Well before “Battle Hymn of the Tiger Mother,” Chua and Rubenfeld wanted to collaborate on a project. “For a while we were going to write a book about Jewish people and Chinese people,” she said, “and it was going to be how different the cultures were.” But then they noticed some historical similarities. “If you take Jews in the 1900s, 1910s, it’s like, ‘You have to listen to your father,’ too!”

Chua and Rubenfeld met in the mid-’80s, when she was in her second year at Harvard Law School and he was in his third. She had just made The Law Review, where he was already an editor, and a mishap at what she calls “the nerdiest volleyball game of all history” almost landed them in the emergency room.

“We were on opposite sides, and we both went up for the ball,” she recalled. She got a bloody lip; he got a black eye. “In fact, we were on the same team,” Rubenfeld said by way of correction. “We weren’t on opposite sides.”

He invited her for coffee, and she accepted. Rubenfeld was trying to democratize The Law Review by doing away with the grueling competitive process in favor of a lottery, which made Chua — a child of immigrants and an ardent believer in the meritocracy — suspicious. “I found the conversation irritating,” she said. “All these people went to private schools; I went to a public school, and I clawed my way into this thing.” She laughed. “I was just there to try to do well, and Jed was leading revolutions.”

When Chua described her first impressions of Rubenfeld, the word “cool” came up several times, and she enunciated it in a way that made it clear she was using it as a term of derision. Asked how she went from mistrusting the cool kid to marrying him, she recalled how, over time, she realized that his intelligence revealed some effort. He wasn’t just coasting by on his good looks and his privilege — coasting being the unforgivable sin in the Chua cosmos. She talks about hard work as both a practical and a moral imperative. Forgoing hard work is a mark of arrogance, which leads to complacency, which leads to intergenerational decline. In “Battle Hymn,” she casts the forced march of music lessons as an attempt to counteract the smug satisfactions of privilege, writing of her determination “not to raise a soft, entitled child.”

Chua grew up feeling anything but entitled. She was born in Champaign, Ill., to Chinese parents from the Philippines. Her father was a Ph.D. student in electrical engineering; her mother was a chemist who eventually gave up her career to care for four daughters, the youngest of whom has Down syndrome. Amy was the oldest. When their father came home from work, she would take off his shoes and socks before bringing him his slippers. Expectations were high, and they were clear. An A-minus was not merely unacceptable but “unthinkable.” Amy spoke only the family’s Hokkien dialect until she was 4, when she was thrown into a nursery school where everyone spoke English. But an English slip of the tongue at home would be met with a “whack of the chopsticks.”

Rubenfeld’s upbringing wasn’t nearly so severe. His parents rebelled against their Orthodox Jewish backgrounds to become, as he puts it, “very liberal, very permissive.” His father was a successful psychotherapist; his mother was an art critic. They didn’t push their three children to get good grades. When Rubenfeld was 12, his parents told him he could take violin lessons or tennis lessons. He chose tennis. “The message in my family was: Kids should go out and find out what they want to do. And that was great for us all, individually. But as a family, things didn’t work out that well. My parents were separated when I was in college. They got divorced. And they practically weren’t speaking to each other for the rest of their lives.”