was impossible that he should not 
betray. There is no obligation to perform the impossible. 
Therefore he did not sin, and did not deserve to be punished. 
This destroys justice and religion, together with the fear 
of God. 

LAUR. God foresaw the sin, but He did not force the man 
to commit it. Sin is voluntary. 

ANT. This volition was necessary, since it was foreseen. 

LAUR. If my knowledge does not give existence to things 
past or present, neither can my foreknowledge give existence 
to future things. 

ANT. This comparison is misleading. Neither the present 
nor the past could be changed; they are already necessary. 
But the future, in itself susceptible of change, becomes, 
through foreknowledge, fixed and necessary. Let us suppose 
that a pagan god boasts that he knows the future: I should 
ask him which of my feet I shall put foremost, and then I 
should do the opposite of what he predicted. 

LAUR. This God knows what you will want to do. 

ANT. How can He know, since I shall do the opposite of 
what He says, and I assume He will say what He thinks ? 

LAUR. Your supposition is a false one. God will not 


answer you, or, if He did answer you, your veneration for 
Him would make you hasten to do what He said: His predic- 
tion would be to you a command. But we have changed our 
question. We are not concerned with what God will predict, 
but with what He foresees. Let us return to foreknowledge, 
and distinguish between the necessary and the certain. It 
is not impossible that that which is foreseen will not happen, 
but it is infallible that it will happen. It is possible for me 
to become a soldier or a priest, but I shall not become one. 

ANT. That is where I have you. The philosophers' Rule 
demands that whatever is possible should be considered as 
existing. But if what you say is possible, that is to say an 
event different from what has been foreseen, did actually 
happen, then God would have been mistaken. 

LAUR. Philosophers' Rules are not oracles for me. This 
one in particular is not accurate. Two contradictories are 
often both of them possible, but can they therefore both of 
them exist ? But to enlighten you further, let us suppose that 
Sextus Tarquinius comes to Delphi to consult the oracle of 
Apollo and receives the answer: 

Exul inopsquc cades irata pulsus ab urbc. 1 

The young man complains: C I have brought you a royal 
present, O Apollo; and yet you reveal to me so unhappy a 
fate*. Apollo answers: 'Your present is pleasing to me, and 
I perform what you ask of me; I tell you what will happen. 
I know the future but I do not make it. Go and complain to 
Jupiter and to the Fates'. It would be absurd of Sextus, 
would it not, if after this he went on complaining to 

ANT. He will say: 'I thank you, holy Apollo, for not 
having paid me with silence, for having disclosed to me the 
truth. But how comes it that Jupiter is so cruel to me, and 

1 'You will die poor and in exile, driven in anger from your 


prepares so hard a fate for an innocent man, who is religious 
and who worships the gods ? ' 

LAUR. 'You an innocent man?' answers Apollo. 'Know 
that you will be proud, that you will commit adulteries, and 
that you will be a traitor to your country/ Could Sextus 
answer: 'It is you who are the cause of this, Apollo; you 
force me to do it by foreseeing it' ? 

ANT. I admit that he would have lost his reason if he 
answered thus. 

LAUR. Neither then can the traitor Judas complain of 
God's foreknowledge. And this is the solution of your 

ANT. The satisfaction you have afforded me has exceeded 
my hopes; you have done what Boethius was unable to do. 
I shall be grateful to you all my life. 

LAUR. But let us pursue our story a little further. Sextus 
says: 'No, Apollo, I will not do what you say'. 

ANT. 'What!' says the god, 'am I then to be a liar? I 
repeat again you will do everything that I have just said.' 

LAUR. Perhaps Sextus will pray to the gods to change 
his fate, to give him a better heart. 

ANT. He will receive the answer: 

Desinefata deumflecti sperare precando. 1 

He will not be able to give the lie to divine foreknowledge. 
But what will Sextus say ? Will he not burst into complaints 
against the gods? Will he not say: 'What? Am I not then 
free ? Is it not in my power to follow virtue ? ' 

LAUR. Apollo may say to him: 'Know, my poor Sextus, 
that the gods have made every man what he is. Jupiter 
has made the wolf ravening, the hare timid, the ass stupid, 
the lion brave. He has given you a soul which is wicked and 
incorrigible. You will act in accordance with your nature, 

1 ' Hope not that the fates of the gods may be turned aside 
by prayers/ 


Jupiter will treat you as your actions deserve. By the Styx 
he has sworn it'. 

ANT. I confess that it seems to me that Apollo, in excusing 
himself is accusing Jupiter more than Sextus. And Sextus 
would reply: 'Jupiter condemns in me his own crime it is 
he alone who is guilty. He could have made me quite other 
than I am. But, made as I am, I am bound to act as he has 
willed. Why then does he punish me? Was I able to resist 
his will? 1 

LAUR. I confess that I also am brought to a standstill. I 
have called the gods Apollo and Jupiter on to the stage, 
to distinguish for you between the foreknowledge and the 
providence of God. I have shown that Apollo, or foreknow- 
ledge, is not injurious to freedom, but I cannot give you 
satisfaction concerning the decrees of the will of Jupiter, that 
is to say the commands of providence. 

ANT. You have rescued me from one abyss, and you plunge 
me into a deeper one. 

LAUR. Remember our contract. You have dined with me, 
and you are asking me for supper also. 

ANT. Now I see your adroitness. You have caught me, 
it is not an honest contract. 

LAUR. What more can I do? I have given you wine and 
meat of my own growing, such as my little estate can provide. 
Nectar and ambrosia you must ask of the gods such divine 
food cannot be found among men. Listen to St. Paul, that 
chosen vessel who was caught up into the third heaven, who 
heard there unspeakable things. He will reply by invoking 
the parallel of the potter, the incomprehensibility of the ways 
of God, and our admiration for the depth of His wisdom. 
Yet it is well to note that we do not ask why God foresees the 
event, for that we understand; it is because it will happen. 
But we ask why He orders it so, why He hardens the heart 
of one, why He takes pity on another. We do not know 
what reasons He may have for it, but the fact that He is very 


good and very wise is enough to make its judge them good. And 
as He is just also, it follows that His decrees and His opera- 
tions do not destroy our freedom. Some have sought for a 
reason. They have said that we are made of a corrupt and 
impure mass of mud. But Adam and the angels were made 
of silver and gold, and they sinned none the less. Some- 
times, also, our hearts are hardened after regeneration. We 
must then seek another cause of evil, and I doubt if even the 
angels know it. For they continue happy and praising God. 
Boethius paid more attention to the answer of philosophy 
than to St. Paul's. This is the cause of his failure. Let us 
believe in Jesus Christ, who is the virtue and wisdom of God ; 
He teaches us that God desires the salvation of all, that He 
desires not the death of a sinner. Let us trust in the Divine 
mercy, and let us not, through our vanity and our malice, 
become incapable of enjoying it. 

This dialogue of Valla's is beautiful, although there are 
points to criticize in it here and there. But its chief defect 
is that it cuts the knot, and seems to condemn Providence 
under the name of Jupiter. Let us therefore proceed further 
with our little fable. Sextus, after leaving Apollo at Delphi, 
goes to seek Jupiter at Dodona. He offers sacrifices and then 
sets forth his grievances. 'Why have you condemned me, 
O great God, to be wicked and to be unfortunate? Change 
my lot and my heart, or recognize your fault.' Jupiter 
answers: 'If you are ready to renounce Rome, the fates 
shall spin you other destinies; you shall become wise, you 
shall be happy'. 'Why must I renounce the hope of a 
crown?' asks Sextus; 'can I not be a good king?' 'No, 
Sextus/ answers Jupiter, 'I know best what you need. If 
you go to Rome you are lost.' Sextus could not make up 
his mind to so great a sacrifice, left the temple, and gave 
himself up to his fate. Theodorus, the High Priest, who had 
witnessed the dialogue between the god and Sextus, addressed 


Jupiter thus: 'Your wisdom is worthy of adoration, great 
Master of the gods, you have convinced this man of his fault. 
Henceforth he must attribute his misfortunes to his evil will; 
he has not a word to say. But your faithful adorers are 
astonished: they would wish to admire your goodness as well 
as your greatness. It rested with you to give him another 
will'. 'Go to my daughter Pallas/ said Jupiter, 'she will 
teach you what I had to do.' 

Theodoras journeyed to Athens. He was commanded to 
sleep in the temple of the goddess. As he dreamed, he found 
himself transported into an unknown country, where stood a 
palace of inconceivable brightness and vast size. The god- 
dess Pallas appeared at the gate encircled with rays of 
blinding majesty. 

Qualisque videri 
Coelicolis et quanta solet. 1 

She touched the face of Theodorus with an olive branch, 
which she held in her hand. He immediately became able 
to bear the divine brilliance of the daughter of Jupiter and 
of all the things she was to show him. 'Jupiter, who loves 
you/ she said, 'has entrusted you to me to be instructed. 
Here you see the palace of the Fates, whose guardian I am. 
Here are representations, not only of what happens, but also 
of everything that is possible. Jupiter reviewed them all 
before the beginning of the existing world, arranged the 
possibilities into worlds, and chose the best of them all. 
Sometimes he comes to this place to give himself the pleasure 
of going through things, and of renewing his own choice, 
with which he cannot fail to be satisfied. I have only to 
speak and we shall see an entire world, which my father could 
have produced, and in it will be represented everything that 
can be required of it. And by this means it is possible to 

1 ' In the guise and grandeur in which she is wont to appear 
before the denizens of heaven.' 


know too what would happen, if such and such a possibility 
had to exist. And if the conditions are not clearly enough 
determined, there will be as many such worlds as one can 
desire, different from one another, which answer the same 
question in different ways, and in as many ways as is possible. 
You studied geometry when you were young, like all well- 
educated Greeks. You know, then, that when the con- 
ditions of a point we are looking for do not sufficiently 
determine it, and there are an infinite number of them, they 
all fall in what the geometricians call a locus, and this locus 
at least (which is often a line) is determined. In the same 
way you can imagine an ordered series of worlds, all of which 
(and they alone) contain the case you are concerned with, 
and which vary its circumstances and consequences. But if 
you suppose a case which differs from the actual world no 
more than in one single definite thing and in the consequences 
of that, then one certain determined world will afford the 
answer. These worlds are all here; that is to say in idea. 
I will show you some where you will find, not exactly the 
same Sextus whom you have seen (that is impossible, since 
he carries always with him what he is to be), but Sextuses 
like him, who possess all that you already know of the true 
Sextus, but not everything which is already in him without 
being perceived, nor consequently all that is yet to happen 
to him. You will find in one world a Sextus very happy and 
exalted, in another a Sextus satisfied with a mediocre con- 
dition, Sextuses of all kinds and of an infinite number of 

Thereupon the goddess led Theodoras into one of the 
apartments. When he was inside it was no longer an 
apartment, it was a world, 

Solemque suum, sua sidera norat. 1 

By the command of Pallas, Dodona appeared with the 
1 'A sun of its own it knew, and stars of its own.' 


temple of Jupiter, and Sextus leaving it. He was heard to 
say that he would obey the god. He went to a town lying 
between two seas, like Corinth. There he bought a little 
garden, and while digging in it he found treasure. He 
became a rich man, loved and respected, and died in ripe 
old age, beloved by the whole city. Theodorus saw his whole 
life at a glance, like a performance on the stage. In this apart- 
ment lay a large book filled with writing. Theodorus could 
not refrain from asking what it meant. 'It is the, history of 
the world we are now visiting/ answered the goddess, 'it is 
the book of its destinies. You have seen a number on the 
forehead of Sextus look up in the book the place the 
number indicates.' Theodorus looked it up and found there 
the story of Sextus in more detail than the one he had seen 
in brief. 'Put your finger on whatever line you please/ said 
Pallas, 'and you shall see represented in actual fact in all its 
details what the line tells in outline.' He obeyed, and saw 
appear all the details of a part of the life of Sextus. 

They passed into another apartment, and behold ! another 
world, another Sextus, who, leaving the temple with the 
determination to obey the god Jupiter, went to Thrace. 
There he wedded the king's daughter, his only child, and 
succeeded him. He was adored by his subjects. They went 
to other rooms and beheld ever fresh scenes. 

The apartments were arranged in a pyramid; the higher 
up they were the more beautiful they became, and the more 
beautiful the worlds they represented. At last they reached 
the topmost apartment, which completed the pyramid, and 
which was the most beautiful of all. For the pyramid had a 
beginning, but there was no end to it to be seen. It had an 
apex but no base; it grew and grew to infinity. This was 
because, as the goddess explained, out of an infinity of possible 
worlds, there is the best of all possible worlds, otherwise God 
would not have made up his mind to create one at all, but 
there is no world which has not less perfect ones below it, and 


that is why the base of the pyramid stretches down to in- 
finity. When Theodorus entered this topmost apartment, he 
was caught up in an ecstasy. The goddess had to come to 
his aid and restore him by putting a drop of divine liquid on 
his tongue. He could not contain himself for joy. ' We are 
in the actual world,' said the goddess, 'and you are at the 
source of happiness. This is what Jupiter is preparing for 
you here, if you continue to serve him faithfully. Here is 
Sextus as he is and as he actually will be. He rushes from 
the temple in a rage, he scorns the advice of the gods. You 
can see him travelling to Rome, bringing destruction with 
him, violating the wife of his friend. Here he is exiled with 
his father, defeated, wretched. If Jupiter had here taken a 
Sextus who was happy at Corinth, or who was king of Thrace, 
it would no longer have been this world. Yet he could not 
fail to choose this world, which surpasses all others in per- 
fection, and which forms the apex of the pyramid: otherwise 
Jupiter would have renounced his wisdom, and would have 
banished me, his daughter. You see that my father did not 
make Sextus wicked. He had been wicked from all eternity, 
and always of his own free will. Jupiter did nothing but 
grant him existence, which his wisdom could not refuse to 
the world which contains him. He made him pass from the 
region of possible to that of actual beings. The crime of 
Sextus serves great ends: it makes Rome free, from it is born 
a great empire, which will furnish great examples. But that 
is nothing compared with the totality of this world, whose 
beauty you will admire when, after a happy passing from this 
mortal condition into a better state, the gods shall have made 
you capable of knowing it. ' 

At this moment Theodorus awoke, gave thanks to the god- 
dess, and praised the justice of Jupiter, Inspired by what he 
had seen and heard, he continued in his office of high priest 
with all the zeal of a true servant of his god, and with all the 
joy of which mortal man is capable. It appears to me that 


this continuation of the story throws light on the difficulty 
on which Valla did not wish to touch. If Apollo adequately 
represented the divine science of vision (which is concerned 
with existences), I hope that Pallas has represented well 
enough what is called the science of pure intelligence (which 
is concerned with everything that is possible), in which one 
must finally seek the source of things. 



