"“India, Rome, Ireland and Iran” [are the] “areas in which priesthoods are known to have been significant” ... “Long after the dispersion of Indo-Europeans, we find a priestly class in Britain in the west, in Italy to the South, and in India and Iran to the east. Though these cultures are geographically distant from one another... they have striking similarities in priestly ritual, and even in religious terminology. For example, taboos pertaining to the Roman flAmen (priest) closely correspond to the taboos observed by the Brahmans, the priests of India.” [Like the Indian priesthood, the curriculum of the] “Celtic Druids … involved years of instruction and the memorization of innumerable verses, as the sacred tradition was an oral one”.... “Celts, Romans and Indo-Iranians shared a religious heritage dating to an early Indo-European period…”"