St-Calais was known to his contemporaries as an intelligent and able man. He had an excellent memory. Frank Barlow, a historian, describes him as a "good scholar and a monk of blameless life". Besides his copy of the "Decretals", he left at his death over fifty books to the monks of Durham, and the list of those volumes still exists. His best-known legacy is the construction of Durham Cathedral, although the nave was not finished until 1130. The construction technique of combining a pointed arch with another rib allowed a six-pointed vault, which enabled the building to attain a greater height than earlier churches. This permitted larger celestory windows, and let more light into the building. The technique of the six-pointed vault spread to Saint-Etienne in Caen from which it influenced the development of early Gothic architecture near Paris. The system of rib vaulting in the choir was the earliest use of that technique in Europe. The historian Frank Barlow called the cathedral "one of the architectural jewels of western Christendom".