The Barddas of Iolo Morganwg, Vol. I., ed. by J. Williams Ab Ithel, , at sacred-texts.com
This author has preserved one of the Triads of the Druids, which is as follows:--
Now, it is remarkable that we have one Triad in the series called "Trioedd Doethineb," which very much resembles the above, so much so as to impress us with the belief that it was the original model after which the Greek Triad was compiled. It runs thus,
Diogenes says, moreover, that the Druids among the Britons were the same as the Philosophers among the Greeks, the Magi among the Persians, the Gymnosophistæ among the Indians, and the Chaldæans among the Assyrians; and so undoubtedly they were in respect of the origin and substance of their religion.