Chelsea Clinton’s speech on Thursday night at the Democratic National Convention worked in large part because it was full of precise, and often deeply personal, details about her mother. As Slate’s Ruth Graham notes, it stood in pointed contradistinction to those given by Donald Trump’s children, which “made their father sound inspirational but barely involved in their lives.” More tellingly, though, there’s now objective evidence that people were actually listening carefully to even the most minor asides in Chelsea Clinton’s paean to her mother.

Many of the most deeply felt moments in Clinton’s speech came when she alluded to her family’s love of books and reading. Painting a picture of her mother as someone who was always there for her, she recalled, “My earliest memory is my mom picking me up after I’d fallen down, giving me a big hug, and reading me Goodnight Moon.” Later, she described the way her parents would challenge her to describe what she had learned at school each day, adding, “I remember one week talking incessantly about a book that had captured my imagination, A Wrinkle in Time.”

In both stories, the books in question aren’t especially important, since Chelsea Clinton declined to say anything else about either. If you’re already familiar with them, they might tell you something about the family’s values and interests, but those qualities remain largely tertiary to Clinton’s remarks. Little more than texture, then, they’re there to show that Clinton actually has a connection to her mother—that Hillary Clinton is human and real, someone she talks to about real things, like books. The titles evoke the nerdy, charming Chelsea Clinton that America has known for decades, associatively imbuing her mother with a hint of authenticity.

Ornamental as these details may have been, however, people were clearly paying attention. When I checked Amazon’s sales stats for the two books just after Clinton mentioned them, Goodnight Moon was at No. 55 on the site’s best-seller lists while A Wrinkle in Time came in at No. 376. Since Amazon updates its public-facing comparative sales stats hourly, it’s not clear whether interest in the books spiked immediately. When I looked at the books again 12 hours later, their position had changed, dramatically in the case of Madeleine L’Engle’s classic young adult novel.* In the intervening time, A Wrinkle in Time had vaulted into the site’s Top 100 books list, landing at No. 85. Goodnight Moon, meanwhile, had climbed into the Top 50, where it currently resides at No.43. (I didn’t pull data for the other book Clinton mentioned, Chugga-Chugga Choo-Choo.)

As data about the effectiveness of a political convention goes, this is hardly the most important, especially relative to polling data. Minor as it is, it’s still potentially significant, however, precisely because it suggests that small things—not just big rhetorical flourishes—matter.

Possibly more meaningful still? Thanks to Clinton’s brief reference, A Wrinkle in Time is now outselling Trump’s Art of the Deal, which currently sits at No. 356.

*Correction, July 29, 2016: This post originally misspelled Madeleine L’Engle’s first name.

