Franz Xaver Wolfgang Mozart came from an illustrious musical lineage. His grandfather was Leopold Mozart, who was a composer and teacher of music, and his father was Wolfgang Amadeus Mozart, the greatest natural talent in musical history and one of its greatest geniuses. His mother was Wolfgang's wife, née Maria Constantia Caecillia Josepha Johanna Aloisia Weber, known as Constanze, a singer who was a daughter of the basso Fridolin Weber. Constanze was also first cousin of another famous composer, Carl Maria von Weber (1786 - 1826). Franz Xaver was the last of Mozart's six children. Only two, both sons, survived infancy. The elder, Karl Thomas Mozart (1784 - 1858), studied music, but in 1810 had an opportunity to became an official with the viceroy of Naples in Milan, and thenceforth worked as an accountant or clerk. Franz Xaver was named after his father's invaluable musical assistant Franz Xaver Süssmayr (whose principal fame rests on his completed edition of Mozart's Reqiuem). This led to some scurrilous speculation that Süssmayr might have been the boy's true father, but there is no evidence whatsoever to support this idea, which seems to have been part of a general effort to denigrate Constanze. Naturally, the boy had no memories of his father, who died before little Franz Xaver was six months old. While it is true that Mozart left the family technically in debt (though not, as has been grossly overstated, in poverty), he also left them considerable goodwill and a valuable legacy of his manuscripts. Constanze prepared them carefully for publication, enabling her to build an income from them and incidentally leaving listeners richer for the care she took to preserve them and issue them in accurate editions. She also received some pension money as Mozart's widow and appeared in concerts of her late husband's music. This got the family through some initial rough times after Wolfgang Amadeus' death. In 1797, Constanze took in as a lodger Georg Nissen, a Danish diplomat, who helped her manage her business affairs and married her in 1807, becoming a very important early biographer of his wife's illustrious first husband. Franz Xaver received his first piano lessons in Prague from another namesake, Franz Xaver Niemetschek, who was an early biographer of his father, while the boy stayed with the musical Dussek family in Prague in 1796. He returned to Vienna and counted several illustrious figures among his teachers, including Sigismund Neukomm, J.N. Hummel, G.J. Vogler, Georg Albrechtsberger, and Antonio Salieri. In 1802, Franz Xaver began to compose and his Opus 1 was a piano quartet. In 1807, Salieri, then his teacher, proclaimed the boy had a "rare talent" and predicted a career "not inferior to that of his celebrated father." At the age of 16, Franz Xaver accepted a job as a tutor in the home of Count Viktor Baworowski, holding the position until December 1810. In 1811, he became a music teacher at the home of the imperial chamberlain, Janiszewski, but gave up that post in 1813 to take up the life of a freelance musician, starting in Lemburg (now L'vov), and teaching. From 1819 through 1821, he undertook a major tour, hitting many major cities and often arranging reunions with his mother (now living in Copenhagen) and his aunt Maria Anna (known to history as Nannerl, Mozart's sister) in Salzburg. He often billed himself as "Wolfgang Amadeus Mozart Jr." He resumed his study of counterpoint with Johann Mederitsch and founded a choir in Lemburg. He settled in Vienna in 1838. In 1841, Salzburg named him honorary concertmaster of the Dom-Musik-Verein and the Mozarteum in Salzburg, and he participated in the 1842 anniversary celebrations honoring his father by playing the Piano Concerto No. 20, K. 466. Franz Xaver's music was not especially important in musical history. His music was strongly influenced by his teacher, Hummel, with brilliant figurations in the piano music. However, it is charming and well-made music and deserves to be revived along with that of other late Classical and early Romantic composers. On his death, he left any of his father's papers as he possessed to the Salzburg institutions preserving his father's documents.