Now the disciples had forgotten to bring any bread; and they had only one loaf with them in the boat. And he cautioned them, saying, ‘Watch out—beware of the yeast of the Pharisees and the yeast of Herod.’ (Mark 8: 14-15)

Once the boat lands the disciples will seek out some bread (this context is clearer in Matthew). I hear Jesus being humorous. But the humor is lost on the disciples.

The Daily Show with Jon Stewart is one inside joke after another. The better you understand the hard news, the funnier this parody of the news. But if you never read, listen, or watch the news the wit of the show is impenetrable.

Understanding the wit of Jesus depends on an awareness that both the Pharisees and the Herodians are working with powerful ideas. The Pharisees offer the supposed security of an orderly way of life. The Herodians offer the supposed security - and opportunities - of alliance with the cultural and political masters of the known world.

Both of these ideas are yeasty - amazing agents of change - in the life of the Jews. But Jesus cautions against both. Neither will bring about the intention of God. Don't eat their bread.

One of the rituals of Passover - probably practiced by Jesus and his disciples - is to remove all the yeast from one's home before the great festival. The yeast of Egypt - alien to the intent of God - is nullified. The ideas of both Pharisees and Herodians are alien to the reign of God.