That Mozart had been able to compose music to such libretti as those of “Don Giovanni” and “Cosi fan tutte” filed him with pained wonder.  Moreover, he had serious views of the dignity of music and of the uses to which it might be put in the drama, and more advanced notions than he has generally been credited with as to how music and the drama ought to be consorted.  Like all composers, he longed to write an opera, and it is not at all unlikely that, like Mendelssohn after him, he was deterred by the general tendency of the opera books of his day.  Certain it is that though he received a commission for an opera early in the year 1803, it was not until an opera on the story which is also that of “Fidelio” had been brought out at Dresden that he made a definitive choice of a subject.  The production which may have infuenced him was that of Ferdinando Paer’s” Leonora, ossia l’Amore conjugale,” which was brought forward at Dresden, where its composer was conductor of the opera, on October 3, 1804.  This opera was the immediate predecessor of Beethoven’s, but it also had a predecessor in a French opera, “Leonore, ou l’Amour conjugal,” of which the music was composed by Pierre Gaveaux, a musician of small but graceful gifts, who had been a tenor singer before he became a composer.  This opera had its first performance on February 19, 1798, and may also have been known to Beethoven, or have been brought to his notice while he was casting about for a subject.  At any rate, though it was known as early as June, 1803, that Beethoven intended to compose an opera for the Theater an der Wien, and had taken lodgings with his brother Caspar in the theatre building more than two months before, it was not until the winter of 1804 that the libretto of “Fidelio” was placed in his hands.  It was a German version of the French book by Bouilly, which had been made by Joseph Sonnleithner, an intimate friend of Schubert, founder of the Gesellschaft der Musikfreunde, who had recently been appointed secretary of the Austrian court theatres as successor of Kotzebue.  Beethoven had gone to live in the theatre building for the purpose of working on the opera for Schikaneder, but early in 1804 the Theater an der Wien passed out of his hands into those of Baron von Braun.  The intervening summer had been passed by the composer at Baden and Unter Dobling in work upon the “Eroica” symphony.  The check upon the operatic project was but temporary.  Baron von Braun took Schikaneder into his service and renewed the contract with Beethoven.  This accomplished, the composer resumed his lodgings in the theatre and began energetically to work upon the opera.  Let two facts be instanced here to show how energetically and how painstakingly he labored.  When he went into the country in the early summer, as was his custom, he carried with him 346 pages of sketches for the opera, sixteen staves on a page; and among these sketches were sixteen openings of Florestan’s great air, which may be said to mark the beginning of the dramatic action in the opera.