Here seems to be the place to refer to the Allegro movement in sonata-form for viola and violoncello which Beethoven gave the title, “Duett mit zwei Augengläsern obbligato von L. v. Beethoven” (Duet with two Eyeglasses obbligato, by L. v. Beethoven), to be found in the volume of sketches from this period (1784-1800) which the British Museum bought from J. N. Kafka in 1875.[80] There ought to be a hint as to the identity of the two players “with two eyeglasses obbligato.” Here is also the place for the three Duos for Clarinet and Bassoon first published by André in Offenbach. The Sextet for Wind-Instruments published by Breitkopf and Härtel in 1810 (it received the opus number 71 later), belongs to this period. Sketches for the last movement, which differ from the ultimate form, however, are found amongst the sketches for the Pianoforte Sonata, Op. 10, No. 3. The inception of the Sonata must fall sometime between the middle of 1796 and the middle of 1798, since the subscription for it was opened in the beginning of July, 1798, and other works of a similar character were already completed in 1797. It is, therefore, possible to place the origin of the earlier movements of the Sextet in an earlier period, say 1796-97, a proceeding which is confirmed by the circumstance that the beginning is found before sketches for “Ah, perfido!” (which was composed in 1796 at the latest), on a sheet of sketches in the Artaria collection. The Kafka volume of sketches in the British Museum contains sketches for the minuet and trio of the Sextet, “Ah, perfido!” and the Pianoforte Sonata, Op. 49, No. 2. This fact also indicates the year 1796. Beethoven let the work lie a long time. It had its first hearing at a chamber concert for the benefit of Schuppanzigh in April, 1805; but it was not until 1809 that he gave it out for publication. On August 3rd of that year he wrote to Breitkopf and Härtel: “By the next mail-coach you will receive a song, _or perhaps two_, and a sextet for wind-instruments,” and on August 8th: “The sextet is one of my earlier things and, moreover, was written in a single night--nothing can really be said of it beyond that it was written by an author who at least has produced a few better works; yet for many people such works are the best.” The statement that the work was written in a single night must be taken in a Pickwickian sense, for sketches of it have been found.