Sometimes the story goes like this: The Catholic Church attacked the Holy Land in 1095 and relations between Christians and Muslims have been poisoned ever since. This simplistic interpretation is not only false, it misses the real significance of the Crusades. They reacquainted Europe with her past, helped bring her out of the so-called Dark Ages and mark the beginning of a new era in Western history, the High Middle Ages, which laid the foundation for transforming epochs like the Renaissance and Scientific Revolution. They also led to the thought of one of Catholicism’s greatest philosophers, St. Thomas Aquinas.
It is well known in the seventh and eighth centuries Muslim armies swept across the Middle East, North Africa and even into Spain. By 750 AD, this Muslim empire replaced the Roman Empire as the dominant power in this region of the world. But what is less well-know is how the Muslims embraced the Greco-Roman culture they encountered. Conquest brings disparate civilizations together. Specifically, conquering Alexandria, Egypt, once the intellectual center of Hellenistic Greece, meant Muslim intellectuals had broad access to the greatest works of the classical world. They studied Hippocrates and Galen, translated them into Arabic, provoking advances in Muslin medicine. They translated Pythagoras and Euclid, leading to progress in Muslim math. Algebra and Algorithm are Muslim words, deriving from the titles of the works of one of Islam’s great mathematicians, Muhammad in Musa al-Khwarizmi, the greatest Muslim mathematician of the Middle Ages. They preserved the writings of Archimedes and Ptolemy, the father of map-making. The title of his famous work, The Almagest, comes from the Arabic word al-majesti.
The most important thinker Arabs encountered was Aristotle. Not all of Aristotle’s works were lost to the West after the fall of Rome, but many were. Most importantly his cosmology had fallen out of favor in the Christian West. Thanks to St. Augustine, Plato remained a highly reputable pagan philosopher, certainly more so in Church eyes than Aristotle because Plato believed in the immortality of the soul and posited the existence of an eternal, perfect realm, or idea. Aristotle loved the material world too much for most Church Fathers. He even believed in an infinite world without a creator. But he was beloved by Muslims, earning titles like The Wise Man and First Teacher. His scientific and empirical thought was transfused across the Muslim Empire in Arabic translations by Muslim philosophers like al-Kindi and al-Farabi, or as the Muslims called him, The Second Teacher. A Golden Age in Muslim intellectual history bloomed. By the turn of the first millennium, Muslim medicine, Muslim science and Muslim mathematics were the most advanced in the world.
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The Crusades (and the accompanying Reconquista of the Iberian Peninsula) changed all of this. For two hundred years, Christian soldiers voyaged eastward and into Spain, ostensibly attempting to free these areas from Muslim control, but in reality, opening Christian Europe to Muslim works. Or more precisely, they reacquainted Europe with her own culture heritage. After Muslim preservation, the works described above were translated from Arabic into the dominant European language, now Latin. Literally thousands of manuscripts appeared, quite an impressive number before the printing press. Abelard of Bath (b.1075), for example, completed translations of al-Khwarizmi and Euclid from Arabic into Latin. Gerard of Cremona (b.1114) translated dozens of works, including Ptolemy’s Algamest. And Averroes (b. 1126) remains an important figure in the history of Western thought for his popularization of Aristotle. This was a turning point in Western intellectual history because it ignited what historians have labeled as a “Twelve Century Renaissance” during which time the works of the above authors were recovered, translated and studied. It may not be as famous as the subsequent fifteenth and sixteenth century Renaissance centered in Florence, Italy, but it laid the foundation for the latter. Europe was about to become a center for science, math and philosophy once again.
Specific examples include Robert Grosseteste (b.1175), Roger Bacon (b.1214) (not too be confused with Francis Bacon) and Leonardo Fibonacci (b.1170). Grosseteste was an Oxford don who trained Franciscans in the rigors of university theology. Deeply influenced by Aristotle, Grosseteste studied math, astronomy, and light. Furthermore, he may have been the first Christian European to engage in serious experimentation in six hundred years. His most famous disciple was Bacon, a Franciscan himself. He experimented with gunpowder, explained how it should be manufactured and noted its potential on the battlefield. Bacon believed knowledge of nature promoted technological development, five centuries before the Scientific and subsequent Industrial Revolution. He and Grosseteste are the fathers of the English scientific tradition that culminated in the works of Francis Bacon, Robert Boyle and Isaac Newton.