ACADEMIC, 109, 113, 126, 190 

Academy, the: a philosophical school founded by Plato. Its 

members are referred to in these pages as the Academics, 

49, 5i 

Adam, xii-xiii, xx, 58-61, 64-66, 68, 251, 262 
Albert the Great (11931280): a Dominican monk, theologian, 

philosopher, and alchemist, 99 
Altdorf, vii 

Apollo: Greek god, 259, 260-2, 267 
Aquinas, Thomas (c. 1227-74) : * ne greatest theologian of the 

Western Church. Author of Summa Theologiae, 54, 65, 99 
Archimedes (c. 287-212 B.C.) : the most famous geometer of the 
ancient world, with a gift for mechanical inventions, xii, 62, 
194, 234, 238, 240-1, 251 
Aristotelians, 217 
Aristotle (384-322 B.C.) : famous Greek philosopher, pupil of Plato 

and tutor of Alexander the Great. He wrote works on 

logic, metaphysics, ethics, politics, biology, etc., 48, 98-9, 

102. 125, 142-3, 155, 193 
Arnauld, Antoine (1612-94): distinguished French theologian, 

mathematician, and logician, part-author of the Logique de 

Port-Royal. Defended the Jansenists against the Jesuits: 

vii, xi-xii, xxxi, 52-87, 97 n., 116, 235 
Athens, 263 
Atomists, 213 
Augustine, Saint (354-430) : the greatest philosopher among the 

early fathers. Author of De Civitate Dei and Confessions, 185 
Averroists : followers of Averrhoes (i 126-98), an Arab philosopher 

and commentator on Aristotle. He maintained the eternity 

of matter and the mortality of the individual soul, 156 

Bacho, John (d. 1346): better known as Baconthorp, from the 
place in Norfolk where he was born. A Carmelite monk 
and Schoolman, 99 

Bacon, Francis (1560-1626): philosopher and man of affairs. 
Generally regarded as the earliest of modern philosophers 
in England. Author of the Novum Organum, a famous 
work on logic and scientific method, 47, 199 

Barbara : a mood of the syllogism, 182-3 
U95 271 


Barbaras, Hermolaus (1454-95) : a learned Italian diplomat and 

interpreter of Aristotle, n 

Basnage, Jacques (1655-1723) : French Protestant theologian, 241 
Bayle, Pierre (1647-1706): author of the famous Dictionnaire 

Historique et Critique. He maintained the impossibility of 

reconciling faith with reason. Much of Leibniz's Theodicee 

is concerned with refuting his arguments, xv, xxxi, 5, 12, 

88-96, 118-40, 151, 242, 257 
Berkeley, George (1684-1753): Irish bishop and empiricist 

philosopher. Author of An Essay towards a New Theory 

of Vision and a Treatise concerning the Principles of Human 

Knowledge. Referred to by Leibniz as 'the man in 

Ireland/ 243 
Berlin, viii 

Berlin Academy, viii 
Bernier, Fra^ois (1625-88): a French traveller, author of 

Voyages, an account of a sojourn in the East, 118 
Bernouilli, Jacques (1654-1705): a Swiss mathematician, 243 
Blainville, 179 

Bodeman's Catalogue, 241, 248-57 
Boethius, C. (480-524) : a Roman philosopher and statesman, 

author of De Consolatione Philosophiae, 267, 260, 262 
Bosses, Bartholomaeus des (1668-1728): Jesuit theologian, 243 
Bossuet, Jacques Benigne (1627-1704): orator and preacher, 

known particularly for his funeral orations; Bishop of 

Meaux, 250 
Bourget, Louis (1678-1742): a merchant who became a scholar, 

with a bent for natural philosophy, 245 
Boyle, Robert (1627-1691): the famous Irish chemist and 

physicist, who gave his name to Boyle's law of the pressure 

of gases, vii, 48 
Burnet (or Burnett). Thomas (1635-1715): Scots lawyer and 

divine, 243 

Caesar, Julius (102-44 B.C.), 128-40 

Catellan (or Catalan), Jean de ( 7-1725), Bishop of Vallence, 

Caroline (1683-1737): wife of George II of England. Much 
interested in philosophy and literature. Clarke dedicated 
to her his edition of his correspondence with Leibniz (1717), 


Cartesians: followers of Descartes. Leibniz regarded Male- 
branche as the most important of these. He does not 
regard himself or Spinoza as Cartesians, xiv, xx-xxi, 5, 23, 
55, 62-3, 88-96, in, 118, I2I-2, 130-2, 148, 151, 165, 
185, 195, 205, 217, 230 

Cartesian theory of the quantity of motion, xxxi 

Cesar e: a mood of the syllogism, 184 


Chinese, 175, 179 

Christian V (1646-99) : King of Denmark and Norway from 

1670 to 1699, 39 
Christian faith, 159 
Christian Mathematicians, 193 
Church, the, 57 
Circe: an enchantress in Homer's Odyssey who was able to turn 

men into beasts, 257 

City of God, 19, 29, 56, 86-7, 107, 155, 236 
City of Minds, xi, xxv, 19, 86 
Clarke, Samuel (1675-1729): Newton's most famous disciple, 

xv, xxi, xxxii, 192-229 
Commercium Epistolicum, 116 
Copernicus, Nicolas (1473-1543): famous Polish astronomer, 

author of De Revolutionibus Orbium Coelestium, in 
Cordemoy, Geraud de (d. 1684): a French Cartesian, 103 
Corinth, 265-6 
Coste, Pierre (1668-1747): French translator and critic, known 

especially for his translation of Locke's Essay (1700), 141 

Daedalus, 257 

Darapti: a mood of the syllogism, 184 

Datisi: a mood of the syllogism, 184 

De Diaeta, 102 

Delphi, 259, 262 

Democritus: Greek philosopher born about 81 B.C., 101, 103, 
131* i35 165, 193-4 

Des Argues, Gaspard (1593-1662) : French mathematician, especi- 
ally addicted to the methods of pure geometry, 176 

Descartes, Rene" (1596-1650): French philosopher, physicist, and 
mathematician. His followers are known as Cartesians. 
His chief works are Di scours de la Methode and Meditaiiones 
de Pnma Philosophia, vii, xiv, xxi, xxii, n, 18, 47-8, 50-1, 
85. 9*-5 103-4. "3-14. 153. 216, 239-42 

Dictionnaire Historique et Critique , 5, 13, 118, 126-140, 151 

Dijon, 136, 189 

Disamis: a mood of the syllogism, 183 

Discours de Metaphysique, 53-7, 236 

Dogmatists, 189 

Dresden, viii 

Dutch East India Company, 82 

Dynamics, 108, 116, 118, 227 

Elector-Archbishop of Mainz, John Philip von SchOnborn, bishop 

of Wflrzburg and Worms (elector 1647-73), vii, viii 
Emperor of the Moon, 214 
Empire, viii 
England, viii 


Epicurean: follower of Epicurus, 134, 136, 157, 207 

Epicurus (341-270 B.C.) : a Greek philosopher who taught that 

pleasure is the sovereign good, 135, 189, 193-4 
Equilibria, De, 194 

Essay on the Human Understanding, xvii, 141-91 
Euclid (450-380 B.C.) : Greek geometer. His Elements are the 

basis of plane geometry, 48, 144, 223, 238 
Europe, viii 
Eve, xii, 65, 252 
Exposition of the New System, xxxi, 97-109 

Fates, the, 259 

Florence, 217 

Fludd, Robert (1574-1637) : sought to promulgate in England 
theosophical views like those of Paracelsus (1493-1541), 167 

Fontenelle, Bernard le Bovier de (1657-1757): member of the 
Academic Fran9aise and from 1687 secretary to the Aca- 
de*mie des Sciences. His writings were mainly popu- 
larizations of scientific ideas. He pronounced a memorial 
oration on Leibniz, viii 

Foucher, Simon (1644-1696) : a Canon of Dijon who professed 
philosophical scepticism, xxxi, 45-51, 109, 117, 189-90 

Galileo (1564-1642) : a famous Italian astronomer, author of 
Dialogo dei due massimi sistemi del mondo on the Ptolemaic 
and Copernican systems, 47-8, 234, 239-42 

Gassendi, Pierre (1592-1655): French philosopher, mathema- 
tician, and astronomer, 47, 99, 165, 249-50 

Genoa, xxiii, 66 

George I (1660-1727): Elector of Hanover; King of England 
(1714-27), viii 

Germany, 66 

Ooclenius, Rudolphus (1547-1628) : German philosopher and poet, 
author of Lexicon Philosophicum Graeco-Latinum, 201 

Gospel, 236 

GOttingen, 77 

Great Mogul, 78 

Greeks, 144, 264 

Guericke, Otto von (1602-86): German physicist. Invented 
the pneumatic machine, 216-17 

Hanover, viii, 114 

Harlequin, 214 

Hartsoeker, Nicolas (1656-1725): a Dutch physicist, mainly 

concerned with the making of microscopes and telescopes. 

His correspondence with Leibniz about the philosophy of 

nature is extant, 100, 117, 244 


Hegel, Gottfried W. F. (1770-1831): German philosopher, xxvii 
Hercules : the most famous of the heroes of Greek mythology, 147 
Herrenhausen, 204 
Hessen Rheinfels, Landgraf Ernst von (1623-93): statesman 

and soldier, keenly interested in philosophy. He acted 

as go-between in the early stages of Leibniz's correspondence 

with Arnauld, 52, 57, 61 
Hippocrates (born c. 460 B.C.) : greatest physician of antiquity, 

14, 102, 150 

Htstoire des Outrages des Savans, 119 
Hobbes, Thomas (1588-1679): English philosopher, author of 

Leviathan, 193, 242 
Holy Writ, 251 
Homer: Greek poet of tenth or eleventh century B.C.; reputed 

author of the Iliad and the Odysscv, 127 
Hume, David (1711-76): English philosopher, author of A 

Treatise of Human Nature, vii, xxv, xxvii-xxix 
Huygens, Christian (1629-95): Dutch physicist, mathematician, 

mechanician, and astronomer, vii, 115, 241, 245 

Jansenists, 52 

Jesuits, 52 

Jesus Christ, 57, 155, 236, 262 

John Frederick, Duke of Brunswick (d. 1679) . vni 

Journal de Pans, 114, 116 

Journal des Savans, 117, 118, 190 

Judas, 56, 258, 260 

Jupiter: Roman name for Zeus, the king and father of the 

gods, 259, 261-3, 265-6 
Jupiter: the planet, 86 
Jurieu, Pierre (1637-1713): French Protestant theologian, 

famous for his polemics with Bossuet, 197 

Kant, Immanuel (1724-1804): famous German philosopher, 

vii, xxvii-xxix 

Kant's Copernican Revolution, xxvii 
Kingdom of Heaven, 236 

La Loubere, Simon de (1642-1729): he wrote a book on Siam, 

where he had lived for three months, 163 
Lantin, Jean Baptiste (1620-95) : traveller and scholar, 136 
Leeuwenhoek, Antony van (1632-1723): Dutch naturalist. He 

made microscopes and demonstrated the circulation of the 

blood, 100, 245-6 
Leipzig, vii 


Locke, John (1632-1704): English philosopher, author of Essay 
concerning the Human Understanding, xvii-xix, xxv, xxvii- 
xxix, 55, 133, 141-91, 192, 243 

London, vii, viii 

Louis XIV, le Grand (1638-1715): King of France (1643-1715), 
vii, 179, 239 

Magdeburg, 216 

Mahomet (c. 571-632) : founder of Islaraism. Caliph is the title 

given to the sovereigns who held spiritual and temporal 

power after Mahomet, 50 
Maintenon, Fran9oise d'Aubign6 Marquise de (1635-1719): 

mistress and afterwards wife of Louis XIV of France, 250 
Malebranche, Nicolas de (1638-1715): French metaphysician 

and Catholic priest, generally referred to by Leibniz as the 

'author of the Recherche de la Verite.' vii, 75, 93-4, 96, 

100, 104, 195, 239, 241 
Malpighi, Marcello (1628-94): Italian scholar, physiologist and 

anatomist, 100 

Mathematical Principles of Philosophy and of Nature, 198, 224 
Meaux, see Bossuet 

Melissus (born c. 470 B.C.) : Greek philosopher, 102 
Molyneux, William (1656-98): Irish philosopher and friend of 

