Geoffrey Rush's breakthrough performance was his portrayal of the pianist David Helfgott in the 1996 film "Shine," for which he won the Oscar for lead actor. Seventeen years later, he finds himself playing a musician of a different sort in "The Book Thief": Hans Hubermann, a German house painter and amateur accordionist who takes in a 10-year-old foster daughter (Sophie Nelisse) amid the chaos of World War II.

Speaking at the Envelope Screening Series, Rush talked about how getting acquainted with the accordion  helped him understand the character of Hans on a deeper level.

"He's a [very good] accordion player," Rush said, using a bit of colorful language. "That appealed. I always love a task. I like having some extraneous element to the character that doesn't really drive the plot but gives you something to play with, that you can hopefully dig into some deeper, subterranean rhythms in the character."

VIDEO: 'The Book Thief': Watch actor Geoffrey Rush discuss the film

Rush received the instrument (technically a bandonica, a relative of the accordion) months before filming and eventually took lessons. "The moment I held it, it was like I went, 'Ah, this is this character's lungs,'" Rush said. "Because all I could hear was the breathing of the bellows, and there's just a beautiful rhythm."

Rush also appreciated that his character was an amateur. "He's not playing to be virtuosic or anything like that. So for me, they became a little bit like, for a relatively inarticulate character … the moments with the accordion sort of became my mini-monologues. I thought, 'I can express things in this that I could never say in words.'"

For more from Rush on "The Book Thief," watch the video above.

ALSO:

'The Butler' at the academy: Freedom Riders, palpable pain

'12 Years' stars, other actors talk up costumes, characters and more

'American Hustle' and 'Wolf of Wall Street' come late to the Oscar party