If only the wheel of fate rolled smoothly, we could all leap aboard with a good running start. But it does not; it whirls and jerks and spins in place, and to seize it for but a moment is to be lucky. For a very select few, however, it seems to stop and wait like an obliging private elevator. So it did for T. J. Clark, who in 1973 made his debut with a pair of path-breaking books: Image of the People: Gustave Courbet and the Second French Republic, 1848–1851 and The Absolute Bourgeois: Artists and Politics in France, 1848–1851. Here was art history of a new kind, one that looked just as much at art’s political life as its aesthetic—perhaps more so. For Clark, then just thirty, the books were career-making.

His debut was timed exquisitely. Previously, it had been a point of honor among modernist critics that one judged art independently of all considerations of politics and morality. To burd ...