The following is a freely translated excerpt from a public letter written by the Rebbe in the closing days of the Jewish year 5716 (September 1956)
In order that the audit should be accurate and the right resolutions be made, one must be careful not to overstate one’s virtues and achievements. It is no less important, however, not to exaggerate one’s deficiencies and failings. For feelings of despondency–not to mention despair, G-d forbid–are one of greatest hindrances in a person’s endeavor to better himself.
Unfortunately, it is possible that, even if one does not exaggerate one’s faults, an honest accounting will show the negative side of one’s spiritual and moral balance scale as quite formidable—perhaps, even, outweighing one’s positive side. But also in such a case, a person has no cause for despair.
For (in addition to the deep regret over the past and the firm resolve for future change which the audit should elicit) one must always remember that everything good and holy is eternal and indestructible–as these stem from the soul, the spark of G-dliness within man–while negative deeds are only temporary, and can be rectified and eradicated through true and proper teshuvah (repentance).
The appreciation of the above truth should call forth in every individual, regardless of what his stocktaking of the previous year shows, a feeling of encouragement and hope for the future—knowing that only his good deeds are eternal, and have illuminated his own life, that of his family, and of all Israel (for “all Jews are accountable for each other,” bound to each other as a single entity).
From this it is also obvious that even if one sees signs of a general decline–that humanity, as a whole, is not getting any wiser or more virtuous–in truth, the good in the world grows greater and more powerful every year, every day, and every moment. For each moment’s good deeds are added to the accumulating good in the world.
So even if the not-good seems to be prevailing, this can only be temporary. Ultimately, the good shall gain the upper hand and the negative shall be utterly nullified. For the Creator and Ruler of the universe has decreed that, ultimately, all will do teshuvah, and that He will accept their teshuvah, so that “none shall be forsaken.”
 Published in Likkutei Sichot, vol. IX, pp. 417-419.
 Talmud, Shavuot 39a.
 II Samuel 14:14. See Deuteronomy 4:29-31 and 30:1; Mishneh Torah, Laws of Repentance, 7:5.
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