Locke, 176-7 
Monadology, ix, xxxi-xxxii 

Nantes, 179 

New Essays, xvii, xxvii, xxxi, 14191 

Newton, Isaac (1642-1727): English mathematician, physicist, 
astronomer, and philosopher; author of Philosophiae Natu- 
ralis Principia Mathematica and Optiks, viii, xx, xxxii, 157, 
162, 192-229, 243-4 

Nouvelles de la Republique des Lettres, 88, 152 

Nova Zembla, 144 

Nuremberg, vii 

Odyssey, 127 

Oldenburg, 179 

Oldenburg, Henry (1615-77): natural philosopher and man of 

letters, vii 

Optics, 192, 195, 208, 227 
Ovid, 249 

Pallas Athene: Greek goddess of war and wisdom, 263-7 
Paris, vii, viii, xxiii, 66, 88, 179 

Parmenides (born c. 539 B.C.) : Greek philosopher, 102 
Patin, Gui (1602-72) : French writer and physician, 249 


Paul, Saint, 143, 261-2 

Pellisson, Paul (1624-93) : French historian, 250 

Peripatetics : name given in antiquity to the followers of Aristotle, 
e.g. Theophrastus, Eudemus, and others, 131 

Phaeacians, 127 

Phaedo, Plato's, 55 

Philosophical Dictionary, 201 

Physical Hypothesis, 136 

Plato (429-347 B.C.) : famous Greek philosopher, founder of the 
Academy and writer of Dialogues. His most famous work 
is The Republic, 48, 51, 55, Si, 142-3, 147, 171, 193 

Platonist, in, 131 

Pliny, the younger (62 -c. 120): Roman man of letters, 101 

Poiret, Pierre (1646-1719): French philosopher, influenced by 
the Cartesian method and later converted to mysticism, n 

Port-Royal Logic, xii 

Princess of Wales, see Caroline 

Principles of Nature and of Grace, xxxi 

Principles of Physics, 117 

Pythagoras (born c. 582 B.C.) : Greek mathematician and philo- 
sopher, 193 

Quietists : a seventeenth-century religious sect whose best-known 
member was Molinos, who believed that Christian perfection 
consisted in the love of God and the inaction of the soul, 156 

Recherche de la Verite, 93-4, 96, 100, 104, 190 

Regis, Pierre (1656-1726) : French physician, exiled by the Edict 

of Nantes. He spent the rest of his life practising at 

Amsterdam, 100 
Roberval, Gilles Personne de (1602-75) : French mathematician, 


Rohan, Henri, Due de (1579-1638): a French general, 179 
Romans, 144 
Rome, 262, 266 
Rorarius, Girolomo (1485-1556): Italian man of letters, who 

upheld the view that animals have rational minds, 5, 13, 126 
Royal Society, vii 

St. Petersburg, viii 

Sarmatia: a vast country of eastern Europe. The power of the 

Sarmatians was destroyed by the Goths in the third century 

and they were merged with the Slavs, 39 
Saturn, the planet, 84, 86 
Scaliger, Julius (1484-1558): a Renaissance scholar, author of 

DC Causis Linguae Latinac, 143 


Schoolmen (or Scholastics), Schools, xiv, 4-5, 54, 74, 98-9, 122, 

143, 158, 166, 172-3, 183, 201, 233, 251 
Senate, the, 129 
Sextus Tarquimus (d. 496 B c.) : son of the last King of Rome 

His outrage on Lucretia brought about the ruin of the 

monarchy, 259-66 
Socimans. a sect not believing in the Trinity, founded by the 

Italian Protestant Socin (Lelio) (1525-62), 197 
Socrates (468-400 B c ) : Greek philosopher, 55 
Sophia (1630-1714)- Electress of Hanover, mother of George 1 

of England, vn 
Sophia Charlotte (1668-1705): daughter of the above, Electress 

of Brandenburg, and afterwards Queen of Prussia, a friend 

and student of Leibniz, vin 
Spinoza, Baruch (1632-77) : Dutch philosopher, author of Elhnti 

geometnco ordine demonstrata, vn, xm, 196, 242 
Stoics, 30, 143, 220 
Styx, 261 
Swammcrclam, John (1637-80) Dutch naturalist, 100 

Theodicy, xxxii, 56, 193-4, 2C M 2II 2 4 2 2 57-^7 

Thomas, Saint, see Aquinas 

Thrace, 265-6 

Torricelli, Evangehsta (1608-47) : Italian physicist and geometer, 

pupil of Galileo, 217 
Trinity, the, 159, 250 

Ultimate Origination of Things, xxxi, 32-41 

Valla, Laurentius (1405-1457): philologist and historian to the 

King of Spain, 257-62, 267 

Vallismeri, Antonio (1661-1730): Italian naturalist, 245-6 
Vienna, viii 
Virgil (70-19 B c ): Latin poet, author of the Aeneid, 250 

Worcester, Edward Stillingfleet, Bishop of (1635-99): his con- 
troversy with Locke originated in the anti-religious use to 
which Tolland in Christianity Not Mysterious turned some 
of Locke's views, 155, 157, 159, 160-2 

Zeno, born beginning of the fifth century B c Greek philosopher, 


AcciDENis, 3, 4, 2i<>, 223 
Affinity , 138 

Aggregation, ix, xm, xxi-n, 
xxv, 3, 32-3, 76-9, So, 82 -3, 

117. MO 
alff07)T'/)piov, 2O2 
Algebra, 233 
aXXo7\wTricu, 22O 
Analysis, xx f xxvin, \xxi, 180-8, 


Angels, 123, 125, 155, 256, 262 
Apperception, x-xi, xviii, 4, 23, 

146-8, 151, 153, 168-9, 174-5, 

Appetition, x, 5-6, 11, 17, 

21-2, 99, 137, 180 
Arithmetic, xix, xxvu, 27, 45, 

144-5, 1 08, HH, 198 
Astronomy, 108 
Atoms, xxi, 3, 98, 103, 117, 

134-7, 148, 152, 165, 172, 

209-10, 213 
Attraction, 102, 10^ 
Automatism, automaton, xvi, 

xxxi, 6, 15, 22, io(>, 122, 

124, 128-34 

Body, soul and, xv-xvn, 17, 22, 
51, 56, 85, 97, 104-6, no, 
114-15, 118, 122, 128, 136, 
149, 151, 159, 176, 105, 207, 

Bomtas extnnseca, 243 

Bourgeois, 83 

Brain, 195 

Brutes, xi, xxvii, 5, 8, 24, 86-7, 
100, no, 130-2, 145-6, 155, 
163, 165, 169. 174. 257 

Calculus, differential, vin 

Categories, xxvin 

Centres of force, xxii 

Chiaroscuio, 178 

Cohesion, 157 

Colour, 81, 244 

Conatus, 130 

Conception, 17-18, 25, 240 

Contingency, xx, 9, n, 26, 04, 

68-9, 71, 182, 210-11, 251 
Continuity, law of, xvn-xix, 

152, 150 

Continuum, 76, So, 98 
Contradiction, principle of, x, 

xx, 8, 182-3, IC >3 211, 251 
Conversions, 183-4 
Currency, 243 

Demonstrative knowledge, 24, 

1 86, 188-9, 235 
Determinism, xn, xxvi-xxvn 
Deus ex machma, 104, 115, 121, 


Development, 41 
Differential calculus, viii 
Dogmatism, xxvm-xxix 
Dreams, 83, 105, 121, 189-91 
Duration, 220, 223, 228 
Dynamics, xin-xv, xxiv, xxvi, 

xxxii, 194 

*K0e<m, 221 
Elective choice, 56 
Elements, xxi, 214, 240 
Energy, 135. 138-9 
Entelechy, 5-6, n, 14-16, 99 
Equilibrium, xiv 




Eternal truths, 8, 10-11, 24, 
33. 36, 46. 62, 72, 144, 170, 

234. 2 57 
Ether, 91, 203 
Ethics, xxv 
Extension, xiv, xxi-xxiv, 3, 55, 

80, 95-6, 98, 109, 117, 125-6, 

161, 202, 205, 214, 216, 218, 


Faculty, 129, 135, 158, 166-7, 

i?3. iSi 

Faith, 250 

Fanatics, 30 

Fatalism, 201 

Finite material universe, 224 

Fluid, 81, 117, 156 

Force, xiii-xv, xxi-xxiv, xxv, 
27, 88-96, 98-0, 106, 111-16, 
126, 133-4, J 94 202 > 208, 

Freedom, xii, xv-xvi, xxy- 
xxvi, xxxii, 58, 61, 64, 69, 
71, 106-7, 250-2, 257-67 

Genus, 161, 164 

Geomancy, 236 

Geometry, vii, xix, xxvi-xxvii, 
24, 27, 32, 35-7, 45, 48, 55, 
70, 76, 92, 144, 168, 178, 182, 
187-8, 190-1, 194, 198, 206, 
215, 223, 236, 251, 264 

Grace, 19, 29, 166, 193, 235 

Gravity, xxii, 35, 91, 123, 157, 
16*, 218 

Habit, xviii, 8, 170-1, 252 

History, 48 

Hypothetical necessity, 33, 58, 

propositions, 45-6 

Identical propositions, xx, 9, 

45, 79, 182-5 
Identity, 150 
of indiscernibles, 204, 206, 


Idols, 199, 202, 206 

Immediacy, of ideas, 185 

of sensation, 185 

Immediate experience, 190 
Immortality, xvi, 24, 56, 154-6 

160, 163, 1 66, 239 
Impenetrability, xxi 
Incomplete notions, xiii, 172, 

213, 216 
Indiscernibles, identity of, 204, 

206, 213-14 

Individuation, principle of, 215 
Induction, 143, 170, 187 
Inertia, xxi 
Innate ideas, xix, xxix, 146, 

1 68 

knowledge, 169 

principles, 144, 167 

truths, 1 68, 171 

Insensible perceptions, 152, 154 
Intellect, xxviii, 173 
Intelhgentia mundana, 197 

supramundana, 1978, 202 

Interaction, xii-xv, xxii, xxv 


Intrinsic denomination, 172 
Introspection, xxix 
Intuitive knowledge, 181-6, 

Invention, 187, 196 

Judgment, 175-6, 187 
Jurisprudence, 144 
Justice, 86, 258 

Kinetic energy, xiv 
Knowledge, demonstrative, 24, 
186, 188-9, 235 

innate, 1 69 

intuitive, 181-6, 188-9 

sensitive, 188-9 

Koival {vvotai, 143 

Laws of motion, 27, 37, 251 

of nature, 193, 202, 208 

Logarithms, 225 



Logic, viii, xi, xvii, xix-xx, 
xxiv-xxv, xxvh-xxviii, xxxi, 
24, 27, 182-91 

Lymph, 84-5 

Machine, xi, xiv, xxxi, 5, 14, 
18, 22, 40, 79, 81, 88, 98, 
roi-3, iof>, 121, 124-5, 127, 
129-33, I 4. I( > 2 . T 96, 203, 
208, 236, 241 

Magnetic rays, 217 

Martyrs, 30 

Mass, xx-xxn, 22, 89, 103, 1 06, 
109-11, 217 

Material universe, finite, 224-5 

Materialism, 55, 131,193,196,198 

Mathematical points, xxi 

principles of philosophy, 

193, 198 

Matter, 26, 96, 103, 140, 153, 
201, 217, 248 

all interconnected, 14, 156 
an incomplete being, 135 

-cannot think, 159-60, 

' r >5-7 

essentially an aggregate, 

- geometrical laws of, 37 

- gravitation of, 157, 162 
infinitely divided, 15, 156 

- - natural laws of, in 
not capable of perception, 

not eternal and necessary, 

216, 226 

not passive, xxi 

quantity of, 194, 209-10, 

sometimes without weight, 


Maxims, 188 
Mean science, 56 
Mechanics, xiv, xxvi, 35, 55, 

74, 80, 98, 108, 129, 165, 

229, 241 

metaphysical, 35 

Mechanism, 180 
Medicine, 241 

Metamorphosis, ib, 25, 138 
Metaphor, 176 
Metaphysical mechanics, 35 

points, xxi-xxii 

principles of philosophy. 

Metaphysics, vm, 25, 27, 36, 

45. 55. 74. 7 ( >. < So L 92, 95, 
98, 104, 107-8, 121, 144, 
161-2, 194, 204, 213, 215, 

*35* 2 4 
Metempsychosis, 16, 25, 100, 

155. 222 

Method of exclusions, 187 
Metonymy, 176 
Microscope, 50, 204, 240 
Mind, 30, 99, 167, 174 

and body, 112, 116, 161 

can give itself thoughts, 

finite, 209 

._^ nature of, xv--xx, xxiv 

not a tabula rasa, xxvi- 

xxix, 168-70 

perfection of, 234-5 

Minds, xxii, 23, 38, 133, 140, 1 59 
are unities, 21 

are whole parts, 40 

city of, xxv, 29, 86-7, roi 


distinguished from brute 

souls, x-xi, 8, 1 8, 24, 28-9, 

86-7, 99-100 

each a world apart, 107 

individual, xxv 

Miracle, xvi, 53, 63-4, 99, 105. 

116, 122-3, I2 7. T 5 8 l6 3. 

