... photography is an imprint or transfer off the real; it is a photochemically processed trace causally connected to the thing in the world to which it refers in a manner parallel to fingerprints or footprints or the rings of water that cold glasses leave on tables. The photograph is thus generically distinct from painting or sculpture or drawing. On the family tree of images it is closer to palm prints, death masks, the Shroud of Turin, or the tracks of gulls on beaches.