This book deals with the life and thought of an original but neglected religious thinker who, perhaps more than any other in the history of Jewish thought, grappled with the problems inherent in the idea of God's unity. Rabbi Aaron Horowitz is generally acknowledged to be the most outstanding, systematic exponent of the profound Habad theory of Hasidism. With the renewed interest in Jewish mysticism in general and Hasidism in particular, this work can serve as an excellent introduction to the more intricate and stimulating ideas of the Movement, normally to be found only in recondite tomes written in difficult Rabbinic Hebrew and therefore beyond the scope of even serious students of the subject. One of the most striking features of the book is the way it demonstrates that there is a close affinity between Habad thought and Far Eastern spirituality. Dr Jacobs has succeeded in bringing a vanished world to life for the modern reader.