After eighteen years as Rector of St James’s, Piccadilly, I made it a life’s project to learn to play all the music Bach wrote for the organ – an unrealistic ambition, as the work of peace-building has since occupied all my time. In 2000, I founded The Soul of Europe with a group of friends, to help those in post-war situations realise Nelson Mandela’s words, “If you want to make peace with your enemy, you have to work with your enemy. Then he becomes your partner.”

Peace-building is rather like a journey towards an ever-receding horizon. In this journey we are called to imagine ourselves in a relationship with our enemies. Peace-building is a vocation; not so much a goal to be pursued as a calling to be heard. It is a prompting born out of a capacity to bring to both something unforeseen, which suggests a shared future into which former enemies walk together towards a horizon striving for community.

These lofty ideas informed my work in Bosnia, as a group of us encouraged the rebuilding of a Sinan mosque in Banja Luka, one of 15 destroyed in the Bosnian War. This work was to be a sign of Muslim–Christian collaboration. Later we responded to an invitation by the owners of a mine in Omarska, which had been used as a killing camp, to bring the survivors – all Muslim – together with Bosnian Serbs to agree on a memorial for those murdered there during the first years of the war.

Now in Kosovo we are being invited to bring together Orthodox Serbs in the monasteries of Dečani and Peć with the Kosovo Albanians who live around them. The monasteries stand isolated in a country that was once part of Serbia. These religious communities feel threatened and monks and nuns travel with armed escorts. It is, of course, unacceptable that religious communities should live like this.

While involved in these tricky endeavours I have persisted with Bach. The prompting I have described is nourished by the music I play. Playing the music changes the way in which I see the world. It redresses the balance from a less bleak view of human affairs to a more sane and hopeful perspective.

In peace-building this means tackling the long process of dismantling the ‘victim’ mentality, shared by both those who suffered and by those who inflicted pain, helping those caught up in the traumas of conflict, still being waged years after the war ended, and in addressing the ignorance and cynicism of international bureaucrats.

Bach’s organ music is immeasurably life-enhancing; saturated with intimations of hope.

Listening to music is one thing; playing it oneself is another; performing for others yet another again. After years of impatience with technical difficulties that pepper Bach’s scores, I am now realising that learning to overcome these in order to perform them is like opening the door within a house containing many treasures. As each difficulty is overcome, more or less, and complex passages begin to feel safe under fingers and feet, so more doors open, each one reaching deeper into the heart of the music, tracking the stream of Bach’s extraordinary genius to its source.

The source of creativity is an undiscovered country. Virginia Woolf said: “We do not know our own souls, let alone the souls of others. Human beings do not go hand in hand the whole stretch of the way. There is virgin forest in each; a snowfield where even the print of bird’s feet is unknown.”

But it is possible to get close.

In Albert Schweitzer’s seminal study of Bach published in 1911, he writes to those who are performing Bach’s cantatas (but true for organists also): “Only he who sinks himself in the emotional world of Bach, who lives and thinks with him, who is simple and modest as he, is in a position to perform him properly.”

At present I am immersed in the Great Eighteen Chorale Preludes Bach completed in Leipzig towards the end of his life. In the Lutheran tradition the congregation sit while singing and listen first to the improvisation, a chorale prelude, which leads into the hymn. Bach inherited and extended this tradition. Shortly before he died he collected, revised and rewrote a selection of chorale preludes originally composed some 20 years earlier.

The average length of each piece is five minutes. They are miniatures in length only. With astonishing condensed complexity yet emotional directness Bach illustrates the words of Lutheran hymns; he empathises with the words. “To God the glory” and “Save me, Jesus” are scrawled across the manuscripts.

The music transcends Lutheranism. It is not necessary to be a believer to appreciate the music; however, as a performer it helps to share this aspect of Bach’s faith to be able to express the sheer intensity of these chorale preludes that makes them so compelling.

Bach’s life was punctuated by the devastation of death. By the age of 10 he had been orphaned, and thereafter one member after another of his close family died. Much of his music reflects a longing for death, as if death were a way of escaping his grief and being reunited with those he loved. Many of the Chorale Preludes express a longing for peace, for union with God. Some express grief and others an ecstatic longing.

But there is more. Bach clearly had a particular affection for the Gloria. Schweitzer wrote: “Bach never forgets the melody is supposed to be an angel’s song.” Angels herald a new order. They are here, there and then they are gone. The Gloria chorale preludes are ravishing in their lightness and sparkle.

Other chorale preludes are majestic, exuberant, even defiant. The conclusion of one, a Fantasia that celebrates the gifts of the spirit at Pentecost, becomes a whirlwind, a breathless agitation of a sixteen-note figure; it ends abruptly with two flourishes of Hallelujah, as if to say: “That’s that!”

Robert Schumann tells how his friend Mendelssohn played Deck My Soul with Gladness, and said afterwards: “If life were to deprive me of hope and faith, this single chorale would replenish me with life.”

Bach’s music is a testimony to the gift of hope for the human spirit; there is a quality of anticipation and unfolding as the music moves forward to resolution. One of three settings in the Eighteen of the Advent hymn Come Now, the Heathens’ Saviour is a heart-stopping lyrical meditation on the longing for the coming of Christ. The pedals play a steady tread, leading the listener into the mystery of the Incarnation.

Peace-building is not glamorous work. Peace-building demands boundless patience and persistence. Setbacks are frequent. The fundamental inspiration for peace-building is found among those who take the risk of sitting together with their enemies.

Bach’s music is also an inspiration. His elaborate counterpoint reflects the complexity of our endeavours, as his music weaves its way to a logical, simple and graceful conclusion. That is why I enjoy learning, playing and performing his music – whilst working for peace.

Donald Reeves is a Director of The Soul of Europe (www.soulofeurope.org) and author of The Memoirs of a ‘Very Dangerous Man’, published by Continuum.