The Artist's Sketchbook

I have been taking sort of an unofficial poll for years. When I meet artists I ask them if they keep a sketchbook. It seems to me that the time invested in a sketchbook correlates directly to the level of an artist's development. Often they are the catalyst for all kinds of new work. A sketchbook is so personal and so interesting to me. It is more than drawing or painting, it is a kind of visual thinking or poetry for which there are no words. This book also provides an ongoing visual dialogue that the artist has with him/herself. I just met and artist who keeps a small sketchbook of self-portraits. He does a different one each day. A bit narcissistic, but it is a good way to study the portrait. A sketchbook is a very intimate possession and a way of sharing oneself. I always feel privileged when an artist shows me his or her sketchbook. I can say that I have more started many more sketchbooks than I have completed but I am working on it. Maybe I will start a sketchbook blog though one probably already exists. At any rate, I would love to hear what others feel about sketchbooks.