Censorinus, On the Birthday 12.3-4

hominum quoque mentes et ipsae, quamvis Epicuro reclamante, divinae suam naturam per cantus agnoscunt. denique quo facilius sufferant laborem, vel in navis meatu a rectore sumphonia adhibetur; legionibus quoque in acie dimicantibus etiam metus mortis classico depellitur. ob quam rem Pythagoras, ut animum sua semper divinitate imbueret, priusquam se somno daret et cum esset expergitus, cithara, ut ferunt, cantare consueverat, et Asclepiades medicus phreneticorum mentes morbo turbatas saepe per symphonian suae naturae reddidit. Herophilus autem, artis eiusdem professor, venarum pulsus rhythmis musicis ait moveri.

Humans’ minds also recognise their nature through song, being themselves divine (although Epicurus disagrees). Accordingly during a ship’s voyage, for example, so that the crew can bear their labour more easily, the steersman employs harmonious sound; and when the legions are fighting in battle, their fear of dying is driven away by the trumpet. This is why (as they say) before Pythagoras went to sleep and when he got up, he used to sing to the lyre, so as to imbue his soul with its own divinity; and Asclepiades the doctor often returned the minds of the insane, which had been disturbed by some illness, to their proper nature by means of harmony. And moreover Herophilus, the professor of that same art [of medicine], says that the pulse of the blood vessels move to musical rhythms.