In his middle age, a Belgian painter named James Ensor once complained that he was "infected with respectability." It bothered him, he said, that well-bred young ladies who used to turn their backs on him "now smile at me with all their teeth." But if Ensor became respectable, it was the age that had changed, not Ensor. He kept on painting some of the most ghoulishly disagreeable canvases of modern times—and heard himself hailed as Belgium's greatest 20th-century artist. Last week, two years after his death at 89, Manhattan's Museum of Modern Art put on a retrospective show of his work.
Actually,...