in compound bodies, where there is change of parts. The Monads have no windows through which anything can enter or go forth. It would be impossible for any accidents to detach themselves and go forth from the substances, as did formerly the "sensible species" of the Schoolmen. Accordingly, neither substance nor accident can enter a Monad from without.

8. Nevertheless Monads must have qualities, otherwise they would not even be entities. And if simple substances did not differ in their qualities, there would be no means by which we could become aware of the changes of things, since all that is in compound bodies is derived from simple ingredients, and Monads, if they were without qualities, would be indistinguishable one from another, since they do not differ in quantity. Consequently, a plenum being supposed, each part of space could in any movement receive only the just equivalent of what it had had before, and one state of things would be indistinguishable from another.

9. Moreover, each Monad must differ from every other, for there are never two beings in nature perfectly alike, and in which it is impossible to find an internal difference, or one founded on some intrinsic denomination.

10. I assume, furthermore, that every created being, and consequently the created Monad, is subject to change; and likewise that this change is continual in each.

II. It follows, from what we have now said, that the natural changes of Monads proceed from an internal principle, since no external cause can influence their interior.

12. But, besides the principle of change, there must also be a detail of that which changes [un détail de ce qui change], which constitutes, so to speak, the specific nature and the variety of the simple substances.

13. This detail must involve multiplicity in the unit [unité] or in that which is simple. For, as all natural changes proceed by degrees, something changes and something remains unchanged, and consequently there must be in the simple substance a plurality of affections and relations, although there are no parts.

14. This shifting state, which involves and represents multiplicity in the unit, or in the simple substance, is nothing but what

we call Perception, which must be carefully distinguished from apperception, or consciousness, as will appear in the sequel. Here it is that the Cartesians have especially failed, making no account of those perceptions of which we are not conscious. It is this that has led them to suppose that spirits are the only Monads, and that there are no souls of brutes or other entelechies. It is owing to this that they have vulgarly confounded protracted torpor with actual death, and have fallen in with the scholastic prejudice, which believes in souls entirely separate [from bodies]. For this reason, also, ill-affected minds have been confirmed in the opinion that the soul is mortal.

15. The action of the internal principle which causes the change, or the passage from one perception to another, may be called Appetition. It is true, the desire cannot always completely attain to every perception to which it tends, but it always attains to something thereof, and arrives at new perceptions.

16. We experience in ourselves the fact of a multiplicity in the simple substance, when we find that the least thought of which we are conscious includes a variety in its object. Accordingly, all who admit that the soul is a simple substance, are bound to admit this multiplicity in the Monad, and M. Bayle should not have found any difficulty in this admission, as he has done in his Dictionary, article "Rorarius."

17. Besides, it must be confessed that Perception and its consequences are inexplicable by mechanical causes, that is to say, by figures and motions. If we imagine a machine so constructed as to produce thought, sensation and perception, we may conceive it as magnified the same proportions being preserved to such an extent that one might enter it like a mill. This being supposed, we should find in it on inspection only pieces which impel each other, but nothing which can explain a perception. It is in the simple substance, therefore, and not in a compound, or in a machine, that we must look for the phenomenon of perception. And in the simple substance we find nothing else - nothing, that is, but perceptions and their changes. Therein also, and therein only, consist all the internal actions of simple substances.

18. We might give the name of entelechies to all simple substances or created Monads, inasmuch as there is in them a certain completeness (perfection), (exovơi tò évtelés). There is a certain sufficiency (avтápкeta) which makes them the sources of their own internal actions, and, as it were, incorporeal automata. 19. If we choose to give the name of soul to everything that has perceptions and desires [appétits], in the general sense which I have just explained, then all simple substances or created Monads may be called souls. But as feeling [le sentiment] is something more than simple perception, I am willing, that the general name of Monads or entelechies shall suffice for those simple substances which have perception only, and that the term souls shall be confined to those in which perceptions are more distinct, and accompanied by memory.

