The reason for his exceptional success is that he is the rarest of birds, a Heldentenor who can sing the largest Wagnerian roles but who also is agile enough to sing Verdi and Puccini. His enormously powerful voice has that rare "zing" to cut through the largest orchestra, making him enormously valuable to the world's great opera houses. The Italians call it squillo, that brightness in the sound that seems to project his voice effortlessly, and which sets apart the great tenors such as Pavarotti, Carreras and Domingo.

O'Neill's career first took off when he was asked to cover for Placido Domingo at the Met, learning first-hand from the master to whom he is now often compared. "He is my idol. I hold him in the highest respect. His voice has this extremely energised, burnished bronze core – there is real testosterone in the sound. We are both good pianists and we would sit together at the piano and he would say, 'try it this way', and I would. I learnt so much from him and I just love it when people say that they hear Placido in my singing."

It was also Domingo who introduced him to Daniel Barenboim, who in turn thrust O'Neill onto the world's stage as the great new Wagnerian Heldentenor.

Daniel Barenboim is one of the great musicians of our time, probably the most famous Jewish conductor, and conversely one of the great interpreters of Richard Wagner, a noted anti-Semite whose music became interlinked with the Third Reich. Even more surprisingly, Barenboim is both an Israeli and Palestinian citizen, and has this beautiful dream that music might be able to serve as a platform for dialogue between these mutually exclusive world views. He explains his interest in resolving such contradictions thus: "The impossible has always attracted me more than the difficult. If there is some sense behind it, to attempt the impossible is, by definition, an adventure, and it gives me a feeling of (meaningful) activity which I find attractive and it has the added advantage that failure is not only tolerated but expected".

In 1999, Barenboim and the Palestinian intellectual and musician Edward Said came up with an inspired musical response to the Israeli-Palestinian problem, namely the East West Divan Orchestra. Named after Goethe's collection of verses inspired by the Sufi poetry of Hafiz and Goethe's deep love of Islamic culture, it brings Arab, Persian, Palestinian and Israeli musicians to play music together each year. O'Neill not only had the best vantage point as a soloist with the orchestra to witness this phenomenon, but also found himself propelled into opera's "A league" as a result of his engagement with Barenboim's impossible dream.

Barenboim constantly states that "the Divan is not a love story, and it is not a peace story. It has very flatteringly been described as a project for peace but it isn't. It's not going to bring peace, whether we play well or not. The Divan was conceived as a project against ignorance It is absolutely essential for people to get to know the other, to understand what the other thinks and feels, without necessarily agreeing with them. I'm not trying to convert the Arab members of the Divan to the Israeli point of view, and I'm not trying to convince the Israelis to the Arab point of view. But I want to create a platform where the two sides can disagree and not resort to knives."

He reminds us that the first wave to hit the beach rarely reaches its objective, but through their sacrifice, subsequent waves can ride on their shoulders to achieve those objectives. It is not ignoble or futile to fail, if the example you give inspires people, or shames those who are complacent, to change their thinking and subsequently their behaviour. Any chance at a utopian future is always earned on the back of the striving of pioneers who rarely glimpse any real evidence of success. The early results to date have seen Divan graduates earn jobs in the finest orchestras across Israel and the Middle East, Europe and the US. Clearly Barenboim's utopian plan is seeding a more humanistic reality that will effect change in unpredictable and unexpected ways, and O'Neill would be very happy and not at all surprised if Barenboim were, one day, to get the Nobel peace prize for his efforts, despite his protestations.

"I did the 10th anniversary tour with Mr Barenboim and the East West Divan performing large chunks of Die Walkure and Tristan and Isolde. The players came from Iran, Lebanon, Jordan, Turkey, Syria, Spain, Israel and Palestine. I remember Barenboim was very hard on them – he really cracked the whip. Rehearsals were like the tower of Babel. He addressed the players in a smorgasbord of languages: Hebrew, French, Spanish, English, German, Italian, even Russian. In the first violins, Guy Braunstein, later the concertmaster of the Berlin Philharmonic, was playing next to a 13-year-old boy called Yamen Saadi from Nazareth who had only been playing the violin for a few years. This Jewish wunderkind and this Palestinian young violinist ended up sitting together in the orchestra for five years." O'Neill remembers the extraordinary 2009 tour, which featured a complete performance of Beethoven's Fidelio at the Proms and the Salzburg festival and elsewhere: "Doing an opera about a political prisoner was very close to the true situation of those players' lives."

Touring with the Divan orchestra also made O'Neill more aware of New Zealand's achievements reconciling their indigenous Maori and Anglo-European cultures. "When I was a kid, we wanted to be bi-cultural like Canada – but by that Canadians were talking about resolving the tensions between their English and French cultures, not their indigenous population. I am always very honoured to return and sing in New Zealand because our country has really sorted it out. We love having the haka at the rugby and hearing the national anthem sung in te reo (the Maori language). In my own case I have worked hard to be able to sing well in Maori."

O'Neill is happy to fly from one end of the world to another to sing in the great opera houses of Europe and the United States but he sees his future primarily at home.

"I just love that I can live in New Zealand and fly to the northern hemisphere and sing all of this great repertoire, but my priority is my three kids and my wife, being around to take the kids to football practice and to go to the beach. I want to sing in New Zealand and Australia at the height of my career and not just when I am finishing up. I want to be here singing in my prime, inspiring the next generation of singers, just as I was by those legendary Kiwi singers who came before me."

Simon O'Neill will headline Voices in the Forest on November 30 at the National Arboretum.

Chris Latham is creative director of Voices in the Forest. voicesintheforest.com simononeill.com.