timaeus   

and of true wisdom, and has exercised his intellect more than any
other part of him, must have thoughts immortal and divine, if he
attain truth, and in so far as human nature is capable of sharing in
immortality, he must altogether be immortal; and since he is ever
cherishing the divine power, and has the divinity within him in
perfect order, he will be perfectly happy. Now there is only one way
of taking care of things, and this is to give to each the food and
motion which are natural to it. And the motions which are naturally
akin to the divine principle within us are the thoughts and
revolutions of the universe. These each man should follow, and correct
the courses of the head which were corrupted at our birth, and by
learning the harmonies and revolutions of the universe, should
assimilate the thinking being to the thought, renewing his original
nature, and having assimilated them should attain to that perfect life
which the gods have set before mankind, both for the present and the
future.
Thus our original design of discoursing about the universe down to
the creation of man is nearly completed. A brief mention may be made
of the generation of other animals, so far as the subject admits of
brevity; in this manner our argument will best attain a due
proportion. On the subject of animals, then, the following remarks may
be offered. Of the men who came into the world, those who were cowards
or led unrighteous lives may with reason be supposed to have changed
into the nature of women in the second generation. And this was the
reason why at that time the gods created in us the desire of sexual
intercourse, contriving in man one animated substance, and in woman
another, which they formed respectively in the following manner. The
outlet for drink by which liquids pass through the lung under the
kidneys and into the bladder, which receives then by the pressure of
the air emits them, was so fashioned by them as to penetrate also into
the body of the marrow, which passes from the head along the neck
and through the back, and which in the preceding discourse we have
named the seed. And the seed having life, and becoming endowed with
respiration, produces in that part in which it respires a lively
desire of emission, and thus creates in us the love of procreation.
Wherefore also in men the organ of generation becoming rebellious
and masterful, like an animal disobedient to reason, and maddened with
the sting of lust, seeks to gain absolute sway; and the same is the
case with the so-called womb or matrix of women; the animal within
them is desirous of procreating children, and when remaining
unfruitful long beyond its proper time, gets discontented and angry,
and wandering in every direction through the body, closes up the
passages of the breath, and, by obstructing respiration, drives them
to extremity, causing all varieties of disease, until at length the
desire and love of the man and the woman, bringing them together and
as it were plucking the fruit from the tree, sow in the womb, as in
a field, animals unseen by reason of their smallness and without form;
these again are separated and matured within; they are then finally
brought out into the light, and thus the generation of animals is
completed.
Thus were created women and the female sex in general. But the
race of birds was created out of innocent light-minded men, who,
although their minds were directed toward heaven, imagined, in their
simplicity, that the clearest demonstration of the things above was to
be obtained by sight; these were remodelled and transformed into
birds, and they grew feathers instead of hair. The race of wild
pedestrian animals, again, came from those who had no philosophy in
any of their thoughts, and never considered at all about the nature of
the heavens, because they had ceased to use the courses of the head,
but followed the guidance of those parts of the soul which are in
the breast. In consequence of these habits of theirs they had their
front-legs and their heads resting upon the earth to which they were
drawn by natural affinity; and the crowns of their heads were
elongated and of all sorts of shapes, into which the courses of the