Wolfgang Amadeus Mozart (1756 – 1791) was a prolific and influential Austrian composer of the Classical era. His output of over 600 composition. Mozart is among the most enduringly popular of classical composers and many of his works are part of the standard concert repertoire. Mozart lived at the center of Viennese musical life, and knew a great number of people, including not just his fellow musicians, but also theatrical performers, fellow transplanted Salzburgers, and many aristocrats, including a fairly close acquaintance with the Emperor, Joseph II. Mozart's physical appearance was described by tenor Michael Kelly, in his Reminiscences: "a remarkable small man, very thin and pale, with a profusion of fine, fair hair of which he was rather vain".