The leaders of Lubavitch would often deliver a series of interrelated discourses, developing the full depth and breadth of their spiritual, philosophical theses. One of the most famous, is this, a 61-part serial delivered by Rabbi Shalom Dov Ber Schneersohn, the fifth Lubavitcher Rebbe, begun on Rosh Hashana 5666 (1905) through the close of 5668 (1907). Elder Chasidim once declared that this work contained "the revelations of the light of Moshiach." This emended edition includes comments and explanations by the Rabbi Yosef Y. Schneersohn and Rabbi Menachem M. Schneerson, respectively the sixth and seventh Lubavitcher Rebbes.