So when a man surrenders to the sound of music and lets its sweet, soft, mournful strains, which we have just described, be funnelled into his soul through his ears, and gives up all his time to the glamorous moanings of song, the effect at first on his energy and initiative of mind, if he has any, is to soften it as iron is softened in a furnace, and made workable instead of hard and unworkable: but if he persists and does not break the enchantment, the next stage is that it melts and runs, till the spirit has quite run out of him and his mental sinews (if I may so put it) are cut, and he has become what Homer calls "a feeble fighter".
Plato, The Republic
mind, music