14. This shifting state, which involves and represents multitude in unity, or in the simple substance, is nothing else than 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. Hence, 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 multitude 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 multitude in the Monad, and Mr. Boyle should not have found any difficulty in this admission, as he has done in his dictionary—Art. 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, perception, we may conceive it 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—not in the compound, or in machinery—that we must look for that phenomenon; 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 acts 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), (ἔχουσι τὸ ἔντελες). There is a sufficiency (αὐτάρκεια) 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 all that has perceptions and desires, in the general sense which I have just indicated, all simple substances or created Monads may be called souls. But as sentiment is something more than simple perception, I am willing that the general name of Monads and Entelechies shall suffice for those simple substances which have nothing but perceptions, and that the term souls shall be confined to those whose 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 and dreamless sleep. In this state the soul does not differ sensibly from a simple Monad; but since this state is not permanent, and since the soul delivers herself from it, she is something more.
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 awaking from a state of stupor, we become conscious of our perceptions, we must have had 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.