The Alter Rebbe explains the Talmudic phrase, “All those who sing go out in song” as referring to the song of the angels. Likewise, the Jewish souls in Gan Eden also sing to Hashem.
From what do the angels and souls “go out” through song? The Alter Rebbe quotes the Maggid, who explains that through song the angels and souls transcend their limitations (albeit exceedingly refined limitations, for they are altogether spiritual entities).
Likewise, although Hashem set up a world of limitation, song has a tremendous power in the service of Hashem; it can elevate the person completely above the limitations of the Bestial Soul and the world in general. This was the reason that the Levites sang melodies in the Beis HaMikdash while the Kohanim were offering the sacrifices.
And since “The prayers come in place of the sacrifices,” in prayer one should also rise above all limitations, until one transcends the limitations of the body entirely, with the soul almost expiring in an overwhelming love for Hashem. (This also explains why it is praiseworthy (when practical) to incorporate song into one’s prayers.)
This expresses the awesome power of music when used as Hashem intended—to bring one to the most sublime levels of divine service.
Unfortunately, in order to enable us to have free choice, until Moshiach redeems us (may it happen today!), “Hashem created this one opposite this one”—every force that exists in holiness must have a parallel force in unholiness.
So just as holy Jewish music has the power to raise one to the greatest heights of love of Hashem, so can unholy, non-Jewish music, degrade the Jew to the depths of evil, may G–d save us. It too casts away limitations, but in the opposite way.
“Man is born a wild donkey.” We are born with a Bestial Soul that possesses intense, untamed, and self-destructive character traits. By serving Hashem through prayer, Torah study, and observance of the Mitzvos, one weeds out the negative character traits and harnesses the raw energy of the Bestial Soul to the service of the Divine Soul, as it is written, “With the strength of an ox, there is much grain.”
However, listening to goyisheh (non-Jewish) music elicits a desire for perikas ol, a desire to cast off all these constructive “limitations.” All the hard work that one did to live with self-control and establish boundaries is undone. This music excites and strengthens the Bestial Soul in a very unhealthy way, causing the Divine Soul to become hidden. One’s negative character traits resurface with even more intensity, and the raw energy of the Bestial Soul is directed to behaviors that are both spiritually and physically harmful, may G–d save us.
All this would be true of goyisheh music even if it didn’t have words; all the more so, considering the fact that in modern times, the lyrics of this music often communicate immodest and heretical messages.
Based on Sefer HaMa’amarim Basi LeGani, Vol. 2, p. 54 ff.
 Likkutei Torah, Pinchas 77c.
 Shabbos 51b.
 Likkutei Torah, Berachah 98a. Cf. Sefer HaSichos 5703 p. 111 ff.
 Berachos 26a-b.
 Koheles 7:14.
 Iyov 11:12.
 Mishlei 14:4.
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