TIMAEU [23]
dwell with their victors, and from being many become one. And owing to
these affections, all things are changing their place, for by the
motion of the receiving vessel the bulk of each class is distributed
into its proper place; but those things which become unlike themselves
and like other things, are hurried by the shaking into the place of
the things to which they grow like.
Now all unmixed and primary bodies are produced by such causes as
these. As to the subordinate species which are included in the greater
kinds, they are to be attributed to the varieties in the structure
of the two original triangles. For either structure did not originally
produce the triangle of one size only, but some larger and some
smaller, and there are as many sizes as there are species of the
four elements. Hence when they are mingled with themselves and with
one another there is an endless variety of them, which those who would
arrive at the probable truth of nature ought duly to consider.
Unless a person comes to an understanding about the nature and
conditions of rest and motion, he will meet with many difficulties
in the discussion which follows. Something has been said of this
matter already, and something more remains to be said, which is,
that motion never exists in what is uniform. For to conceive that
anything can be moved without a mover is hard or indeed impossible,
and equally impossible to conceive that there can be a mover unless
there be something which can be moved-motion cannot exist where either
of these are wanting, and for these to be uniform is impossible;
wherefore we must assign rest to uniformity and motion to the want
of uniformity. Now inequality is the cause of the nature which is
wanting in uniformity; and of this we have already described the
origin. But there still remains the further point-why things when
divided after their kinds do not cease to pass through one another and
to change their place-which we will now proceed to explain. In the
revolution of the universe are comprehended all the four elements, and
this being circular and having a tendency to come together, compresses
everything and will not allow any place to be left void. Wherefore,
also, fire above all things penetrates everywhere, and air next, as
being next in rarity of the elements; and the two other elements in
like manner penetrate according to their degrees of rarity. For
those things which are composed of the largest particles have the
largest void left in their compositions, and those which are
composed of the smallest particles have the least. And the contraction
caused by the compression thrusts the smaller particles into the
interstices of the larger. And thus, when the small parts are placed
side by side with the larger, and the lesser divide the greater and
the greater unite the lesser, all the elements are borne up and down
and hither and thither towards their own places; for the change in the
size of each changes its position in space. And these causes
generate an inequality which is always maintained, and is
continually creating a perpetual motion of the elements in all time.
In the next place we have to consider that there are divers kinds of
fire. There are, for example, first, flame; and secondly, those
emanations of flame which do not burn but only give light to the eyes;
thirdly, the remains of fire, which are seen in red-hot embers after
the flame has been extinguished. There are similar differences in
the air; of which the brightest part is called the aether, and the
most turbid sort mist and darkness; and there are various other
nameless kinds which arise from the inequality of the triangles.
Water, again, admits in the first place of a division into two
kinds; the one liquid and the other fusile. The liquid kind is
composed of the small and unequal particles of water; and moves itself
and is moved by other bodies owing to the want of uniformity and the
shape of its particles; whereas the fusile kind,