Pezron was a Doctor of Theology at the Cistercian College of St.
Bernard in Paris and abbot of La Charmoie.In his time, he was known in France as a chronologist.
Pezron traced Welsh and Breton origins to the Celts of ancient writers, and traced the Celts further to eponymous hero-patriarchs from Gaul to Galatia.
Pezron believed the Welsh language came from a mother tongue called Celtick, a language that was only a theory to other authors.
Pezron's fairly unscientific book was popular and reprinted until the early nineteenth century.