laws (books 7 - 12)
some things are in motion and others at rest. "And do not things which
move a place, and are not the things which are at rest at rest in a
place?" Certainly. "And some move or rest in one place and some in
more places than one?" You mean to say, we shall rejoin, that those
things which rest at the centre move in one place, just as the
circumference goes round of globes which are said to be at rest?
"Yes." And we observe that, in the revolution, the motion which
carries round the larger and the lesser circle at the same time is
proportionally distributed to greater and smaller, and is greater
and smaller in a certain proportion. Here is a wonder which might be
thought an impossibility, that the same motion should impart swiftness
and slowness in due proportion to larger and lesser circles. "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?
Cle. Which are they?
Ath. Just the two, with which our present enquiry is concerned.
Cle. Speak plainer.
Ath. I suppose that our enquiry has reference to the soul?
Cle. Very true.
Ath. 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
Ath. 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 co-incident 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.
Ath. And which of these ten motions ought we to prefer as being
the mightiest and most efficient?
Cle. I must say that the motion which is able to move itself is
ten thousand times superior to all the others.
Ath. Very good; but may I make one or two corrections in what I have
Cle. What are they?
Ath. When I spoke of the tenth sort of motion, that was not quite
Cle. What was the error?
Ath. According to the true order, the tenth was really the first
in generation and power; then follows the second, which was
strangely enough termed the ninth by us.
Cle. What do you mean?