Especially so if he calls to mind the contamination of his soul with the sin of youth and the blemish he has wrought thereby in the supernal worlds—the source of his soul. The fact that they were sins of “youth,” belonging to a time and to a spiritual level from which he may presently be far removed, is irrelevant in these supernal worlds—where everything is timeless, and it is as if he had caused the blemish and defiled himself this very day, G-d forbid.

וּבִפְרָט כְּשֶׁיִּזְכּוֹר טוּמְאַת נַפְשׁוֹ בְּחַטַּאת נְעוּרִים, וְהַפְּגַם שֶׁעָשָׂה בָּעֶלְיוֹנִים, וְשָׁם הוּא לְמַעְלָה מֵהַזְּמַן, וּכְאִלּוּ פָּגַם וְנִטְמָא הַיּוֹם – חַס וְשָׁלוֹם – מַמָּשׁ.

True, he may already have repented sincerely and thereby removed the blemish and cleansed himself. But the essence of repentance is in the heart, and in the heart, there are many distinctions and levels. Moreover, everything depends on what kind of a man he is (—the greater his stature, the higher the level of repentance required of him) and on the time and place in which he now stands, as is known to the knowing.

וְאַף שֶׁכְּבָר עָשָׂה תְּשׁוּבָה נְכוֹנָה, הֲרֵי עִיקַּר הַתְּשׁוּבָה – בַּלֵּב, וְהַלֵּב, יֵשׁ בּוֹ בְּחִינוֹת וּמַדְרֵגוֹת רַבּוֹת, וְהַכֹּל לְפִי מַה שֶּׁהוּא אָדָם, וּלְפִי הַזְּמַן וְהַמָּקוֹם, כַּיָּדוּעַ לַיּוֹדְעִים.

Whenever and wherever one is less tempted by a particular sin, a deeper and loftier level of repentance is expected of him for having committed that sin than at a time when he is more strongly tempted and must fight more insistently to resist that temptation. Similarly, time and place create other differences with respect to repentance. Therefore, judging by one’s present situation, his earlier repentance may be inadequate in erasing his past sins. Perhaps, then, the absence of a higher form of repentance required of him now causes his sins to interpose between himself and G-d, preventing the light of his soul from penetrating his heart—as the Alter Rebbe continues:

Consequently, now, at this time, when observing himself he sees that “the light of the soul does not penetrate into him,” it is evident that either (a) today his repentance has not been accepted and his sins [still] separate him from G-dliness or (b) it is desired that he be raised to a more sublime level of repentance, coming from a point yet deeper in his heart than his earlier repentance.

וְלָכֵן, עַכְשָׁיו בְּשָׁעָה זוֹ, שֶׁרוֹאֶה בְּעַצְמוֹ דְּלָא סָלִיק בֵּיהּ נְהוֹרָא דְנִשְׁמְתָא, מִכְּלָל, שֶׁהַיּוֹם לֹא נִתְקַבְּלָה תְּשׁוּבָתוֹ, וַעֲוֹנוֹתָיו מַבְדִּילִים, אוֹ, שֶׁרוֹצִים לְהַעֲלוֹתוֹ לִתְשׁוּבָה עִילָּאָה יוֹתֵר, מֵעוּמְקָא דְלִבָּא יוֹתֵר.

Far from indicating Divine displeasure, the rejection of his repentance in this latter case points to Divine favor: a desire to raise this person to yet greater heights of repentance. Hence the difficulties in his divine service and the timtum halev—so that he will call forth greater resources from within himself and repent more deeply.

For this reason, King David said, despite the fact that he was a tzaddik, who was also able to say of himself: “My heart is a void within me,”9 which means (as Rashi comments, “The evil impulse is as if dead within me”10—despite this, he would still say:) “My sin is constantly before me.”11

וְלָכֵן אָמַר דָּוִד: "וְחַטָּאתִי נֶגְדִּי תָמִיד".

Why was it necessary for a man of David’s caliber to constantly bear in mind his past sins? Surely he had repented for them adequately! Obviously, then, the memory is necessary in order to spur one on to greater heights within the ranks of holiness, to deeper levels of repentance, as said earlier.12