Western Europe and translated into Latin during the Renaissance of the 12th century and 13th century. Cathedral schools began in the Early Middle Ages as centers of advanced education, some of them ultimately evolving into medieval universities. During the High Middle Ages, Chartres Cathedral operated the famous and influential Chartres Cathedral School. The medieval universities of Western Christendom were well-integrated across all of Western Europe, encouraged freedom of enquiry and produced a great variety of fine scholars and natural philosophers, including Robert Grosseteste of the University of Oxford, an early expositor of a systematic method of scientific experimentation; and Saint Albert the Great, a pioneer of biological field research The Italian University of Bologna is considered the oldest continually operating university. Philosophy in the High Middle Ages focused on religious topics. Christian Platonism, which modified Plato's idea of the separation between the ideal world of the forms and the imperfect world of their physical manifestations to the Christian division between the imperfect body and the higher soul was at first the dominant school of thought. However, in the 12th century the works of Aristotle were reintroduced to the West, which resulted in a new school of inquiry known as scholasticism, which emphasized scientific observation. Two important philosophers of this period were Saint Anselm and Saint Thomas Aquinas, both of whom were concerned with proving God's existence through philosophical means. The Summa Theologica by Aquinas was one of the most influential documents in medieval philosophy and Thomism continues to be studied today in philosophy classes. Theologian Peter Abelard wrote in 1122 "I must understand in order that I may believe... by doubting we come to questioning, and by questioning we perceive the truth". In Normandy, the Vikings adopted French culture and language, mixed with the native population of mostly Frankish and Gallo-Roman stock and became known as the Normans. They played a major political, military, and cultural role in medieval Europe and even the Near East. They were famed for their martial spirit and Christian piety. They quickly adopted the Romance language of the land they settled in, their dialect becoming known as Norman, an important literary language. The Duchy of Normandy, which they formed by treaty with the French crown, was one of the great large fiefs of medieval France. The Normans are famed both for their culture, such as their unique Romanesque architecture, and their musical traditions, as well