 Desiderius Erasmus of Rotterdam (1467?–1536) was not a systematic philosopher although we discern in the large body of his writings a certain Erasmian habit of mind. He often reflected on subjects that invite philosophical inquiry: the influence of nature versus nurture, the relationship between word and thing, the ideal form of government, the nature of faith, and the theory of knowledge. Erasmus’ views on these subjects are of interest to historians today, even if they are unstructured, because his works circulated widely and his influence in Northern Europe was pervasive. In modern parlance, he was an opinion maker. If a general label is needed, Erasmus’ thought is best described as “Christian Humanism”, that is, a philosophy of life combining Christian thought with classical traditions. He embraced the humanistic belief in an individual’s capacity for self-improvement and the fundamental role of education in raising human beings above the level of brute animals. The thrust of Erasmus’ educational programme was the promotion of docta pietas, learned piety, or what he termed the “philosophy of Christ”. As a biblical scholar he supported the humanistic call Ad fontes, a return to the texts in the original language and therefore promoted the study of the biblical languages Hebrew, Greek, and Latin. He was in the vanguard of modern philology. His pioneering edition of the Greek New Testament shows that he had an understanding of the process of textual transmission and had developed text-critical principles. In politics, Erasmus embraced consensus, compromise, and peaceful cooperation, ideals he recommended to the participants in the Reformation debate, albeit with little success. Considered a forerunner of the Reformation by his contemporaries, he broke with Martin Luther over the latter’s sectarianism. More fundamentally, the two men disagreed over heuristics and engaged in a polemic over the question of free will. Erasmus took a skeptical position vis-à-vis Luther’s assertions. Unlike the reformer, he did not believe in the clarity of Scripture and used consensus and tradition as criteria to settle questions that did not allow a rational conclusion. Erasmus rarely ventured into doctrinal questions, however, favoring simple faith and devotion over dialectics and scholastic speculation. The circulation of Erasmus’ works was temporarily curtailed when the Catholic Church put them on the Index of Forbidden Books, but his ideas saw a revival during the Enlightenment when he was regarded as a forerunner of rationalism. His most famous work, The Praise of Folly, has remained in print to the present day, a distinction shared by few books from the 16th century.