No other composer influenced Fernando Sor more than Wolfgang Amadeus Mozart. Sor's Introduction and Variations, op. 9 are based on the aria 'Das klinget so herrlich' from the opera 'The Magic Flute'. In his theoretical guitar treatise 'Méthode pour la guitare' Fernando Sor explicitly describes the tonal possibilities of the instrument and compares its tonal colours with those of orchestral instruments. In his Opus 9 he skillfully implements this concept in the well-crafted an felicitous introduction, which then develops into an orchestral overture.