Likutei Moharan 5:3/ליקוטי מוהר"ן ה׳:ג׳

13. Now, the essence of joy is found in the heart, as is written (Psalms 4:8), “You have put joy in my heart.” But it is impossible for the heart to rejoice unless a person removes the crookedness in his heart, so that he might have a straight heart. Then he will merit <true> joy, as is written (ibid. 97:11), “and joy for the straight of heart.”

2And the heart’s crookedness is made straight by means of thunder. As our Sages taught: Thunder was only created to straighten the crookedness of the heart (Berakhot 59a). Thunder corresponds to the voice a person releases <with great force> while praying. From this [voice], thunder is generated.

3As stated in the Zohar (III, 235b): When the voice is released and encounters the rain clouds, the voice is transmitted to the creation—and this is thunder. For thunder is essentially from gevurot (severities), as is written (Job 26:14), “Who can understand the thunder of His gevurot (strength)?”

4This is the why [when hearing thunder] we recite the blessing “… for His might and gevurah fill the universe.” These gevurot are an aspect of might and strength. A person releases the voice with great force, and this voice strikes the rain clouds—i.e., the aspect of <upper> mentalities from where drop after drop descends. As is brought in the Zohar (III, 235b): “a well of fresh water, and drops from LeBaNon” (Song of Songs 4:15) —from the LiBuNa (whiteness) of the mind.

5And when [this voice] strikes the rain clouds, then “the voice is transmitted to the creation”—i.e., the aspect of thunder. This is the meaning of “The sound of Your thunder was in the sphere” (Psalms 77:19) —i.e., in the sphere of the mind. For when it encounters the skull, the voice is converted into thunder and is transmitted to the creation. {“My mouth will speak wisdom and the meditation of my heart will be understanding” (Psalms 49:4).}

6This <corresponds to> “My mouth will speak wisdom….” The speech that leaves my mouth strikes wisdom—i.e., the sphere of the mind. As a result, “the meditation of my heart will be understanding”—i.e., <the heart> will be stirred by the thunder. <This is because> the voice stimulates kavanah (Berakhot 24b).

7This is what our Sages taught: When a person has fear of Heaven, his words are heard (Berakhot 6b). For when someone possesses fear of Heaven, his voice is converted into thunder. This is because thunder is from the side of Yitzchak, as in, “the thunder of His gevurot .” This causes his words to be heard—i.e., “the voice is transmitted to the creation.” For hearing is linked to [the fear of Heaven], as is written (Habakkuk 3:2), “O God, I heard of Your message; I feared” (Zohar III, 230a).

8And this is the explanation of “geborei koach (mighty ones) who do His bidding, hearkening to the sound of His word” (Psalms 103:20). [As] the Zohar (I, 90a) states: “They merit hearing voices from Above.” In other words, by means of the gevurot, thunder is generated. This causes the heart to hear—i.e., “the meditation of my heart will be understanding”—as is written (1 Kings 3:9), “Give Your servant a hearing heart [to judge Your people].” And then his words are “transmitted to the creation”; this being “hearkening to the sound of His word.”

9This also corresponds to the sound of the shofar—i.e., the shofar-horn of the ram, the ram of Yitzchak (Zohar III, 235b) —which is an aspect of “the thunder of His gevurot .”

10This, then, is the meaning of (Psalms 89:16), “Happy is the nation who knows the shofar’s blast.” Specifically “knows,” because the voice hits the mind—corresponding to rain clouds—and is converted into the aspect of thunder. And whoever hears the shofar blown by a man who is God-fearing and pious, will certainly have no fear of thunder the entire year. As it is written: “With sounds [of thunder] and lightning You revealed Yourself to them, and with the shofar-sound You appeared to them.” You appeared to them through the sound of the shofar, [protecting them] from thunder and lightning.