What is here spoken of false prophets we may apply to all whose dress and speech promise one thing, and their actions exhibit another. But it is specially to be understood of heretics, who by observing temperance, chastity, and fasting, surround themselves as it were with a garment of sanctity, but inasmuch as their hearts within them are poisoned, they deceive the souls of the more simple brethren.
We would ask those heretics who affirm that there are two natures directly opposed to each other, if they admit that a good tree cannot bring forth evil fruit, how it was possible for Moses, a good tree, to sin as he did at the water of contradiction? Or for Peter to deny his Lord in the Passion, saying, “I know not the man?” Or how, on the other hand, could Moses’ father-in-law, an evil tree, inasmuch as he believed not in the God of Israel, give good counsel?
