Photographs by Paul Strand, August Sander, Robert Frank, Diane Arbus, Paul Graham, Katy Grannan, Greg Halpern & Vanessa Winship respectively.
"The city has been described as the natural habitat of civilized man. It is in the city that man developed philosophy and science, and became not merely a rational but a sophisticated animal. This means, for one thing, that it is in the urban environment — in a world which man himself has made — that mankind first achieved an intellectual life and acquired those characteristics which most distinguish him from the lower animals and from primitive man. For the city and the urban environment represent man’s most consistent and, on the whole, his most successful attempt to remake the world he lives in more after his heart’s desire. But if the city is the world which man created, it is the world in which he is henceforth condemned to live. Thus, indirectly, and without any clear sense of the nature of his task, in making the city man has remade himself.”
— Robert Park, “Human Nature and the City” in “The City as Social Laboratory”, from On Social Control and Collective Behaviour 
"The gathering of photographers and the photographed around the camera was not contingent on a pragmatic answer to the question of whether photography could help them. Instead, it was motivated by the scopic regime that photography established — a photograph produced in the course of an encounter between photographer and photographed is created and inspired by a relation to an external eye, the eye of the spectator. It is not the same eye that is present in the situation, but one for the sake of which the photographed is willing to be photographed and the photographer is willing to take the photographs. (…)
This spectator’s eye deterritorializes photography, transforming it from a simple, convenient, efficient, (relatively) inexpensive and easily operable tool for the production of pictures into a social, cultural, and political instrument of immense power. The gap between these two dimensions of photography is newly expressed in each photographic act, summoning a supplementary eye, or at least alluding to the existence of an empty place, a potential place that enables the act of photography to occur while the participants acknowledge that they are not alone in front of the other. Photography thus enables its users to produce images that go beyond the simple technical actions required to produce them, attaining something that transcends the here and now. The reason they enjoy such status is due to the fact that as soon as they have appeared in the world, it is impossible to dismiss them. Their presence cannot be subsumed under the reign of a higher authority. They are independent.”
— Ariella Azoulay “The Civil Contract of Photography” in The Civil Contract of Photography