Although Mendelssohn was most famous during his lifetime as a composer, virtuoso pianist, and conductor, he also enjoyed an enviable reputation as a highly skilled organist. The instrument had fascinated - one might almost say mesmerized - him from earliest youth, but aside from a year or so of formal training at the age of about twelve or thirteen, he was entirely self-taught. He never held a position as church organist, and he never had any organ pupils. Nevertheless, the instrument played a uniquely important role in his personal life. In the course of his many travels, whether in major cities or tiny villages, he invariably gravitated to the organ loft, where he might spend hours playing the works of Bach or simply improvising. Although the piano clearly served Mendelssohn as an eminently practical instrument, the organ seems to have been his instrument of choice. He searched out an organ loft, not because he had to, but because he wanted to, because on the organ he could find catharsis. Indeed, as he once exclaimed to his parents, after reading a portion of Schiller's Wilhelm Tell, "I must rush off to the monastery and work off my excitement on the organ!" Mendelssohn's public performance on the organ in Germany was rare, and he gave but one public recital - in the Thomas-Kirche in Leipzig in 1840. In England, however, he evidently felt more comfortable on the organ bench and played there often before large crowds. Indeed, he performed as Guest Organist twice at the Birmingham Music Festivals, in 1837 and 1842. Given Mendelssohn's profound affinity for the organ, it is remarkable that he composed but relatively little for the instrument, and assigned an Opus number to only two works - his Three Preludes and Fugues for Organ (Op. 37) and his Six Sonatas for the Organ (Op. 65). A small number of organ works, plus sketches and drafts, were scattered among his musical papers; most of these only gradually found their way into print, and it was not until the late twentieth century that an edition of his complete organ works was finally published. This volume is intended as a companion to that edition.