particular, were seized by a peregrinatio pro Christo. It was Irish monks who converted the pagan English kingdoms. When the Synod of Whitby in a.d. 664 opted for Roman custom instead of Celtic, it was not the end of Celtic Church influence in England, and another full century elapsed before Celtic missionaries ceased to be welcome among the English.

Celtic monks took their teachings as far east as Kiev, north to Iceland, and south even into Italy, where they established their own monasteries and churches. Their philosophers, such as Pelagius, Hilary, and others, added to the store of Christian wisdom. Eriugena the Irishman (ca. a.d. 810–877) is considered the most considerable philosopher in the western world between Augustine of Hippo and Thomas Aquinas.

In Latin and in Celtic languages, there survive many Lives of the founding fathers (and mothers) of Christianity among the Celts. These Lives are a typically Celtic mix of allegory and legend—often the stories of the Celtic saints are mixed with former traditions so that the Lives become part of Celtic mythology itself. St. Brigid, for example, is often mixed with the traditions of the goddess of fertility, and many saint’s days were grafted onto existing pagan feast days. The saints of the Celtic Church are numerous, for the designation “saint” was given to all missionaries and teachers of distinction, signifying that they were eminent men and women.

It was, of course, under the auspices of the monks and scholars of the Celtic Church that the mythology of the Celts began to be written, and, unfortunately for posterity, many of the monks, with their newfound Christian zeal, sought to bowdlerise the myths with Christian images and morality. Nevertheless, the uniqueness and vitality of pre-Christian Celtic mythology and philosophy still shines through the thin Christian veneer.

By the twelfth century the Celtic Church had been absorbed into Rome, although as late as the fourteenth century in Scotland there were still bodies of Celtic monks (Culdees, or Céile Dé, servants of God) clinging to the old cultural customs. The Céile Dé order was a monastic one that sought to revive the purity and austerity of early Celtic monasticism. It is said they were founded by Mael Ruain, founder of the monastery of Tallaght (d. a.d. 794).