Everything is back to front this evening! It is the students who are giving the lesson through their singing.The political world is crying out for harmony; it longs to hear and be heard but it does not always succeed. So I am very much looking forward to listening to this music because it is first and foremost a lesson in dialogue between cultures, something politics can no longer afford to be without.

The word "dialogue" is bandied around so much these days that it has almost become a cliché. But is it ever put into practice?

Politics has not always been able to prevent clashes between different cultures and civilisations. It seems as if the world is divided into good and evil, with everyone convinced that they are on the side of good.

And dialogue seems to have been lost in the process. Instead there is a tendency to put up more barriers, more often than not at the dividing point between the haves and the have-nots. And, as every singer knows, if you are facing a wall when you sing, all you hear is the sound of your own voice.

Sometimes these barriers are intangible: like our attitude to foreigners and the trouble we have here in our rich countries giving refugees a fitting welcome.

But often they are extremely tangible:

like the barbed wire that has been erected between Africa and Europe, making our continent into a fortress.

like the barrier that separates Israel from Palestinian territories. And Palestine is in danger of being left to fend for itself.

or like the letter that the Iranian president wrote to the US president and which has so far remained unanswered.

In order to escape this spiral of violence and find common ground, we have to listen and talk to the other side. We have to respond even if we don't always agree with what they are saying. We have to understand their situation and the values they defend, perhaps even speak their language or at least have some understanding of the way they think.

It is easy to talk about dialogue between cultures but it is quite a different matter putting dialogue into practice. It is no picnic; it requires constant, unremitting effort. Dialogue between cultures is possible, however, even in difficult situations.Take Nigeria, for example. It is multiethnic, Christian and Muslim and yet it has been able to rid itself of a dictatorship and, despite violent clashes, seeks to maintain a delicate balance between the different religions and ethnic groups.

Culture is a good place to start

And now some young French speakers and English speakers have also started a dialogue that knows no borders and reaches across the ocean to give us tonight's concert. Of course they are not here to resolve a conflict or end a war but to perform a musical work.  Perhaps this is where we should begin, by finding a common language: in this instance, music. Just as the conductor Daniel Barenboim is already doing by bringing young Israeli and Arab musicians together to play side by side in the West-Eastern Divan Orchestra.

Another dialogue I particularly cherish and which finds expression today is the dialogue between science and art. At a time when young people are losing interest in the exact sciences, these choral singers demonstrate - like Einstein and Rubinstein before them - that people can be drawn to both science and music. By bringing this dialogue to life, the students are giving us a lesson in humanism. Or course they are studying to become engineers, mathematicians, historians or psychologists but they also find time to sing, thus embodying an ideal inspired by the Renaissance and Ancient Greece and Rome: the ideal of rounded human beings who find fulfilment both in the sciences and in the arts, who are equally at ease talking about philosophy as they are talking politics and practising archery.

This humanism, which gives pride of place to the arts and culture, is one of the foundations of our society. Culture is the infrastructure that connects people; culture makes it possible for people to wing their way across oceans, and perhaps, too, it is the driving force, the energy that motivates people to move mountains. This image is particularly inspiring to me as part of my time is spent digging tunnels.

By both singing and studying, this transatlantic choir reminds us that we have several strings to our bow. It is up to us to make these strings vibrate, it is up to us to listen to one another. Unlike crotchets and minims, human nature is not simply black or white; it is a rich and intricate tapestry of colours.

Acceptance of the complex nature of the world is perhaps the attitude that will open the way to dialogue.

Thank you for coming here tonight to remind us of this through your singing.

The music lesson