The Hasidic outlook shrinks from studying books of moral teaching and sees them as an inadequate substitute for a live teacher.
The author of such a book, even when he derives its contents solely from the Torah itself, expresses them in his own way; indeed, it is not only legitimate but also inevitable that a person should understand and create according to his own personality and the nature of his soul.
So every book expresses, to a significant extent, the personality and spirit of its author.
As a result, the book remains closed to the outside reader, not because it is difficult to understand but because these matters are inherently “hidden matters belonging to God.”
It is impossible to relate oneself to them and experience them, because this experience is so individual, so unique to each person, that it cannot be generalized.
Consequently, however important and holy these books may be, they do not serve the purpose of granting a true and direct perception; they cannot touch that fine, unique, and sensitive point that defines each individual.
—Rabbi Adin Steinsaltz, Opening the Tanya