Under the general title of the _Epopee courtoise_--the Epopee of Courtesy--may be grouped those romances which are either works of pure imagination or of uncertain origin, or which lead us back to Byzantine or to Celtic sources. They include some of the most beautiful and original poems of the Middle Ages. Appearing first about the opening of the twelfth century, later in date than the early _chansons de geste_, and contemporary with the courtly lyric poetry of love, they exhibit the chivalric spirit in a refined and graceful aspect; their marvels are not gross wonders, but often surprises of beauty; they are bright in colour, and varied in the play of life; the passions which they interpret, and especially the passion of love, are felt with an exquisite delicacy and a knowledge of the workings of the heart. They move lightly in their rhymed or assonanced verse; even when they passed into the form of prose they retained something of their charm. Breton harpers wandering through France and England made Celtic themes known through their _lais_; the fame of King Arthur was spread abroad by these singers and by the _History_ of Geoffrey of Monmouth. French poets welcomed the new matter of romance, infused into it their own chivalric spirit, made it a receptacle for their ideals of gallantry, courtesy, honour, grace, and added their own beautiful inventions. With the story of King Arthur was connected that of the sacred vessel--the graal--in which Joseph of Arimathea at the cross had received the Saviour's blood. And thus the rude Breton _lais_ were elevated not only to a chivalric but to a religious purpose.