What is the purpose of art?

It is interesting that something so seemingly universal as art can be so difficult to define. Einstein considered his theories to be great works of art, but could this really be true? I think so. It seems to me that at its very core, the purpose of art is to express something. Be it complex or simple, common or absurd, an expression of any sort could probably be considered art. I think that Einstein considered his theories to be art because to him, behind the complex mass of numbers and equations, the elegance of the universe is revealed. I suppose another way of putting it would be to say that the purpose of art is to present a way to look at our world. Or another world, for that matter. I know that my answer doesn’t offer any profound insight, but I don’t really have any deep insight to offer. I do like how Januszczak puts it: “its job is to change your weather.” But maybe art actually is a cat like Saltz says.