Humankind lingers unregenerately in Plato’s cave, still reveling, its age-old habit, in mere images of the truth. But being educated by photographs is not like being educated by older, more artisanal images. For one thing, there are a great many more images around, claiming our attention. The inventory started in 1839 and since then just about everything has been photographed, or so it seems. This very insatiability of the photographing eye changes the terms of confinement in the cave, our world. In teaching us a new visual code, photographs alter and enlarge our notions of what is worth looking at and what we have a right to observe. They are a grammar and, even more importantly, an ethics of seeing. Finally, the most grandiose result of the photographic enterprise is to give us the sense that we can hold the whole world in our heads—as an anthology of images.