Law and medicine were important academic disciplines in the Middle Ages, but theology was “the queen of sciences” because it involved the study of God, who made all knowledge possible. Paris became the place to study theology. In the first decades of the twelfth century, students from across Europe crowded into the cathedral school of Notre Dame (NOH-truh DAHM) in Paris.

University professors (a term first used in the fourteenth century) were known as “schoolmen” or Scholastics. They developed a method of thinking, reasoning, and writing in which questions were raised and authorities cited on both sides of a question. The goal of this method was to arrive at definitive answers and to provide rational explanations for what was believed on faith.

The Scholastic approach rested on the recovery of classical philosophical texts. Ancient Greek and Arabic texts entered Europe in the early twelfth century by way of Islamic intellectual centers at Baghdad, Córdoba, and Toledo (see “Life in Muslim Spain” in Chapter 8). The major contribution of Arabic culture to the new currents of Western thought rested in the stimulus Arabic philosophers and commentators gave to Europeans’ reflections on ancient Greek texts and the ways these texts fit with Christian teachings. One of the young men drawn to Paris was Peter Abelard (1079–1142), the son of a minor Breton knight. Abelard was fascinated by logic, which he believed could be used to solve most problems. He was one of the first Scholastics, and commented, “By doubting we come to questioning, and by questioning we perceive the truth.” Abelard was severely censured by a church council, but his cleverness, boldness, and imagination made him a highly popular figure among students.

Abelard’s reputation for brilliance drew the attention of one of the cathedral canons, Fulbert, who hired Abelard to tutor his intelligent niece Heloise. The relationship between teacher and pupil passed beyond the intellectual. Heloise became pregnant, and Fulbert pressured the couple to marry. The couple agreed, but wanted the marriage kept secret for the sake of Abelard’s career. Furious at Abelard, Fulbert hired men to castrate him. Abelard persuaded Heloise to enter a convent, and he became a monk. Their baby, baptized Astrolabe for a recent Muslim navigational invention, was given to Heloise’s family for adoption. The two became leaders of their communities — Abelard an abbot and Heloise a prioress — but they never saw each other again, though they wrote letters, which have become examples of the new self-awareness of the period.

In the thirteenth century Scholastics devoted an enormous amount of time to collecting and organizing knowledge on all topics. Such a collection was published as a summa (SOO-muh), or reference book. There were summae on law, philosophy, vegetation, animal life, and theology. Saint Thomas Aquinas (1225–1274), a Dominican friar and professor at Paris, produced the most famous of these collections, the Summa Theologica, a summation of Christian ideas on a vast number of theological questions, including the nature of God and Christ, moral principles, and the role of the sacraments. In this, and many of his other writings, Aquinas used arguments that drew from ancient Greek philosophers, especially Aristotle, as well as earlier Christian writers. Aquinas was both a theologian and a philosopher: he wrote sermons, prayers, commentaries on books of the Bible, and argumentative works on aspects of Christian theology such as the nature of evil and the power of God, but also commentaries on several of Aristotle’s works.

In these, he investigated the branch of philosophy called epistemology, which is concerned with how a person knows something. Aquinas stated that first one knows through sensory perception of the physical world — seeing, hearing, touching, and so on. He maintained that there can be nothing in the mind that is not first in the senses. The second way knowledge comes is through reason, through the mind exercising its natural abilities.

In all these works, Aquinas stressed the power of human reason to demonstrate many basic Christian principles, including the existence of God. To obtain true Christian understanding, he wrote, one needed both reason and faith. (See “Primary Source 10.4: Thomas Aquinas on Reason and Faith.”) His ideas have been extremely influential in both philosophy and theology: in the former through the philosophical school known as Thomism, and in the latter especially through the Catholic Church, which has affirmed many times that they are foundational to Roman Catholic doctrine.