I. Whether each (part) of us is immortal, or the whole perishes, or one part of us is dissipated and corrupted, but another part perpetually remains, which part is the man himself, may be learnt by considering conformably to nature as follows: Man, indeed, is not something simple, but there is in him a soul, and he has also a body, whether it is annexed to us as an instrument, or after some other manner. However this may be, it must be admitted, that the nature and essence of each of these must be thus divided. Since the body, therefore, is itself a composite, reason shows that it cannot remain (perpetually the same) ; and sense likewise sees that it is dissolved and wastes away, and receives all-various destructions; since each of the things inherent in it tends to its own (i.e. to the whole form from which it was derived), and one thing belonging to it corrupts another, and changes and perishes into something else. This, too, is especially the case when the soul, which causes the parts to be in friendly union with each other, is not present with the corporeal masses. If each body, likewise, is left by itself, it will not be one, since it is capable of being dissolved into form and matter, from which it is also necessary that simple bodies should have their composition. Moreover, as being bodies they have magnitude, and consequently may he cut and broken into the smallest parts, and through this are the recipients of corruption. Hence, if body is a part of us, we are not wholly immortal. But if it is an instrument (of the soul) it is necessary that being given for a certain time, it should be naturally a thing of this kind. That, however, which is the most principal thing, and the man himself, will be that with reference to the body which form is with reference to matter, since this according to form is as body to matter; or according to that which uses, the body has the relation to it of an instrument. But in each way soul is the man himself.