"Moshe Halbertal's book will be a revelation to anyone interested in religious, philosophical, psychological, or political concealment. It has wide implications for the political craving for transparency, and dazzling insights into depth psychology (such as Freud's) and esoteric tendencies in philosophy (such as Wittgenstein's). The book manifests not only immense learning and virtuosity in reading Jewish texts but also genuine wisdom."--Avishai Margalit, Institute for Advanced Study"Halbertal's virtuosic exploration of a major dimension of medieval Jewish thought opens new vistas in Jewish philosophy and mysticism."--Moshe Idel, Hebrew University of Jerusalem"This is the most conceptually penetrating book that I can imagine on concealment and revelation in premodern Jewish thought. An original foray into a subject that has not been well developed, it has the makings of a classic. In particular, the essay on esotericism is rich and substantial. There can be no question of the book's brilliance."--Noah Feldman, author of Divided by God"Original, consistently interesting, and thought-provoking. This book exhibits the author's knack for synthesizing complicated technical material with clarity and verve, and making it accessible to both scholars in adjacent fields and to general readers."--Bernard Septimus, Harvard University"This book's taxonomy of esoteric knowledge and attempt to establish its importance both as a thing in itself and as an object of study are absolutely fascinating and indeed captivating. The book made an important aspect of medieval Jewish intellectual and spiritual life much less forbidding to me than it had been before, and it should make similar bodies of esoteric knowledge and esoteric movements--like late antique gnosticism and late medieval Christian mysticism--more approachable also."--William Chester Jordan, Princeton University