It’s 1am and the West-Eastern Divan Orchestra is at play. A Syrian and an Egyptian joke about who has the most national pride. Yoni, an Israeli, plays an energetic game of table tennis with an Iranian. The Iranian is winning.

This is both the private and public face of Daniel Barenboim’s celebrated Israeli-Arab youth orchestra. It’s private because we are at the Divan’s summer camp, a former monastery west of Seville, where the orchestra live and rehearse for two weeks before they tour, including two Proms performances next week. But also the public face: the Divan projects itself as a model of harmony set against the Middle East conflict. And Barenboim certainly has performed a minor miracle by fostering enduring friendships among individuals who, on paper at least, remain enemies. However, harmony comes at a cost; the Divan exerts a degree of control over its young charges and the reality can be less than democratic.

Barenboim, a musical prodigy born in Buenos Aires but raised in Israel, founded the orchestra in 1999 with his great friend, the Palestinian intellectual Edward Saïd. Both men believed that music was a dialogue – a shared experience of playing and listening. Their purpose in founding the orchestra, naming it after Goethe’s poems exploring ideas of “the other”, was to encourage dialogue between two estranged peoples through music.

About 70 young musicians played in the first concerts in Germany. But as the maestro’s musical ambitions for his orchestra have grown, so has the Divan. This year, 120 musicians – the youngest 12, the oldest 30 – from Israel, Palestine, Jordan, Lebanon, Egypt, Syria and Iran are playing a massive programme: the Brahms Symphony No 4, Haydn’s Sinfonia Concertante, three Wagners including Act I of Die Walküre and Schoenberg’s Variations for Orchestra.

The Divan also includes a Spanish contingent, a nod to the Andalusian regional government, which helped to set up the Barenboim-Said Foundation. Four players from Gustavo Dudamel’s Simón BolÍvar Youth Orchestra of Venezuela swell the brass (and to the Divan girls’ delight, they play late-night salsa gigs).

There is more to the Divan than music, however. It is a philosophy that aims to teach logic in the midst of the illogical Middle East conflict. And this is where the students can diverge from Barenboim and Saïd’s humanitarian vision. For Arabs and Israelis alike the Divan is foremost a musical opportunity. The students benefit from teaching of the calibre they would never receive back home. And with its high profile, the Divan has become an international springboard. It is hard to find Israeli players, especially, who still live in their homeland.

Daniel Cohen, 24, a conductor and violinist who studies in London, joined the orchestra in 2003. “As time went by it became a cultural fascination and an opportunity to meet people from the Arab world,” he reflects. “But the initial reason was to work with Barenboim. It’s a once-in-a-lifetime opportunity.”

Barenboim is a paternal figure for some, greeting them at lunch and larking about with the youngest Palestinian kids who train in a separate junior orchestra. But when “the maestro” takes rehearsals the anticipation and focus are palpable. Texting and joking stop abruptly. Barenboim goads and charms his players towards excellence through long rehearsals lasting from morning to 10.30 at night. He stamps his feet when the violins mess up: “Play in tempo!” he orders. “Don’t fuss around!”

Wherever possible Arab and Israeli share a music stand. Naturally Arab and Israeli mix, but once rehearsals end they are just as likely to sit apart if only for the ease of speaking their mother tongue. They chat about ambitions and the usual teen concerns. But in the evenings they are encouraged to attend discussions and film screenings related to the Middle East conflict. It could be the outspoken Israeli author David Grossman or the documentary Route 181: Fragments of a Journey in Palestine-Israel.

These are left-wing contributors and many Israeli members feel that they are denied a full discussion. “You don’t see any extreme right-wing Israelis here,” says Daniel Mazaki, originally from Tel Aviv and in his second year with the Divan. Some believe that Barenboim’s personal thinking further skews the playing field. “The Israeli side is represented by someone so pro-Palestinian, so extreme, that it doesn’t reflect the common vision of Israelis you meet on the street,” adds Guy Eshed, the Divan’s 29-year-old lead flute, also from Tel Aviv.

Why is this Israeli vacuum allowed to happen? For Mariam Saïd, wife of the late Edward Saïd, who coordinates the discussions, equality is not important. “There is no need to balance the discussions,” she says. “We are equal as people but it’s not like: ‘you say this, I say that’. The idea is to make the students use their reason.”

For first-timers the debates provoke an emotional outpour. One claimed that he was asked by a monitor to sit down as he spoke agitatedly about the Jewish suffering. “They told me: ‘This is not a debate’.” He added: “I have great respect for the maestro, but I won’t not speak about my beliefs and my country.”

But perhaps this sacrifice is necessary to achieve the greater good, which is understanding and coexisting with the other side. In my few days with the Divan there were no discussions to attend. But my impression is that each individual – Arab and Israeli alike – is pushed through a sort of Divan process of logic. “At first you use your ammunition of suffering to block discussion,” Daniel Cohen says. “But with time and experience of one conversation after another just exploding in your face, you listen and you learn the language.”

Remarkably, tension rarely spreads beyond the discussions; Divan friendships are resilient. But one occasion when the situation on the ground did spill over was the Israel-Lebanon war in 2006. “The project hit a wall that year,” remembers Nabeel Abboud Ashkar, 29, a violinist from Nazareth. Many of the Lebanese and Syrians didn’t, or couldn’t, attend the summer workshop, and Arabs and Israelis sat apart at mealtimes. Barenboim demanded that tables be mixed and an uneasy calm was restored only after the Divan took the unprecedented step of issuing a public statement condemning the violence.

Barenboim maintains that the Divan is not a political project yet politics suffuse its make-or-break moments. The first time they played Wagner, for instance, it was put to a vote. For many members, the Divan’s performance in Ramallah, on Arab soil, in 2005, was their first encounter with the Palestinian settlements.

The West-Eastern Divan is many things to its individual musicians. For some it is simply an incredible musical opportunity and a source of friendship. For others it is a chance to connect with their roots; Palestinian Israelis connect with other Arabs for the first time. For everyone it is a learning process. Barenboim is asking these students to transcend their personal history and emotions.

It’s a big ask, yet the players find a way of accommodating it. Tyme Khleifi is a Christian Palestinian living in Ramallah in the West Bank. “Every day it’s stress, delays, bad treatment,” she says. Yet reflecting on the personal journey she has begun, Khleifi says: “The cornerstone of the Divan is that each side acknowledges there are two sides to stories. We don’t agree but not agreeing doesn’t mean that you don’t understand.”

The Divan Orchestra performs at the Proms, August 14 2008, 7pm and 10.15pm, at the Albert Hall (0845 401 5040, bbc.co.uk/proms)

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