The definition of art itself isn't something a lot of people think about. Most prefer to simplify the concept down to "self-expression" which, all-in-all, is a bit retarded. When a baby wails for a diaper change, no one could argue that it isn't expressing itself but would we be prepared to claim that the baby is creating art? Of course not. The baby is just bitching. So clearly, there is a margin, a line that is crossed where the chaotic is by some means synthesized into what we recognize as art. And usually, in order to earn this recognition, it must fit some specific form.
The most universally recognized forms fall into three categories: the visual arts, the literary arts, and the musical arts. While each is equally ancient, they all contribute differently to the spectrum of self-expression. The visual and literary tend toward conveying ideas, working by analogy to get you to think about one thing while presenting you with another. While music also works to convey ideas it does so less by analogy than it does raw emotional appeal. Unlike literature and art, you can't "disagree" with music, at least not in its pure form; you can only like or dislike it.
What determines our like or dislike of music, at least in my opinion, is our self-image. We pick and choose music that matches who we want to be or what we feel. Our musical choices are reflections of intensely personal choices regarding who we are and who we want to think we are.
This also applies to the artists that produce music. Rock stars are so often ego-driven because that's what drives their music. Classic rock and roll is simply the projection of super-sized ego, displayed so that we can all feel a little bit of what it's like to live with that sort of confidence and vicariously partake in all the debauchery we've always wanted but never had the opportunity to enjoy.
But rock and roll is just one example. Looking back on history we can see how different cultures and ideologies have used music to their advantage. Medieval Christianity made use of the Gregorian chant, the Nazis had "The Ride of the Valkyries", and the hippies had the peace loving anthems of the Beatles and their ilk. It's easy to see how each example here was a projection of self-image; the Gregorian chant inspired solemn awe, "The Ride of the Valkyries" has a powerful sense of triumphant supremacy embedded in every note, and the Beatles, of course, are laid-back and whimsical. But, pausing a moment to dwell on the Beatles, it is possible to learn something even more important about music. The Beatles began their career as a happy, pop group, with uniform looks and uniformly happy but simple music. Yet at the end of their run they were somewhere very different from where they started, pushing the edge of experimental music and promoting a lifestyle of individuality rather than happy conformity. This happened not so much because the Beatles themselves changed but because the culture around them did and the music adapted to suit it. And what this means is crucial. Music is not form of media for the creation of ideas, but is actually the product of the ideas themselves. It is a direct reflection of how we perceive ourselves not just as individuals, but as a culture.
Just look at the last 50 years of music! You can identify the decade of a song without knowing the title or even the artist; the sound itself associates with a decade. The Sixties had the first folk music, the Seventies saw the birth of punk and disco, the Eighties had a hedonist/macho mix of party music and metal, the Nineties had mass-produced pop, and the Oughties (as the last decade is apparently supposed to be called) saw the creation of indie music. It is possible to trace a direct correlation between the moods and attitudes of the times to the music they produced. Is it any surprise that apocalyptic metal emerged in a time when thermonuclear war seemed a very real possibility?
So, assuming I'm correct here, what does this all mean? Well, if you create music, it means that you should now have a deeper understanding of both the formation of your art and how to craft it. If you listen to music, you might realize why it is you listen to the music that you do. And if you're like me, obsessed with what this all means in the long run, you're now looking through your music library the same way an ancient oracle might comb through the entrails of a dead goat. And if that's the case, then somewhere, between those metaphorical chunks of liver and small intestine, you are starting to see something very interesting taking shape. Something very interesting indeed.