Merlin is, of course, familiar to all readers of this journal as the great magician of the Arthurian cycle. More than that, he can within that cycle's own terms of reference be regarded as its originating author: it is he who devised the Round Table, he who engineered the conception of Arthur himself, he whose foreknowledge contained the whole glory and downfall of the Arthurian age. But what are the roots of this enigmatic figure? Much has been written about the many aspects of this question. The present contribution will review this scholarship; indeed, as the reader will see, most of the associations and interpretations to be discussed below have already been proposed by other, often much earlier, scholars. Building on the work of these illustrious predecessors, I shall undertake to approach the problem anew: examining the earliest evidence, placing it in the broader context of the narrative traditions of the Celtic peoples, and suggesting possible sources.

This study will involve comparanda in the literatures of both Wales and Ireland; there are various ways in which such similarities can be explained. A resemblance may be purely coincidental: this becomes less likely the closer the resemblance but should never be ruled out categorically. The Welsh sources may reflect Irish influence: scholars are no longer making the sweeping claims for such influence that were formerly taken for granted, but there is no doubt that it existed, and that it was important. Or the Irish sources may reflect Welsh (or more generally British) influence, as is, for instance, generally held to be true of the story of Suibne (to be discussed below). It can also be the case that both Ireland and Wales have drawn on the same external sources, whether written or oral; or, finally, both may draw upon the more ancient traditions of the ‘common Celtic’ culture from which both descend.5 Each instance must be judged on its own merits, with no preconceived preference for one or another of these scenarios.

In a search for Merlin's kindred, it is natural to turn first to the twelfth-century author Geoffrey of Monmouth. By some scholars, indeed, Geoffrey has been taken to have invented Merlin outright.