165-6, 193, 198, 203, 218 
Modality, 103 
Mode, 8 1 
Monad, ix-xi, xxiii-xxiv, xxvii 

3-20, 21-3, 28, 151, 214 
Moral laws, 229 
Morals, 144, 160-1, 166, 251 
Motion, laws of, 27, 37, 251 

perpetual, 192 

quantity of, xiv, 55, 88, 

96, 113, 118, 227 



Motive, 210-12 
Music, 30, 39, 223 

Natural, and supernatural, 

202- 3 

hght, 1 08 

Necessary truths, xix, xxvii, 8, 

n, 24, 72, 143-0, 168-70, 

182, 234 
Necessity, formal, 37 

hypothetical, 33, 58, 60 

material, 37 

mechanistic, xxv 

metaphysical, 33, 35-6, 


moral, xxvi, 210-1 1 

physical, 35 

Occult qualities, 163-4 
Optics, 178, 191 

Perception, 5, 103, 131, 137- 
40, 146, 173, 174-81, 188 

arid apperception, x, xviii, 

4-5, 23, 148, 175 

natural, 84 

of agreement and disagree- 
ment, 191 

Perceptions, 8, n, 15, 21, 126 

confused, 23 -4, 28, 85, 

123, 138-40 

conscious, xi, 5-7 

distinct, 12, 28 

internal, 105-0 

minute, 1 50 

of animals, 24 

unconscious, 5-7, 148-9 

Perfectihabiae, n 

Perfection, metaphysical, 38 

moral, 38 

physical, 38 

Perspective, 13, 175 

Petitio principi i, 171, 213 

Phenomena, xvii, 22, 46, 53, 
55, 68, 74, 76-82, 105, 108, 
ii2, 1 20-1, 126, 167 181, 
190-1, 243 

Physics, vn, xiii-xv, xx-xxiv, 
xxvi, xxxii, 25, 41, 45, 55, 
76, 81, 92, 108, 136, 152-3, 
i 6 1-2, 240-1 

Planets, 218 

Plenum, xxiii, 4, 14, 22, So, 
156, 210 

Pneumatics, 152-3 

Politics, 153, 251 

Possibility, xxvin, 62-4, 66, Og 

Potency, xiv-xv, 37, 173 

Predestination, xxvi, xxxii 

Pre-established haimony, xv, 
xxv-xxvi, 17-18, 22, 20, 
113-15, 128, 151, 190 

order, 193 

Preformation, 16, 24 

Probability, 189 

Prolepses, 143 

Psychology, xvii-xix, xxvii, 
xxix, xxxi 

Punctum saliens, 245 

Quantity of motion, xiv, 55, 
88-<}6, 113, 118, 227 

Rationalism, xx, xxviii-xxix 

Reductio ad absurdum, xn, 198 
Reflection, 8, 24, 146, 148-9, 

173-4, 181, 248 
Religion, 160-1, 166, 258 

Christian, 40 

natural, 192 

Reminiscence, Platonic theory 

of, 147, 171 
Resuscitation, 101 
Revelation, 29, 166 

Sagacity, 186-7 
Sceptics, 126, 163 
Self, the, xiii, xxiv, 8, 24 
Self-consciousness, 163 
Semina aeternitatis, 143 
Sensitive knowledge, 1 88-9 
Sensorium, 195, 201-2 
Sin, 258 

philosophical and theo- 
logical, 252-3 



Sophisms, 176, 210 

Soul, 23, 77, 84. 90, 144, 148, 

152, 153, 156, 188, 202 
a dominant entelechy, 16, 


- a little world, 171-2 

and body, xv xvii, 17, 22, 

5i 5^. S 5t 97. 104-0, no, 
114-15, 118, 122, 128, 130, 

149, 151. 159. *7 tJ . *95. 207. 

a substantial form, 7(1 

a true unity, 103 

- everything which has per- 
ceptions and apperceptions, (> 
immateriality of, 159-00, 
1 66, 192 

never separate, 154 

only God can hurt, 237 
-- represents the universe, 


- simple and indivisible, ix, 

Souls, 7, 15 

brute, x-xi, 5, 24, 100-1 

considered as automata, 


entelechies, 99 

natural laws in, in, 114 

rational, 8, 24, 28, 155 

Space, xxii-xxiv, xxxii, 4, 14, 

126, 135, 152, 161-2, 172, 

192, 194-5, 199-210, 215-28 
Species, xii, 62, 70, 72, 84, 105, 

no, 113, 158, 172 
Spontaneity, xxvm, 105, 120-1 
Subject and predicate, xii--xin, 

xvii, xxv-xxvi, 67, 71-3 
Substance, xxxi, 3, 4, 83, 126, 

146, 152, 205, 235 
general idea in both body 

and mind, 161 

God, 10, 257 

immaterial, 131, 103-4, 


- material, 163-4, 166 
nature of, xi-xiii, xiv, xv, 

XXV, 21 

Substance of the soul, 130, 139, 

primary, 26 

spiritual, 160, 103 

Substances, 6, 49, 54, 77, mo, 


all inter-connected, 84-5 

communication of, 07, 
105-6, 108-12, 115-10, 120 3, 

J 32- 3 
individual, xin, xv, 53, 

06, 70 

no interaction, 104 

real unities, xxiv, 71)- 80 

represent the universe, 13, 

17. 150 

simple, 17, 22, 99 
Substantial forms, 76-8, 80, 99, 

1 10 

terms, 80 

Sufficient reason, principle of, 

x, xx, xxvii-xxix, 8, 25, 32, 

194, 198, 200, 204, 209, 

211-13, 251 

Superhuman spirits, 10, 29, 50 
Supernatural, 203, 208, 227 
Syllogism, xx, xxxn, 182-5 
Synthesis, xxvni, 187 

Tabula rasa, x\vi-xxix, 55, 143, 

147, 169, 172-3 

Theology, natural, 144, 194, 225 
Time, xxn-xxiv, xxxii, 14, 126, 

161, 172, 199200, 206, 208-9, 

215-16, 220, 223-8, 257 
Traces, 63, 123, 223 
Traction, of atoms, 157 
Transcendental method, xxvii 
Transformations, 100-1 
Transient activity, 112 
Transmigration, 101 
Truths, contingent, 34 

essential, 33 

eternal, 33, 72, 170, 234 

innate, 168, 171 

metaphysical, 33 

necessary, xix, xxvii, 168- 

70, 182, 234 



Truths of experience, 170 
of fact, xx, xxviii, 9, 62, 

72, 182, 185, 191 
of reason, xx, xxviii, 9, 

182, 185, 191 
primary, 185 

universal, xix, 

xxviii, 170, 181 

Understanding, xxviii, 146, 170 
Universe, finite, 224 

Vacuum, xxiii, 157, 217, 220, 

Velocity, xviii, 90-6, 108, 119, 

221, 226 

Vis viva, xxi-xxiii 
Vision, 31, 68, 175, 267 
Void, 98, 121, 152, 156, 172, 

201, 208,210,214,216-17, 228 

Will, the, 211 See Freedom 
Zopyra, 143 







In Cloth Binding 

In Special Library Binding 

Abo Selected Volumes in Leather 



In each section of this list the volumes are arranged, as 
a general ride, alphabetically under the authors* names. 
Where authors appear in more than one section, a reference 
is given, viz.: (See also FICTION). The number at ike end 
of each item is the number of the volume in the series. 
Volumes obtainable in Leather are marked L 


Audubon tbe Naturalist, Life and Adventures of. By R. Buchanan. 601 
Baxter (Richard). Autobiography of. Edited by Rev. J. M. Lloyd 

Thomas. 868 

Beaconsfleld (Lord), Life of. By J. A. Fronde. 6CC 
Berlioz (Hector), Life of. Translated by Katharine F. Boult. 602 
Black well (Dr Elizabeth): Pioneer Work for Women. With an Introduc- 
tion by Mrs Fawcett. 667 
L BoBwell's Life of Johnson. 2 vols. 1-2 

(See ato/> TRAVEL) 

Browning (Robert), Life of. By E. Dowden. 701 
Buxton (Sir Thomas i'owell), Memoirs of. Edited by Charles Buxton. 

Introduction by Lord Buxton. 773 

I< Byron's Letters. Introduction by Andr6 Maurois. 931 
Carey (William), Life of: Shoemaker and Missionary. 395 
Carlylo's Letters, and Speeches of Cromwell. 3 vols. 266-8 
,, Reminiscences. 875 

(See also EBB AYS and HISTORY) 
JL Cellini's (Benvenuto) Autobiography. 51 
Gibber's (Colley) An Apology for his Life. 668 
Constable (John). Memoirs of. By C. R. Leblie, R.A. 563 
Cowper (William), Selected Letters of. Intro, by W. Hadley, M.A. 774 

De Qulncey'a Reminiscences of the Lake Poets. Intro, by E. Rhys. 163 

(See also ESSAYS) 

De Retz (Cardinal): Memoirs. By Himself. 2 vols. 735-6 
Evelyn's Diary. 2 vols. Introduction by O. W. E. Russell. 220-1 
Forster's Life of Dickens. Intro, by O. K. Chesterton. 2 vols. 781-2 

(See also FICTION) 
Fox (George), Journal of. Text revised by Norman Penney, F.S.A. 

Introduction by Rufus M. Jones, LL.D. 754 
Franklin's (Benjamin) Autobiography. 316 
Fronde's Life of Benjamin Disraeli, Earl of Beaconafleld. 666 
L OaskeU's (Mrs) Life of Charlotte Bronte. Intro, by May Sinclair. 318 
Qibbon (Edward), Autobiography of . Intro, by Oliphant Smeaton. 611 

(See also HIHTOKY) 

Gladstone, Life of. By G. W. E. Russell ('Onlooker'). 661 
Hastings (Warren), Life of. By Capt. L. J. Trotter. 452 
Helps' (Sir Arthur) Life of Columbus. 332 
Hodson. of Hodson's Horse. By Capt. L. J. Trotter. 401 
Holmes' Life of Mozart. Introduction by Ernest Newman. 564 
Houghton's Life and Letters of Keats. Introduction by Robert Lynd. 801 
Hutchinson (Col.) Memoirs of. Intro. Monograph by F. P. G. Guizot. 317 
living's Life of Mahomet. Introduction by Professor E. V. Arnold. 513 
Johnson's Lives of the Poets. Intro, by Mrs Archer -Hind, M.A. 770-1 
Lamb (Charles), Letters of. 2 vols. 342-3 

Lewes' Life of Goethe. Introduction by Havelock Ellis. 260 
Lincoln (Abraham), Life of. By Henry Bryan Binus. 783 

(Se-e also ORATORY) 

Lockhart's Life of Robert Burns. Introduction by E. Rhys. 150 
L Life of Napoleon. 3 

Life of Sir Walter Scott (abridged). 55 

Mazzinl, Life of. By Bolton King, M.A. 562 [Newcastle. 722 

Newcastle (First Duke of), Life of, and other writings by the Duchess of 
--- By Capt. LUJ. Trotter 396 


BIOGRAPHY continued 

Pepys' Diary. Lord Braybrooke's 1854 ed. 2 vols. 53-4 

Plutarch's Lives of Noble Greeks and Romans. Dry den 'a Translation. 
Revised, with Introduction, by Arthur Hugh dough. 3 vola. 407-0 

Rousseau, Confessions of. 3 vole. 859-60 

Scott's Lives of the Novelists. Introduction by George Salntsbury. 331 
(See also FICTION and POETHT) 

Seebohin (Frederic): The Oxford Reformers. With a Preface by Hugh 
E. Soebohm. 665 

Smeaton's A Life of Shakespeare, with Criticisms of the Plays. 514 

Southey'8 Life of Nelson. 52 

Strickland's Life of Queen Elizabeth. 100 

Swift's Journal to Stella. Newly deciphered and edited by J. K. Moor- 
head. Introduction by Sir Walter Scott. 757 

Vasari's Lives of the Painters. Trans, by A. 13. Hinds. 4 vols. 784-7 

Voltaire's Life of Charles XII. Introduction by Ht. Hon. J. Burns. 270 

Walpole (Horace), Selected Letters of. Intro, by W. Hadley, M.A. 775 

Wellington, Life of. By G. R. Gleiff. 341 

Wesley's Journal. 4 vols. Intro, by Rev. F. W. Macdonald. 105-8 

Woolman's (Johu> Journal and Other Papers. Introduction by Vida D. 
Scudder. 402 


jEschylus* Lyrical Dramas. Translated by Professor J. S. Blaokie. 62 
Aristophanes' The Frogs, The Clouds, The Thcszuophorians. 516 

The Acharnians, The Kniphts, and The Birds. Frere's 

Translation. Introduction by John P. Maine. 344 
Aristotle's Politics. Introduction by A. D. Lindsay. 605 

Poetics, etc., and Demetrius on Style, etc. Edited by 

(See also PHILOSOPHY) [Rev. T. A. Mozon. 901 

Caesar's The Gallic War and Other Commentaries. Translated by W. A. 

MoDevitte. 702 

Cicero's Essays and Select Letters. Intro. Note by de Quinoey. 345 
L Epictetus, Moral Discourses, etc. Elizabeth Carter's Translation. Edited 

by W. II. D. Rouse, M.A. 404 

Euripides' Plays in 2 vols. Introduction by V. R. Reynolds. Translated 
by M. Wodhull and R. Potter, with Shelley's 'Cyclops* and Dean 
Milman's 'Bacchanals.' 63, 271 

Herodotus. Rawlinsjon's Translation. Edited, with Introduction, by 
E. H. Blakeney, M.A., omitting Translators' Original Essays, and 
Appendices. 2 vols. 4056 

L Homer's Iliad. Lord Derby's Translation. 453 
L Odyssey. William Cowper's Translation. Introduction by Miss 

F. M. Stawcli. 454 

Horace. Complete Poetical Works. 515 
Hutchinson's ( W. M. L.) The Muses' Pageant. Vols. I, II, and ITT. 581. 

606, and 671 
Livy*s History of Rome. Vols. I-VI. Translated by Rev. Canon Roberts. 

