По этому поводу из сихи Ребе:
Every matter has its source in the Torah. Thus the spreading of the wellsprings of Chassidus outward, the revelation and dissemination of P’nimiyus HaTorah to Jews who are found in the outer peripheries begins from [a parallel initiative within the realm of Torah study]: that P’nimiyus HaTorah will be revealed within the teachings of Nigleh, the revealed dimension of Torah law, to the extent that they are joined in absolute unity.
Before the Alter Rebbe, there were also Torah giants who achieved prominence in both Nigleh and Nistar, the Torah’s mystic secrets. Obviously, their involvement in the Torah’s mystic secrets transformed their approach to Nigleh. Nevertheless, they would regard [these disciplines] as two different realms: the revealed and the hidden.
[Against this background,] the Alter Rebbe brought about a new development, joining together both aspects of the Torah in complete unity.
( Сиха полностью )