According to most classical music theorists, music is made to evoke emotional and spiritual responses, studying music to enhance personal graces and virtues. For example in Castiglione`s courtisan`s book:
"..that the movement of the celestial spheres creates natural harmonic tones, that the formation of our souls follows the same reasoning, thence music awakens and, as it were, revives their virtues."(Book I, ch.XLVII)
Martin Luther`s view is more emotional, stating that
"We can mention only one point (which experience confirms), namely, that next to the Word of God, music deserves the highest praise. She is mistress and governess of those human emotions….which as masters govern men or more often overwhelm them….For whether you wish to comfort the sad, to terrify the happy, to encourage the despairing, to humble the proud, to calm the passionate, or to appease those full of hate….what more effective means than music could you find?"
It would be very enlightening not only to consider music as the agent of emotional arousal but also a master over emotion as well, like what Plato considered music not just to be the medium of inspiration to be a better man but also a metaphysical means for free imagination or almost everything:
"music is a moral law. It gives soul to the universe, wings to the mind, flight to the imagination, and charm and gaiety to life and to everything".
One of the most outstanding exhibitions of this spirit will be by John Dryden`s poem for St. Cecilia's Day, 1687:
What passion cannot music raise and quell!
When Jubal struck the corded shell,
There are also lores of Arion taming a dolphine and Orpheus the beasts with music, the latter even convinced Hades to release his wife on condition. Hades as a god, he should be a reasonable deity, as a paragon of reason, he was like the beast of irrationaliy overcomed. But no much explanations from classical times about how music affect people had been given other than metaphysical allegories about the power of music. All the rest are about the basic musical theories of music making. Music itself is almost purely metaphysical, from classical evaluations, not just passion, also reason can be overcomed in their best. It is quite amazing to notice that music can serve as a space encompassing human passion and reason, making both of them mutually convertable and communicative between themselves: beasts and men can be moved to reason from passion, and gods from reason to passion.
Human understanding in classical terms also has various schools: intuitive, analytical, objectivist, subjectivist. When looking onto the classical evaluations of music as a means of such power and worth, our modes of understanding would sound a bit off-climactic, however, not unethical. But it surely will be very off-topic to go for all the understanding modes before one can actually enjoy music in the way that is self-sufficient. My answer would be, music is music, it is self-sufficient as an art form and a way of enlightenment, the delights and enlightenment it brings are also self-sufficient therefore requires no mandates of understanding whatever the modes can be. In short, if you do not enjoy music, why bother? just go do some math and eat; if enjoy, then how to understand it, is totally up to personal ways/modes, everything else would be as practical as anything, as free as one should be free, but the enjoyment is always the thing that matters. To try to codify any musical understanding is only for the short term, music will always go with the most foundamental ways possible of human life: always enjoy it first.