Merlin is a partly lost French epic poem written by Robert de Boron in Old French and dating from either the end of the 12th or beginning of the 13th century. The author reworked Geoffrey of Monmouth's material on the legendary Merlin, emphasising Merlin's power to prophesy and linking him to the Holy Grail. The poem tells of his origin and early life as a redeemed Antichrist, his role in the birth of Arthur, and how Arthur became King of Britain. Merlin's story relates to Robert's two other reputed Grail poems, Joseph and Perceval. Its motifs became popular in medieval and later Arthuriana, notably the introduction of the sword in the stone, the redefinition of the Grail, and turning the previously peripheral Merlin into a key character in the legend of King Arthur.