Forest Path Sketch or Finished Piece?

forestpath.jpg

This Forest Path collage on mixed media paper came from a day of experimenting with stamps, printing and playing around with texture. At first I thought I'd use it as a background for something, but this morning, I kind of like it as it is. I've been reading a lot about abstract art (collage in particular) and playing around with the idea in my sketchbooks. This is the first one I've done that "feels" complete. For the abstract artists out there: How do you know when a piece is finished?