Along the peak of the nave, in a tunnel running its length, I found the ties that held the pulleys of the canvases over the windows. The best windows, I decided, would be the huge ones of the north and south transepts. I made a diagram in the dust, trying to decide what season it was and from which direction the sunlight would come—pure theory to me, but at this moment I was in a fever of brilliance. All the windows had to be clear. I could not decide which was best.