After Beethoven, musicians began to define genius as the ability to conjure tempests and earthquakes in the soul. Hence, the “Romantic era”, the era of tempest, sentiment, and the search for the thunderous and sublime.
This teaches man to identify music with getting outside of one’s mind. Over time, musicians find an easier way to give this ecstasy. Beating drums and pulsating rhythms move the body irresistibly- which is why drums are beaten in galleys or on forced marches. A new kind of music arises that gives primacy to rhythm, and this extreme rhythm causes extreme motion in the body, which in turn gives the feeling of extreme life- for life in animals is motion. This feeling of extreme life is caused apart from the spirit (which is most appealed to by harmony) or the mind (most appealed to by melody). According primacy to rhythm is the distinctive feature of twentieth century music: Dixieland, jazz, blues, gospel, rock, and rap. This music draws its root inspiration from slave music- music that was sung to keep bodies moving, while keeping minds and spirits empty (who wants to think about life under such circumstances?)
We, however, use this music as though it were for our leisure- when in fact it is only useful to keep us numb while living the life of a slave. This use, moreover, only applies when the structure of the music is not intrinsically perverse. This music was, at best, designed for the times when we want our brains and spirits to go numb, and our bodies to keep moving. It therefore has no place in the leisured, contemplative, emotional, or spiritual life. In fact, it only has a place in life when we would rather not be living.
My hypothesis, summarized, is this: Romantic era music strove for a divine emotional experience, beyond all reason in a swell of passion and ecstasy. Modern music keeps this fundamental kernel of the irrational, but strives to find it in things that are bodily. We sought to become gods apart from reason and ended up- as always- like beasts.