They are selling postcards of Hitler in the gift shop at the Guggenheim Museum. To be precise, they are selling photographic reproductions of a work entitled Him, a polyester portrayal of the Führer that is one of the works by Maurizio Cattelan in his retrospective at the museum. I can imagine being outraged or at least troubled by the postcards in the gift shop, except that by the time I saw them I had already been bombarded by this exhibition in which nearly all of Cattelan’s oversized neo-Dadaist baubles have been hung from the ceiling of Frank Lloyd Wright’s rotunda. Cattelan’s Hitler doll—like his Picasso doll, his bicycle, his dinosaur, and the rest of the 128 items in this stupefyingly sophomoric show—is engineered for offense, irony, comedy, or who knows what else. Those who are bothered by the Hitler postcards in the gift shop are naturally going to be dismissed as insufficiently hip. The same goes for those who are disturbed by the sight of one of the world’s greatest public spaces once again turned over to an art world charlatan as his personal playpen. My own feeling is that the postcards, however misbegotten, are speech we accept, although not necessarily embrace, in a society we prize for its openness. What is really disquieting is the event that has occasioned these postcards. “Maurizio Cattelan: All”—that’s the title of the show—amounts to hate speech directed at the sponsoring institution.

I’m sorry to be a party pooper. From what I could see when I visited the other day, museumgoers were perfectly content as they meandered up and down the ramps at the Guggenheim, snapping pics of Cattelan’s pixies on their iPhones. Of course, museumgoers also seemed happy—maybe more happy, I’m not sure—looking at the Impressionist and Post-impressionist paintings in a gallery off the rotunda. And everybody was definitely all smiles as they came out of the Guggenheim into a spectacularly lovely November afternoon. The truth is that Cattelan’s presence at the Guggenheim has nothing to do with what the public may or may not want. Cattelan is at the Guggenheim because the big money in the art business is behind him. The other day, one of his minor works, a miniature model of two elevator doors, sold for just over a million dollars at Christie’s. (It comes in an edition of ten, one of which is hanging on Fifth Avenue and 89th Street.) And that was one of the more modest prices at Christie’s contemporary sale on November 8, where a Robert Gober Prison Window went for $3.3 million and a 1961 Roy Lichtenstein for $43.2 million.

The collector Eli Broad was quoted, at the end of the auction, explaining that “People would rather have art than gold or paper.” To which it seems to me the only response is that people who have millions of dollars to spend on a Cattelan, a Gober, or a Lichtenstein are not what used to be known as “the people.” Never mind. What “the people” are more and more seeing when they go to museums is what Eli Broad and a few other collectors and dealers with very deep pockets think they should see. At that same Christie’s auction, the gallerist Larry Gagosian bought an early Cy Twombly for $5.2 million. Twombly, who died in July, is nowadays regarded by some as one of the giants of modern art. His reputation is so high that over the summer the Dulwich Picture Gallery in London mounted an exhibition, “Twombly and Poussin: Arcadian Painters,” that paired him with the seventeenth-century French artist who redefined classicism for the modern world. Whatever one may think of Twombly—and I like some of his earlier work quite a bit—the Dulwich show was a rather astonishing example of reputation inflation. And who, pray tell, sponsored “Twombly and Poussin”? I can’t say I was surprised, on opening the exhibition catalogue, to discover that the sponsor was none other than Larry Gagosian.

Money and culture have never been easily disentangled, nor would one want them to be, considering that culture is by no means cost efficient. But there are different forms of patronage and different kinds of entanglements. And culture is now in retreat before the brute force of money. Even the most easygoing commentators can see the writing on the wall, and some critics who might have been expected to be amused by the Cattelan retrospective have not enjoyed the show. Who knows? Maybe they’re tired of partying in a funhouse where they will never be more than dinner guests. As for the people who buy and sell Maurizio Cattelan, my guess is they don’t give a damn what critics—or for that matter museumgoers—say.

