When we turn to the great Aryan epics, the _Iliad_ and the _Odyssey_; the _Volsungs_; the _Nibelungs_; _King Arthur and his Round Table_; the _Ramâyanâ_ and the _Mahâ Bhâratâ_; the _Shah Nameh_, and so forth, we find similarities of incident and episode which point to a common derivation from old Aryan myth. That common synonyms occur in cognate languages is to be expected, but so far as the names and the characteristics of the heroes and heroines are concerned, the phonetic identity is proven in a far less number of cases than the solar mythologists, working on their too exclusive method, argue. The key which for them unlocks the meaning of every Aryan myth is Sanskrit. In tracing the history of the Indo-European family of speech, it served as the starting-point, because it has more than any other member preserved the roots and suffixes, if not in their oldest, still in their most accessible form. And in tracing the course of Indo-European mythology, it is in the Vedic texts, chiefly the most ancient, the _Rig-Veda_, that we find the materials for comparative study, since in these venerable hymns of a Bible older than our own are preserved the earliest recorded forms of that mythology. That is to say, we have not in any European branch of Aryan speech any documentary relic of the age of the _Rig-Veda_, otherwise we might find ourselves in possession of more ancient relics of that speech. So that although the value of Sanskrit as the guide without which knowledge of the Aryan mother-tongue would have remained vague, indeed have been beyond reach, cannot be over-estimated, we must not accept as of universal worth what is local and special in it.[36]
The phonetic kinship and actual identity which comparative philologists have sought to establish between the proper names of gods and heroes of the Greek and Vedic mythologies (for the inquiry has been chiefly restricted to these two), is based on the collection of rules by which we can at once tell what sounds in one language correspond to those of its kindred tongues, called, after its discoverer, "Grimm's Law." This law gave the quietus to theories of common origin and variation of words based on specious resemblances (theories satirised by Dean Swift in his derivation of _ostler_ from _oatstealer_), and introduced a scientific method into etymological study.