The study of Indo-European religion has a relatively recent origin, for the very existence of the Indo-European language grouping was not recognized until a celebrated lecture given by Sir William ("Oriental") Jones in 1786. Speaking to the Royal Asiatic Society of Bengal, Jones first observed that there were striking philological similarities between Greek, Latin, Sanskrit (the ancient language of India), and Persian, too numerous and precise to be explained by simple borrowing or chance. Going further, he suggested that the Celtic and Germanic languages exhibited many of the same features and argued that all of these geographically and historically far-flung languages were best understood as separate derivates of a common parent language, a language nowhere preserved in written form, but which might be reconstructed through systematic comparison of the derivate stocks.

Later research has confirmed the relations among these languages, adding not only Germanic and Celtic firmly...