Then understood they that he bade them not beware of the leaven of bread, but of the doctrine of the Pharisees and of the Sadducees.
All Commentaries on Matthew 16:12 Go To Matthew 16
Jerome
AD 420
This was a favorable opportunity for instruction which was ordered by the Savior. He said, “Beware the leaven of the Pharisees and the Sadducees.” He taught them what the five loaves and seven that had nourished five thousand and four thousand men in the desert signified. He showed that there is a spiritual understanding underlying these events, even if the import of the sign is clear. For if the leaven of the Pharisees and the Sadducees indicated not physical bread but twisted narratives and heretical teaching, then might not also the food by which the people of God were nourished signify the true and complete doctrine? Someone might inquire, “How is it that they do not have the loaves? For they immediately boarded the boat after the seven baskets had been filled.” But the Scripture testifies to the fact that they had forgotten to take food with them. Remember the leaven about which even the apostle speaks when he writes, “A little leaven spoils the whole dough.” The sort of leaven of which he speaks is something like the kind that Marcion and Valentinus and all heretics exhibited. It is to be avoided by all means. Leaven has this power, that, if mixed with flour, that which seemed small would grow into something larger and draw to its own essence the whole loaf. So too with heretical doctrine, if it tosses even a tiny spark into your heart, in a short time a huge flame grows beneath and draws to itself a person’s entire substance. It was then that they finally understood that he had not meant them to beware simply of the leaven of bread but of the teaching of the Pharisees and Sadducees. .
