SHNEʾUR ZALMAN OF LYADY (1745–1813) was the founder of the Habad school of Hasidism. Born into a prominent Jewish family in Liozno, Belorussia, Shneʾur Zalman had an extensive rabbinic education before he became associated with the Hasidic movement. At the age of twenty he joined the circle of students around Dov Ber of Mezhirich (Mie̹dzyrzecz, Poland) and was immediately recognized as a person of unusual intellectual abilities. Dov Ber encouraged him to continue with his legal studies as well as to cultivate his developing mastery of the Zohar and the Lurianic mystical writings. Legend has it that he was the teacher of Dov Ber's son, Avraham "the Angel" (1739/40–1777), in exoteric matters while the latter initiated him into the secrets of Qabbalah. Shneʾur Zalman's profound legal knowledge is reflected in the Shulhan ʾarukh shel...