Chrétien de Troyes was one of the most influential writers of his age and a major contributor to the Arthurian legend, having given us both Lancelot and the Holy Grail. The problem is that we have no originals of Chrétien's texts. MS BN fr. 794, by a copyist who names himself, Guiot, contains 5 of Chrétien's romances, along with a few other goodies, but it was probably created some 50 years after Philip of Flanders' death in 1191--after Chrétien stopped writing and almost certainly after his death. Since the Guiot manuscript forms the basis for modern editions of Chrétien's main romances, we may well consider Guiot as a kind of co-author with Chrétien; he is hugely influential in what we think of as Chrétien's work. However, study of other manuscripts suggests that he is not always the most complete or accurate reflection of what scholars guess Chrétien wrote. There are 15 mss. of the Perceval, plus some fragments, and apparently it is no easy task to reconstruct their "families" (that is, which manuscripts were copied from the same, usually lost, copy of the lost original).
