There are some times when Jesus criticizes His disciples for not understanding the points that He is making that I can see why Jesus is frustrated. The message Jesus is trying to convey seems so obvious now, after 2,000 years of history and reflection. But today (Mk 8: 14-21), when Jesus blasts the disciples pretty-strongly for not understanding what He is talking about when He refers to the "leaven of the Pharisees and the leaven of Herod," I confess that I can sympathize with the disciples. The metaphor Jesus is using is more-than-a-bit obscure. Just what is He talking about when Jesus refers to "the leaven of the Pharisees and the leaven of Herod"? Leaven is more commonly called yeast. It is what makes bread rise, for example. It is powerful, and a bit goes a long way. It can transform ordinary dough into something quite different-- from flat bread to a bread that is high and light. And it seems like the role of yeast in bread is at least somewhat on Jesus' mind when He uses this expression, since He then asks the disciples questions about His miraculous feeding of 5,000 and 4,000 people and the amount of bread left over-- baskets and baskets full. Maybe it is as simple as this: Jesus wants His disciples (and us) to remember that what He can do for us is so much more important than the earthly "leaven" of those who do not know Him, like Herod or the Pharisees. Pay attention to me, Jesus seems to be saying, rather than worrying about the kind of things that those who are not my followers worry about. This whole discussion arises-- let us remember-- out of the fact that the disciples had forgotten to bring bread along for their journey. Stop worrying about that, Jesus seems to be saying, and look at how easily and lavishly I can provide for you. Worry about earthly things can be destructive, toxic even, and a little of it can cause huge changes in one's perspective and attitudes-- like a little yeast can make a big change. Maybe that's all Jesus wants us to realize.