As the opus numbers suggest, the five string trios are relatively early works. Beethoven had sent opus 3 to print in early 1796, and in the same year, he began his compositional work on the Serenade op. 8, which was then followed by the three Trios op. 9. This marked the definitive close of Beethoven's work on this genre. Nevertheless, the five pieces are thoroughbred Beethoven and often played to this day. Also included in the volume is the piece designated in the autograph as “Duet for two obligato eye-glasses” that Beethoven had apparently written for two myopic friends.