The familiarity of certain photographs builds our sense of the present and immediate past. Photographs lay down routes of reference, and serve as totems of causes: sentiment is more likely to crystallize around a photograph than around a verbal slogan. And photographs help construct--and revise--our sense of a more distant past, with the posthumous shocks engineered by the circulation of hitherto unknown photographs. Photographs that everyone recognizes are now a constituent part of what a society chooses to think about, or declares that it has chosen to think about. It calls these ideas "memories," and that is, over the long run, a fiction. Strictly speaking, there is no such thing as collective memory--part of the same family of spurious notions as collective guilt. But there is collective instruction.
All memory is individual, unreproducible--it dies with each person. What is called collective memory is not a remembering but a stipulating: that _this_ is important, and this is the story about how it happened, with the pictures that lock the story in our minds. Ideologies create substantiating archives of images, representative images, which encapsulate common ideas of significance and trigger predictable thoughts, feelings. Poster-ready photographs--the mushroom cloud of an A-bomb test, Martin Luther King, Jr., speaking at the Lincoln Memorial in Washington, D.C., the astronaut walking on the moon--are the visual equivalent of sound bites. They commemorate, in no less blunt fashion than postage stamps, Important Historical Moments; indeed, the triumphalist ones (the picture of the A-bomb excepted) become postage stamps.