I teach a university course on "Philosophy and Music." But that's meant somewhat tongue in cheek, too, as it isn't at all clear that music has even a potential to be "philosophical" in any serious sense of the word. Still, Plato (and Pythagoras before him) believed that mathematical relations were audible in music and, as math expresses eternal Being (not the mere appearances of "becoming" in the realm of the senses, the shadow realm of the famous cave allegory), Plato considered music to be a very high form of philosophical expression. He wasn't, of course, the last to do so; my favorite would have to be Schopenhauer, for whom music functions as a kind of empirical validation of his entire metaphysics.
Be that as it may, what does, or can, music—sequences of tones—"express"? The examples in this thread, from the OP's onward, cite lyrics, which might as well be "poetry" and not "music." But can instrumental music express ideas? Or, for that matter, even "emotions"? I know we all think it can—obviously, dance music at a funeral would be inappropriate, while languid melodies in a minor key will hardly enliven your party. But why do we think this? How can it do this?
Maybe that's a topic for another thread. In any case, with this problem in mind, I'll mention again John Cage's 4'33".