The things we do with words are reflected in texts and we do things with texts just as we do things with words. This book sets out to explore how texts function in a given discourse community, and how the functions that texts may have in that particular community can be identified and assessed from a diachronic perspective. It systematically distinguishes general discourse functions (e.g. religious instruction) from more specific text functions (e.g. exegesis, exhortation), and outlines co-occurrence patterns of text functions for selected genres. A contrastive view of the evolution of these profiles ties the changes in individual genres to the complex and dynamic network of which they are a part. Combining corpus methodology with detailed qualitative discussion, this book identifies text functions as the performative centre of texts and shows how language variation and change strongly depend on the dynamics of the complete network of genres in the domain.