This study of Così fan tutte is based on a detailed examination of the original manuscripts in Krakow, Berlin, Frankfurt and Vienna. The long discredited idea that Mozart composed in his head before committing the ensuing masterpieces to paper in flawlessly written full scores has received new currency, at least in the popular imagination, thanks to the memorable portrayal of Salieri in a scene in Amadeus where he is given sight of a pile of his rival’s unblemished autographs. The manuscript of Così fan tutte is elegantly written, especially in the early stages of Act I, and superficially it does seem relatively free from correction, but upon closer inspection abundant signs of the composer at work soon catch the eye. As Tyson demonstrated in his seminal study of this opera, palaeographic features such as ink colours, copying sequences, the foliation system, numbering sequences and continuity directions, all have much to contribute to an understanding of the compositional process. In Part I of this study, these features will be examined in detail for the purpose of illuminating Mozart's working methods, and also, insofar as this is possible, in order to establish a chronology of how Così fan tutte was put together.

The composition of any opera in the late eighteenth century was the product of an active collaboration between the composer and his performers. It has long been accepted that when writing an aria, Mozart would first consult its singer, listening carefully to any views expressed, but the nature of these essentially creative interventions from performers, especially during the critical phase when ideas and drafts were being brought to fruition, is difficult now to ascertain. In the autograph of Così fan tutte, however, there are fascinating hints of the collaborative nature of the dealings between composer and performer. This relationship will be considered through a detailed analysis of the process of revision in three arias. Other aspects of the compositional process also left clear traces in the autograph. Mozart's concern for the effective musical representation of drama on stage, his care in the choice of wind instrumentation, and his ceaseless quest to improve matters of fine detail are evident throughout.

The use of an autograph to shed light on its author's working practices is hardly controversial, but palaeographic evidence can also be deployed in support of theories of a more speculative character.