It’s always interesting to see how a great man responds to basic questions from a younger person for an idea of what’s primary in the great man’s eyes. We have an instance of just that in Letter 20.
In response to his question about the true nature of Mussar, R’ Salanter replies to this young person that it’s rooted in the practical, commonplace things of life, and we learn that in fact “there aren’t exact boundaries” (i.e., hard and fast rules) when it comes to applying Mussar, in that it touches not only on the many daily events but on the breadth and width of man’s heart as well, which is boundless. And we’re reminded that “advice touching on one area can’t be applied to another”.
And the master must know that difficult (i.e., “touchy”) subjects call for “a gentle approach” and will take longer to rectify, even though the one offering the advice should hope for quick success. But isn’t that a contradiction? It certainly is, but both perspectives are necessary for success, and “a person with a good heart who knows himself well (and his motivations) would know overall how to balance the two”.
In any event, “it’s imperative to be engaged in character development” in order to succeed in Mussar, and in order to do that, one must “understand human conduct” which at bottom forswears the sort of “self-restraint and self-denial” that are essential to spiritual development.
Yet the student of Mussar must also engage regularly in deep Talmudic analysis and the study of practical Halacha, as well as guard his health and well-being, and to be courteous. And he must be a true student of human character, yet his main course of study should be that of Torah.
One must also balance two perspectives if he’s to be a leader of others: he must consider himself “a leader among (other) leaders” and yet “a pliant young person” too. R’ Salanter ends this letter with the warning “not to be strict and overbearing with others” or to “insist that he’s right and must be listened to”. Instead, he should be “gentle and pleasant”.
And Letter 21 makes the point that a Mussar instructor must also offer classes in Talmud to lay non-scholars — most especially to allow them to see the process of deriving the halacha from the Talmudic process, and to know that it’s to be carried out in the spirit of the fear of Heaven. For the most important thing to know is what’s to be done and what’s to be avoided which one only knows through the study of practical halacha.