Man: [looking at a Stieglitz's photo of 'Equivalents'] Is this a photograph of water?
Stieglitz: What difference does it make of what it is a photograph?
Man: But is it a photograph of water?
Stieglitz: I tell you it does not matter.
Man: Well, then, is it a picture of the sky?
Stieglitz: It happens to be a picture of the sky. But I cannot understand why that is of any importance.