This study critically examines previous approaches to textual criticism and editorship, and using the "Parzival" ms. Cgm 19 and the "Tristan" ms. Cgm 51 develops the argument that every medieval version of a text possesses inherent value and represents the cultural knowledge of its age and that this can only be appreciated if divergent mss. are not simply seen as deficient variants of an 'original text'. The study makes an important contribution to the present lively debate on the principles of modern editorship and the medieval concept of text.