Likutei Moharan 76:5/ליקוטי מוהר"ן ע״ו:ה׳

15. Therefore, a person needs to renew his intellect daily, as it is written (Lamentations 3:23), “They are renewed every morning…”; and it is also written (Morning Liturgy), “With His goodness, He renews….” {Renewing the mind—i.e., meriting new intellect, so that one’s intellect is constantly expanding—is the aspect of sight. For the intellect’s perception corresponds to vision. One knows and understands the thing clearly, as though his eyes see it very distinctly. This is as it is written (Genesis 3:7), “Then the eyes of both of them were opened”—and Rashi comments: This is said with respect to wisdom. This is brought a number of times in the Rebbe’s teachings.}

2Now, the power of vision has two aspects. Someone with strong vision can see from afar and does not have to get close to the thing he needs to see. But someone whose vision is weak has to get close to the thing he wants to see and look at it carefully.

3The same applies to the service of God. One person has a clear mind. He is able to pray and study Torah without arduous concentration. Another person has to [work to] collect his thoughts before speaking. If he speaks before contemplating, his words lack thought— corresponding to “the back of the words.” This is the aspect of constricted mentalities, which are judgments. But someone whose mind is clear has expanded consciousness, which is the aspect of mercy and kindness.

4This is as in the teaching of our Sages, of blessed memory: Great is dae’ah, for it is positioned between two Divine Names, as it is said (1 Samuel 2:3): “for El (the Omnipotent One) of dae’ot is YHVH (God)” (Berakhot 33a). El is lovingkindness, as it is written (Psalms 52:3), “the lovingkindness of El lasts throughout the day.” And YHVH is mercy, as it is written (Psalms 119:156), “Great is Your mercy, O YHVH .

5However, it is impossible to pray with a clear mind unless one first repents fully for one’s sins. This is as it is written (Deuteronomy 30:6), “Then God <your Lord> will circumcise your heart”—which Targum renders as: God will remove the foolishness of your heart—<“to love God your Lord”>. Of which repentance is this said? [It refers] to repentance motivated by love, on account of which every last trace is effaced.

6<And concerning the verse,> “Return, O mischievous sons; I will heal their waywardness” (Jeremiah 3:22), our Sages, of blessed memory, <said>: This is difficult to understand. “Mischievous [sons]” suggests rooting out [one’s sins], leaving no taint at all, whereas “I will heal” suggests that a taint does remain. They answer that the one is [repentance] out of love, whereas the other is [repentance] out of fear (Yoma 86a). When motivated by love, no trace remains. Such a person has a clear mind and can pray without arduous concentration, and so is able to renew his intellect daily.