It took a little more than two years—from December 1782 to January 1785—for Mozart to complete his six "Haydn” string quartets. In April 1783, in a letter in which he offers two new concertos to French editor Jean Georges Sieber, Mozart, very business-like, states: "I am also working on 6 quartets for 2 violins, viola and bass—If you wish to print these as well, I will give them to you—but for these, I will not be as inexpensive—I cannot let go of the six quartets for less than 50 Louis d'or—hence, if you can, and want to do business with me, simply write, and I will give you an address in Paris where you can collect my works in exchange for payment.” From the start, Mozart must have conceived these new quartets as a series of six, since at the time the letter to Sieber was written only the first quartet, in G major (K. 387), was finished. The second "Haydn” quartet, in D minor (K. 421), was completed in June of the same year, and was followed by quartets K. 428 in E-flat major (June-July 1783), K. 458 in B-flat major (November 1784), K. 464 in A major (January 1785), and K. 465 in C major, "Dissonance” (January 1785). We learn of the completion of this series in a letter from Leopold to his daughter, dated January 22, 1785, which also gives a glimpse of Mozart's musical activity in Vienna: "I've just received 10 lines from your brother, in which he says that his first subscription concert will be held on febr. 11; and that this will continue every Friday; that during the third week of Lent he most assuredly will have a day to organize for Heinrich a concert at the theatre; that I should come soon—that last Friday he sold his 6 quartets to Artaria for 100 ducats and that he had them performed for his dear friend Haydn and other good friends.” The dedication to Haydn is perhaps more than simply a tribute by a young composer to his elder, more than the token of a new friendship. The six new quartets can also be seen as being part of a dialogue between two great composers: we can certainly speak of the "influence” of Haydn on Mozart's style, but we can also think of the quartets as somewhat "answering” questions of style, form and genre raised by Haydn's op. 33 string quartets. The six quartets op. 33, published in 1781, had a tremendous impact on the development of the classical style. Haydn had worked from the uniquely homogeneous sound of the string quartet to create a counterpoint which, without ever striving for the baroque's perfect equality of voices, spread more evenly than before the forces at play in the nascent classical style. The rich and transparent texture resulting from what can be called a "thematic counterpoint” is in turn exploited by Mozart in his 1782-85 quartets. For example, rather than accompanying his melodies with simple divertimento-style repeated eighth-notes, as was the case in early quartets such as K. 160 or K. 169, he supports them with a background of weaving lines and motifs which enhances their natural lyricism. The classical style was build upon the sometimes rigid punctuation of the sentence, the period, and the perfect cadence. As a result, composers often had to rely on short transitional motifs such as scales, alternate thirds, etc., to assist the passage from one theme to another or from one thematic group to another. All this disappears in the works of Haydn and Mozart of the early 1780s, in favor of greater continuity and fluidity. Transitions start acquiring characteristics usually associated with the development—in other words, the pull toward greater dramatic tension now begins as soon as the main thematic material of a movement has been presented (especially in sonata-form movements), as can be heard in the opening movements of both K. 387 and K. 464. While Haydn's works sometime seem to spring from the playful game between small isolated formal elements—a game in which they constantly invent for themselves new possibilities—Mozart's works appear to be drawn from a greater perspective: one first hears the breadth of the lyricism, the vastness of the tonal plains, and only later does the detail reveal its importance. If, however, Mozart seems (as opposed to Haydn) more "melodic” than "thematic,” it is because the most significant details are always introduced subtly and discreetly, as are the delicately dissonant passing notes and appogiaturas which, at first, serve to color the melodic turn of the two quartets' main themes, but later extend the realm of their influence, start eroding the tonal foundations, and destabilize the progress of the modulations. Apart from the works of Haydn, Mozart, in his first years in Vienna, also gets acquainted with most of the works of Johann Sebastian Bach available at the time. In February 1782, he writes to his sister: "Baron van Swieten, to whose home I go every Sunday, has entrusted me with all the works of Sebastian Bach and Handel (after I played them for him).” In April of that same year, he writes to Leopold: "I go to Baron van Swieten's every Sunday at twelve o'clock—and there, we only play Bach and Handel. I am collecting fugues by Bach, by Sebastian as well as by Emmanuel and Friedemann.” We learn here that the famous 19th-century Bach "rediscovery” was little more than a myth. But more important, we see that what really interested Mozart when studying baroque composers was the fugue, the apex of contrapuntal art. Many works of the early 1780s testify to this interest—the transcriptions for string trio (K. 404a) and string quartet (K. 405) of fugues from The Well-tempered Clavier and The Art of Fugue, the Prelude and Fugue for piano in C major, K 394—and we can also attribute to these years many of Mozart's fugue fragments for different instrumental formations (such as the fugue fragment in G minor for string quartet of 1783 or 1784). In Mozart's style, baroque counterpoint thus combines with classical counterpoint—in a more rafined, complex and integrated manner than had been, for example, the fugue in the early string quartets—both serving the dramatic progress of the works. In the development of the first movement of K. 464—essentially a sequence of stretto episodes—it is the successive entries of the voices that destabilizes the rhythm and increases the dramatic tension. The last movement of K. 387 is more daring: forms and genres are mixed, fugue, sonata, divertimento, and even touches of opera buffa.
