A Dilettante's Guide to Art

1001 Paintings You Should See Before You Die acknowledges the question "What is Painting?"
The answer: "Who cares?"

Sometime in the middle of the 19th century painting started to get a little screwed up. It began to worry. Painters stopped simply doing what they were doing and started spending more and more time trying to figure out what they were doing and why. They got into the "What Is?" question. "What is Painting?", "What is Art?" "What Is…?"It’s hard to blame them for it. The "What Is?" question was in the air. Chalk it up to the vast and traumatic transformations that ushered in modern times. Everybody was trying to figure out what was different and what was still the same. In painting, the biggest change was in the abandonment of representation as the central task. Nobody was interested in problems of perspective anymore, in figuring out how best to make the world of three dimensions look vaguely like itself on the canvas of two dimensions. And yet, for some reason, people still felt the desire to paint. Who knows why?
Maybe...
link