In dealing with the subject of 'Celtic Religion' the first duty of the writer is to explain the sense in which the term 'Celtic' will be used in this work.

It will be used in reference to those countries and districts which, in historic times, have been at one time or other mainly of Celtic speech.

It does not follow that all the races which spoke a form of the Celtic tongue, a tongue of the Indo-European family, were all of the same stock.

Indeed, ethnological and archaeological evidence tends to establish clearly that, in Gaul and Britain, for example, man had lived for ages before the introduction of any variety of Aryan or Indo-European speech, and this was probably the case throughout the whole of Western and Southern Europe.

Further, in the light of comparative philology, it has now become abundantly clear that the forms of Indo-European speech which we call Celtic are most closely related to those of the Italic family, of which family Latin is the best known representative.