A tape recording of a class on Shaar HaYichud (The Gate of Unity) of the Mittler Rebbe, given by Rabbi Yossi Markel.

This book, Shaar HaYichud, authored by the Holy Rabbi Dov Ber of Lubavitch, is known as THE KEY to the teachings of Chassidus, and it’s mastery is a prerequisite for all students of Chassidic thought and methodology.

This is because it bring absolute clarity to the methodology of Chassidic Contemplation (Hitbonenut) and the process by which HaShem created the universe from nothing, known as the chaining down of the worlds (Seder Hishtalshelut). It is therefore the foundation to unlocking the secrets of Kabbalah and the treasure troves of Chassidus.

The original text is available here: https://chabadlibrary.org/books/adhaam/ner/3/index.htm

The English translation and commentary of the text is available here: http://truekabbalah.com/the-gate-of-unity-english/