Robin Williams' portrayal of John Keating was one of his iconic roles, and this drama about boys at a prep school in 1959 still endures. Here are 15 things you may not have known about Dead Poets Society

Carpe diem.

1. The movie was loosely based on the screenwriter's life.

Dead Poets Society was written by Tom Schulman, who also wrote Honey, I Shrunk The Kids and What About Bob? It was the first screenplay he sold to Hollywood, though not the first one he wrote—in fact, Schulman wrote four scripts before Dead Poets Society. The story is based in part on his experiences at Montgomery Bell Academy, a prep school in Nashville, Tennessee. Most of the characters were modeled on people he knew from real life.

2. The main character, John Keating, was based on two of Schulman's teachers.

Keating was based on Harold Clurman, who taught at the Actors and Directors Lab, and Samuel Pickering, who taught Schulman's sophomore English class. While Keating's inspiring speeches may have come from Clurman, his quirky teaching style came from Pickering. In an essay, Pickering says he sometimes taught class while standing on a desk (as Keating does) or in a trashcan. One of his students remembers Pickering making him stand on a chair and flap his arms every time the class said the word “nevermore” while reading Edgar Allan Poe's The Raven.

“I did such things not so much to awaken students as entertain myself,” he wrote. “If I had fun, I suppose I thought, the boys would have fun, too, and maybe even enjoy reading and writing.”

3. The studio considered turning Dead Poets Society into a musical.

They even had a title: The Sultans of Strut. Apparently, it was going to be like Fame.

4. Originally, Jeff Kanew, who did Revenge of the Nerds, was going to direct it.

Kanew wanted Liam Neeson to play Keating, but the studio wanted Robin Williams. For his part, Williams seemed reluctant to work with Kanew, which led to a disastrously botched first day of shooting, according to Schulman:

“The studio wanted Robin Williams, and Robin wouldn't say no, but he wouldn't say yes, to working with that director. In fact, we prepped the movie, built the sets—it was going to be shot outside of Atlanta—and Robin just didn't show up for the first day of shooting. He never said he would, but Disney kept trying to pressure him by moving forward. After the first day he didn't show up, they canceled the production and burned the sets. We actually have dailies of the sets burning.”

5. Dustin Hoffman was going to direct—and star in—the movie.

After Kanew, Hoffman signed on to direct, as well as play the role of Keating, but there were scheduling conflicts and arguments about the start date. Finally, the studio gave the movie to Peter Weir, who directed Witness and Gallipoli and would later direct The Truman Show.

6. In the screenplay, John Keating is dying of cancer.

The movie is faithful to Schulman's screenplay except for a scene where the boys discover that Keating has Hodgkin's disease. The scene was intended to show the audience why Keating is so intent on seizing the day, but Weir thought the movie was stronger without it. He told Schulman, “You don’t have to explain it.”

7. Filming was moved from Georgia to Delaware because of snow.

The movie was originally going to be filmed in Rome, Georgia, but the director wanted snow to enhance the feel of a New England prep school. Since snow is expensive to replicate, they moved filming to Delaware, where snow is free.

8. The movie is rife with literary references—both well-known and obscure.

Keating tells the boys to sound their “barbaric yawp” from Walt Whitman's Leaves of Grass. He quotes Henry David Thoreau's line from Walden, “The mass of men lead lives of quiet desperation.” The boys chant lines from Vachel Lindsay's almost-forgotten poem "The Congo": “Then I saw the Congo, creeping through the black, cutting through the forest with a golden track.” Shakespeare, Robert Frost, Alfred Lord Tennyson, and Lord Byron are also mentioned.

Of course, the most memorable literary reference is the use of Whitman's elegy for Abraham Lincoln. At the end of the movie, after Keating has been fired, the boys climb on their desks and declare their loyalty by saying, “Oh Captain, My Captain.”

9. Robin Williams was stiff in the role, until he started improvising.

When Williams first arrived on set, his portrayal of Keating was wooden and uncomfortable, so Weir suggested they improvise. He asked Williams what he wanted to “teach” the class, and he said Shakespeare. Then Williams did an improv of Marlon Brando and John Wayne doing Shakespeare, a scene that made it into the movie. After that, he relaxed into the role, and the movie started to work.

10. A Decent Chunk of Williams' Lines Were Improvised.

And not just the scene mentioned above. Producers estimate about 15% of Robin Williams' dialogue was improvised by the actor.

11. The director made the young actors live together.

Since the characters in Dead Poets Society live in a boarding school, Weir had the boys room together so they could bond. He also made them study movies, radio shows, and music from the 1950s.

12. The cave is fake.

The cave where the society meets wasn't an actual cave, but rather a set piece made of latex. It was, however, based on a real location—Wolf Cave in Delaware.

13. Lara Flynn Boyle had a bit part in the movie, but it was cut.

Here's the deleted scene.

14. Not everyone liked the film—Roger Ebert Especially.

While Dead PoetsSociety was generally well received, some critics thought it was emotionally manipulative and intellectually shallow. Ebert gave it two stars and said of the film: “It is, of course, inevitable that the brilliant teacher will eventually be fired from the school, and when his students stood on their desks to protest his dismissal, I was so moved, I wanted to throw up.”

15. Ethan Hawke credits a scene with Williams for introducing him to the possibilities of acting.

In an interview with Jian Ghomeshi, Ethan Hawke talks about the impact working with Robin Williams on Dead Poets Society had on his career, particularly in a scene where Keating teaches him to sound his “barbaric yawp.”

“That was the scene where I was supposed to read a poem in front of the class and it was the first time in my life that I ever experienced the thrill of acting and the thrill of losing yourself. You know, there's this whole thing in the public that acting is this huge celebration of the personality and the ego, of course, and the irony is that whenever it's any good, it's devoid of ego. It's a high that I've chased my whole life since that day with Robin. It's this way of losing yourself, where you lose yourself inside a story, a story that's in service of something way beyond you. And I felt that in Dead Poets Society.”