July 23, 2015 6:47 AM EDT

For the second time this Summer, readers are getting a new book from a beloved author whose oeuvre was supposedly complete. Dr. Seuss’s What Pet Should I Get? publishes in July to considerably less controversy than Harper Lee’s Go Set a Watchman but with one striking similarity: both were likely precursors to famous works.

Theodor Seuss Geisel died in 1991, but it was just two years ago that his widow Audrey and longtime secretary Claudia Prescott discovered a box containing unpublished text and drawings. Among them was a draft of What Pet, in which the narrator and his sister Kay search for a new friend from a pet store. This will be his first new book since his death; last year’s Horton and the Kwuggerbug was cobbled from magazine work.

Seuss’s publisher believes What Pet’s stars are prototypes of the characters from 1960’s One Fish Two Fish Red Fish Blue Fish, a best seller not just among Seuss’s 44 works but among all children’s books.

Eight decades after a line-drawn boy named Marco turned a ho-hum horse and wagon into a zebra-drawn chariot in And to Think That I Saw It on Mulberry Street, the appetite for Seuss is undiminished. The print run for What Pet is 1 million; total Seuss sales top 650 million copies.

Seuss’s peers say his work endures because those Technicolor drawings and slyly sophisticated rhymes carved out a unique space in the genre. “As a child, [I was] captivated by the writing and the intricate detail of the illustrations,” says Sandra Boynton, the best-selling author of Moo, Baa, La La La! Jon Klassen, who won a Caldecott Medal in 2013 for This Is Not My Hat, describes Seuss’s work as “incredibly self-contained, not derivative of anything.” Eloise illustrator Hilary Knight cites Seuss’s “totally original” style: “The lasting characters that are born in children’s books become part of our culture, and better still, part of our lives.”

Cathy Goldsmith, a Random House vice president, worked with Seuss as an art director in his later years and was tasked with coloring What Pet. “You’ve got to be careful that you’re doing a service, not a disservice, to somebody’s reputation,” she says of the decision to publish posthumously. “We’re also respectful enough and grateful enough for what he did write to have not published this if we thought it wasn’t worthy.”


This appears in the August 03, 2015 issue of TIME.

Contact us at editors@time.com.

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