Buying Art

Art... what is it?
I've been thinking about this a lot lately. I love art. All kinds of art. I love trying to create my own art. The learning process, etc... I love looking at art. But why?
I recently bought myself a small piece of art or sculpture. While at the makerfaire I saw these incredible items made by Bathsheba Grossman (website). I couldn't really afford the "large" sculpture (about 3-4"), so I bought the smaller one (approx 1"). A bit pricy at $80 (imho), but it's such a unique item that I couldn't resist. When I try to explain what makes this piece of art unique, I can see their eyes glaze over, and I can hear their thoughts... "you bought this why?" :)
I also have it on my bookshelf at home now and realized - it doesn't do anything but sit there. That's pretty much true of all art. So why buy it? I have other paintings and photos in my apartment, but most have been given to me. One I bought for $20 and framed myself. A few other prints I have. I also have a real nice sculpture from Bowen designs of a famous Frank Frazetta painting called "death dealer" that I paid the most for. Yet... it still doesn't do anything. Then I realized as I was looking at my art... I can tell you where I purchased each one. I can tell you a story behind each one. It is as if a part of my memory is now captured by each of those pieces of art. There is a definte connection now of my memory and those pieces. Is this what spurs us to buy art? capturing a moment of not just beauty but also a memory? I think so.
What do you think art is? Have you ever bought a piece of art?