Mitchell points to one of Bernstein's most famous compositions, the song Maria from West Side Story, which opens with a tritone. Also referred to as "a devil in music", a tritone is a dissonant interval between two notes and was used regularly in avant garde music of the early 20th century.
"What pop song opens with a tritone?" asks Mitchell. "Bernstein knew how to push the boundaries in terms of complexity and yet find his way into the wider culture. We all take Maria for granted now."
Ironically, Bernstein the composer came to see West Side Story, his masterpiece packed with songs still recognised and loved today, as a millstone, the work that defined him until his death in 1990.
"I think there's a perception that West Side Story is 'only' a Broadway show," says Mitchell, "as though there's some qualitative difference in whether it's performed on West 42nd Street in Times Square [ie, Broadway] or West 57th Street where Carnegie Hall is."
The NZSO concert, which also features sometime Postmodern Jukebox vocalist Morgan James, steers closer to Broadway than Carnegie Hall. It includes music from West Side Story, On the Town and the jazzy operetta Candide, recently in Auckland as part of the arts festival.
All three of those works contain tunes aplenty so if Bernstein is undervalued as a composer, perhaps it's at least partly his own fault. West Side Story debuted in 1957; the following year he became music director of the New York Philharmonic, a position he held until 1969. During that period he composed only two major works, the Chichester Psalms and his Symphony No.3, Kaddish.
But while his reputation as a composer waned, Bernstein's conducting and educational careers flourished, cementing his profile as the most famous classical musician of the age. Among his achievements were 53 young people's concerts, all broadcast on television, and, with the New York Philharmonic, he toured the world including a 1974 trip to New Zealand.
John Ure was a young horn player and vividly remembers the Philharmonic's Christchurch concert.
"To this day it's the most wonderful concert I've ever attended," says Ure.
It's no small claim from someone who has been to literally hundreds of concerts as a performer and arts administrator. Still an active player with Hamilton's Opus Orchestra, in 2016 Ure was made an MNZM for his services to music.
After the concert, Ure briefly met the man himself.
"The dressing room door was open; there was a desk, a glass of water and two minders, one on either side of him. He was sitting in the chair looking absolutely washed out, with this big white towel around his neck. So I walked in, we said a few words and I shook his hand and told him how wonderful the performance was. He looked up at me and his eyes brightened a little."
For all Bernstein's achievements, there's a sense of unfulfilled promise. As the music critic Alex Ross noted in 2007, even after leaving the Philharmonic, Bernstein never regained the compositional momentum he enjoyed in his 30s.
So, in Bernstein's centenary year, should we reassess his contribution?
"One wishes that Bernstein had done more in his later years and been able to sustain the focus he had early on," says Alex Ross today. "But if you look at what he wrote in the early and mid-1950s, what he accomplished in a very brief period is incredible.
"Bernstein was an extraordinary character; he accomplished so much, so eventually you get over this question of disappointment. Maybe we're finally steering away from what might have been and focusing on what is: an incredibly rich body of work."
Concert preview
What: NZSO, conducted by Brett Mitchell, Bernstein at 100
Where and when: Wellington, May 11; Auckland May 18
