Haydn never discussed his compositional ideas in much detail, either in the interviews he gave to an early biographer or in his surviving correspondence. Moreover, relatively few sketches of his compositions have been preserved. Therefore, attempts to reconstruct Haydn's compositional thought, and in particular his formal logic, must rely on evidence drawn from close analyses of the works themselves. Using his symphonies as its subject, this book attempts to clarify what Haydn's fundamental principles of formal logic might have been. It shows how Haydn employed those basic compositional principles to structure his forms, providing explanations that account for specific details of individual movements as well as the relationships between the movements. Beyond what they show about Haydn's formal thought and the individual works discussed, the analyses in this book also have a larger purpose: to argue in support of the idea that compositions cannot be analysed in a meaningful manner if the analysis is divorced from the work's historical context.