To Florus 6.7

He presses into all his writings the claim that only Adam and Eve were made good by God—that is, subject to no natural guilt—and that they sinned by free will, but so greatly that they overthrew everything God had established in their nature. He says: ‘The devil planted that sin far greater and deeper than the sins familiar to people. Therefore, through that great sin of the first human, our nature was changed for the worse there, and not only became sinful but also generates sinners. Yet the very sickness through which the power of living well perished is not nature but a defect. That sin which changed the human being for the worse in paradise, because it is far greater than we can judge, is inherited by everyone born’ (compare Augustine, Marriage and Sexual Desire 2.34.57–58).

See how openly he explained his meaning! Those first humans, he says, had a good nature, but committed a sin so monstrous and immeasurable that they destroyed the power to live well, extinguished the light of free will, and established a necessity of sinning thereafter. No one born from their stock could strive toward the beauty of virtues, turn away from vices, and attain holiness.