The shadow’s the thing. Outside shadows are blue, I read, because they are lightened by the blue sky and not the yellow sun. Their blueness bespeaks inestimable distance… So shadows define the real. If I no longer see shadows are ‘dark marks’, as do the newly sighted, then I see them as making some sort of sense of the light. They give the light distance; they put it in its place. They inform my eyes of my location here, here O Israel, here in the world’s flawed sculpture, here in the flickering shade of the nothingness between me and the light.
– Annie Dillard. Pilgrim at Tinker Creek.