But think of Hiroshima and what comes to mind is the mushroom cloud. Awesome in its way, with its bulbous head and towering stem, it is nonetheless an abstract image freed from human agency. The lack of visual evidence of the atom bomb's effect has helped us to forget its devastating impact. To see is to remember. Up until now, there have been few publicly available images of what happened on the ground when the first atomic bomb exploded. As a result, Hiroshima has become, as the novelist Mary McCarthy wrote in 1946, "a kind of hole in human history." These images go some way towards filling in this hole in our historical memory. Taken during the weeks following the bombing, they show a landscape that is eerily vacant and quiet, like ruins from a vanished civilization. But why were they taken and by whom? And how is it that they ended up in a pile of garbage?

These photographs are significant not only for their visual message but also for their very existence as a group, for their cohesive documentation of an event of which we have few other still images. Although the images taken by the Physical Damage Division don't depict the human suffering of the atomic bomb they do provide a vital function. They say: this is what we, mankind, are capable of unleashing upon each other. Like ruins, they refer back into time (this is what we have done, are capable of doing) while simultaneously warning of a future we have not yet encountered (they give substance to our terror of the use of another nuclear weapon).