Why the curse is pronounced on the serpent in this manner, that he shall go on his breast and on his belly, and eat dust, and be at enmity with the woman? (Genesis 3:16).
The words in themselves are plain enough, and we have evidence of them in what we have seen. But the real meaning contains an allegory concealed beneath it; since the serpent is the emblem of desire, representing under a figure a man devoted to pleasure. For he creeps upon his breast and upon his belly, being filled with meat and drink like cormorants, being inflamed by an insatiable cupidity, and being incontinent in their voracity and devouring of flesh, so that whatever relates to food is in every article something earthly, on which account he is said to eat the dust. But desire has naturally a quarrel with the outward sense, which Moses here symbolically calls the woman; but where the passions appear to be as it were guardians and champions in behalf of the senses, nevertheless they are beyond all question still more clearly flatterers forming devices against them like so many enemies; and it is the custom of those who are contending with one another to perpetrate greater evils by means of those things which they concede. Forsooth they turn the eyes to the ruin of the sight, the ears to hearing what is unwelcome; and the rest of the outward senses to insensibility. Moreover they cause dissolution and paralysis to the entire body, taking away from it all soundness, and foolishly building up instead a great number of most mischievous diseases.