It has been more than 25 years since a young Ethan Hawke stepped on his desk to salute his teacher, portrayed by Robin Williams, in "Dead Poets Society."

Hawke, 43, has taken on some 50 roles since and this year received his third Oscar nod for best adapted screenplay for "Before Midnight," shared with Richard Linklater and Julie Delpy.

His 12-year "Boyhood" project with Linklater has won critical praise, while his documentary on classical pianist Seymour Bernstein has also been warmly received at recent film festivals.

Hawke spoke with Reuters about "Seymour: An Introduction," its underlying themes on art and mentorship, and how Williams helped him find his "barbaric yawp."

Q: What were some of the biggest lessons you learned from Seymour?

A: One of the ways that (teachers and mentors) can be most helpful is helping us see our blind spots, when we delude ourselves. It's so hard for us, as people, to have real self-awareness about where we're deluded - little ways in which we lie to ourselves, or have been lying to ourselves for decades. And when you work with somebody who really respects you and who genuinely wants you to grow, you feel that they can help you to see where you're hurting yourself.

Q: Do you think classical music is under appreciated?

A: All of the higher art forms are suffering ... It's like we're literally indoctrinating our children to be distracted all the time.

Q: How do you feel about classical music?

A: It's the same way I feel about Shakespeare. Is it wonderful to be educated about it? Yes, it is. But if you do Shakespeare and you play it correctly, high school students who'd never heard Shakespeare will love it. They'll laugh, they'll be moved, it's beautiful and if you hear Bach played well, it stops your heart. You don't need an education to love that music.

Q: Seymour talks about the pitfalls of perfecting technique at the expense of the art. Do you see that in acting?

A: A lot of young people - talented people - will come at it with this huge emotion and it's wonderful, but it's completely out of control. They don't know when to be funny, they don't know when to be serious, they don't know when to be emotional. The trouble with cinema is they leave it up to the director to decide all this stuff ... They can make a decent performance out of it, because it's all edited. But when you act on the stage, you have to do that for yourself.

Q: You played Todd Anderson in "Dead Poets Society" opposite Robin Williams. What was that experience like?

A: I think the sadness with Robin is this person that brought the world so much joy, and to have it be revealed that we didn't do the same for him.

When we're young, it's easier to find mentors and teachers and "Dead Poets Society" is about that. It's about young people with a great mentor who's telling them to hear their own voice: "What will your verse be?"

Something happened to me with Robin. It's the scene where he writes on the chalkboard, "I sound my barbaric yawp over the rooftops of the world," which is a Walt Whitman quote. And he wants me to sound my barbaric yawp. It's a very difficult scene to play and the director wanted to do it in one take. He wanted it to have an authenticity and it was one of the most wonderful experiences of my life. And when it was over, Robin just held my hand, and whispered, "Remember this." Very, very beautiful moment for me, you know? And I've hunted, sought that moment out again, all the time.

My thoughts about his passing were extremely sad, but it was clear to me in 1988 that this is a person who was in serious pain, that he carried with him for decades.

(Editing by Mary Milliken and Matthew Lewis)