Before Mozart had reached the age of twenty he wrote six sonatas for a certain Baron Duernitz, who, by the way, forgot to send the promised payment in return. Of these, Otto Jahn remarks that "their healthy freshness and finished form entitle them still to be considered as the best foundation for a musical education." Freshness is indeed the best term to describe both the thematic material and the developments. Four of them (Nos. 1, 2, 3, and 5) consist of the usual three movements; No. 4 commences with a long Adagio in two sections, each of which is repeated. Two graceful Minuets (the second taking the place of a Trio) follow, and the third movement is an Allegro in sonata-form. No. 6 has for its second movement a Rondeau en Polonaise, and for its third, a Theme with variations. The Rondo of No. 3 (in B flat) is unusually long; it contains two episodes, one in the relative minor, the other in the subdominant. The next three sonatas (in C, A minor, and D) are of greater importance. They are all said to have been written at Mannheim. The first was most probably the one mentioned in a letter of 1777 written by Mozart to his father. He describes a public concert given on the 22nd of October, and says: "Then I played alone the last Sonata in D, then my Concerto in B flat, then a Fugue in C minor, and a splendid Sonata in C major out of my own head, with a Rondo at the end." The "last Sonata in D" was the last of the set of six noticed above. In reference to the Sonata in C, the expression "out of my own head" would seem to indicate that it had not at that time been written out. Mozart was right to speak of the work as "splendid." The bold opening subject, the well-contrasted second theme, the short but masterly development, the original leading back to the principal subject, and the many variations in the recapitulation section, fully justify his qualification. The slow movement is full of charm, and the Rondo, with its elaborate middle section, is of the highest interest. The 2nd Sonata, in A minor, is, next to the one in C minor, Mozart's finest effort in this department of musical literature. And there is a story connected with it. Capellmeister Cannabich's eldest daughter Rosa had captivated the young composer; he wrote to his father about her, and described her as "a pretty, charming girl," and added, "she has a staid manner and a great deal of sense for her age (the young lady was only thirteen); she speaks but little, and when she does speak, it is with grace and amiability." On the very next day after his arrival in Mannheim he began to write this sonata for her. The Allegro was finished in one day. Young Danner, the violinist, asked him about the Andante, and Mozart replied: "I mean to make it exactly like Mdlle. Rose herself." This was the picture to which he worked. One of Beethoven's finest sonatas, the C sharp minor, was inspired by a beautiful girl: a strong appeal to the emotions calls forth a composer's best powers.