AN APPRECIATION of the phenomenon known as Druidism (so far as our evidence will permit) must allow for a development of hundreds of years and over thousands of miles. It must take into account contacts between the Celts and peoples who were of kindred ancestral heritage (such as the Indo-European Latins and Germans), as between the Celts and those (perhaps among the earlier population groups of the British Isles or of the eastern parts of the continent) who were not. It must allow for the possibility that Druidism may have had variant characteristics contemporaneously in different parts of the Celtic sphere at any given time; but it should admit the fact that Druidism was apparently also pan-Celtic in nature ( Hubert 1988b: 226-27).
Crucial as well to a better understanding of the institution is recognition that rarely, if ever, do foreign observers (or even, for that matter, internal converts to an external religion, such as Christianity) view an endemic phenomenon with the same eyes as the indigenous population. Since the vast majority of Celtic materials attesting to this feature of Celtic culture are provided by Irish tradition (albeit in forms recorded, mostly, by Christian