Sometimes I have an idea for a piece first, and often that comes from something I'm reading. I then start sifting through my studio for the right images to give that idea form. Often, though, I'm struck by how lovely or strange or moving a particular piece of paper is, and it will suggest a direction for a new work.
Before the last hundred years or so, artworks in the European/American tradition were mostly made of the same few luxury materials: oil paint on canvas, tempera on wood panel, stone or bronze, gold leaf on vellum. It was that way, in the European/American tradition, for maybe more than a thousand years. A hundred and ten years ago, though, in the summer of 1912, Georges Braque had an incredible insight: he could paste down a piece of wallpaper that had been printed to look like wood onto his artwork and forego drawing the wood himself. This was revolutionary - it opened up the whole world for artists. After Braque, artists could make art out of anything. To me, this revolutionary gift is as important in the history of art as the discovery of perspective in the Renaissance.