Full Idea
Music has harmonic motions like the orbits of the soul, and is not for irrational pleasure, but to reduce to order any disharmony in the revolutions within us.
Gist of Idea
Music has harmony like the soul, and serves to reorder disharmony within us
Source
Plato (Timaeus [c.362 BCE], 47d)
Book Reference
Plato: 'Timaeus and Critias', ed/tr. Lee,Desmond [Penguin 1971], p.65