THE story of Merlin, we have seen, appears as far back as the time of Nennius in fairly close connection with the story of Arthur; that is, only a few paragraphs before the account of Arthur's twelve battles. It tells of the boy of marvellous birth, whose name, according to Nennius, was Ambrosius, and according to Geoffrey, Ambrosius Merlin, and then simply Merlin.
How a closer union of this story and the Arthurstory came about cannot be said; but by the time Geoffrey of Monmouth writes, Merlin was already an important personage at Arthur's court, a sage revered for his prophetic powers. The first time the enlarged story of Merlin takes definite independent shape, with Merlin as the central figure, is in the Merlin of Robert de Boron , which seems to have borrowed a good deal of its material from Geoffrey's account. This poem, which was soon turned into prose, dealt not only with Merlin's life, but also with Arthur's career up to his coronation. For some reason or other, romancers whose names are not certainly known decided to carry the adventures of Merlin beyond that point; accordingly, early in the thirteenth century there were composed two different continuations to the prose version of Robert de Boron's poem. One of these, because it had the greater currency, is commonly called the