It is more than reasonable to say that Chretien de Troyes is one of the best-known Medieval authors (he is thought to have created the character of Lancelot). And Perceval, the Story of the Grail was supposed to be his fifth verse. Alas, the verse was never finished.
Nominally, Perceval marks the first time the story of a person seeking to find the Holy Grail was ever put to paper. It tells the story of a young man called Perceval, who, after coming across several Knights, desires to become a Knight himself. To that end, he travels to King Arthur's Court and eventually defeats a vaunted Knight, stealing his armor in the process. Perceval embarks on an exciting journey, meeting people like the Fisher King along the way, to find the Holy Grail.
Not only did Perceval receive positive reviews, it is a highly influential work. It reframed Europe as an enthusiastic continent and created some of the most interesting and recognizable stories and characters in the world.