603, 669, 670, 749. 765, and 756 

Lucretius: On the Nature of Things. Translated by W. E. Leonard. 750 
L Marcus Aureliuft* Meditations. Introduction by W. H. D. Rouse. 9 
Plato's Dialogues. 2 vols. Introduction by A. D. Lindsay. 456-7 
L Republic. Translated, with an Introduction, by A. D. Lindsay. 64 
Plutarch's Moralia. 20 Essays translated by Philemon Holland. 665 
Sophocles' Dramas. Translated by Sir G. Young, Bart. 114 
Tbuoydides' Peloponncsian War. Crawley's Translation. 455 
L Virgil's jEneid. Translated by E. Fairfax -Taylor. 161 

Eclogues and Georgics. Translated by T. F. Royds, M.A. 222 
Xenophon's Cyropeedia. Translation revised by Miss F. M. Stawell. 672 


L Anthology of Prose. Compiled and Edited by Miss S. L. Edwards. 075 
Arnold's (Matthew) Essays. Introduction by G. K. Chesterton. 115 
Study of Celtic Literature, and other Critical Essays, 

with Supplement by Lord Strangford, etc. 4*5 8 
(See also POETRY) 
L Bacon's Essays. Introduction by Oliphant Smeaton. 10 

(See alto PHILOSOPHY) 

Bagehot's Literary Studies. 2 vols. Intro, by George Sampson. 620-1 
L Brown's Rab and his Friends, etc. 116 

Bnrke's Reflections on the French Revolution and contingent Essays 
Introduction by A. J. Grieve, M.A. 460 {See afeoORA 


Canton's (William) The Invisible Playmate, W. V., Her Book, and In 
(Sfce also FOB YOUNG PEOPLE) [Memory of W. V. 566 

Carlyle's Essays. 2 vols. With Notes by J. Russell Lowell. 703-4 

Past and Present. Introduction by R. W. Emerson. 608 
Sartor Resartna and Heroes and Hero Worship. 273 


Castigli one's The Courtier. Translated by Sir Thomas Hoby. Intro- 
duction by W. H. D. Boose. 807 

Century of Essay*, A. An Anthology of English Essayists. 653 
Chesterfield's (Lord) Letters to his Son. 823 
L Chesterton's (G. K.) Stories, Essays, and Poems. 913 

Coleridge's Biographla Literaria. Introduction by Arthur Symons. 11 
Essays and Lectures on Shakespeare, etc. 162 

(See also POKTRY) 

De la Mare's (Walter) Stories, Essays, and Poems 940 (Ready Spring 1938) 

De Qninoey's (Thomas) Opium Eater. Intro, by Sir G. Douglas. 223 

The English Mall Coach and Other Writings. 

Introduction by S. Hill Burton. 609 
(See also BIOGRAPHY) 

Dryden's Dramatic Essays. With an Introduction by W. H. Hudson. 568 
Elyot's Oouernour. Intro, and Glossary by Prof. Foster Watson. 227 
L Emerson's Essays. First and Second Series. 12 
L ,, Nature, Conduct of Life, Essays from the 'Dial.* 322 

Representative Men. Introduction by E. Rhys. 279 
Society and Solitude and Other Essays. 567 

(See also POETRY) 

Florio's Montaigne. Introduction by A. R. Waller, M.A. 3 vols. 440-2 
Froude's Short Studies. Vols. I and II. 13, 705 


Gilflllan's Literary Portraits. Intro, by Sir W. Robertson Niooll. 343 
Goethe's Conversations with Eokermann. Intro, by Havolock Ellis. 

851. (See also FICTION and POETRY) 
Goldsmith's Citizen of the World and The Bee. Intro, by R. Church. 902 

(See also FICTION and POETRY) 
Hamilton's The Federalist. 519 

Hazlitt's Lectures on the English Oomio Writers. 411 
Shakespeare's Characters. 65 

Spirit of the Age and Lectures on English Poeta. 459 
Table Talk. 321 

Plain Speaker. Introduction by P. P. Howe. 814 
L Holmes* Autocrat of the Breakfast Table. 66 
Poet at the Breakfast Table. 68 
,, Professor at the Breakfast Table. 67 
L Hudson's (W. H.) A Shepherd's Life. Introduction by Ernest Rhys. 926 

Hunt's (Leigh) Selected Essays. Introduction by J. B. Priestley. 29 
i, Huxley's (Aldous) Stories, Essays, and Poems. 935 
Jrving*s Sketch Book of Geoffrey Crayon. 117 

Lander's Imaginary Conversations and Poems: A selection. Edited 

with Introduction by Havelock Ellis. 890 
L Lamb's Essays of Ella. Introduction by Augustine Birrell. 14 

Lowell's (James Russell) Among My Books. 607 

Macaulay's Essays. 2 vole. Introduction by A. J. Grieve, M.A. 225-6 
Miscellaneous Essays and The Lays of Ancient Rome. 439 

(See also HISTORY and ORATORY) 
Machiavelli'B Prince. Special Trans, and Intro, by W. K. Marriott. 280 

(See also HISTORY) 

Martinengo-Cesaresco (Countess) : Essays in the Study of Folk-Songs* 673 
Mazzini'e Duties of Man, etc. Introduction by Thomas Jones, M.A. 224 
Milton's Areopagitica, etc. Introduction by Professor O. E. Vaughan. 795 

(See also POBTRY) 

L Mltford's Our Village. Edited, with Introduction, by Sir John Squire. 927 
Montagu's (Lady) Letters. Introduction by R. Brfmley Johnson. 69 
Newman's On the Scope and Nature of University Education, and a 
paper on Christianity and Scientific Investigation. Introduction by 
(See also PHILOSOPHY) [Wilfred Ward. 723 

Osborne's (Dorothy) Letters to Sir William Temple. Edited and con- 
notated by Judge Parry. 674 

Penn's The Peace of Europe. Some Fruits of Solitude, etc. 724 
Prelude to Poetry, The. Edited by Ernest Rhys. 789 

' Discourses. Introduction by L. March Phillip pa. 119 


i. Rhys's New Book of Sense and Nonsense. 813 

Rousseau's Emile. Translated by Barbara Foxley. 518 


L Ruskin's Crown of Wild Olive and Cestus of Aglaia. 323 
Elements of Drawing and Perspective. 217 
Ethics of the Dust. Introduction by Grace Rhys. 282 
Modern Painters. 5 vols. Introduction by Lionel Gust. 208-12 
Pre-RaphaeUtism. Lectures on Architecture and Painting, 
Academy Notes, 1855-9, and Notes on the Turner Gallery. 
Introduction by Laurence Bin yon. 218 
L Sesame and Lilies, The Two Paths, and The King of the Golden 

River. Introduction by Sir Oliver Lodge. 219 
., Seven Lamps of Architecture. Intro, by Selwyn Image. 207 
Stones of Venice. 3 vols. Intro, by L. March Phillipps. 213-15 
Time and Tide with other Essays. 450 

Unto This Last, The Political Economy of Art. 216 

Spectator, The. 4 vols. Introduction by G. Gregory Smith. 164-7 
Spencer's (Herbert) Essays on Education. Intro, by O. W. Eliot. 504 
Sterne's Sentimental Journey and Journal and Letters to Eliza. Intro. 
(See also FICTION) [by George Salntsbury. 796 

L Stevenson's In the South Seas and Island Nights' Entertainments. 769 
L Yirginibus Puerisque and Familiar Studies of Men and 

(See also FICTION, POETRY, and TRAVEL) [Books. 765 

Swift's Tale of a Tub, The Battle of the Books, etc. 347 

Table Talk. Edited by J. O. Thornton. 906 

Taylor's (Isaac) Words and Places, or Etymological Illustrations of 
History, Ethnology, and Geography. Intro, by Edward Thomas. 517 
Thackeray's (W. M.) The English Humourists and The Four Georges. 
Introduction by Walter Jerrold. 010 

(See also FICTION) 
L Thoreau's Walden. Introduction by Walter Raymond. 281 

Trench's On the Study of Words and English Past and Present. Intro- 
duction by George Sampson. 788 
Tytlor's Essay on the Principles of Translation. 168 
Walton's Compleat Angler. Introduction by Andrew Lang. 70 


Aimard's The Indian Scout. 428 

L Ainsworth's (Harrison) Old St. Paul's. Intro, by W. E. A. Axon. 522 
The Admirable Crichton. Intro, by E. Rhys. 804 

L ,. The Tower of London. 400 

Windsor Castle. 709 

Rookwood. Intro, by Frank Swinnerton. 870 

American Short Stories of the Nineteenth Century. Edited by John 

Cournos. 840 
L Austen's (Jane) Emma. Introduction by R. B. Johnson. 24 

Mansfield Park. Introduction by R. B. Johnson. 23 

L Northanger Abbey and Persuasion. Introduction by 

R. B. Johnson. 25_ _ --,.. 

. B. Johnson. 22 

Pride and Prejudice. Introduction by B 
Sense and Sensibility. Intro, by R. B. 

Johnson. 21 

Balzac's (Honore de) Atheist's Mass. Preface by George Saintsbury. 229 
.. Catherine de Medici. Introduction by George 

Saintsbury. 419 
M Christ in Flanders. Introduction by George 

Salntsbury. 284 

Cousin Pons. Intro, by George Saintsbury. 463 
Eugenie Grandet. Intro, by George Saintsbury. 169 
Lost Illusions. Intro, by George Saintsbury. 656 
Old Goriot. Introduction by George Salntsbury. 170 
The Cat and Racket, and Other Stories. 349 
The Chouans. Intro, by George Saintsbury. 285 
The Country Doctor. Intro. George Saintsbury. 530 
, The Country Parson. 686 
The Quest of the Absolute. Introduction by George 

Saintsbury. 286 

The Rise and Fall of Cesar Birotteau. 596 
The Wild Ass's Skin. Intro, by George Saintsbury. 26 
Ursula Mirouet. Intro, by George Saintsbury. 739 

FICTION continued 

Barbusse's Under Fire. Translated by Fitcwater Wray. 798 
L Bennett's (Arnold) The Old Wives' Tale. 919 
L Blackmore's (R. D.) Lorna Doone. 304 

L Borrow'a Lavengro. Introduction by Thomas Secoombe. 119 
L Romany Rye. 120 (See also TRAVEL) 
L Bronte's (Anne) The Tenant of Wildfell Hall and Agnes Grey. 685 
L (Charlotte) Jane Byre. Introduction by May Sinclair. 287 
L ,. Shirley. Introduction by May Sinclair. 288 

The Professor. Introduction by May Sinclair. 417 

L , Villette. Introduction by May Sinclair. 351 

L (Emily) Wuthering Heights. 243 

Burney's (Fanny) Evelina. Introduction by R. B. Johnson. 352 
Butler** (Samuel) Erewhon and Erewhon Revisited. Introduction by 

Desmond MacCarthy. 881 
The Way of All Flesh, introduction by A. J. Hoppe. 895 

, ) The Woman in White. 464 

L Conrad's Lord Jim. Introduction by R. B. Cunninghame Graham. 925 
L Converse's (Florence) Long Will. 328 

Dana's (Richard H.) TwoYears before the Mast. 588 
Daudet's Tartarin of Tarascon and Tartarin of the Alps. 423 
Defoe's Fortunes and Misfortunes of Moll Flanders. Intro, by G. A. Aitken. 
Captain Singleton. Introduction by Edward Garnett. 74 [837 
Journal of the Plague Year. Introduction by G. A. Aitken. 289 
Memoirs of a Cavalier. Introduction by G. A. Aitken. 283 

CHARLES DICKENS' WORKS. Bach volume with an Introduction by G. K. 


L American Notes. 290 L Little Dorrit. 293 

L Barnaby Rudge. 76 L Martin Chuzzlewit. 241 

L Bleak House. 236 L Nicholas Nickleby. 238 

L Child's History of England. 291 L Old Curiosity Shop. 173 
L Christmas Books. 239 L Oliver Twist. 233 

L Christmas Stories. 414 L Our Mutual Friend. 294 

L, David Copperfield. 242 L Pickwick Papers. 235 

s, Dombey and SOD. 240 Reprinted Pieces. 744 

Edwin Drood. 725 Sketches by Boz. 237 

& Great Expectations. 234 L Tale of Two Cities. 102 

Hard Times. 292 L Uncommercial Traveller. 536 

Disraeli's Coningsby. Introduction by Langdon Davies. 535 
Dobtoev sky's (Fyodor) Crime and Punishment. Introduction by 

Laurence Irving. 501 
Letters from the Underworld and Other Tales. 

Translated by O. J. Hogarth. 654 
.. Poor Folk and The Gambler. Translated by C. J. 

Hogarth. 711 

The Possessed. Introduction by J. Mlddleton 

Murry. 2 vols. 861-2 f533 

Prison Life In Siberia. Intro. by Madame Stepniak. 

The Brothers Karamazov. Translated by Con- 

stance Garnett. 2 vote. 802-3 
The Idiot. 682 
Du Maurier's (George) Trilby. Introduction by Sir Gerald du Maurier. 

