Guillén de Castro in his Mocedades del Cid presents us with a characterization of his hero which differs radically from the Cid of the Romancero and the Crónicas. He transforms the renowned medieval warrior into a courtly knight. Ernest Mérimée in the Première Partie des Mocedades del Cid de Guillen de Castro (Toulouse, 1890, page cvi) takes note of the metamorphosis and attributes it to the playwright's inventive genius. But in his brochure, The Cid Theme in France in 1600 (Minneapolis, 1920), Gustave L. Van Robsbroeck casts some doubt on this point of view by bringing to light a novel by Antoine Du Périer, La Eayne et l'Amour d'Arnoul et de Clayremonde (Paris, 1600), containing features similar to the Castro story including the element of courtliness, which, of course, obviously antedate the play. His conclusion is that “There existed a common source—probably a Spanish source—for both the Eayne et L'Amour d'Arnoul et de Clayremonde and Las Mocedades del Cid” (p. 15). Barbara Matulka further enlarges on the subject in her The Cid as a Courtly Hero: from Amadis to Corneille (New York, 1928, pp. 6–40). She notes an early treatment of the courtly Cid theme in Feliciano de Silva's Florisel de Niquea (1532–51) representing books x, xi, and xii of the Amadis series, and cites Jimenez de Ayllon's Los Famosos y Herôicos Hechos del Invencible Cavallero el Cid Ruy Diaz de Bivar (1568) to show that the Cid had been introduced to court prior to the Mocedades and to point out that Ayllon's epic contains situations and details similar to those found in the play. These works, Miss Matulka claims, have been influential through intermediary links between them and our dramatic piece. There is no question but that she is partially correct in her contention, and this we shall endeavor to prove through the discussion of materials which she failed to utilize at the time she made her investigation.