“My uncle used to let me pretend they were bricks," Linden says, startling me. He eases a thick hardcover from the shelf, hefts it in either hand, and then places it back. "I like to build houses out of them. They never came out exactly like I'd planned, but that's good. It taught me that there are three versions of things: the one I see in my mind, and the one that carries onto the paper, and then what it ultimately becomes."For some reason I'm finding it difficult to meet his eyes. I nod at one of the lower shelves and say, "Maybe it's because in your mind you don't have to worry about building materials. So you're not as limited.""That's astute," he says. He pauses. "You've always been astute about things.”