On the Institution of Music (De institutione musica)

Pythagoras said that a flute player should play a spondee A slow, solemn poetic meter consisting of two long syllables.: because when he perceived that the youth's raging wantonness was stirred by the speed of the rhythms and the gravity of the player, he calmed them. But to briefly touch upon similar examples:

Terpander
Arion
Ismenias

Terpander and Arion of Methymna, of Lesbos and Ionia, [helped] the most serious diseases by the aid and protection of song. Ismenias the Theban is said to have wiped away all the troubles of many Boeotians who were tormented by the pains of sciatica original: "ischiadia," referring to hip or sciatic nerve pain through his musical modes.
Empedocles

But also Empedocles, when a certain guest in a fury was about to attack his host with a sword because the host's father had condemned him by accusation: Empedocles is said to have changed the mode of his singing, and thus he restrained the youth's resentment. Indeed, the power of the art of Music became so well known mnotuit likely "innotuit" (became known) to the studies of ancient philosophy that Pythagoras and his followers, when they released their daily cares in sleep, would use certain songs so that a gentle and quiet slumber might creep over them. Likewise, when they woke up, they purged the stupor and confusion of sleep with certain other modes. They did this, no doubt, because the whole of our soul and body is joined together by a musical adaptation. For as the affections of the body are, so also the pulses of the heart are mixed with movements and modes.

Democritus
Hippocrates

This is what Democritus is said to have passed on to the physician Hippocrates, when Hippocrates visited him while he was being held in custody for the sake of medical treatment, as all the citizens of Democritus thought he was insane.

But to what purpose are these things? Because it cannot be doubted that the state of our soul and body seems to be composed, in a certain way, by the same proportions. Hence it is that even infants are delighted by a sweet song; but something harsh and mixed suspends them from the pleasure of hearing.

Every age and every sex also experiences this excessively. Although they may be divided by their actions, they are nevertheless joined by one delight in Music. For what happens when, in mourning, they modulate their very laments willingly? This is especially characteristic of women: that the cause of weeping might become sweeter through a certain song. Indeed, it was the custom among the ancients that the song of the flute should lead the mourning.

Custom
and
Statius

Papinius Statius is a witness to this in this verse: The heavy horn bellows with its curved tip; the flute now accustomed to lead the tender spirits of the dead. original: "Cornu grave mugit adunco. tibia nunc teneros suetum producere manes." From Statius's Thebaid. And he who cannot sing sweetly nevertheless sings something to himself. Not that he performs what he sings with any great pleasure, but because, bringing forth a certain mild sweetness from the mind, they are delighted in whatever way they bring it forth. Is it not also manifest that the minds of those fighting in war are kindled by the song of trumpets? If it is likely that anyone can be moved from a peaceful state to fury and anger, there is no doubt that a more modest mode can restrain a disturbed mind or excessive desire. Because when someone receives a song more willingly with their ears and mind, they are also led, not of their own accord, to the point where the body also shapes some movement similar to the song being heard. And the mind itself, remembering, plucks some melody it has heard. So that from all these things it appears clearly and without doubt: that Music is so naturally joined to us that we could not be without it even if we wished to. Therefore, the intention of the mind must be directed so that what is implanted by nature can also be held and understood by science. For just as in sight it is not enough to see raw colors and shapes unless one also investigates what their properties are; so it is not enough to be delighted by musical songs unless one also learns by what true proportion they are joined together.