Feast of St #Willibrord (658-739). From Northumbria, he studied from age 20 to 32 in the Abbey of Ráíth/Cluain Melsigi (Clonmelsh in Carlow). There he learned the Dionysian method of calculating Easter #computus from Ecgberht, bringing it in turn to the Franks, along with the BC/AD date system. Irish books on computus followed, as the Franks sought answers to questions already answered in Ireland.

More on the Irish and computus here: https://www.irishphilosophy.com/2018/04/01/irish-computus/

#IrishPhilosophyOTD