The Introduction deals with various aspects of the study of these ancient myths and legends which have been the inspiration of a national literature infused with much grandeur and sublimity. The historic Aryan controversy, of which the science of comparative mythology is a by-product, is passed under review, and it is shown to what extent philological theories regarding race problems have been modified during recent years as a result of the adoption of broader and more exact methods of ethnic and archæological research and the ever-extending study of comparative mythology. There has also been condensed much important data dealing with the early phases of Aryo-Indian civilization accumulated for historical purposes by industrious and painstaking Sanskrit scholars who have been engaged in investigating and systematizing the internal evidence of the various religious poems and treatises. It will be found that no general agreement has yet been reached regarding Aryo-Indian chronology, but it now appears to be well established that although there were early cultural as well as racial “drifts”, fresh invasions, which had far-reaching results in the social and religious life of northern India, occurred at a late period in what is known as the Vedic Age. In consequence, the problem presented by this ancient civilization tends rather to grow more complex than to become simplified. Its origin is still wrapped in obscurity. At the very dawn of history Aryo-Indian culture had attained a comparatively high state of development, and a considerable period must be allowed for its growth. Even some of the ancient Vedic hymns, addressed by priests to the deities, are styled “new songs”, which suggests the existence of an older collection. Many of them also afford indications that immemorial beliefs were in process of change and fusion. The sublime deities, Varuna and Mitra (Mithra), for instance, were already declining in splendour. Yet they must have been closely associated with Indra, king of the gods, in the unknown Aryan homeland, as is made evident by an inscription recently deciphered at Boghaz Köi, in Asia Minor, which refers to them as deities of the mysterious Mitanni people who were of Aryan speech like the settlers in the Punjab. There is no evidence, however, that the Mitanni rulers gave recognition to the fire god Agni, who in India was exalted as the twin brother of Indra. The problem involved may not be devoid of ethnic significance, although the identity of the Agni-worshipping section of the early raiders remains obscure.