What are the motifs in On Photography by Susan Sontag?

Photography changes perception is a recurring idea. The text presents numerous photographs or photographic assemblages which have shaped the world in which we live by altering our perception of the world. An early example deals with the author's initial viewing of photographs of victims of the Nazi holocaust. Like many, the author's essential innocence vanished upon the first traumatic viewing of these images of abject horror. Another example, with more of a social grounding in American politics, concerns the Farm Security Administration's 1935 photographic project to document the harsh conditions faced by poverty-stricken families in America's depressed rural regions.