||The main Habad work of Kabbalah and Hasidus wherein the "Alter Rebbe" develops a systematic theosophical doctrine on the conceptions of G-d and the world and of man and his religious obligations, based on the Kabbalah of R. Isaac Luria in its original form combined with the Hasidism of the Ba'al Shem Tov and especially that of the maggid of Mezhirich.
R. Shneur Zalman of Liady (1745–1813), the founder of Habad Hasidism. He was according to family traditions born in Liozna, Belorussia, on the 18th of Elul. After his marriage in 1760 he devoted himself to Torah study. Concluding that he knew "a little about learning, but nothing about prayer" in 1764 he decided to learn about Hasidism from R. Dov Baer the Maggid of Mezhirech, leader of the Hasidic movement. In Mezhirech he became one of the inner circle of the Maggid's pupils. Although he was one of the youngest pupils, the Maggid had a high opinion of him, and in 1770 delegated to him the task of composing a new and up-to-date Shulhan Arukh. R. Shneur Zalman worked on this book for many years, but published only small parts of it. About one-third was printed posthumously (the rest had been destroyed by fire) and is known as the "Shulhan Arukh of the Rav" (1814). Though not a chasidic work, it represents - as the Maggid had intended - a great halakhic achievement. It evidences R. Shneur Zalman's superb Hebrew style, his ability to provide lucid explanation, and profundity without complexity. It became an authoritative halakhic source among observant Jews.