Philosophical esotericism-the practice of communicating one's unorthodox thoughts "between the lines"-was a common practice until the end of the eighteenth century. Despite its long and well-documented history, however, esotericism is often dismissed today as a rare occurrence. Walking listeners through both an ancient (Plato) and a modern (Machiavelli) esoteric work, Arthur M. Melzer explains what esotericism is-and is not. It relies not on secret codes, but simply on a more intensive use of familiar rhetorical techniques like metaphor, irony, and insinuation. Melzer explores the various motives that led thinkers in different times and places to engage in this strange practice, while also exploring the motives that lead more recent thinkers not only to dislike and avoid this practice but to deny its very existence. The first comprehensive, book-length study of the history and theoretical basis of philosophical esotericism, Philosophy Between the Lines is "a treasure-house of insight and learning. It is that rare thing: an eye-opening book.