Every soul is immortal: for whatever is continually moved is immortal; but that which moves another and is moved by another, when it ceases to move, ceases to live. Therefore that only which moves itself, since it does not quit itself, never ceases to be moved, but is also the source and beginning of motion to all other things that are moved. But a beginning is uncreate: for every thing that is created must necessarily be created from a beginning, but a beginning itself from nothing whatever; for if a beginning were created from any thing, it would not be a beginning. 52. Since then it is uncreate it must also of necessity be indestructible; for should a beginning perish, it could neither itself be ever created from any thing, nor any thing else from it, since all things must be created from a beginning. Thus then the beginning of motion is that which moves itself: and this can neither perish nor be created, or all heaven and all creation must collapse and come to a stand-still, and never again have any means whereby it may be moved and created. 53. Since then it appears that that which is moved by itself is immortal, no one will be ashamed to say that this is the very essence and true notion of soul. For every body which is moved from without, is soulless, but that which is moved from within of itself, possesses a soul, since this is the very nature of soul. But if this be the case, that there is nothing else which moves itself except soul, soul must necessarily be both uncreate and immortal. This then may suffice for its immortality.