A song writtenin 1842 by the German composer Mendelssohn lostfor nearly 150 year has been found among thepapers of a musician in America. More details fromRebecca Jones.

You are listening to music that no one has heard for nearly 150 years. Mendelssohn wrote thissong in 1842. It was a private commission and the manuscript was never published. And it'sbeen played first by the pianist Christopher Glin and the singer Amy Williamson from the RoyalCollege of Music.

What's your reaction to hearing this for the first time?

Well, it's lovely to hear it and beautifully sung. It's a very short song, very simple, not at allelaborate yet very effective. And Mendelssohn like all great composers, in addition to writingintricate works, could also write very straightforward masterpieces, which are neverthelessvery expressive. I mean, all composers have their better days and off days, but this iscertainly not one of Mendelssohn's off days.

What do we know about how the song came to be written?

We know quite a lot about its history in that it was written at the specific request of anacquaintance of his in Berlin in 1842.

We are having a look at the manuscript now.

It's just a single page manuscript, but at the end, it has this inscription by Mendelssohn withhis customary wonderful signature. And Mendelssohn's signatures are work of art inthemselves.

So that's how we can be sure that this is genuinely by him.

It is in fact genuine. That's right. And there is also with the manuscript a little letter thatMendelssohn wrote a few days later. And the letter is significant because it makes it clear thathe (had) written this song specifically and he asked him not to let other people have it to copyand so on.

So therefore, it is quite possible that what we've just listened to is the first publicperformance of this song.

I think almost certainly.