The rise in prominence of universities in Europe from the late twelfth century increased exponentially the demand for manuscripts for students. It was in this context that Peter Lombard, bishop of Paris (1158-1160) and a teacher in the schools of Notre Dame, wrote his theological encyclopaedia Sentences. The compendium consists of four books: the first concerns itself with proof of the existence of God, the second with creation, the third deals with the Incarnation of the Word and the fourth with the sacraments. Lombard's work served as one of the core texts for late-medieval Christian theology students.