(born c. 1100, Novara, Lombardydied Aug. 21/22, 1160, Paris) French bishop and theologian. He studied in Bologna and taught theology in the school of Notre-Dame, Paris. He was consecrated bishop of Paris in 1159. His Four Books of Sentences (1148–51), a systematic collection of teachings of the Church Fathers and opinions of medieval theologians, served as the standard theological text of the Middle Ages. In it Peter touched on every doctrinal issue, from God and the Trinity to the four last things (death, judgment, hell, and heaven). He asserted that sacraments are the cause and not merely the signal of grace and that human actions may be judged good or bad according to their cause and intention.