R’ Salanter’s next two letters (15 and 16) also touch on the Days of Judgment, but they veer off from there to make other points as well. He begins letter 15 with a heartfelt word of gratitude for his corresponds’ commitments to build a Mussar House in their city, and then he turns to the Days of Judgment with their act in mind. He emphasizes the fact that the most important thing to do in the course of that auspicious time of year is to resolve to avoid specific sins. The most difficult and grave sin to avoid, R’ Salanter underscores, is theft. If you can’t resist it on all levels, he allows, then at least avoid the most serious degrees of it this year — and more so in the years to come.
(While most of us wouldn’t dare walk up to someone and take something from him right there and then, nonetheless some of us would find it very easy to cheat him behind his back, cheat the government, overcharge for products, etc. While much is made about other sins we’re all capable of and should avoid, little is said about this terrible and insensitive sin when a lot should be said.)
One way to rectify the sin of stealing in fact, R’ Salanter goes on, is to give back to society in return. As such, perhaps the best thing to give to undo theft would be to donate toward the building of a Mussar House where people could learn the harm done by theft and other serious sins.
In fact, the operative principle in bettering yourself is to try not to commit sins which are easy enough for you to avoid. So if you’re guilty of being lax to a degree in Torah-study because of your professional responsibilities, for example, you’d do well to concentrate on studying things that you can set to memory and review them whenever you can in the course of your long business day (concentrating perhaps on business and professional halachos).
Returning to the theme of the Days of Judgment in Letter 16, R’ Salanter responds to the very broad and vital question raised by his disciples as to how to fight the yetzer harah. R’ Salanter reluctantly declares that he’s too old by that point to explain at length how to do that, which is the point of all of our lives at bottom. But he offers that one of the best ways is to use the period of time preceding Yom Kippur to “immerse yourself in Mussar study”, so as to manifest “a broken heart and humbled heart” over your current spiritual standing, and to pour out your soul to G-d Almighty. Doing that will undoubtedly positively affect the year to come, and will encourage you to continue studying Mussar, as “an inner awakening will overcome all resistance from the yetzer harah”.