So where do we go from here? I have spent years asking myself that question, and if anything I’m farther from an answer than ever before. I would, however, recommend that anybody who wonders about these matters take a look at “Diego Rivera: Murals for the Museum of Modern Art,” a fascinating exhibition at MoMA accompanied by an important catalogue. In 1931 Diego Rivera was the second artist selected for a one man show at MoMA; Matisse had been the first. One of the moving forces in the founding of the museum, just two years old at the time, was Abby Aldrich Rockefeller, who took an interest in Rivera’s work and lent financial support to the exhibition. She was much involved in getting Rivera, an avowed Leftist, the commission for a vast mural at Rockefeller Center, a building project dedicated to the glories of capitalism. The mural was to be devoted to the theme of man at the crossroads. And the project was nearing completion when it was scrapped by the Rockefellers, who paid Rivera the rest of his fee, sent him packing, and destroyed the mural, unwilling to accept either Rivera’s flattering portrait of Lenin or his unflattering portrait of John D. Rockefeller Jr. or both, it is not clear. This ugly history is retold in a catalogue essay by Leah Dickerman, the MoMA curator who organized the exhibition and has emerged in recent years as one of our most lucid and persuasive students of early twentieth-century art. To the tangled relations between the Rockefellers and Rivera, Dickerman offers no simple explanation, but rather a complex dynamic, with modernism and capitalism and Leftism sometimes at loggerheads, although not always. The portrait she gives of Rivera’s time in New York is tantalizing.

Rivera created for the MoMA exhibition a group of portable frescoes meant to give a taste of the immense wall decorations he was painting in Mexico at the time. They make a striking temporary display in the museum today, where they have been set into the walls so that we feel their planar force. Some of the frescoes recapitulate passages from his Mexican work. Others, done after he arrived in New York, are direct responses to the city as it descended into the Depression, with the towers of the Art Deco city looming above a wharf where homeless people sleep in a dormitory. Rivera’s work here is compelling and coarse, strong on journalistic rhetoric and weak on pictorial invention. The exhibition—and here I feel the same fine curatorial imagination that Dickerman brought to her collaboration with architecture and design curator Barry Bergdoll on MoMA’s great 2009 Bauhaus show—enriches and complicates our understanding of the Museum of Modern Art’s own history. Alfred H. Barr, Jr., the museum’s founding director, is too often nowadays regarded as a rigid formalist. Nothing could be farther from the truth. And in reminding us that among his first great projects was a show dedicated to the Mexican Leftist Diego Rivera, whom Barr had met in Moscow, Dickerman takes us one step closer to reclaiming the extraordinarily complex story of the Museum of Modern Art.

There was no aspect of modern experience that did not interest Barr. He was moved by the evangelical power of abstract art, and also believed that representational art of one kind or another had a future. (America’s abstract avant-garde sometimes criticized Barr as hopelessly conservative.) One of the minor delights of this show are the pages of Rivera’s 1928 Moscow Sketchbook, with view after view of parades awash in red flags and banners, the cumulative effect cinematic, fueled by Rivera’s feeling for surging crowds and populist exhilaration. During the period Rivera was in Moscow filling his sketchbook, Trotsky was expelled from the Communist Party, and by the time Rivera arrived in New York for the MoMA show he was a Trotskyite and thus aware of the Stalinist perils that no amount of brilliant red banners could disguise. Rivera’s Moscow Sketchbook was owned by none other than Abby Aldrich Rockefeller, who gave it to the Museum of Modern Art, a souvenir of the pageantry of Soviet Communism deposited in an American museum by the matriarch of one of capitalism’s defining dynasties. The ironies are almost incalculable. And we must not forget that Rivera was himself a fashionable figure in the early 1930s, at home in café society. As I said before, art and money can never be disentangled, nor would we want them to be. But there is money and there is money. And what Rockefeller money did for American art in the 1930s is a far cry from what the rich are doing to American art eighty years later.

Jed Perl is The New Republic’s art critic.