The Boke of Gostely Grace is the anonymous Middle English version of the Liber specialis gratiae by the German visionary Mechthild of Hackeborn (1241-1298). The original Liber, compiled at the convent of Helfta in Saxony, presents Mechthild's visions as she experienced them in the liturgy of the Christian year. Her famous visions of the Sacred Heart follow, along with instructions on the religious life in community and her visions of the afterlife. The Middle English version adapts the text to a new fifteenth-century audience, probably a Birgittine community such as the newly founded Syon Abbey on the Thames near London; it emphasises imagery of the dance of the liturgy, the vineyard and the Sacred Heart in new and vivid terms, while other aspects, such as the bridal imagery, are played down. Within a generation, the English text had become popular among the nobility, and stimulated lay piety and private prayer.

While scholars have traced the influence and reception of many continental European women writers, Mechthild's revelations have often escaped their attention, through the lack of suitable editions.

This edition of Bodley 220, the manuscript written in the London area, includes introduction, commentary and glossary, and breaks new ground in the study of late medieval vernacular translation and women's literary culture.