Apollon’s yearning for the lyre was unquenchable. He reckoned that the instrument was well worth the fifty cows, and he admired his brother for having invented it. He praised the lyre, whose sound has a threefold effect: joyfulness, love and sweet sleep.
Kerényi identifies the lyre’s transfer from Hermes to Apollo as a mythologically pivotal exchange, the instrument bearing three simultaneous effects—joyfulness, love, and sleep—that encapsulate its power as a civilizing and psychic force.
, The Gods of the Greeks, 1951thesis