The Druids left us no written record of their religion, or the belief system of our ancient Irish ancestors. What we know has been patched together from later Christian interpretations of the myths and legends, and the writings of observers such as Julius Caesar, but none of it can be proven to be fact.
Reincarnation is a Latin word, meaning “entering the flesh again.” As far back as the 1st century BCE, Alexander Cornelius Polyhistor wrote that the Gauls teach “that the souls of men are immortal, and that after a fixed number of years they will enter into another body.”
Julius Caesar wrote of the Celts in his ‘De Bello Gallico’ that “the principal point of their doctrine is that the soul does not die and that after death it passes from one body into another….. a firm belief in the indestructibility of the human soul, which, merely passes at death from one tenement to another; for by such doctrine alone, they say, which robs death of all its terrors, can the highest form of human courage be developed.”
Although these writers are referring to the Celts of Europe, it is reasonable to suppose that the Irish people of the same time period may have held similar beliefs. Indeed, there is much evidence to support this in the stories of Irish mythology.n the Tochmarc Étaíne, ‘The Wooing of Étaín’ from the Mythological Cycle, Etain is transformed by magic into a butterfly. After fourteen years, she lands in a cup of wine which is drunk by the wife of Etar, a warrior of the Ulaid. Etar’s wife swallows the butterfly and becomes pregnant, and thus Etain is reborn into human form a thousand years after her first birth.This story illustrates the Celtic acceptance of transformation, ie the temporary taking of another shape, and transmigration, when the soul transfers into another body following an actual rebirth.