In an article in yesterday’s Washington Post, Blake Gopnik reports that revisionist thinking in art history is that all those nudes in Western art are actually about sex. Stupid me. Here I was, bopping along, thinking they were about rutabagas.

For example, take Titian’s reclining Venus d’Urbino -- a lovely, buck-naked lady whose eyes gaze straight out at us while her hand perches tantalizingly on top of her crotch. For years, art historians have held forth on why that picture is Art with a capital “A,” and not Sex with a capital “S.” Erotic, yes, but overtly sexual? No. And art history students, eager to pass their art history exams, have obligingly written reams of essays parroting their professors’ explanation of art as sublimation and the nude as the ideal form and all that other sort of poppycock.

Art historians such as the British scholar Charles Hope and the Columbia art historian David Rosand are now straightening things out for us. They’re saying nudes are not merely about sex, but that they’re out and out sexy -- as in horny-satisfying sexy, and that they range from fancy versions of pinups to elegant pornography (albeit discreetly confined to foreplay). Gopnik quotes the feminist art historian Amelia Jones, at the University of Manchester in England: "I think it's essential that we understand [the great nudes in art history] as objects in the context of men wanting to look at naked women.”

That sounds about right to me. In his article, Gopnik deftly traces the path of dirty pictures (a k a “nudes”) from the Renaissance straight through to Marcel Duchamp’s Étant donnés, now permanently installed at the Philadelphia Museum. This last famously enigmatic and unpleasant (to say the least) work consists of a splayed female nude lying on some dry grass that can be seen only through a peephole. Duchamp had secretly worked on it for the last 20 years of his life.

Quick aside: I’ve always found Duchamp’s last work to be much like a crime scene of the exceedingly grisly sort, where the body is chopped up and left abandoned in a field. But the work is important. Through it we come to terms with the hideous modern degradation of human sexuality. The Philadelphia Museum, celebrating the 40th anniversary of their installation of Étant donnés, has mounted a special Duchamp exhibition that includes photographs of the piece as it was being built, as well as additional explanatory material to supplement the permanently installed Duchamp exhibition. I saw the exhibition this past Saturday -- thank goodness, only after I’d seen the stunning Arshile Gorky show that I’d travelled specifically to Philadelphia to see. Duchamp taken without some real art can be difficult to handle.

Back to the subject at hand. The great art historian Leo Steinberg, in The Sexuality of Christ and in Modern Oblivion (1984), is one of the few art historians I can think of who delved directly into sex and the eroticism in Christ’s nudity in art. For the most part, art historians always stick to stylistic analysis comparing this or that artist, picture, or sculpture. Their preferred word is “sensuous” -- followed by “erotic” -- but rarely “sexual.”

Duchamp played out the end game of the Western nude by taking it all the way to the point where it became an ornate form of ironic pornography. I’m not sure there’s any place else to go with the nude after Duchamp, but darn if a few contemporary artists (like John Currin and Jeff Koons) aren’t trying.

Artists have known all along what many art historians are apparently only now discovering. All art is deeply erotic. If it commands our attention, it means it triggers a deep longing in our hearts, if not our flesh.

Otherwise, it’s not art.