As a kid, one of the highlights of my summer vacation was sitting underneath a tree in my grandmother’s backyard and getting lost in a book. I don’t get a three-month summer break anymore, but tucking away with a juicy novel when it’s hot outside is a ritual I still return to.

So what makes for a good summer read and how did this practice even emerge in the first place? That’s what we set out to find out on this week’s episode of Explain It to Me, Vox’s weekly call-in podcast.

To find the answer we spoke with Donna Harrington-Lueker, author of Books for Idle Hours: Nineteenth-Century Publishing and the Rise of Summer Reading. Summer reading is a practice she knows well. “As a teenager, let’s just say I was a bit bookish,” she says. “That meant that when my family went for its one-week vacation a year — which was a big treat — they were on the beach and I was in some kind of a bunk bed with Moby Dick or Siddhartha.”

Below is an excerpt of our conversation, edited for length and clarity. You can listen to the full episode on Apple Podcasts, Spotify, or wherever you get podcasts. If you’d like to submit a question, send an email to askvox@vox.com or call 1-800-618-8545.

How did this idea of summer reading even start? Have we always grabbed books when it’s hot out?

No, not really. My research focused on the 19th century, and I started looking at newspaper articles, advertisements........

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