Giuseppe Torelli (1658-1709) is today best known for his concertos for strings, in which genre he was a pioneer, and for his music with solo trumpet. In his own day, however, he was equally productive as a composer for small-scale ensembles, which is to say primarily of sonatas. A little-known manuscript in the British Library contains three single-movement duets for two violins by him that on one hand look back to the long tradition in Italy of the didactic duet, which originated in the Renaiss...