In 1922, while visiting his family estate on Lake George in Upstate New York, Alfred Stieglitz began work on Equivalents, an extended photographic study of cloud formations. An ardent champion of photography as a legitimate fine art form, Stieglitz believed that the Equivalents marked the culmination of everything he had learned about the medium—particularly, that what makes a photograph great is the manner in which its visual forms express emotions that parallel the artist’s own inner state. He intended these photographs, which verge on abstraction, to function like music in that they are nonrepresentational yet highly evocative.