De Opificio Mundi

Now, the first approaches of the male to the female have a pleasure in them which brings on other pleasures also, and it is through this pleasure that the formation and generation of children is carried on. And what is generated by it appears to be attached to nothing rather than to it, since they rejoice in pleasure, and are impatient at pain, which is its contrary. On which account even the infant when first brought forth cries, being as it seems in pain at the cold. For coming forth on a sudden into the air from a very warm, and indeed, hot region—namely, the womb, in which it has been abiding a considerable time, the air being a cold place and one to which it is wholly unaccustomed, it is alarmed, and pours forth tears as the most evident proof of its grief and of its impatience at pain.

For every animal, it is said, hastens to pleasure as to the cud which is most indispensable and necessary to its very existence; and, above all other animals, this is the case with man. For other animals pursue pleasure only in taste and in the acts of generation; but man aims at it by means of his other senses also, devoting himself to whatever sights or sounds can impart pleasure to his eyes or ears.

And many other things are said in the way of praise of this inclination, especially that it is one most peculiar and kindred to all animals.

But what has been already said is sufficient to show what the reasons were on account of which the serpent appears to have uttered a human voice. And it is on this account that Moses appears to me in the particular laws also which he issued in the respect to animals, deciding what were proper to be eaten, and what were not, to have given especial praise to the animal

For the serpent fighter appears to me to be no other than temperance expressed under a symbolical figure, waging an interminable and unrelenting warfare against intemperance and pleasure. For temperance especially embraces economy and frugality, and pares down the necessities to a small number, preferring a life of austerity and dignity. But intemperance is devoted to extravagance and superfluity, which are the causes of luxury and effeminacy to both soul and body, and to which it is owing that in the opinion of wise men life is but a faulty thing, and more miserable than death.