With the original illustrations. 863 

Dumas' Black. Tulip. Introduction by Ernest Rhys. 174 
Chicot the Jester. 421 

Le Chevalier de Maison Rouge. Intro, by Julius Bramont. 614 
Marguerite de Valois ('La Reine Margot'). 326 
The Count of Monte Criato. 2 vols. 393-4 
The Forty-Five. 420 
The Three Musketeers. 81 
The Vicomte de Bragelonne. 3 vols. 593-5 
Twenty Years After. Introduction by Ernest Rhys. 175 
Edgar's Cressy and Poictiers. Introduction by Ernest Rhys. 17 
Runnymede and Lincoln Fair. Intro, by L. K. Hughes. 320 


Edgeworth's Castle Rackrent and The Absentee. 410 
I. Eliot's (George) Adam Bede. 27 
Felix Holt. 353 
Middlemarch. 2 vols. 854-5 

L Mill on the Floss. Intro. Sir W. Robertson Nicoll. 326 

L Romola. Introduction by Rudolf Dircks. 231 

L ,. Scenes of Clerical Life. 468 


FICTION continued 

F.liot's (George) Silas Marner. Introduction by Annie Matheaon. 121 
I, English Short Stories. An Anthology. 743 

Erclunann-Chatrian's The Conscript and Waterloo. 354 

,, The Story of a Peasant. Translated by O. J 

Hogarth. 2 vols. 706-7 
Fenimore Cooper's The Doorslayer. 77 

The Liant of the Mohicans. 79 

I, ., The Pathfinder. 78 

,. The Pioneers. 171 

The Prairie. 172 

Ferrior's (Susan) Marriage. Introduction by H. L. Morrow. 816 
Fielding's Amelia. Intro, by George Saintsbury. 2 vols. 852-3 

Jonathan Wild, and The Journal of a Voyage to Lisbon. 

Introduction by George Saintsbury. 877 

Joseph Andrews. Introduction by George Saintsbury. 467 
.. Tom Jones. Intro, by George Saintsbury. 2 vols. 355-6 
Flaubert's Madame Bovary. Translated by Eleanor Marx-Aveliug. 

Introduction by George Saintabury. 808 
Salammbo. Translated by J. S. Chartres. Introduction by 

Professor F. C. Green. 869 
French Short Stories of the 19th and 20th Centuries. Selected, with 

an Introduction by Professor F. C. Green. 896 
L Galsworthy's (John) The Country House. 917 

Gait's Annals of a Parish. Introduction by Baillie Macdonald. 427 
GaskelTs (Mrs) Cousin Phillis, etc. Intro, by Thos. Seccombe. 615 
I, ,. Cranford. 83 

Mary Barton. Introduction by Thomas Seccombe. 598 
North and South. 680 

Sylvia's Lovers. Intro, by Mrs Elite Chadwick. 624 

Gleig's (G. R.) The Subaltern. 708 
Goethe's Wilhelxn Meister. Carlyle's Translation. 2 vols. 599-600 

(.SVe also ESSAYS and POETRT) 
Gogol's (Nlcol) Dead Souls. Translated bv O. J. Hogarth. 726 

Tares Bulba and Other Tales. 740 
L Goldsmith's Vicar of Wakefleld. Introduction by J. M. D. 295 

(See also ESSAYS and POETRY) 

Goncharov's Oblomov. Translated by Natalie Duddington. 878 
Gorki's Through Russia. Translated by C. J. Hogarth. 741 
Harte's (Bret) Luck of Roaring Camp and other Tales. 681 
Hawthorne's The House of the Seven Gables. Intro, by Ernest Rhys. 176 
L ,. The Scarlet Letter. 122 

The Blithedalo Romance. 592 

The Marble Faun. Intro, by Sir Leslie Stephen. 424 
I, Twice Told Tales. 531 


JL Hugo's (Victor) Les Miserables. Intro, by S. R. John. 2 vols. 363-4 
L Notre Dame. Introduction by A. C. Swinburne. 422 

Toilers of the Sea. Introduction by Ernest Rhys. 509 

Italian Short Stories. Edited by D. PettoeUo. 876 
James's (G. P. R.) Richelieu. Introduction by Rudolf Dircks. 357 
L James's (Henry) The Turn of the Screw and The Aspern Papers. 912 

Kingsley's (Charles) Alton Locke. 462 

L. Hereward the Wake. Intro, by Ernest Rhys. 29tt 

i, ,, Hypatia. 230 

L ,. Westward Ho 1 Introduction by A. G. Grieve. 20 

Yeast. 611 

(Henry) Geoffrey Hamlyn. 416 
Ravenshoe. 28 

L Lawrence's (D. H.) The White Peacock. 914 

Lever's Harry Lorrequer. Introduction by Lewis Melville. 177 
L Loti's (Pierre) Iceland Fisherman. Translated by W. P. Balnea. 920 
L Lover's Handy Andy. Introduction by Ernest Rhys. 178 
L Lytton's Harold. Introduction by Ernest Rhys. 15 
L ., Last Days of Pompeii. 80 

.. Last of the Barons. Introduction by R. G. Watkin. 18 
Rienzi. Introduction by E. H. Blakeney, M.A. 532 
(See also TRAVEL) 
MacDonald's (George) Sir Gibble. 678 

(See also ROMAKOB) [(Mrs Hinkson). 374 

Manning's Mary Powell and Deborah's Diary. Intro, by Katherine Tynan 
., Sir Thomas More. Introduction by Ernest Rhys. 19 

FICTION continued 

Marryat's Jacob Faithful. 618 

L ,, Mr Midshipman Easy* Introduction by R. B. Johnson. 82 
Percival Keene. Introduction by R. Brimley Johnnon. 358 
M Peter Simple Introduction by R. Brixnley Johnson. 232 
The mug's Own. 680 
L Maugham's (Somerset) Cakes and Ale. 932 

Maupassant's Short Stories. Translated by Marjorle Laurie. Intro- 
duction by Gerald Gould. 907 

Melville's (Herman) Moby Dick. Introduction by Ernest Rhys. 179 
Omoo. Introduction by Ernost Rhys. 297 

Typee. Introduction by JErm-st If bys. 180 

L Meredith's (George) The Ordeal of Richard Feverol. 016 

Merixnee's Carmen, with Provost's Manon Lescaut. Introduction by 

Philip Henderson. 834 
Mlckiewicjs's (Adam) Pan Tadense. 842 
L Moore's (George) Esther Waters. 933 

Mulock's John Halifax, Gentleman. Introduction by J. Shaylor. 1 23 

Neale's (J. M.) The Fall of Constaninqple. 655 

Paltook's (Robert) Peter Wilkins; or. The Flying Indians. Introduction 

by A. H. Sullen. 676 

Pater's Marina the Epicurean. Introduction by Osbert Burdett. 903 
Peacock's Headlong Hall and Nightmare Abbey. 327 
li Poe's Tales of Mystery and Imagination. Intro, by Padraio Colum. 338 

(See alto POETRY) 
Provost's Manon Lescaut, with Merimee's Carmen. Introduction by 

Philip Henderson. 834 
L Priestley's Angel Pavement. 938 

Pushkin's (Alexander) The Captain's Daughter and Other Tales. Trans. 

by Natalie Duddtngton. 898 

QuiUer-Couch's (Sir Arthur) Hetty Wesley. 864 [2 vote. 865-6 

Radcliffe's (Ann) Mysteries of Udolpho. Intro, by R. Austin Freeman. 

L Reade's (O.) The Cloister and the Hearth. Intro, by A. C. Swinburne. 29 

Reade's (O.) Peg Wofflngton and Christie Jobnstone. 299 

Richardson's (Samuel) Pamela. Intro, by G. Saintsbury. 2 vols. 683-4 

Clarissa. Intro, by Prof. W. L. Pbelps. 4 vois. 


Russian Authors, Short Stories from. Trans, by R. S. Townsond. 768 
Sand's (George) The Devil's Pool and Francois the Waif. 634 
Scbeffel's Kkkohard: a Tale of the Tenth Century. 629 
Scott's (Michael) Tom Cringle's Log. 710 

Abbot, The. 124 L Ivanhoe. Intro, by Ernest Rhys. l 

Anne of Geierstein. 125 L. Kenilworth. 135 

I. Antiquary. The. 126 L Monastery. The. 136 

Black Dwarf and Legend of Old Mortality. 137 

Montrose. 128 Peveril of the Peak. 133 

Bride of Lammermoor. 129 Pirate, The. 139 

Castle Dangerous and The Snr- Quentin Durward. 140 

geon's Daughter. 130 x. Redgauntlet. 141 

Count Robert of Paris. 131 x, Rob Roy. 1 42 

L Fair Maid of Perth. 132 St. Ronan'a Well. 143 

Fortunes of Nigel. 71 Talisman. The. 144 

L Guy Mannering. 133 L Waverley. 76 

L Heart of Midlothian, The. 134 L Woodstock. Intro, by Edward 
Highland Widow and Betrothed. 127 Garnett. 72 

(See, also BIOGRAPHY and POETRY) 
Shchedrln'B The Golovlyov Family. Translated by Natalie Duddington. 

Introduction by Edward Garnett. 908 
Shelley's (Mary Wollstoneoaaft) Frankenstein. 616 
Sheppard's Charles Auohester. Intro, by Jessie M. Middjeton. 506 
Bienktewicz (Henryk). Tales from. Edited by Monica M. Gardner. 871 
Shorter Novels, Vol. I. Elizabethan and Jacobean. Edited by Philip 

Vol.*!!. Jacobean and Restoration. Edited by Philip 

Henderson. 841 

Vol. III. Eighteenth Century (Beokford's Vathek, 

Walpole's Castle of Otranto, and Dr. Johnson's 

Smollett's Peregrine Pickle. 2 vole. 838-9 JRamelAs). 866 

Roderick Random. Introduction by H. W. Hodges. 790 
L Sterne's Tristram Shandy. Introduction by George SainUbury. 617 
(See alto ESSAYS) 


FICTION continued 

L Stevenson's Dr JekyU and Mr Hyde. The Merry Men, and Other Tales 
L The Master of Ballantrae and The Black Arrow. 764 [767 

L Treasure Inland and Kidnapped. 763 

St Ives. Introduction by Ernest Rhys. 904 

(See also ESSAYS. POETRY, and TRAVEL) 
Surtees* .Tarrocks' Jaunta and Jollities. 817 

L Tales of Detection. Edited, with Introduction, by DorothyL. Sayen. 928 
Thackeray's Rose and the Rinr and other stories. Intro. by Walter Jerrold. 
L Esmond. Introduction by Walter Jerrold. 73 [369 

Newcomes. Introduction by Walter Jerrold. 2 vols. 466-6 

Pendennis. Intro, by Walter Jerrold. 2 vols. 426-6 

Roundabout Papers. 687 

L Vanity Fair. Introduction by Hon. Whitelaw Reid. 298 

Virginians. Introduction by Walter Jerrold. 2 role. 607-8 

(See also ESSAYS) 

L Tolstoy's Anna Karenina. Trans, by Rochelle 8. Townsend. 2 rota. 612-13 
Childhood, Boyhood, and Youth. Trans, by C. J. Hogarth. 501 
Master and Man, and other Parables and Tales. 469 
., War and Peace. 3 vote. 525-7 
Trollope's (Anthony) Barcheeter Towers. SO 
Dr. Thome. 360 

Framley Parsonage. Intro, by Ernest Rhys. 181 

The Golden Lion of Oranpere. Introduction by 

Sir Hugh Walpole. 761 

Chronicle of Barset. 


M The Last Chronicle of Barset. 2 vole. 391-2 

Phineas Finn. Intro, by Sir Hugh Walpole. 2 role, 

The Small House at Afflngton. 361 1832-3 

The Warden. Introduction by Ernest Rhys. 182 
Turgenev'H Fathers and Sons. Translated by O. J. Hogarth. 742 

. . . . 

Liza. Translated by W. R. S. Ralston. 677 

^Virgin Soil. _ Translated by Rochelle S. Townsend. 628 
E Wes's"(H:^7rThe^mie"Maohineand The Wheels of Chance. 915 

Voltaire's Candide and Other Tales. _ _ _ 
: Walpole's (Hugh) Mr Perrin and Mr Traill. 

. . . 

Whyte-Melville's The Gladiators. Introduction by J. Mavrogordato. 623 
Wood's (Mrs Henry) The Channinga. 84 
Yonge's (Charlotte M.) The Dove in the Eagle's Nest. 329 

The Heir of Redclyffe. Intro. Mrs Meynell. 362 


Zola's (Exnile) Germinal. Tanslated by Havelook Ellis. 897 

Anglo-Saxon Chronicle. The. Translated by James Ingram. 624 
Bede's Ecclesiastical History, etc. Introduction by Vida D. Soudder. 479 
Burnet's History of His Own Times. 85 
L Carlyle's French Revolution. Introduction by H. Belloo. 2 vols. 31-2 

(See alto BIOORAPHY and ESSAYS) 

L Creasy's Decisive Battles of the World. Introduction by E. Rhys. 300 
De JoinriUe (See Villehardouin) 

Duruy's (Jean Victor) A History of France. 2 vols. 737-8 
Finlay*s Byzantine Empire. 33 

Greece under the Romans. 185 

Fronde's Henry VIII. Intro, by Llewellyn Williams, M.P. 3 vols. 372-4 
Edward VI. Intro, by Llewellyn Williams. M.P.. B.O.L. 376 
Mary Tudor. Intro, by Llewellyn Williams, M.P., B.O.L. 477 
History of Queen Elizabeth's Reign. 5 vols. Completing 

Fronde's 'History of England,' in fo vols. 683-7 
(See also ESSAYS and BIOGRAPHY) 

Gibbon's Decline and Fall of the Roman Empire. Edited, with Introduc- 
tion and Notes, by Oliphant Smeaton, M.A. 6 vols. 434-6, 474-6 

(See also BIOGRAPHY) 

Green's Short History of the English People. Edited and Revised by 
L. Cecil Jane, with an Appendix by R. P. Farley, B.A. 2 vols. 727-8 
Grote's History of Greece. Intro, by A. D. Lindsay. 12 vols. 186-97 
Hallam's (Henry) Constitutional History of England. 3 vols. 621-3 
Holinshed's Chronicle as used in Shakespeare's Plays. Introduction by 

Professor Allardyce Nicoll. 800 
Irvine's (Washington) Conquest of Granada. 478 

(See alto ESSAYS and BIOGRAPHY) 

Josephus* Wars of the Jews. Introduction by Dr Jacob Hart. 712 
L Maca olay's History of England. 3 vols. 34-6 
(See also ESSAYS and ORATORY) 

HISTORY continued 

Maine's (Sir Henry) Ancient Law. 734 

Merivale's History of Home. (An Introductory vol. to Gibbon.) 433 

Mignet's <F. A. M.) The French Revolution. 713 

Milman's History of the Jews. 2 Tola. 377-8 

Mommsen's History of Rome. Translated by W. P. Dick&on, LL.D. 

