One of the joys of reading the Times Literary Supplement (TLS), the British book review journal that arrives in my mailbox more or less on schedule four times a month, is that it periodically includes lengthy essays drawn from lectures or from introductions to new books that are aimed at that borderline place between the educated layperson and the browsing academic. TLS’s editors often group a selection of each week’s works by theme, and its July 6 issue included several interesting reviews related to medieval heresy. One sentence in the piece stopped me in my tracks: “he” (I’ll tell you whom in a moment) “frames what he is not sure of within the boundaries of what he is sure about.”