20. For we experience in ourselves a state in which we remember nothing, and have no distinct perception; as when we are in a swoon or in a profound or dreamless sleep. In this state the soul does not differ perceptibly from a simple Monad; but since this state is not permanent, and since the soul delivers itself from it, the soul is something more than a bare Monad.

21. And it does not by any means follow, in that case, that the simple substance is without perception. That, indeed, is impossible, for the reasons given above; for it cannot perish, neither can it subsist without affection of some kind, which is nothing else than its perception. But where there is a great number of minute perceptions, and where nothing is distinct, one is stunned; as when we turn round and round in continual succession in the same direction, whence arises a vertigo, which may cause us to faint, and which prevents us from distinguishing anything. And possibly death may produce this state for a time in animals.

22. And as every present condition of a simple substance is a natural consequence of its antecedent condition, so its present is big with its future.

23. Then, as on waking from a state of stupor, we become conscious of our perceptions, we must have perceptions, although unconscious of them, immediately before awaking. For each

perception can have no other natural origin but an antecedent perception, as every motion must be derived from one which preceded it.

24. Thus it appears that if there were no distinction no relief, so to speak — no enhanced flavor in our perceptions, we should continue forever in a state of stupor; and this is the condition of the naked Monad.

25. And so we see that nature has given to animals enhanced perceptions, by the care which she has taken to furnish them with organs which collect many rays of light and many undulations of air, increasing their efficacy by their union. There is something approaching to this in odor, in taste, in touch, and perhaps in a multitude of other senses of which we have no knowledge. I shall presently explain how that which passes in the soul represents that which takes place in the organs.

26. Memory gives to the soul a kind of consecutiveness * which resembles [imite] reason, but must be distinguished from it. We observe that animals, having a perception of something which strikes them, and of which they have previously had a similar perception, expect, through the representation of their memory, the recurrence of that which was associated with it in their previous perception, and incline to the same feelings which they then had. For example, when we show dogs the cane, they remember the pain which it caused them, and whine and run.

27. And the lively imagination, which affects and excites them, arises either from the magnitude or the number of their previous perceptions. For often a powerful impression produces suddenly the effect of long habit, or of moderate perceptions often repeated.

28. In men as in brutes, the consecutiveness of their perceptions is due to the principle of memory-like empirical physicians, who practice without theory. Indeed we are mere empirics in three-fourths of our acts. For example, when we expect that the sun will rise to-morrow, we judge so empirically, because it has always risen hitherto. It is only the astronomer who judges by an act of reason.

29. But the knowledge of necessary and eternal truths is what

* The term is equivalent to association of ideas.

distinguishes us from mere animals. It is this which gives us Reason and the Sciences, and raises us to the knowledge of ourselves and of God; and it is this in us which we call a reasonable soul or spirit [esprit].

30. It is also by the knowledge of necessary truths, and by their abstractions, that we rise to acts of reflection, which give us the idea of that which calls itself "I," and which lead us to consider that this or that is within us. And thus, while thinking of ourselves, we think of being, of substance, simple or compound, of the immaterial, and of God himself. We conceive that that which in us is limited, is in him without limit. And these reflective acts furnish the principal objects of our reasonings.

31. Our reasonings are founded on two great principles, that of contradiction, by virtue of which we judge that to be false which involves contradiction, and that to be true which is opposed to, or which contradicts the false,

32. And that of sufficient reason, by virtue of which we judge that no fact can be real or existent, no statement true, unless there be a sufficient reason why it is thus, and not otherwise, although these reasons very often cannot be known to us.

33. There are also two kinds of truths, those of reasoning and those of fact. 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, we may discover the reason of it by analysis, resolving it into simpler ideas and truths, until we arrive at those which are primitive [primitifs].

34. It is thus that mathematicians by analysis reduce speculative theorems and practical canons to definitions, axioms, and postulates.

35. And finally, there are simple ideas of which no definition can be given; there are also axioms and postulates, in a word, ultimate principles, which cannot and need not be proved. And these are identical propositions, the opposite of which contains an express contradiction.

36. But there must also be a sufficient reason for contingent truths, or truths of fact, that is, for the series of things diffused through the universe of created objects, or else the process of