Ethan Hawke has recalled how his late co-star Robin Williams "didn't ask permission" to go off-script when they filmed their 1989 drama Dead Poets Society. The Training Day actor, who was 18 when he made the film, revealed that the "comic genius" opened his eyes to a different way of acting on the set of Peter Weir's film. During a career retrospective video for Vanity Fair, the Before Sunrise actor recalled that Williams was still new to dramatic acting at the time and brought his improvisational skills to the set. "Robin Williams didn't do the script, and I didn't know you could do that. If he had an idea, he just did it. He didn't ask permission," he shared. "And that was a new door that was opened to my brain, that you could play like that. And Peter liked it, as long as we still achieved the same goals that the script had." The coming-of-age drama starred Williams as an unorthodox English teacher at an elite boarding school who inspires his unruly students - including Hawke's Todd Anderson - through poetry. Hawke acknowledged that directing Williams was "not an easy thing to do", but Weir respected the fact that he and Williams had "a very different way of working". "They didn't judge one another or resist one another," he explained. "They worked with each other. That's exciting - that's when you get at the stuff of what great collaboration can do. You don't have to be the same, but you don't have to hate somebody for being different than you are. And then the collective imagination can become very, very powerful, because the movie becomes bigger than one person's point of view." Dead Poets Society won the Oscar for Best Original Screenplay, and received nominations for Best Picture, Best Director and Best Actor for Williams.