Although a half cadence marks the end of the transition section in most sonata-form expositions and recapitulations, in many of Haydn's sonata-form movements — especially those from around the 1760s — the end of the transition is instead articulated by a firm perfect authentic cadence. This establishes a point of harmonic resolution, rather than momentum, at this crucial formal juncture. As such, it yields an overall formal shape that departs from "textbook" sonata-form descriptions, which are based largely on later stylistic norms. The practice of having a strong tonic arrive in the middle of the exposition or recapitulation is a strategy that Haydn shared with other composers who flourished in the mid-eighteenth century, and it well accords with the descriptions of formal procedures found in Heinrich Christoph Koch's Versuch einer Anleitung zur Composition.