Anyway, he called his sketch book a prop, because he used it to distract whilst he worked out what he was going to say next, and also as protection, something to have in his hand when he was telling his stories. So there's two very valid functions of sketching. It both labels you to the world, and protects you from it.
And... and... thinking about this, about how people like to see what you are drawing, it replaces you. That invisibility that I try to find, and said only worked in one direction. I was wrong, it works all round, it just becomes camouflage, and the person watching me sketch is looking, not at me, but at the drawing. And their comments are usually about themselves, about what they think, or what they would do. Sort of taking possession of the drawing for themselves, which is all any of us do to art in the first place.
Better find a good sketch to go with this thought.
Called this one check shirt, and, I have to be honest, can't remember when this one was drawn, so that's two theories out the window in one go.