By Ray Furlong
BBC correspondent in Berlin
A previously unknown composition by Johann Sebastian Bach has been discovered by researchers in Germany.
The piece was composed for soprano, strings and bass continuo
The vocal piece was found among papers removed from the historic Anna Amalia Library in Weimar before a devastating fire there last September.
The piece is a musical accompaniment to a 12-verse poem composed for the Duke of Saxony in 1713.
Plans are being made for the first performance, under the English conductor Sir John Eliot Gardiner.
A researcher interested in a rare type of 18th Century paper stumbled across the musical treasure.
Rescued from blaze
Announcing the find, the head of the Bach Foundation, Christoph Wolff, said it was not a major work, but "an occasional piece of exceptional quality".
He added that the story of its survival was almost a miracle.
The Anna Amelia Library, housed in a 16th Century rococo palace, burned down in the fire.
A human chain formed by passers-by saved hundreds of volumes, including a 16th Century Martin Luther bible, but thousands of historical works were lost.
"This composition would also have fallen prey to the flames," said Mr Wolff, "and we would never have known about it."
The authenticity of the piece was proved by comparing the handwriting with other Bach manuscripts.