Jill Lepore isn’t the first New Yorker staff writer to sink her teeth into Joe Gould.

Gould, the eccentric, often homeless New York City bohemian (b. 1889—d. 1957), was profiled twice by legendary journalist Joseph Mitchell: In 1942, his article “Professor Sea Gull” highlighted Gould’s claim of writing the longest book in history—a chronicle of everyday New Yorkers, entitled Meo Tempore or The Oral History of Our Time—on a tremendous collection of notebooks and scrap paper. In 1965, “Joe Gould’s Secret” revealed that the work likely never existed.

Or did it?

“For me, the captivating thing about Gould wasn’t like, Oh! What a kooky character!” says Lepore, author of Joe Gould’s Teeth. “The thing for me about Gould was, My god, what if that oral history existed? What an incredible archive! It’s like the idea of the Federal Writers’ Project records or the kind of thing StoryCorps does now, but nearly a century old....That’s totally [exciting] to someone with my interests as a historian.”

Lepore teaches American history at Harvard. Her works include a rigorous biography of Benjamin Franklin’s sister, Book of Ages: The Life and Opinions of Jane Franklin (2013), and The Secret History of Wonder Woman (2014), which places the popular comic book character in the context of the women’s liberation movement. She specializes in the unsung, marginalized, and forgotten—exactly as Gould claimed to.

As Mitchell quoted Gould in “Professor Sea Gull”: “I’ll put down the informal history of the shirt-sleeved multitude—what they had to say about their jobs, love affairs, vittles, sprees, scrapes, and sorrows—or I’ll perish in the attempt,” Lepore writes.

One spring semester, Lepore assigned the Mitchell profiles to her students. In asking them to create a timeline of Gould’s mysterious life, she quickly tumbled down the rabbit hole.

“There ought to be a DANGER sign,” Lepore writes in Joe Gould’s Teeth, a book-length expansion of her New Yorker feature by the same title. “Writers tumble into this story and then they plummet. I have always supposed this to be because Gould suffered from graphomania—he could not stop writing—which is an illness, but seems more like something a writer might have to envy, which feels even rottener than envy usually does because Joe Gould was a toothless madman who slept in the street. You are envying a bum: Has it come to this, at last? But then you’re relieved of the misery of that envy when you learn that everything he wrote was dreadful. Except, wait, that’s worse, because then you have to ask: Maybe everything you write is dreadful, too? (WARNING: Do not ask this question from the bottom of a well.) But then, in one last twist, you find out that everything he wrote never even existed. Still, either way, honestly, it’s depressing as hell.”

Gould was Harvard educated; he was a bum. Perhaps a genius, likely insane. He had tons of famous literary friends and, for a time, an anonymous patron. He was self-aggrandizing, beggarly, and a knave. He lied to friends and harassed perceived foes, like the Guggenheim Foundation grant officials who received a rude, racially charged harangue in 1934.

“By now, hardly anyone could fail to see, he was mean; he was vicious,” Lepore writes of Gould at that time. “He was wretched and abandoned. He smelled; he was covered with sores and infested with bedbugs. He was terribly, terribly ill. [e.e.] Cummings made him sit on the windowsill so he wouldn’t leave lice on the furniture.”

But Gould’s worst offense, as per Joe Gould’s Teeth, is his deleterious obsession with an African American artist named Augusta Savage. She was a sculptor, a teacher (whose school became the Harlem Community Art Center), an activist, and one of the most important figures of the Harlem Renaissance. He harassed, stalked, and likely assaulted her; ultimately, she fled to rural Saugerties, New York, where she lived the rest of her life.

Lepore’s interest soon transferred from rooting out the Oral History to discovering Savage.

“I was looking for the oral history for a long time, and then I was looking for Augusta Savage for the rest of the time,” Lepore says. “The one thing that could come out of this book, that would make me happy to have done it, is if someone would write just a knockout biography of Savage. She’s quite fascinating, and it would be a great contribution for someone to do that.”

To inspire a biography of Gould would not be to her taste.

“Really, I was so done with Gould,” she says. “I find writing essays so much easier than writing books, because a book is a kind of a race against restlessness—it’s not quite boredom, it’s kind of like I want to be writing something else—but Gould, especially, is a person you don’t want to spend any large time with.”

Megan Labrise writes “Field Notes” and features for Kirkus Reviews.