The Introduction and Variations on a Theme by Mozart, Op. 9, were written by Fernando Sor and first published in London in 1821. A second edition was later published in France, though lacking the coda, one variation, and presenting some small differences. It is speculated that it could have been published as a simplified version, though later (in 1827) the original version was published in France. The Variations, dedicated to Sor's brother Carlos, consitute a fine example of his work, and are considered among his best pieces. The technical skills required make this set of variations an almost obligatory repertoire item for aspiring guitarists. The theme is taken from a melody in Mozart's Magic Flute, near the end of Act I.