With a review of the work by E. A. Freeman. 4 vote. 542-5 
L Motley's Dutch Republic. 3 vote. 86-8 

Parkman's Conspiracy of Pontlao. 2 vole. 302-3 

Paston Letters, The. Based on edition of Knight. Introduction by 

Mrs Archer-Hind, M.A. 2 vols. 752-3 

Pilgrim Fathers, The. Introduction by John Maaefleld. 480 
L Pinnow's History of Germany. Translated by M. R. Brailsford. 929 
Political Liberty, The Growth of. A Source-Book of English History. 

Arranged by Ernest Rhys. 745 

Prescott'a Conquest of Mexico. With Introduction by Thomas Secoombe, 
M.A. 2 vols. 397-8 

,. Conquest of Pern. Intro, by Thomas Secoombe, M.A. 301 
Slsmondi's Italian Republics. 250 

Stanley's Lectures on the Eastern Church. Intro, by A. J. Grieve. 251 
Tacitus. Vol. I. Annals. Introduction by E. H. Blakeney. 273 

m Vol. II. Agrlcola and Germania. Intro, by E. H. Blakeney. 274 
Thierry's Norman Conquest. Intro, by J. A. Price, B.A. 2 vols. 198-9 
Villehardouin and De Join vl lie's Chronicles of the Crusades. Translated, 

with Introduction, by Sir F. Marzials, C.B. 333 
Voltaire's Age of Louis XIV. Translated by Martyn P. Pollack. 780 


L Anthology of British Historical Speeches and Orations. Compiled by 

Ernest Rhys. 714 

Bright's (John) Speeches. Selected with Intro, by Joseph Sturge. 252 
Burke's American Speeches and Letters. 340 

(See also ESSAYS) 

Demosthenes: Select Orations. 646 
Fox (Charles James): Speeches (French Revolutionary War Period). 

Edited with Introduction by Irene Cooper Willis, M.A. 759 
Lincoln's Speeches, etc. Intro, by the Rt. Hon. James Bryce. 206 

(See also BIOGRAPHY) 
Macaulay's Speeches on Politics and Literature. 399 

(See also ESSAYS and HISTORY) 
Pitt's Orations on the War with France. 145 


L A Kempls' Imitation of Christ. 484 

Ancient Hebrew Literature. Being the Old Testament and Apocrypha. 

Arranged by the Rev. R. B. Taylor. 4 vols. 253-6 
Aristotle, The Nlcomachean Ethics of. Translated by D. P. Chase. 

Introduction by Professor J. A. Smith. 547 

(See also CLASSICAL) 
Bacon's The Advancement of Learning. 719 

(See also ESSAYS) 
Berkeley's (Bishop) Principles of Human Knowledge, New Theory of 

Vision. With Introduction by A. D. Lindsay. 483 
Boehme's (Jacob) The Signature of All Things, with Other Writings. 

Introduction by Clifford Bax. 569 

Browne's Religio Medici, etc. Introduction by Professor O. H. Herford. 92 
Bunyan's Grace Abounding and Mr Badman. Introduction by G. B. 

Harrison. 815 (See also ROMANCE) 

Burton's (Robert) Anatomy of Melancholy. Introduction by Holbrook 

Jackson. 3 vols. 886-8 

Butler's Analogy of Religion. Introduction by Rev. Ronald Bayne. 90 
Descartes' (Rene) A Discourse on Method. Translated by Professor John 

Veitch. Introduction by A. D. Lindsay. 570 

L Ellis' (Havelock) Selected Essays. Introduction by J. S. Collie. 930 
I, Gore's (Charles) The Philosophy of the Good Life. 924 

Hobbes' Leviathan. Edited, with Intro, by A. D. Lindsay, M.A. 691 
Hooker's Ecclesiastical Polity. Intro, by Rev. H. Bayne. 2 vols. 201-2 
Hume's Treatise of Human Nature, and other Philosophical Works. 

Introduction by A. D. Lindsay, M.A. 2 vols. 548-9 
James (William): Selected Papers on Philosophy. 739 
Kant's Critique of Pure Reason. Translated by J. M. D. Melklejohn. 

Introduction by A. D. Lindsay, M.A. 909 


Keble's The Christian Tear. Introduction by J. O. Shairp. 690 
King Edward VI. First and Second Prayer Books. Introduction by th 

Right Rev. Bishop of Gloucester. 448 
L Koran, The. Rodwell's Translation. 380 

Latimer's Sermons. Introduction by Canon Beaching. 40 

Law's Serious Call to a Devout and Holy Life. 91 

Leibniz's Philosophical Writings. Selected and trans, by Mary Morris. 

Introduction by C. R. Morris, M.A. 905 
Locke's Two Treatises of Girl) Government. Introduction by Professor 

William S. Carpenter. 751 

Malthus on the Principles of Population. 2 vols. 692-3 
Mill's (John Stuart) Utilitarianism, Liberty, Representative Government. 

With Introduction by A. D. Lindsay, M.A. 482 

v Subjection of Women. (See Wollstonecraft, Mary, under SCIENCE.) 
More's Utopia. Introduction by Judge O'Hagan. 461 
L New Testament. Arranged in the order in which the books came to the 

Christians of the First Century. 93 
Newman's Apologia, pro Vita Sua. Intro, by Dr Charles Sarolea. 836 

(See also ESSAYS) 
Nietzsche's Thus Spake Zarathustra. Translated by A. Tille and 

M. M. Bozman. 892 

Paine's Rights of Man. Introduction by G. J. Holyoake. 718 
Pascal's Pensees. Translated by W. F. Trotter. Introduction by 

T. S. Eliot. 874 [C.I.B. 403 

Haxuayana and the Mahabharata, The. Translated by Roinesh Dutt, 
Kenan's Life of Jesus. Introduction by Right Rev. Chas. Gore, D.D. 806 

Robertson's (F. W.) Sermons on Religion and Life, Christian Doctrine, 
and Bible Subjects. Ea " ' ---.-- 

Burnett. 3 vols. 37-9 

and Bible Subjects. Each Volume with Introduction by Canon 

Robinson's (Wade) The Philosophy of Atonement and Other Sermons. 

Introduction by Rev. F. B. Meyer. 637 

Rousseau's (J. J.) The Social Contract, etc. 660 (See also ESSAYS) 
St Augustine's Confessions. Dr Pusey's Translation. 200 
L St Francis: The Little Flowers, and The Life of St Francis. 485 
Seeley's Ecoe Homo. Introduction by Sir Oliver Lodge. 305 
Spinoza's Ethics, etc. Translated by Andrew J. Boyle. With Intro- 
duction by Professor Santayana. 481 
Swedenborg's (Emmanuel) Heaven and Hell. 379 

The Divine Love and Wisdom. 635 

The Divine Providence. 658 

L ., ., The True Christian Religion. 893 


Anglo-Saxon Poetry. Edited by Professor R. K. Gordon. 794 
Arnold's (Matthew) Poems, 1840-66, including Thyrsis. 334 
Ballads, A Rook of British. Selected by R. B. Johnson. 572 
Beaumont and Fletcher, The Select Plays of. Introduction by Professor 

Baker, of Harvard University. 506 

Bjttrnson's Plays. Vol. I. The Newly Married Couple, Leonardo, A 

Gauntlet. Trans, by R. Farqubarson Sharp. 625 

Vol. II. The Editor, The Bankrupt, and The King. 

Translated by R. Earquharsou Sharp. 69(5 

Blake's Poems and Prophecies. Introduction by Max Plowman. 792 
z. Browning's Poems, 1833-44. Introduction by Arthur Waugfc, 41 
I, Browning's Poems. 1844-64. 42 

The Ring and the Book. Intro, by Chas. W. Hoaell. 502 

L Burns' Poems and Songs. Introduction by J. Douglas. 94 
Byron's Poetical and Dramatic Works. 3 vols. 480-8 
Calderon: Six Plays, translated by Edward FltzGerald. 819 
L Chaucer's Canterbury Tales. Edited by Principal BurreU, M.A. 307 
ColerMge, Golden Book of. Edited by Stopford A. Brooko. 43 

(See also ESSAYS) 
Cowper (William). Poems of. Edited by H. I'Anson Fausset. 872 

(See also BIOGRAPHY) 
L Dante's Divine Comedy (Gary's Translation). Specially edited by 

Edmund Gardner. 308 

Donne's Poems. Edited by H. I'Anson Fausset. 867 
Dryden's Poems. Edited by Bonamy Dobree. 910 
Eighteenth-Century Plays. Edited by John Hampden. 818 
Emerson's Poems. Introduction by Professor Bakewell, Yale, U.S.A. 716 
L Knffllnh Religious Verse. Edited by G. Lacey May. 937 



Everyman and other Interludes, including eight Miracle Plays. Edited 

by Ernest Rhys. 381 

L FtteGerald's (Edward) Omar Khayyam and Six Plays of Calderon. 810 

L Goethe's Faust. Parts I and II. Trans, and Intro, by A. O. Latham. 335 

(See. also ESSA.YB and FICTION) [well. 921 

L Golden Book of Modern English Poetry, The. Edited by Thomas Cald- 

Golden Treasury of Longer Poems, The. Edited by Ernest Rhys. 746 

Goldsmith's Poems and Plays. Introduction by Austin Dobson. 415 

{See also ESSAYS and FICTION) 

Gray's Poems and Letters. Introduction by John Drlnkwater. 028 
Hebbel's Plays. Translated with an Introduction by Dr O. K. Allen. 694 
Heine: Prose and Poetry. 911 

Herbert's Temple. Introduction by Edward Thomas. 309 
Herrick's Hesporides and Noble Numbers. Intro, by Ernest Rhys. 310 
L Ibsen's Brand. Translated by F. E. Garrett. 716 
L Ghosts, The Warriors at Helgoland, and An Enemy of the People. 

Translated by R. Farquharson Sharp. 552 
L Lady Inger of Ostraat, Lore's Comedy, and The League of 

Youth. Translated by R. Farquharson Sharp. 729 
Peer Gynt. Translated by R. Farquharson Sharp. 747 
L , A Doll's House, The Wild Duck, and The Lady from the Sea, 

Translated by R. Farquharson Sharp. 494 
The Pretenders, Pillar* of Society, and Rosmersholm. Translated 

by R. Farquharson Sharp. B59 

Jonson's (Ben) Plays. Introduction by Professor SchelJing. 2 vols. 489 -90 
Kalldaea: Shakuntala. Translated by Professor A. W. Ryder. 629 
L Keats' Poems. 101 

Kingsley's (Charles) Poems. Introduction by Ernest Rhys. 793 

L Lanpland's (William) Piers Plowman. 571 

Lessinff's LaocoOn, Minna von Barnhelm, and Nathan the Wise. 843 
L Longfellow's Poems. Introduction by Katherina Tynan. 382 

Marlowe's Plays and Poems. Introduction by Edward Thomas. 383 
L Milton's Poems. Introduction by W. H. D. Rouse. 384 

(See also ESSAYS) 
Minor Elizabethan Drama. Vol. I. Tragedy. Selected, with Introduction. 

by Professor Thorndike. Vol. II. Comedy. 491-2 
L Minor Poets of the 18th Century. Edited by H. I'Anson Fausset. 844 

Minor Poets of the 17th Century. Edited by R. G. Howarth. 873 
L Modern Plays. 942 

Moliere's Comedies. Introduction by Prof. F. O. Green. 2 vole. 830-1 
L New Golden Treasury, The. An Anthology of Songs and Lyrics. 695 

Old Yellow Book, The. Introduction by Charles E. Hodell. 503 
L Omar Khayyam (The Rubalyat of). Trans, by Edward FltrGerald. 819 
L Palsrrave's Golden Treasury. Introduction by Edward Hutton. 96 
Percy's Reliques of Ancient English Poetry. 2 vols. 148-9 
Poe's (Edgar Allan) Poems and Essays. Intro, by Andrew Lang. < 91 

(See also FICTION) 

Pope (Alexander) : Collected Poems. Introduction by Ernest Rhys. 760 
Procter's (Adelaide A.) Legends and Lyrics. 150 

Restoration Plays, A Volume of. Introduction by Edmund Gosse. 604 
L Rossetti's Poems and Translations. Introduction by E. G. Gardner. 627 
Scott's Poems and Plays. Intro, by Andrew Lang. 2 vols. 550-1 

L Shakespeare's Comedies. 153 

Historical Plays, Poems, and Sonnets. 154 
Tragedies. 165 

Poetical Works. Introduction by A. H. Koszul. 3 vols. 257-8 
n's Plays. 95 

Faerie Queene. Intro, by Prof. J. W. Hales. 2 vote. 443-4 
Shepherd's Calendar and Other Poems. Edited by Philip 

Henderson. 879 
Stevenson's Poems-A Child's Garden of Verses, Underwoods, SOUKS of 

Travel, Ballads. 768 (See also ESSAYS, FICTION, and TRAVEL) 
i. Tchekhov. Plays and Stories. 941 

Tennyson's Poems. Vol. I, 1830-56. Introduction by Ernest Rhys. 44 
,, Vol. if, 1857-70. 626 [Harrison. 899 

Webster and Ford. Plays. Selected, with Introduction, by Dr. G. B. 
Whitman's (Walt) Leaves of Grass (I), Democratic Vistas, etc. 673 
Wilde (Oscar), Plays, Prose Writings and Poems. 858 
L Wordsworth's Shorter Poems. Introduction by Ernest Rhys. 203 
M Longer Poems. Note by Editor. 311 



Atlas of Ancient and Classical Geography. Many coloured and line 

Maps; Historical Gazetteer, Index, etc. 451 
Biographical Dictionary of English Literature. 449 
Biographical Dictionary of Foreign Literature. 900 
Dates, Dictionary of. 554 

Dictionary of Quotations and Proverbs. 2 vols. 809-10 
Everyman's English Dictionary. 776 
Literary and Historical Atlas. I. Europe. Many coloured and line MA ps ; 

full Index and Gazetteer. 496 

,, ,, II. America. Do. 553 

III. Asia. Do. 633 

,, IV. Africa and Australia. Do. 662 

Non-Classical Mytholocry, Dictionary of. 632 
Reader's Guide to Everyman's Library. By R. Farquharson Sharp. 

