Photography - the supreme form of travel, of tourism - is the principal modern means for enlarging the world. As a branch of art, photography's enterprise of world enlargement tends to specialize in the subjects felt to be challenging, transgressive. A photograph may be telling us: this too exists. And that. And that. (And it is all 'human.') But what are we to do with this knowledge - if indeed it is knowledge, about, say, the self, about abnormality, about ostracized or clandestine worlds?