Now look at this photograph of a bridge over a canal! Even when I don't want to describe something in detail in a story, I want to be able to visualize it for myself so that I know I'm not building an impossibility into the plot. The physical world, moreover, shapes our lives and should shape the lives of our characters. Okay, so I'm trying to imagine a bridge over a towpath in winter. Here I have the architectural solution for going from one bank to another. Curves and straight lines, bricks and stonework, messy dead grass and moss. I can see the muddy track as well as cobblestones, damp under the bridge, and a gate on the far side. Perfect for giving me assurance now, and you never know when some detail will suggest a future plot development.