28. Neither can we say how far the identity of the corporeal substance continues under its different transformations. The partisans of corpuscular philosophy consider all transformations as mere local motions, and all the variations which we see in bodies as mere results of the different position of the corpuscles among themselves. Leibnitz resolved matter into an infinity of monads, differing from the atoms of Epicurus, but conducing to the substantial invariability of bodies, which are only a collection of indivisible substances, which he calls monads. The Aristotelians believed that, of the changes of bodies, some were accidental, as figure, motion, density, warmth, cold, etc.; others substantial, as the change of wood to ashes. But in all the variety of systems, all admit something permanent, the subject of the changes. The Atomists and Leibnitz evidently admitted the identity of the subject. As to the Aristotelians, although the change which introduced a substantial form different from the first substantially transformed the being, so that after the change of the substantial form it could not be said that one was substantially the other, they still thought there was a common subject in these substantial transformations, and this was what they called the first matter, materia prima. All systems of philosophy admit this clear and evident truth, that in the midst of the transformations of the corporeal world, there is something permanent.
29. This corporeal substance being a reality, must not only exist, but it must be something determinate. This substantial determination of the body, which makes it this particular thing, and distinguishes it in its internal nature, in its essence, from all other bodies of other species, the Aristotelians called the substantial form. The subject of this form, or actuality, which was common to all bodies, they called the materia prima, which was a pure potentiality, a sort of medium between pure nothing and actual being.
30. Ever since there have been schools of philosophy, these points have been disputed; and it is probable they always will be; but it is to very little purpose. We know the existence of the corporeal world, we know its relations to ourselves, we know its properties and its laws, so far as they are subject to our observation; but its intrinsic nature is beyond the reach of our senses, or our instruments. Increased acuteness of observation and improvement in the power and delicacy of instruments, discovers new mysteries, and man finds the barriers which he believed the ne plus ultra, removed from him as he advances. Will he ever be able to pass them? Will he ever make the entire circuit of this scientific world? Is the knowledge of the intrinsic nature of the subject of this infinity of phenomena which astonish us, reserved to the future? It is hard to believe it. The telescope, becoming more perfect, extends the limits of the universe, and seems to behold the infinitely great; the perfection of the microscope, advancing in the opposite direction, regards the infinitely little. Where are the limits? It is probable that man is not permitted to reach them while in this world. The mind of man in its fruitful activity, struggles alternately after the two extremes, but just as he flatters himself he is reaching the last limit, he feels that something stronger than himself withholds him from attaining the object of his noble desires; it is the chain that binds him to the mortal body, and obstructs the flight of his pure spirit.
[CHAPTER VI.]
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.