Despite living in Westwood, with all those wondrous UCLA girls jogging up and down the block, R.B. Kitaj claims to have lost all interest in sex. He’s finally turned 70, and he feels old. (“Nonetheless,” he says, “UCLA is the sexiest acronym in the English language.”) Six years after moving to Los Angeles from London, where for 40 years he was part of a group that included Francis Bacon and Lucien Freud, America’s greatest living figurative painter now comes equipped with a hearing aid, black-framed glasses and a sprawling white beard. He seems to welcome these signs of age, as if he were longing for someone to place a cane in his hand. “I just keep getting older and older,” he says, with something like wonder.

Kitaj talks as much as ever, however. In fact, as he leads me through his house, with lengthy stops in his drawing studio, his Jewish library and his Cézanne room, I find myself caught between looking and listening, unable to do either quite to my satisfaction. There’s just too much verbal and visual information to take in at once. In Kitaj’s world, everything has historical and art-historical roots. When I ask him about the young woman in a portrait he’s working on, he tells me it’s actually his version of a girl in a painting by Toulouse-Lautrec. Showing me an ink sketch David Hockney did of him in 1975 on a bench outside the Academy of Fine Art in Vienna, the legendary art school Kitaj attended in the 1950s, he mentions someone who couldn’t get into the school at all: “Hitler failed the exam two years in a row, after which he disappeared into the bowels of the Viennese underworld. Some people think that’s what drove him nuts, pushed him over the edge, made him really bitter.”

On May 21, Kitaj’s first major art show in Los Angeles since his return to the city will open at L.A. Louver Gallery in Venice. The paintings and drawings are mostly about what he calls “the man-woman story,” or the amatory relations between the sexes, a theme he feels has been neglected by artists for at least three decades now. Typically, he has a theory as to why: Many of the greatest modern figurative painters (Hockney, Warhol, Bacon, etc.) have been gay, while scores of others have been abstract. Even his very straight friend Freud, whose figurative paintings are currently on display at MOCA, rarely shows lovers entwined. “The man-woman story is the greatest story ever told,” Kitaj says. “But since the death of Picasso, almost no one does it.”

Kitaj does, however. One painting (Los Angeles No. 11), painted with a characteristically bold palette, portrays the artist as an old graybeard, stretched out in the bathtub with his late wife, Sandra, from whose youthful breast he seems to be seeking the only sustenance available to him in this world. Another (Los Angeles No. 17) shows the two of them in Orthodox-looking garb, facing each other — eye to eye, mouth to mouth — like a tragic couple from the Old Testament. These paintings have nothing to do with today’s art world, and even less to do with the entertainment capital that features in all their titles. They are simply the projections of one man’s strange and fascinating inner world. Like a Bob Dylan song from Blood on the Tracks, in which railway lines coexist with the Crucifixion, Kitaj has placed his lovers outside time, free to roam the centuries at will.

As usual, Kitaj isn’t afraid to take on the big themes. God’s Back, a drawing based on the story that Moses once saw God from behind, dares to imagine what He looks like from the rear. (I can report that he has unusually broad shoulders and sports what looks like a vaguely gangsterish hat.) There are also portraits of other notables, including sketches of Emily Dickinson and Proust, as well as a gorgeous charcoal-and-pastel rendition of the young Piet Mondrian that makes him look oddly like Lawrence of Arabia. And in one painting, Kitaj and his wife can be seen deep in a lovers’ tussle outside the Fox Theater in Westwood. This wouldn’t be so strange if it weren’t for the fact that both are equipped with wings.

Kitaj talks about painters like Matisse and Picasso, and, traveling further back in time, about Cézanne and Manet and van Gogh, in the way that only a person who thinks about them all day long can. They live on not just in the reproductions he pins to the walls of his studio, and in the hundreds of books that line its shelves, but in his head. Their problems are his problems. The struggles they began, he continues. On a quiet residential street in Westwood, the legacy of the first modern painters survives.

It’s worth emphasizing, however, that Kitaj is very much a contemporary artist whose work is as unmistakably the product of its era as anything by Jasper Johns or Bill Viola. Once in a long while, in a spirit of gentle mischief, he’ll even paint a small abstract. There’s one in his studio now, appropriately modest in size, based on a detail in a Matisse painting that the critic Clement Greenberg once singled out for criticism. (He dubbed it an “unresolved fault.”) Kitaj, who is obsessed both with the history of the Jews and his own Jewishness, calls it My Fourth Jewish Abstract. Naturally, there is a story behind the title.

“My stepfather, Kitaj, was a Viennese refugee scientist, and he used to receive a trade journal called Chemical Abstracts — meaning that they were précis of longer articles. And I never forgot that. So that’s the sense in which I use ‘abstract’ — an abstract from something. I think Ellsworth Kelly abstracts from things occasionally. He sees a curve on a tennis shoe, and it becomes an abstract.” The layers of reference and interpretation embedded in this small painting suggest why Kitaj’s work often has a Talmudic tinge. “I love heaping on the Jewish junk,” he says, “because the more I heap on, the more Jewish it becomes.”

Every few years Kitaj will also indulge his fondness for “Duchampism,” another major 20th-century art movement he played no role in, by going to a store, buying something, taking it home and constructing a ready-made, rather like someone following a recipe in a cookbook. The recipe was given to him by the pop artist Richard Hamilton, based on a talk Duchamp gave at the Museum of Modern Art in New York.

“I follow Duchamp’s instructions implicitly,” Kitaj says, straight-faced. “But you can’t do it too often.” Then he shows me the first piece of Duchampian art he came up with. It’s not a bicycle wheel, and it’s certainly not a urinal. It’s a book, open to display its cover, mounted in a heavy black frame and sealed in glass. The book’s title is The Jews Are They Human?

“Do you know who wrote that?” he asks. “Can you guess?”

Soberingly, the answer turns out to be Wyndham Lewis, the radical 20th-century English novelist and painter. (He soon after recanted his views.) This is Duchampism with a bite.

For a while we sit in Kitaj’s kitchen, over glasses of orange juice, surrounded by paintings and drawings by Freud, Auerbach, Hockney, Jim Dine and others. Aside from his paintings, his major project now is his autobiography, which he works on every morning at a café in Westwood. He starts in 1949 (the first line reads, “I was born on a Norwegian cargo ship, when I was 16 years old”) and plans to take it all the way to the present. This way, he says, if people want to hear about him after he dies, “They’ll be able to hear it from the horse’s mouth.”