It all started with one essay—about some of the problems, aesthetic and moral, posed by the omnipresence of photographed images; but the more I thought about what photographs are, the more complex and suggestive they became. So one generated another, and that one (to my bemusement) another, and so on—a progress of essays, about the meaning and career of photographs—until I’d gone far enough so that the argument sketched in the first essay, documented and digressed from in the succeeding essays, could be recapitulated and extended in a more theoretical way; and could stop.The essays were first published (in a slightly different form) in The New York Review of Books, and probably would never have been written were it not for the encouragement given by its editors, my friends Robert Silvers and Barbara Epstein, to my obsession with photography. I am grateful to them, and to my friend Don Eric Levine, for much patient advice and unstinting help.