The subject of love and adultery in Arthurian romances usually calls to mind the love triangle that unites King Arthur, his wife Queen Guinevere, and the knight Sir Lancelot. The great love affair of Guinevere and Lancelot is often celebrated as an enduring passion that overcomes all obstacles, including the queen's marriage. Lancelot is inspired to accomplish extraordinary feats of prowess because of his love for the queen, and his successes in adventures, tournaments and contests contribute to the chivalric brilliance that establishes the reputation of Arthur's court and the Round Table. Yet even though the knight does great acts of chivalry for his beloved queen, his love for her must remain secret because it betrays the king. And although the queen rewards her knight with public displays of favour, her passionate love for him must remain hidden. Secrecy never adequately hides the queen's love affair from her husband, however, and the lovers are inevitably discovered. Indeed, medieval versions of the story recount a series of repeated episodes in which the love affair is revealed and then covered up again. That is, Arthur sees evidence of his queen's adultery, but he finds a way not to believe what he sees. In the thirteenth-century Old French Vulgate Cycle (also called the Lancelot-Grail Cycle by modern scholars), which combines the story of Lancelot with that of the Holy Grail, the final section, the Mort Artu (Death of King Arthur), recounts that the king repeatedly refuses to believe that Lancelot and Guinevere could betray him.