Mr. Friedman and his wife, Mickey, a design and architecture curator who championed Frank Gehry, moved to New York, but he became restless; retirement didn’t suit him. He consulted for the Nelson Atkins Museum in Kansas City, Mo., developing the Kansas City Sculpture Park. “I became the yard man,” he said. In 1994 he brought in monumental badminton birdies by Mr. Oldenburg and von Bruggen . (In 2009 he was thanked with a gift funded by the Hall Family Foundation: he got to commission anything and chose a 56-foot-high stainless steel sculpture of a tree by Roxy Paine.)
Meanwhile, his services as a yard man were needed in New York. In 2004, he got a call from Debbie Landau, now president of the Madison Square Park Conservancy, who was developing the park with Danny Meyer, who would famously open his first Shake Shack there. She wanted an art program and started with a couple of shows put on by the Public Art Fund. In 2003, she helped establish the Conservancy, and a series of meetings brought her to Mr. Weinberg, who suggested she contact Mr. Friedman, whom he called the father of the modern sculpture garden.
“Adam said, ‘Martin doesn’t have much to do. He’ll come cheap, for free,’” Mr. Friedman said, laughing. “So I did. And I was delighted because I felt like I’d been taken off the shelf, dusted off and given the chance to work with some talented people.”
At the time, the park had just installed a set of huge, angular steel sculptures by his old friend Mark di Suvero, one of whose giant pieces he’d installed at the Walker in the early ’70s. Shortly after retiring, Mr. Friedman had helped Mr. di Suvero with Socrates Sculpture Park, the outdoor art venue Mr. di Suvero, along with a group of artists and community members, had founded in an abandoned landfill in Long Island City in 1986. “We were endangered by—let’s call them entrepreneurs of real estate—who wanted to take this place we had cleaned up,” Mr. di Suvero recalled. “He came in and he taught us how to build a board of trustees.”
The di Suvero show was getting Ms. Landau publicity. “But then it was like, ‘Now what?’” Mr. Friedman suggested she set up an advisory committee, think of the park as a series of galleries in a museum, and, most importantly, have art up all the time. “He said, ‘You shouldn’t just have a show for a few months and then go dark. Museums don’t go dark.’”
Mr. Friedman liked the park. “It’s not wild and woolly, it’s a Beaux-Arts plan,” he said. “The possibility of making special pieces there appealed to me.” So he opened his Rolodex. “When he got to Sol LeWitt, I said, ‘Wow, do you think Sol LeWitt would do something here?’” Ms. Landau remembered. “And he said, ‘Debbie, just call him. Here’s his number.’”
This isn’t that surprising, coming from a man who refers to Marcel Duchamp as “accessible.” In 1965, he interviewed Duchamp onstage at the Walker. “I had seen him a few times, I knew him from New York.” He and Mickey had spent time with him in Paris. “He was accessible. He was at the Marshall Chess Club. You’d pick up the telephone and say, ‘Mr. Duchamp, I’d like to talk to you.’ He’d say, ‘Why not now?’ So we’d meet at some drugstore or something, have a sandwich.”
In 2006, the year before LeWitt died, he displayed two major large new concrete sculptures in Madison Square Park. The following year brought stainless steel tree pieces by Roxy Paine and a film, projected on huge screens, by William Wegman, in which Mr. Wegman’s Weimaraners posed as park patrons and workers. There was an interactive light installation by Rafael Lozano-Hemmer; 2010 saw the biggest splash, that Anthony Gormley installation, the “boneheaded” one.
“He lives in this hell right now,” said Mr. di Suvero, “Everything he did was for the vision of others, and then he had that horrible irony of losing his vision.”
For decades, Mr. Friedman has suffered from macular degeneration; over time, it results in loss of eyesight. In 1959, the year after he became a curator at the Walker, he traveled to Abiquiu, N.M., to visit Georgia O’Keeffe, who was then in her 70s and whose work he wanted to include in an exhibition. He’d written her and gotten strongly worded rejections, so he showed up. She, too, it turned out, had the eye condition. She insisted he take off his glasses, and showed him a series of eye exercises. Then she took him to Ghost Ranch. “She scared me. I kept imagining my head as one of those parched skulls. I kept saying, ‘It’s very hot, Ms. O’Keeffe.’ She said, ‘You’ll get used to it.’” She agreed to participate in the exhibition.
He has fought the condition tooth and nail. He continues to write, by dictating to an assistant. There is the sense, even now, when one is around him, that artistic production, wherever it is to be found, will continue to afford improbably rewarding experiences. On a coffee table in his living room, like a still life, sits the catalog of the 2012 Whitney Biennial, next to a special pair of reading glasses. Squinting at the art world, he still sees it pretty clearly. “I love the idea that the Biennial is now a work in progress and is being redefined,” he said. “It will be very difficult for the Whitney to go back to a conventional Biennial, after this one.”