Translated by Rabbi Aryeh Kaplan, “Rabbi Nachman’s Wisdom,” Breslov Research Institute, pp. 140-141.
You should be able to feel another’s troubles in your own heart. This is especially true when many are suffering.
It is possible to clearly realize another’s anguish and still not feel it in your heart.
When an entire community is in distress, you should surely feel their agony in your heart. If you do not feel it, you should strike your head against the wall.
You should strike your head against the walls of your heart.
This is the meaning of the verse (Deuteronomy 4:39), “Know this day and realize it in your heart.” You must bring the realization from your mind to your heart. Understand this well.
We later heard that the Rebbe once said that this is the meaning of the passage (Isaiah 38:2), “And Hezekiah turned his face to the wall.” The face that he turned was his awareness, bringing it inside the walls of his heart. For one’s true face is his mind, which illuminates it from within.
 See Sichos HaRan 217.
 Yerushalmi Berakhos 4:4 (35a); Sanhedrin 10:2 (51b); Chayay Moharan 17a ($14).
 Likutey Moharan I, 30:4. Cf. Ecclesiastes 8:1.