The Barddas of Iolo Morganwg, Vol. I., ed. by J. Williams Ab Ithel, , at sacred-texts.com
"This method of divination has not been neglected even amongst barbarous nations. For there are Druids in Gaul, with one of whom I was acquainted, namely, Divitiacus Æduus, who enjoyed the hospitality of your house, and spoke of you with admiration. This man not only professed an intimate knowledge of the system of nature, which the Greeks call physiology, but also foretold future events, partly by augury, and partly by conjecture." 1
Cicero does not speak here from vague report; but declares the profession of a man who was personally known to him, who had been his guest, and with whom he had familiarly conversed. And all that he says of him coincides almost exactly with the statements of Cæsar, Strabo, and Diodorus Siculus. The only new fact that we are made acquainted with is, that the Druids sometimes foretold future events "by conjecture;" but perhaps we should not take the word to mean simply a guess, but as synonymous with inference--to signify that they had some foundation for all their vaticinations.
lix:1 De Divinatione, 1, i.