. 'Very true.'
And when you speak of bodies moving in many places, you seem to me to
mean those which move from one place to another, and sometimes have
one centre of motion and sometimes more than one because they turn upon
their axis; and whenever they meet anything, if it be stationary, they
are divided by it; but if they get in the midst between bodies which are
approaching and moving towards the same spot from opposite directions,
they unite with them. 'I admit the truth of what you are saying.'
Also when they unite they grow, and when they are divided they waste
away--that is, supposing the constitution of each to remain, or if that
fails, then there is a second reason of their dissolution. 'And when are
all things created and how?' Clearly, they are created when the first
principle receives increase and attains to the second dimension, and
from this arrives at the one which is neighbour to this, and after
reaching the third becomes perceptible to sense. Everything which is
thus changing and moving is in process of generation; only when at
rest has it real existence, but when passing into another state it is
destroyed utterly. Have we not mentioned all motions that there are,
and comprehended them under their kinds and numbered them with the
exception, my friends, of two?

CLEINIAS: Which are they?

ATHENIAN: Just the two, with which our present enquiry is concerned.

CLEINIAS: Speak plainer.

ATHENIAN: I suppose that our enquiry has reference to the soul?

CLEINIAS: Very true.

ATHENIAN: Let us assume that there is a motion able to move other
things, but not to move itself; that is one kind; and there is
another kind which can move itself as well as other things, working in
composition and decomposition, by increase and diminution and generation
and destruction--that is also one of the many kinds of motion.

CLEINIAS: Granted.

ATHENIAN: And we will assume that which moves other, and is changed by
other, to be the ninth, and that which changes itself and others, and
is coincident with every action and every passion, and is the true
principle of change and motion in all that is--that we shall be inclined
to call the tenth.

CLEINIAS: Certainly.

ATHENIAN: And which of these ten motions ought we to prefer as being the
mightiest and most efficient?

CLEINIAS: I must say that the motion which is able to move itself is ten
thousand times superior to all the others.

ATHENIAN: Very good; but may I make