Whatever the camera records is a disclosure—whether it is imperceptible, fleeting parts of movement, an order that natural vision is incapable of perceiving or a “heightened reality” (Moholy-Nagy’s phrase), or simply the elliptical way of seeing. What Stieglitz describes as his “patient waiting for the moment of equilibrium” makes the same assumption about the essential hiddenness of the real as Robert Frank’s waiting for the moment of revealing disequilibrium, to catch reality off-guard, in what he calls the “in-between moments.”

— Susan Sontag, On Photography, 1977