precept of Apollo,
which advises every one to know himself. For I do not apprehend the
meaning of the God to have been that we should understand our members,
our stature, and form; for we are not merely bodies; nor, when I say
these things to you, am I addressing myself to your body: when,
therefore, he says, "Know yourself," he says this, "Inform yourself of
the nature of your soul;" for the body is but a kind of vessel, or
receptacle of the soul, and whatever your soul does is your own act. To
know the soul, then, unless it had been divine, would not have been a
precept of such excellent wisdom as to be attributed to a God; but even
though the soul should not know of what nature itself is, will you say
that it does not even perceive that it exists at all, or that it has
motion? On which is founded that reason of Plato's, which is explained
by Socrates in the Phaedrus, and inserted by me, in my sixth book of the
Republic.

XXIII. "That which is always moved is eternal; but that which gives
motion to something else, and is moved itself by some external cause,
when that motion ceases, must necessarily cease to exist. That,
therefore, alone, which is self-moved, because it is never forsaken by
itself, can never cease to be moved. Besides, it is the beginning and
principle of motion to everything else; but whatever is a principle has
no beginning, for all things arise from that principle, and it cannot
itself owe its rise to anything else; for then it would not be a
principle did it proceed from anything else. But if it has no
beginning, it never will have any end; for a principle which is once
extinguished cannot itself be restored by anything else, nor can it
produce anything else from itself; inasmuch as all things must
necessarily arise from some first cause. And thus it comes about that
the first principle of motion must arise from that thing which is
itself moved by itself; and that can neither have a beginning nor an
end of its existence, for otherwise the whole heaven and earth would be
overset, and all nature would stand still, and not be able to acquire
any force by the impulse of which it might be first set in motion.
Seeing, then, that it is clear that whatever moves itself is eternal,
can there be any doubt that the soul is so? For everything is inanimate
which is moved by an external force; but everything which is animate is
moved by an interior force, which also belongs to itself. For this is
the peculiar