Michelangelo distinguished between sculpture made “per forza di levare”, by taking material away, and sculpture made “per via di porre”, by adding it, which he thought closer to painting. Photography is on the side of the first. The photographer does not make what appears in the picture: he decides which part of the world goes into the rectangle and which part stays out. John Szarkowski put it in order in The Photographer’s Eye with five ideas: the thing itself, the detail, the frame, time and vantage point.

With Kenna the metaphor falls short. He takes away colour, detail and context, but in a long exposure he also adds: accumulated time. The resulting image never existed at any particular instant; it is an integral the eye cannot perform. Then, in the darkroom, he interprets again with tone, the density of the blacks and the cleanness of the whites.…