SUBSTANTIALITY OF THE HUMAN ME.
31. We have not found perfect unity in corporeal substances: all that are subject to our senses may be resolved into a number of others equally substances in their turn; a body is rather an aggregate of substances, than one substance. We do not find the unity in the bodies; we attribute it to them either inasmuch as they form a common link of our sensations, or inasmuch as we consider the different substances subordinated to one being and governing substance. Thus the parts of an animated body constitute a sort of unity, inasmuch as they are subordinate to the principle which animates them.
32. We do not conclude from this that true unity does not exist in bodies; if we could know their essence, we should doubtless discover it, whether in the monads, as maintained by Leibnitz, or in something else more or less resembling them. Although this knowledge of their essence is denied us, reason leads us to this unity. The composite is formed of parts; if these parts are in turn formed of others, we must at last come to something which has no parts; here we find the indivisible, or rather, the true unity. This reasoning is equally valid, even though we suppose matter to be infinitely divisible. Infinite divisibility would suppose an infinity of parts into which any body may be divided: these parts would therefore exist; these infinitesimal elements would be real: the unity would be in them.
33. Independently of the external world, we find the idea of substance in ourselves; consciousness reveals its real application and perfect unity. Consciousness makes known to us that we think, desire, feel, and experience an infinity of affections, some of which are subject to our will and are the product of the internal activity of our soul; others are independent of us, they come without our will, and often against it, and it is not always in our power to reproduce them even if we wish it.
This ebb and flow of ideas, volitions, and sentiments, have a point in which they are connected, a subject which receives them, remembers them, combines them, and seeks or avoids them; this being, of which we are internally conscious, philosophers have called theme. It is one and identical under all transformations; this unity, this identity, is an indisputable fact which consciousness reveals to us. Who could make us doubt that themewhich thinks at the present moment is not the same which thought yesterday, which thought years ago? Notwithstanding the variety of thoughts and desires, the changes of opinion and will, whocould deprive us of the firm and deep conviction which we have that we are the same who experience them all, that there is something here within us which is the subject of them all?
34. If there were not something in us permanent in the midst of this variety, the consciousness of themewould be impossible. Memory and combination would also be impossible; for there would be within us only a succession of unconnected phenomena. Thinking is impossible without something which thinks and remains identical under the variety of the forms of thought. There is, therefore, within us a simple subject which connects all the changes which occur in it: there is a substance. In it there is unity: the unity which we only find in corporeal substances after an infinite series of decompositions, is presented to us in the spiritual substance, at the first instant, as a simple internal fact, without which, all the phenomena which we perceive within us are absurd, and all experience of the external world impossible.
Without the unity of themethere can be no sensation, and without sensation no experience of the beings around us.