When I read from an essay that I wrote on Hockney’s swimming pools once, two scholars wondered aloud about John Cheever’s “The Swimmer,” and I am often haunted by this moment, as if I should have known better than to write about swimming pools without reading more things great men had said about them. Hockney’s sister describes their mother in the documentary “David Hockney: A Bigger Picture”: “She was a very great power. When I recently ask my father about the portrait he shot of Hockney and his mother, he begins to reminisce about his own late mother sitting on the porch of the house where he grew up.