Ethan Hawke will never forget what he learned from working with Robin Williams on 1989s Dead Poets Society.

During a recent career retrospective video interview with Vanity Fair, the Black Phone 2 actor opened up about what he observed from watching filmmaker Peter Weir direct the late Williams.

Im watching him direct Robin Williams, not an easy thing to do, cause Robin was a comic genius. But dramatic acting was still new to Robin at that time, Hawke recalled. And watching that relationship like, in the room I was four feet away while theyre talking about performance and that was something you dont unsee. He continued, Robin Williams didnt do the script, and I didnt know you could do that. If he had an idea, he just did it. He didnt ask permission. 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.

Hawke said he enjoyed seeing the respect Weir and Williams had for one another, despite having a very different way of working.

They didnt judge one another or resist one another, the Training Day actor explained. They worked with each other. Thats exciting thats when you get at the stuff of what great collaboration can do. You dont have to be the same, but you dont 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 persons point of view. Its containing multiple perspectives.

Dead Poets Society follows Maverick teacher John Keating (Williams), who returns in 1959 to the prestigious New England boys boarding school where he was once a star student, using poetry to inspire his students to new heights of self-expression.

The film won the Academy Award for best writing, screenplay written directly for the screen, while Williams earned an Oscar nom for best actor and Weir for best director. Dead Poets Society was also nominated for best picture.