Alex Katz wife Ada is his most important model and muse. This is also the case in the work ADA X 2. Katz is known for his linear and simplified portraits, which are characterized by an economy of gesture or, as the artist describes it, by the rapid passing of things. His paintings focus on the attitude of a present moment, regardless of the specifics of the subject portrayed. There are numerous historical references in his work, from Japanese block printing, Matisse and Monet to Jackson Pollock, Degas and, of course, Pop Art. The long-term career prospects of a muse are uncertain at best. “After Picasso, only God,” remarked Dora Maar, the artist’s mistress and herself a gifted photographer who spent the second half of her life in cloistered seclusion after her nine-year affair. Modigliani’s last mistress, Jeanne Hébuterne, the one with the swan-like neck and almond eyes, met her end by jumping from a fifth-floor window the day after her painter’s untimely demise. Ada Katz has been Alex Katz’s muse for more than half a century. Her presence is as quiet and omnipresent as the smell of oil paint on his paintings. In the 1960s, he portrayed her as a sleek, mysterious American sphinx in sunglasses and a sweater. Garbo talked; Ada, never. Her deep reserve is such that you can spend a very pleasant hour tête-à-tête with her and still wonder if you ever really met. This petite woman with an eerily familiar face was born Ada Del Moro in the Bronx to Italian parents from Abruzzo. From her mother, a skilled seamstress who made most of her daughter’s clothes for years, she inherited (according to her husband) her keen sense of style and disarmingly broad smile. She says she rather resembles her father, who had “Asian eyes” and “sensual lips.” (The classic Roman nose is still unspoken). This muse was trained as a research biologist at Brooklyn College and New York University. She went to Milan on a Fulbright grant to study tumor genetics and was working at the Sloan-Kettering Institute in New York when she met her future spouse at the opening of his two-person show at the artist-run Tanager Gallery on East 10th Street. (He says she was “already a legend in the art world”; she claims she was “shy about going into galleries.”) That was in October 1957; they married the following February. Did she feel she was signing up for representation in the next millennium? “Never,” she says. “I remember sitting with my hands on my lap, and the man I was interested in looking at my eyes, my ears, my shoulders. The whole thing was just very sensual. And I didn’t think I could handle it. But then it became just this thing that he was doing. I sat there and he painted, and that was it.” The Ada of the paintings tends to be stylishly dressed, but her appeal is less in her clothes than in how she wears them.

She remembers a shocking pink raincoat that appears on a canvas against a dramatic black background: “It was very cheap. I even bought another one in navy,” she recalls.

Their early life together revolved around a tiny art world by today’s standards and its rituals – Tuesday night openings in Uptown, Fridays at the Club on Eighth Street, Saturday trips to galleries and museums. Sometimes she accompanied him to the Cedar Street Tavern, the legendary artists’ hangout where, a decade earlier, Jackson Pollock had opened the door to the men’s room.

When the couple’s son Vincent, a poet, was born in 1960, Ada left her work, never to return, but her roles in the paintings expanded. The bathing beauty, the chic retired bohemian, the cocktail hostess and (increasingly) the self-assured woman of the world could also be cast as a contemporary Madonna. (From about mid-marriage and for about a decade, she produced plays with poets and artists. Most people have family photo albums from when their children were young; the Katzes have quite a body of work. “We didn’t take pictures of each other,” she recalls. “He painted.”

Alex Katz, sitting down a little later, calls his wife “the perfect model”.

“She’s both a European beauty and an American beauty,” he says. “She’s like Dora Maar, the same kind of face, but then her smile is the American-beautiful smile.

His enduring fascination with her face can even be seen on a canvas from last year; although her hair is now elegantly streaked with gray, she is still sincere and inscrutable. Ada X 2 has also been featured as a small portrait in Architectural Digest during a studio visit with Alex Katz.

“The whole thing is strange,” he continues. “Ada was on a Madame Curie track, working 60 hours a week. She didn’t have that much intention of getting married. And I think there were probably three men in New York that she could relate to. So I was just lucky. I fit what she wanted, or what would have been acceptable.”

So it was all down to her? “Yes, definitely,” Alex Katz replies. “No one in their right mind would have said no,” he replies.

This muse chose her artist. Did she shape him too? By what magical osmosis did her strong-willed modesty resemble the extremely controlled surface of his art? Rubbing against his uncompromising vision for some 50 years may have worn the rough edges of her personality so smooth that they are barely perceptible, but she says: “We have no ups and downs. We live together and he works right here. So if it was really bad, we’d have to stop.”

And to hear him tell it, she’s the relentless one. “She’s intense,” he asserts. “There’s no second place in her life. That’s the side you don’t see. She’s very discreet about it.”

This text has been transformed from an article by Leslie Camhi that appeared in the New York Times in 2006.