Now they had forgotten to bring bread, and they had only one loaf with them in the boat. 15 And he cautioned them, saying, “Watch out; beware of the leaven of the Pharisees and the leaven of Herod.” And they began discussing with one another the fact that they had no bread. And Jesus, aware of … More J.C. Ryle on the leaven of false doctrine: The great secret of its success is its subtlety and likeness to truth.