On the Creation of the World (163-164)

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.