" My grandfather said that the Mittler Rebbe wrote specific maamarim and a special book for every different kind of maskil and oveid in the Chassidic community. Shaar Hayichud and Shaarei Ora, however, are general, written for all chassidim.
* Shaar Hayichud is the key to the teachings of Chassidus
Shaarei Ora is the alef-beit of Chassidus "