Introduction by Ernest Rhys. 889 

' Roget's Thesaurus of English Words and Phrases. 2 vols. 630-1 
Smith's Smaller Classical Dictionary. Revised and Edited by E. H. 

Blakaney, M.A. 495 
Wright's An Encyclopaedia of Gardening. 555 


Aucassin and Nicolette, with other Medieval Romances. 497 
Boccaccio's Decameron. (Unabridged.) Translated by J. M. Risir. 

Introduction by Edward Hutton. 2 vols, 845-6 
L Banyan's Pilflfrim's Progress. Introduction by Rev. H. E. Lewis. 204 

Burnt Njal, The Story of. Translated by Sir George Dasent. 558 
L Cervantes' Don Quixote. Motteux's Translation. Lockhart's Intro- 
duction. 2 vols. 385-6 
Chretien de Troves: Eric and Enid. Translated, with Introduction and 

Notes, by William Wistar Comfort. 698 

French Medieval Romances. Translated by Eugene Mason. 557 
Geoffrey of Monmouth's Histories of the Kings of Britain. 577 
Grettir Saga, The. Newly Translated by G. Alnslie Might. 699 
Gudrun. Done into English by Margaret Armour. 880 
Guest's (Lady) Mabinogion. Introduction by Rev. R. Williams. 97 
Beimskringla: The Olaf Sagas. Translated by Samuel Laing. Intro- 
duction and Notes by John Beveridge. 717 
Sagas of the Norse Kings. Translated: by Samuel Laing. 

Introduction and Notes by John Boverldge. 847 
Holy Graal, The High History of the. 445 

Kalevala. Introduction by W. F. Kirby, F.L.S., F.E.S. 2 vols. 259-60 
Le Sage's The Adventures of Gil Bias. Intro, by Anatole Lo Bras. 2 vols. 
MacDonald's (George) P ban tastes: A Faerie Romance. 732 [437-8 

(See also FICTION) 

Malory's Le Morte d' Arthur. Intro, by Professor Rhys. 2 vols. 45-6 
L Morris (William): Early Romances. Introduction by Alfred Noyes. 261 

The Life and Death of Jason. 575 

Morte d' Arthur Romances, Two. Introduction by Luoy A. Paton. 634 
Nibelungs, The Fall of the. Translated by Margaret Armour. 312 
Rabelais' The Heroic Deeds of Gargantua and Pantagrnel. Introduction 

by D. B. Wyndham Lewis. 2 vols. 826-7 

Wace's Arthurian Romance. Translated by Eugene Mason* Laya- 
mon's Brut. Introduction by Luoy A. Paton. 578 


Boyle's The Sceptical Chymist. 559 

Darwin's The Origin of Species. Introduction by Sir Arthur Keith. 811 
(See also TRAVEL) [E. F. Bozman. 922 

L Eddlngton's (Sir Arthur) The Nature of the Physical World. Intro, by 
slid: the Elements of. Todhunter's Edition. Introduction by Sir 

""*-, K.O.B. 891 

>erimental Researches in Electricity. 576 
BLuman Faculty. Revised by Author. 263 
.ss and Poverty. 560 

5>-e: h on e& tto RaU ^ ** of HeaUn * 

Harvey's Circulation of the Blood. Introduction by Ernest Parkyn. 262 
Howard's State of the Prisons. Introduction by Kenneth Ruck. 835 
Huxley's Essays. Introduction by Sir Oliver Lodge. 47 

~ b Lectures and Lay Sermons. Intro. Sir Oliver Lodge. 498 

Anton's Voyages. Introduction by John Masefleld. 610 

Bates' Naturalist on the Amazon. With Illustrations. 446 

Belt's The Naturalist in Nicaragua. Intro, by Anthony Belt, F.L.S. 561 

SCIENCE continued 

Lyell's Antiquity of Man. With an Introduction by R. H. Rastall. 700 
Marx's (Karl) Capital. Translated by Eden and Cedar Paul. Intro- 
duction by O. D. H. Cole. 2 vote. 848-9 
Miller's Old Red Sandstone. 103 
Owen's (Robert) A New View of Society, etc. Intro, by O. D. H. Cole. 799 

L Pearson's (Karl) The Grammar of Science. 939 

Ricardo's Principles of Political Economy and Taxation. 690 
Smith's (Adam) The Wealth of Nations. 2 vols. 412-13 
Tyndall's Glaciers of the Alps and Mountaineering in 1861. 98 
White's Selborne. Introduction by Principal Windle. 48 
Wollstonecraft (Mary), The Rights of Woman, with John Stuart Mill's 
The Subjection of Women. 825 


Anson's Voyages. Introduction by John 
Bates' Naturalist on the Amazon. With 

Belt's The Naturalist In Nicaragua. Intro. _.. , 

Borrow's (George) The Gypsies in Spain. Intro, by Edward Thomas. 697 

L ,. The Bible in Spain. Intro, by Edward Thomas. 151 

Wild Wales. Intro, by Theodore Watts-Dunton. 49 

(See also FICTION) 
BoBwell'B Tour in the Hebrides with Dr Johnson. 387 

' (See also BIOGRAPHY) 

Burton's (Sir Richard) First Footsteps in East Africa. 500 
Cobbett's Rural Rides. Introduction by Edward Thomas. 2 vols. 638-9 

L Cook's Voyages of Discovery. 99 

Oreveeceur's (H. St John) Letters from an American Farmer. 640 
Darwin's Voyage of the Beaglo. 104 

(See also SCIENCE) 

Defoe's Tour Through England and Wales. Introduction by Q. D. H. 
(See also FICTION) [Cole. 820-1 

Dennis' Cities and Cemeteries of Etniria. 2 vols. 183-4 
Dufferin'e (Lord) Letters from High Latitudes. 499 
Ford's Gatherings from Spain. Introduction by Thomas Okey. 162 
Franklin's Journey to the Polar Sea. Intro, by Cant. R. F. Scott. 447 
Giraldufl Cambrensis: Itinerary and Description of Wales. 272 
Haklnyt's Voyages. 8 vols. 264, 265, 313. 314, 338, 339. 388, 389 
Kinglake's Eothen. Introduction by Harold Spender, M.A. 337 
Lane's Modern Egyptians. With many Illustrations. 315 
Mandeville's (Sir John) Travels. Introduction by Jules Bramont. 812 
Park (Mungo): Travels. Introduction by Ernest Rhys. 205 
Peaks, Passes, and Glaciers. Selected by E. H. Blakeney, M.A. 778 

L Polo's (Marco) Travels. Introduction by John Masefleld. 306 

Roberts' The Western Avernus. Intro, by Cunninghame Graham. 762 

Speke's Discovery of the Source of the Nile. 60 _ 
. Stevenson's An Inland Vo 

L Stevenson's An inland Voyage, Travels with a Donkey, and Silverado 
Squatters. 766 


Stow's Survey of London. Introduction by H. B. Wheatley. 589 
Wakeneld's Letter from Sydney and Other Writings on Colonization. 828 
Waterton's Wanderings in South America. Intro, by E. Selous. 772 
Young's Travels in France and Italy. Intro, by Thomas Okey. 720 


L JEsop'a and Other Fables: An Anthology from all sources. 65V 

Alcott's Little Men. Introduction by Grace Rhys. 512 
L ,, Little Women and Good Wives. Intro, by Grace Rhys. 248 
Andersen's Fairy Tales. Illustrated by the Brothers Robinson. 4 
More Fairy Tales. Illustrated by Mary Shillaboer. 822 
Annals of Fairyland. The Reign of King Oberon. 366 

The Reign of King Cole. 366 

Asgard and the Norse Heroes. Translated by Mrs Boult. 689 
Baker's Cast up by the Sea. 539 
L Ballantyne's cW Island. 245 

Martin Rattler. 246 

Ungava. Introduction by Ernest Rhys. 276 

L Browne's (Frances) Granny's Wonderful Chair. Introduction by Doble 

Radford. 112 
Bnlflnoh'B (Thorns*) The Age of Fable. 472 

Legends of Charlemagne. Intro, by Ernest Rhys. 556 



L Canton's A Child's Book of Saints. Illustrated by T. H. Robinson. 61 

. (See also Ess ATS) 

x, Carroll's Alice in Wonderland, Through the Looking-Glass, etc. Illus- 
trated by the Author. Introduction by Ernest Rhys. 836 
,, Tales from Chaucer. 537 

Collodi's Pinocchlo; or, The Story of a Puppet. 538 

L Converse's (Florence) The House of Prayer. 023 (See also FICTION) 
Cox's (Sir G. W.) Tales of Ancient Greece. 721 
Defoe's Robinson Crusoe. Illustrated by J. A. Symington. 59 

(See also FICTION) 

Dodge's (Mary Mapes) Hans Brinker; or, The Silver Skates. 620 
Edgar's Heroes of England. 471 

(See also FICTION) 
L Swing's (Mrs) Jackanapes, Daddv Darwin's Dovecot, illustrated by 

R. Caldecott, and The Story of a Short Life. 731 
Mrs Ovortheway'e Remembrances. 730 
L Fairy Gold. Illustrated by Herbert Cole. 157 
I. Fairy Tales from the Arabian Nights. Illustrated. 249 
FroiBHnrfc'fl Chronicles. 57 

Gatty's Parables from Nature. Introduction by Grace Rhys. 158 
Grimm's Fairy Tales. Illustrated by R. Anning Bell. 56 
Hawthorne's Wonder Book and Tanglewood Tales. 5 

(See also FICTION) 

Howard's Rattlin the Heefer. Introduction by Guy Pocock. 857 
L Hughes' Tom Brown's School Days. Illustrated by T. Robinson. 58 
Ingelow'e (Jean) Mopsa the Fairy. . Illustrated by Dora Curtis. 619 
Jeff erica's (Richard) Bevis, the Story of a Boy. Introduction by Guy 

Pocock. 850 
L Kingsley's Heroes. Introduction by Grace Rhys. 113 

Madam How and Lady Why. Introduction by O. I. Gardiner. 

L Water Babies and Glaucus. 277 [M.A. 777 

(See also POETKY and FICTION) 
Kingston's Peter the Whaler. 6 

Three MidHhipmen. 7 

L Lamb's Tales from Shakespeare. Illustrated by A. Rackham. 8 

(See also BIOGRAPHY and ESSAYS) 
L Lear (and Others): A Book of Nonsense. 806 
Marryat's Children of the New Forest. 247 

Little Savage. Introduction by R. Brimley Johnson. 159 
Masterman Ready. Introduction by R. Brimley Johnson. 160 
Settlers in Canada. Introduction by R. Brimley Johnson. 370 

(Edited by) RattUn the Reefer. 857 
(See also FICTION) 

Martineau's Feats on the Fjords, etc. Illustrated by A. Rackham. 429 
Mother Goose's Nursery Rhymes. Illustrated. 473 
Poetry Book for Boys and Girls. Edited by Guy Pooook. 894 
Reid's (Mayne) The Boy Hunters of the Mississippi. 582 

The Boy Slaves. Introduction by Guy Pocock. 797 

Ruskin's The Two Boyhoods and Other Passages. 688 

(See also ESSAYS) 

L SewelTs (Anna) Black Beauty. Illustrated by Lucy Kemp -Welch. 748 
L Spyri's (Johanna) Heidi. Illustrations by Lizzie Lawson. 431 
L Story Book for Boys and Girls. Edited by Guy Pocock. 934 

Stowe's Uncle Tom's Cabin. 371 
L Swift's Gulliver's Travels. Illustrated by A. Rackham. 60 

(See also BIOGRAPHY and ES.SAYS) 

L Swiss Family Robinson. Illustrations by Chas. Folkard. 430 
Verne's (Jules) Abandoned. 60 Illustrations. 368 

., Dropped from the Clouds. 50 Illustrations. 367 

L Five Weeks in a Balloon and Around the World in Eighty 

Days. Translated by Arthur Chambers and P. Dosages. 
L Twenty Thousand Leagues Under the Sea. 319 779 

The Secret of the Island. 50 Illustrations. 369 
Tonge's (Charlotte M.) The Book of Golden Deeds. 330 

The Lances of Lynwood. Illustrated by Dora 

Curtis. 579 

I* ., The Little Duke. Illustrated by Dora Curtis. 47 o 

(See also FICTION) 








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