In the prologue to the mid-fifteenth-century adaptation of the ‘rhymed story of Erec, the son of King Lac,’ the prosateur describes his work as a ‘transmutation’: ‘… pour ce que l'en m'a presentee le histoire de Erec le filz du roy Lach en rime, je, au plaisir de Dieu, occuperay mon estude ung petit de tamps a le transmuer de rime en prose …’ (Because I have been presented with the rhymed story of Erec, the son of King Lac, I shall, God willing, devote a little time to transposing it from verse into prose …). The term transmuer (to transform or change) suggests the extent of the modifications the adapter performed as he turned Chrétien's poem into prose. Readers of Arthurian romances will be familiar with the techniques the redactor deployed in appropriating Chrétien's text: abbreviation, amplification and rationalization. However, the full compass of the transformations, which occur on a socio-cultural level but more importantly, inform the literary art, may be surprising to them. Indeed, the modifications affect the structure and the meaning of the romance. While the prose text respects the general outline of the story, it abbreviates or omits many elements, but also embroiders, alters and even adds new material. In addition, it changes countless details in such a way that the adaptation is in fact a completely new text.