Here’s something that’s weird but true: a photograph is unlike almost every other art form because it isn’t merely a representation of the world; it is a record of the world. Such is the form’s indexical ontology. When we look at a photograph of a tree, we see the physical reality—the miraculous interplay of physics and light—that transpired at the exact instant the photographer activated the camera. Unlike a painting of a tree, which is a stylized representation of the object, infused with the artist’s sensibility (and, probably, his or her tree-related feelings), a photograph records and ratifies the existence of the actual tree. While the precision of a photographic index depends on a number of factors—the camera in question, whether the photographer used a filter, the extent to which the photo was treated during darkroom emulsification or digital processing—a photograph still serves as a reliable