August 30, 22A (Matthew 16:21-28)

When I taught sixth-grade language arts, I used a set of diagrams called graphic organizers to help my students organize their thoughts. We used Venn diagrams to compare and contrast, writing differences in the outside portions of the overlapping circles and similarities in the center where the two circles meet. To sort ideas into categories, we used a very simple kind of graphic organizer: two columns. One column might be titled “books of the Old Testament” and the other “books of the New Testament.” They’re mutually exclusive. The divisions are clear.

To confuse these columns, to put items meant for one column into the other, is to commit what philosopher Gilbert Ryle called a category mistake. If you’ve mentally sorted bats into the category “birds,” for example, you might waste a lot of time searching for their feathers.

Most of the time, category mistakes result in mere confusion, not in loud condemnations from the Son of God. But poor Peter! Mere moments after Jesus praises him as a star pupil, the foundation from which every generation of believers will be built, Peter messes up in grand fashion. He refuses to believe that Jesus’ ministry will end with betrayal and crucifixion, and he begs Jesus not to speak of such nonsense anymore. Jesus lights into him, accusing the rock of being a stumbling block. “You are setting your mind not on divine things,” Jesus tells him, “but on human things.”