Milo travels through a magical land in Norton Juster’s 1961 classic “The Phantom Tollbooth,” with drawings by Jules Feiffer.

In 1961, an unusual children’s book was published. Written by architect Norton Juster and illustrated by his friend and Brooklyn neighbor Jules Feiffer, “The Phantom Tollbooth” was considered a dubious commercial proposition by its publisher. A little more than 50 years later, it’s sold more than 4 million copies and has been read by untold multiples of that number.

The book is the tale of Milo, a bored boy who journeys into a land divided between words (embodied by the city of Dictionopolis) and numbers (its rival, Digitopolis). His guide on this pun-filled quest is Tock, a watchdog whose body is a ticking alarm clock.

“My father was a punster,” Juster says. “After a while, you start saying, ‘I can do that.’”

Juster will appear at Politics and Prose Thursday morning to discuss the book and its 50th-anniversary annotated edition. The architect and longtime teacher, now retired, has plenty to say about the story and its lessons. Much of what he says is, like “The Phantom Tollbooth” itself, faintly subversive. That reflects one of his major influences, the Marx Brothers movies he saw as a kid.

“They were absolutely insane,” says the 83-year-old. “And then you’d then see them again and again. And you’d realize they made all this good sense.”

While riffing on the radio and movie comedies of his youth, Juster also drew on a more grown-up source, C.P. Snow’s “The Two Cultures,” a 1959 study of the gap between the humanities and the sciences. “I thought it would be kind of fun to play around with it,” he recalls.

Initially, Juster began “The Phantom Tollbooth” as a way to put off another task, a book on urban planning. “I do my best work when I’m trying to avoid something else that I’m supposed to be doing,” he explains.

Juster suggests a similarly freestyle creative approach to the young, aspiring scribes who ask him what it takes to be a writer. “I tell them, ‘Write, and write whatever you want.’”

Politics and Prose, 5015 Connecticut Ave. NW; Thu., 10:30 a.m., free; 202-364-1919. (Van Ness)