To look up is to see how big the universe really is. To look down is to notice the small details in the world around us. It gives us a way to understand the world, whether we are looking at something immense like the sky, or something tiny on the ground. Photographers like Alfred Stieglitz, in his Equivalence series (1925–34), and Sophie Ristelhueber, in Fait (1992), have shown how photography can change how we see and think.