Mendelssohn's earliest surviving compositions date from 1820, and in 1821 he composed the first six of what was to become a total of twelve symphonies for strings. These were written as composition exercises for his teacher, and the completed the set in 1823 when he was 14 years old. The string symphonies were thought lost for many years but they turned up in a library in Berlin after World War Two. These dozen string symphonies quickly led to Mendelssohn's early masterpieces the String Octet written at age sixteen and the Overture To A Midsummer Night's Dream written a year later.
Adagio - A slow introduction begins this work with a nod to the music of J.S. Bach in feeling if not in construction. Towards the end the music lightens in mood and pays homage to Haydn and Mozart.
Allegro - The beginning of the movement proper is a sudden shift in tempo and mood that reflects C.P.E. Bach's empfindsamer Stil with the first theme in early Haydn's Sturm und Drang style. The second theme has a rapid and busy quality that became a trademark of Mendelssohn's style. A third section adds additional material that leads up to the traditional repeat of the exposition. The development section repeats the two themes in various guises with few real surprises but a deftness in handling the material that is amazing for a composer of but 14 years. The recapitulation begins with the first theme, and after a short section of transition the second theme returns in the home key of B minor.
Piu presto - The music increases in tempo and rushes breathlessly in a short coda that ends the work.