Sefer Ha'Arachim Vol. 9 (Achdus - Achdus Hashem part 6) ספר הערכים חב''ד ח' ט

This comprehensive treatment of the basic concepts of Chabad Chassidus is in the form of individual entries arranged alphabetically, similar to the "Talmudic Encyclopedia". Various categories of articles:Summarized Chassidic explication of mystical concepts; Chassidic explanations of concepts in the Talmud, commentators and codifiers; the spiritual essence of the personalities of the Bible: Revelations of Chassidus regarding the practical Mitzvot and their observance; Mitzvot of the "Duties of the Heart" (the intellectual and emotional relationship with G-d); Jewish law and custom, the inner meaning of the world around us, and more.