As a child, his musical fertility matched Mozart's and the content was by no means inferior. The 13 string symphonies, written between the ages of 12 and 14, erupt with melodic ideas and boyish brio. The octet, composed at age 16, is a double-or-quits challenge to the Schubertian quartet: beat that, Vienna. His sister, Fanny, four years older and formidably gifted, was discouraged from composing by her parents and confined to the piano, while Felix courted fame. Neither sibling was content with that decision.