On one of the coldest nights of New York’s winter, hundreds of people lined up outside the New York Public Library. Not for a concert or the latest restaurant opening, but to simply read. The event was simple: read silently for 20 minutes, then turn to a stranger and talk about your book. With the library reaching full capacity, they had to turn people away.

“It was one of those subzero nights,” Brian Bannon, the New York Public Library’s chief librarian, told Fortune. “I thought maybe there was a sneaker sale.”

Instead, “it was a line of 20-somethings waiting to get into the library.”

Coffee shops gave young adults somewhere to work. Bars gave them somewhere to socialize. But as loneliness and digital fatigue reshape how people spend their free time, spaces built around learning are finding there’s growing demand for something many businesses haven’t traditionally sold: the opportunity to think together.

The conversation starter