Theologians in the tradition of Augustine of Hippo often describe sacraments as outward and visible signs of invisible grace. Thomas Aquinas proposed a widely accepted definition in the catholic West when he described a sacrament as "the sign of a sacred thing in so far as it sanctifies men." Medieval theologians differed in their use of the term, with some theologians arguing for as many as thirty sacraments. The Sentences of Peter Lombard identify seven sacraments: baptism, confirmation, the Mass, penance, holy orders, matrimony and extreme unction. This became the standard list of sacraments in the West and East. The Council of Trent (1546-1563) officially codified this in the West.