timaeus   

are by nature visible, found that no unintelligent creature taken as a
whole was fairer than the intelligent taken as a whole; and that
intelligence could not be present in anything which was devoid of
soul. For which reason, when he was framing the universe, he put
intelligence in soul, and soul in body, that he might be the creator
of a work which was by nature fairest and best. Wherefore, using the
language of probability, we may say that the world became a living
creature truly endowed with soul and intelligence by the providence of
God.
This being supposed, let us proceed to the next stage: In the
likeness of what animal did the Creator make the world? It would be an
unworthy thing to liken it to any nature which exists as a part
only; for nothing can be beautiful which is like any imperfect
thing; but let us suppose the world to be the very image of that whole
of which all other animals both individually and in their tribes are
portions. For the original of the universe contains in itself all
intelligible beings, just as this world comprehends us and all other
visible creatures. For the Deity, intending to make this world like
the fairest and most perfect of intelligible beings, framed one
visible animal comprehending within itself all other animals of a
kindred nature. Are we right in saying that there is one world, or
that they are many and infinite? There must be one only, if the
created copy is to accord with the original. For that which includes
all other intelligible creatures cannot have a second or companion; in
that case there would be need of another living being which would
include both, and of which they would be parts, and the likeness would
be more truly said to resemble not them, but that other which included
them. In order then that the world might be solitary, like the perfect
animal, the creator made not two worlds or an infinite number of them;
but there is and ever will be one only-begotten and created heaven.
Now that which is created is of necessity corporeal, and also
visible and tangible. And nothing is visible where there is no fire,
or tangible which has no solidity, and nothing is solid without earth.
Wherefore also God in the beginning of creation made the body of the
universe to consist of fire and earth. But two things cannot be
rightly put together without a third; there must be some bond of union
between them. And the fairest bond is that which makes the most
complete fusion of itself and the things which it combines; and
proportion is best adapted to effect such a union. For whenever in any
three numbers, whether cube or square, there is a mean, which is to
the last term what the first term is to it; and again, when the mean
is to the first term as the last term is to the mean-then the mean
becoming first and last, and the first and last both becoming means,
they will all of them of necessity come to be the same, and having
become the same with one another will be all one. If the universal
frame had been created a surface only and having no depth, a single
mean would have sufficed to bind together itself and the other
terms; but now, as the world must be solid, and solid bodies are
always compacted not by one mean but by two, God placed water and
air in the mean between fire and earth, and made them to have the same
proportion so far as was possible (as fire is to air so is air to
water, and as air is to water so is water to earth); and thus he bound
and put together a visible and tangible heaven. And for these reasons,
and out of such elements which are in number four, the body of the
world was created, and it was harmonised by proportion, and
therefore has the spirit of friendship; and having been reconciled
to itself, it was indissoluble by the hand of any other than the
framer.
Now the creation took up the whole of each of the four elements; for
the Creator compounded the world out of all the fire and all the water
and all the air and all the earth, leaving no part of any of them
nor any power of them outside. His intention was, in the first
place, that the animal should be as far as possible a perfect whole
and of perfect parts: secondly, that it should be one, leaving no