This was not strictly accurate, because some Impressionists were politically reactionary—Degas sided with the French government in the Dreyfus Affair—yet the journalist’s assessment was prescient in a broader sense. If the visual interpretation of seascapes or haystacks was subjective, official opinions on nationhood or race or religion might also bear personal consideration. Few people, relatively speaking, have had the inclination or aptitude to become modernists, yet as each modernist heresy is confronted by the multitudes—and often ultimately assimilated—old orthodoxies are upset anew.

Of course, no heresy, even Kandinsky’s pure abstraction, is universal or eternal; novelty is always evolving and old heretics often fall into their own orthodoxies. Gay notes the example of Mary Cassatt, unable to accept the fauvist upheavals of Henri Matisse. Calling him a fraud, she advised the wealthy collector Louisine Havemeyer that "it is not alone in politics that anarchy reigns."

As for artists, so for historians: At the age of 84, and with a formidable reputation as a scholar of Weimar Germany and Sigmund Freud, Gay is able to follow modernism only so far before his tolerance for new outrages falters and myopic self-contradiction closes in. According to Gay, the decline began in the 1960s, when Pop artists subverted "the modernist ideal by reconciling the irreconcilable, assimilating two essentially distinct areas of art, high art and low, which modernists had thought it crucial to keep apart."

Apparently baffled by art after Pollock, Gay forgets the very diversity of modernism, the range of modernist positions, that is the essence of his book. While Kandinsky probably wouldn’t have appreciated Warhol’s soup cans or Lichtenstein’s comic strips, Picasso and Braque significantly incorporated "low" materials such as newsprint into their impeccably modernist Cubist compositions. And what was the poetically revolutionary use of obscenity by Baudelaire—whom Gay calls "absolutely indispensable ... for the history of modernism"—if not a subversive reconciling of the irreconcilable?

Unable or unwilling to confront this aesthetic continuum, Gay insists that modernism was possible only in a socio-economic framework that passed with the success of Pop art: Pop, and the art that has followed, has not been sufficiently marginalized. "[T]he commercial manufacture of culture has become ever more influential an activity," he writes.

But to critique that commercial manufacture, as Pop art powerfully did, surely was heretically self-aware, and the escalating auction prices on Pop works has been retrospective, no different from the market success of Impressionism.

More damaging still, Gay’s blind disdain for contemporary art makes no distinction between the popular and the marginal, extending to works as visually, conceptually, and historically diverse as Hermann Nitsch’s sadistic performances and Carl Andre’s minimalist floors. Describing Yves Klein’s sublime "Anthropometries" (paintings in which the model’s body was used as a brush) Gay writes that "this is modernist freedom reduced to absurdity." Cassatt, at least, would have agreed.

Predictably, Gay, among many others, blames all of today’s art woes on Marcel Duchamp, "the most quoted prophet—and agent—of art’s pitiable future," whom he nevertheless (also predictably) includes in modernism’s pantheon. In fact, Duchamp is the prophet of Gay’s pitiable frustration, the agent of minimalism’s eternal rejuvenation. The very urgency of modernism in its many guises inevitably pits future against past. Wassily Kandinsky’s canvases retain their inner glow, momentarily aligning us with his non-objective ideal. But it was Duchamp who gave modernism the heretically self-aware independence to constantly reinvent itself.

Art&Antiques San Francisco correspondent Jonathon Keats is a conceptual artist, the art critic for San Francisco magazine and author of two novels.