Photography was invented by nineteenth century artists as an art form for their own purposes. These men were seeking a lasting, literal record of their visual surroundings and they found it. The new combination of illumination, lens, shutter, and flat surface coated with chemicals sensitive to light produced images more lasting, more convincing in their reality, and more richly detailed than painters could produce manually in weeks and months of effort. This alone was enough to throw consternation into the ranks of fellow artists; and, after their first reaction of pleasure in a new kind of image, art critics rallied with the haughty charge that photography was not, and could not be, an art. The actual world in which we live had too strong a grip on photography, they said, and pictures so dependent upon mechanical means could not be called acts of man' s creative imagination. Despite the critics, photographers knew that they had found a new art form, a new mode of expression. They used the new tools as other artists before and after them have used brush and pencil — to interpret the world, to present a vision of nature and its structure as well as the things and the people in it.