“Mindlessly thumbing the lexicon” was my Latin teacher’s expression for being insufficiently prepared for class. (That was at the end of the twentieth century, though it might as well have been the eighteenth.) Once we had a grasp of all but the most abstruse grammar rules, knowing Latin meant knowing the definitions of words even though, except at exam time, there was always a dictionary available to mindlessly thumb. Dictionaries, like the disintegrating paperback Collins Latin Dictionary I used in those days, are ubiquitous and generally treated with a kind of reverence otherwise accorded only to scripture. Dictionaries are of course not sacred texts—no God would be so vengeful as to communicate with His chosen people lexicographically—and yet they are unfairly neglected as objects of academic study. Like other texts, dictionaries should be placed within a historical context and interpreted.