Edward Weston
[Photographer, b. 1886, Highland Park, Illinois, d. 1958, Wildcat Hill, California.]
It cannot be too strongly emphasized that
reflected light is the photograph’s subject matter. 
Jacob Riis
[Photographer and reformer, b. 1849, Denmark, d. 1914, Barre, Massachusetts.]
We used to go in the small hours of the morning to the worst tenements... and the sights I saw there gripped my heart until I felt that I must tell of them, or burst, or turn anarchist, or something... I wrote, but it seemed to make no impression. One morning, scanning my newspaper at the breakfast table, I put it down with an outcry that startled my wife, sitting opposite. There it was, the thing I had been looking for all these years. A four-line dispatch from somewhere in Germany, if I remember right, had it all. A way had been discovered, it ran, to take pictures by flashlight. The darkest corner might be photographed that way.
Barbara Morgan
[Photographer, b. 1900, Buffalo, Kansas, d. 1992, North Tarrytown, New York.]
Light is the shape and play of my thought... my reason for being a photographer.
John Berger
[Writer and critic, b. 1926, London, d. 2017, Paris.]
What makes photography a strange invention is that its primary raw materials are light and time.
Lewis Hine
[Photographer, writer, and reformer, b. 1874, Oshkosh, Wisconsin, d. 1940, New York.]
The dictum, then, of the social worker is “Let there be light;” and in this campaign for light we have for our advance agent the light writer—the photograph.
(1909)
Albert Einstein
[Scientist, b. 1879, Ulm, Württemberg, Germany, d. 1955, Princeton, New Jersey.]
I dislike every photograph taken of me. However, this one I dislike a little bit less.
(On the portrait by Philippe Halsman, who he excluded from his normal characterization of photographers as Lichtaffen—“Light monkeys.”)
Donald McCullin
[Photographer, b. 1935, Finsbury Park, London, lives in Somerset, England.]
It wasn’t my fault if in Sabra and Shatila the light was almost biblical, if what happened in front of my eyes was like a scene out of Goya.
People have always said that the darkroom is my womb, and I suppose that’s true. I like the consistency of the dark. It keeps me safe.
