[CHAPTER XI.]
SIMPLICITY OF THE SOUL.
72. I have confined myself in the preceding chapters to proving the substantiality of the soul; to do which it was only necessary to demonstrate by the testimony of consciousness that there is within us a permanent reality, the subject of the modifications which we experience. I shall now demonstrate that this substance is simple.
To proceed methodically, let us fix the meaning of the word simple. When many beings are united and form a collection, the result is called a composite being; so that there is a true composition wherever beings substantially distinct are united; the band which unites them may be of different species, which produces the diversity of compositions. Simplicity is opposed to composition; the idea of simplicity essentially excludes the idea of composition; as this last includes a number of distinct things which are united to form a whole, the idea of simplicity essentially excludes the idea of number of things united to form a whole. Therefore the simple is strictly one, and there is simplicity in a substance when it is not a collection of substances.
When, therefore, we say the substance of the soul is simple, we mean that it is not a collection of substances, but one substance.
73. The idea of simplicity thus determined with exactness, let us see if it belongs to our soul. As the soul is not given us in intuition after the manner of sensible things, and we only know it by the presence of the internal sense, and by the phenomena which we experience in the depths of our consciousness, we must examine these two sources to see if we can find simplicity in them.
It is an indisputable fact that in all our acts, in all our internal affections, we perceive the identity of the me.[48] There is no identity between things that are distinct: consequently the internal sense at once rejects the multiplicity of the soul. It may be said that this identity does not exist between distinct substances, but that a composite substance is identical with itself, and perhaps the identity revealed by consciousness is only the identity of a composite with itself: but this reply is destroyed by merely examining the testimony of consciousness. That which we perceive as various and multiple is not the me, but that which takes place in the me: we think, we will, we perceive different things; but consciousness attests that what thinks them, wills them, and perceives them, is one and the same, the me. Therefore, the testimony of consciousness alone proves the simplicity of the soul; for it is impossible to explain otherwise how we perceive within us the permanent unity amid the multitude of internal phenomena.