In theatre, prompt books are written by multiple participants engaging in diverse manuscript practices which continually revise the unfixed literary text within its theatrical context. Based on examples of the vast Hamburg »Theatre-Library« from the 1770s to 1850s, this study proposes a transdisciplinary approach towards handwritten artefacts in modern European theatre. Martin Jörg Schäfer and Alexander Weinstock examine the many-handed creation, handwritten transformation and often decades of use of prompt books in a time increasingly dominated by print. This perspective changes our notion of theatre history around 1800 as well as that of literature and authorship.