“On any person who desires such queer prizes,” E. B. White wrote in his classic essay “Here Is New York,” in 1949, “New York will bestow the gift of loneliness.” It remains an essential paradox of the city—that a place with so many people living so close together can also be so isolating. This is one of the phenomena that the photographer Peter Garritano hoped to explore in “Seeking,” a series of portraits of New Yorkers who have posted advertisements in the Strictly Platonic personals section of Craigslist. The world has acclimated to the fact that people might go online to find a mate, but there are fewer formal avenues through which to find friends, perhaps because friendship is not always acknowledged as something that people have to go out in search of. “We already know everyone’s looking for love,” Garritano told me in an e-mail. “I’m more concerned with our social requirements beyond romance.”

Garritano contacted his subjects through their ads (he got no response to “90 or 95%” of the messages he sent, he told me) then arranged the sittings, where he would come up with the mood for the shots more or less on the spot, based on the subjects’ personalities and his interactions with them. “Seeking” presents each portrait alongside the subject’s Craigslist ad, which, taken together, convey a dizzying range of interests, personalities, desires, projects, anxieties. Many of the people posting are new to town, hoping to get a foothold in New York life. “I’m not sure exactly how to approach the city,” a young man writes, adding that he figures that his chiselled looks could earn him some fast cash working in adult entertainment, if only he had a friend to advise him. Others are veteran New Yorkers in need of a change of pace. “Gay White dude who is fed up with his bar fly, drugged out friends,” a man who resembles “a thin Rabbi” writes. A metalhead seeks other metalheads; a woman wants company for Zen meditation. Many are seeking professional connections—masseuses looking for bodies to work on, a yogi looking for students, a young woman who charges ninety dollars an hour to listen to people’s problems and extra if they want to cuddle—but many others say that they just want someone to hang out with: a “vegan bestie,” or someone to share an appreciation of ice skating and Latin dancing.

Garritano said that he sought out ads that seemed genuinely platonic, and yet there’s a whiff of sex in many of them—the woman who is looking for someone to show her around the city and says she’s “open to casual fun as well,” or the man hoping to clean someone’s apartment in the nude. Many make sure to preëmptively shut down sexual requests. The author of an “m4m” ad specifies “no gay guys sorry”; a twenty-year-old woman with pink braces warns, “i already friend zoned you so no funny thoughts.” Even when not directly present in the post, there’s an awareness of sexuality and appearance and how it complicates even the most platonic interactions; there’s a man who lists his location as a physical-rehab center—his portrait shows him lying in a hospital bed—mentions that he “did some male modeling (print, billboard and runway mostly in Asia and Latin America)” and adds, “that was then.”

It’s a bit startling to see the familiar text of Craigslist ads—which can often seem to have dropped out of the sky, with their strange syntax and their unfamiliar details—next to the faces of the people who actually sat down and typed them out. An ad with the subject line “Are you taking the time to enjoy the moment? - m4w,” in which the poster says he’s “seeking others who find simplicity and a slower pace of life poignant and attractive,” accompanies a photo of a man in a black T-shirt, whose skin is white and hairless, with his eyes closed and his face turned toward a bright spot of sun. He looks simultaneously forthright and withholding, vulnerable and self-protective. A number of the portraits have a similar elusive quality. A woman who lists her age as sixty, her body type as “athletic,” her likes as “generosity, fair play, forgiveness,” and her dislikes as “egoism, psychopathy and greed” is captured standing next to a large tree in a park, in slanting evening light. She’s shot from far away, and it’s hard to make out her features, but she’s wearing a pink scarf and sensible shoes and has her hands folded demurely in front of her. She’s looking, she writes, “for somebody who knows what it means when an unexpected tragedy brings you down to your very existence.”

Garritano’s portraits seem to acknowledge that it is an act of bravery, especially in America’s feel-good, can-do culture, to admit that you might be lonely, although, of course, many people feel that way. “I’m just a bit lonely tonight and looking to hang”; “Just bored”; “just want to meet cool people that are fun and down to earth,” his subjects write. “I really don’t like to be alone, but I hate even more the fact that I can do something about it and still choose not to.” There are hundreds of Strictly Platonic ads on Craigslist, and when Garritano met with his subjects he often asked if they had received responses to their listings. Most of them had.