  As with so many important medieval figures, we know little about William's early years. According to one manuscript source, he was born in Aurillac, in the province of Auvergne in south-central France. His birth date is unknown, but since he was a professor of theology at the University of Paris by 1225, a position rarely attained before the age of 35, he is not likely to have been born later than 1190, and scholars have placed his probable birth date some time between 1180 and 1190. He may have come from a poor background, as the Dominican, Stephen of Bourbon (died c. 1261), tells a story of William begging as a young child (Valois 1880, 4). He was a canon of Notre Dame and a master of theology by 1223, and is mentioned in bulls of Pope Honorius III in 1224 and 1225.