The ancient inhabitants of Britain—the Gaelic and British Celts—have been already described as forming a branch of what are roughly called the “Aryans”. This name has, however, little reference to race, and really signifies the speakers of a group of languages which can be all shown to be connected, and to descend remotely from a single source—a hypothetical mother-tongue spoken by a hypothetical people which we term “Aryan”, or, more correctly, “Indo-European”. This primeval speech, evolved, probably, upon some part of the great plain which stretches from the mountains of Central Europe to the mountains of Central Asia, has spread, superseding, or amalgamating with the tongues of other races, until branches of it are spoken over almost the whole of Europe and a great portion of Asia. All the various Latin, Greek, Slavic, Teutonic, and Celtic languages are “Aryan”, as well as Persian and other Asiatic dialects derived from the ancient “Zend”, and the numerous Indian languages which trace their origin to Sanscrit. Not very long ago, it was supposed that this common descent of language involved a common descent of blood. A real brotherhood was enthusiastically claimed for all the principal European nations, who were also invited to recognize Hindus and Persians as their long-lost cousins. Since then, it has been conceded that, while the Aryan speech survived, though greatly modified, the Aryan blood might well have disappeared, diluted beyond recognition by crossing with the other races whom the Aryans conquered, or among whom they more or less peacefully settled. As a matter of fact, there are no European nations—perhaps no people at all except a few remote savage tribes—which are not made up of the most diverse elements. Aryan and non-Aryan long ago blended inextricably, to form by their fusion new peoples. But, just as the Aryan speech influenced the new languages, and the Aryan customs the new civilizations, so we can still discern in the religions of the Aryan-speaking nations similar ideas and expressions pointing to an original source of mythological conceptions. Hence, whether we investigate the mythology of the Hindus, the Greeks, the Teutons, or the Celts, we find the same mythological groundwork. In each, we see the powers of nature personified, and endowed with human form and attributes, though bearing, with few exceptions, different names. Like the Vedic brahmans, the Greek and Latin poets, and the Norse scalds, the Celtic bards—whether Gaels or Britons—imagined the sky, the sun, the moon, the earth, the sea, and the dark underworld, as well as the mountains, the streams and the woods, to be ruled by beings like their own chiefs, but infinitely more powerful; every passion, as War and Love, and every art, as Poetry and Smithcraft, had its divine founder, teacher, and exponent; and of all these deities and their imagined children, they wove the poetical and allegorical romances which form the subject of the present volume.