The works and personality of Moses Maimonides are imprinted on almost all forms of Judaism and have been ever since the twelfth century. Today he’s known by religious and secular alike, having lent his name to schools and hospitals, fitting legacies for a rabbi and a renowned physician who served at the court of the great Saladin. In Jewish circles, RaMBaM (an acronym for Rabbi Moshe ben Maimon) is well known as one of the preeminent Jewish legal authorities of all time and as a great thinker. Today, many seem to want to appropriate his authority for their own ideas. Some consider him a philosopher, forerunner of the rational enlightenment and precursor of reasoned responses to obscurantist superstitions. Others insist that he was a kabbalist, whether during his productive career or on a deathbed conversion. Since he is the single figure of medieval Judaism who looms largest over the subsequent tradition, it might be surprising to hear that he was a revolutionary. But that is exactly the claim of Moshe Halbertal’s welcome addition to the vast literature.