Thought is more important than art. To revere art and have no understanding of the process that forces it into existence, is finally not even to understand what art is.

This quote is saying that thinking deeply and critically is more important than the art itself. Just admiring art without understanding why it was created isn’t enough to really understand it. True appreciation of art comes through understanding why it was created and the thought process (or creative thinking) that went into it. That process of creative thinking is more important than the art itself.