SOURCE: "Euclid's Optics in the Medieval Curriculum," in Archives Internationales D'Histoire des Sciences, Vol. 32, 1982, pp. 159-76.

In the following excerpt, Theisen discusses the impact of Euclid's Optica on Western scholars in the twelfth and thirteenth centuries and maintains that by the thirteenth century, a "firm tradition " of the critical analysis of Euclid's text was established.

Defending the utility of a liberal education, John Henry Newman stressed the advantages of learning " … to think and to reason and to compare and to discriminate and to analyze …"¹. Newman's words are an apt description of one of the chief aims of the medieval curriculum, the formation of a discriminating, critical mind. Although it is true that medieval students were concerned primarily with studying the texts of great writers like Euclid, Aristotle and Boethius, they were encouraged, indeed generally constrained, to work their way through a text in a critical fashion. The medieval...