To Florus 3.167

In that first work I had already argued about fleshly desire or pleasure, also called lust, implanted in the sexes for the reproductive activity of generation. I showed that it is nothing other than one of the body’s instruments, implanted alike in rational and irrational beings and belonging to God’s work, since he equipped our flesh with sensations. Yet Augustine attacks it fiercely, calling it evil—that is, natural sin and the parent of every sin. He tries to persuade us chiefly from its shame, and mocks me for being ashamed to name it directly.