Fibonacci was one of the great mathematicians of the Middle Ages. His father was part of the burgeoning Italian merchant class that emerged during the Crusades. More traveling led to more roads, thereby promoting trade. A thriving economic system linked North Africa and the Middle East with India and China, but to a large degree, Europe lay on the periphery, at least until the Crusades. Fibonacci actually traveled around North Africa (a phenomena less frequent before the Crusades), studied Muslim mathematicians like the aforementioned al-Khwarizmi and made important contributions to European mathematics. Partially thanks to Fibonacci’s Liber Abaci (1202), we no longer use Roman numerals, but the more efficient and precise Arabic-Hindu numbering system that includes the decimal point.
But it was the newly recovered Aristotle that created the most intellectual ferment in the wake of the Crusades. His ultimate acceptance required his ideas be fused with Catholicism, especially his emphasis on logic, which many believed threatened the Catholic emphasis on faith. The first to attempt systemization was Peter Abelard, who may have been the greatest genius of the twelve century, as well as its most controversial figure. He was always armed with texts of Aristotle, some of which had recently been translated from Arabic to Latin. Abelard was probably the most qualified yet least able to reintroduce Aristotle to the Western world. He was a clergyman, but it was not in his nature to follow the rules.
In his most famous work, Sic et Non, Abelard tried to show how Aristotelian logic could be applied to religious issues by taking dozens of contradictory statements from Church fathers. He studied ideas of Church fathers—such as whether Jews had committed a mortal sin when they surrendered Jesus to the Romans—and demonstrated disagreements among them. Some said yes, some said no. Abelard insisted these were merely intellectual exercises, but to his critics, he was intentionally showing inconsistencies. They were probably right. Few in history have antagonized like Abelard and he had many enemies in many places. (His illicit and famous affair with Heloise only underscores this.) He was even briefly excommunicated from the Church and his works were banned. Furthermore, Abelard’s efforts on behalf of Aristotle scandalized many faithful. This debacle meant the synthesis of Aristotle with Christianity would have to wait another one-hundred years.
Enter Catholicism’s greatest philosopher of the second millennium, St. Thomas Aquinas. Aquinas refused to believe that faith and reason were two irreconcilable fields of inquiry. Although Aquinas explicitly condemned some of Aristotle’s positions, such as his belief in an infinite world, Aquinas’ epistemological method combined Aristotelian logic and his emphasis on the material world: Aquinas reasoned that everything, including the physical world, must have a first cause or creator, for how can anything exist without a first cause? He used logic to refute atheism. He engages in natural theology, or the study of God through reason and observation, not just faith: “The existence of God and other like truths about God, which can be known by natural reason, are not articles of faith, but are preambles to the articles; for faith presupposes natural knowledge, even as grace presupposes nature and perfection the perfectible.” (Thomas Aquinas, Summa Theologica, Article 2, Reply to objection 1.) Religious truths can be discovered from observation, even without Scripture or faith. Theology and philosophy are united. Even though Aquinas never would have classified himself as an Aristotelian, without Aristotle, there never would have been Aquinas.
Moreover, following Aristotle, Aquinas saw no problem with accumulating wealth. The poor man is no holier than the rich man if the latter uses his wealth to help others. Refuting the deeply ascetic Franciscans, the Dominican Doctor contends that poverty by itself is not a virtue. To some degree, Aquinas is merely responding to the nascent capitalism in post-Crusades Europe. By the thirteenth century, a scientific-materialism has entered the Western intellectual and cultural tradition. It has never left.
Intellectual revitalization is the real significance of the Crusades. Fields like science, mathematics and philosophy made more progress in the twelve and thirteenth centuries than in the preceding six centuries combined. The Black Death momentarily curbed intellectual growth in the fourteenth century, but by the fifteenth century, Europe was poised to become the world’s dominant civilization.