During the Middle Ages in Europe, philosophical study was restricted to the monasteries, where it was rigidly controlled by the Holy Roman Church. The basic teachings that emerged from these strict confines focused on how people should quietly accept their lot in life, no matter how seemingly awful or unfair, so that they could concentrate on their spiritual growth. Life on earth was described as a kind of hell to be endured so that people might later enjoy their heavenly rewards.

Two events started the changes that would soon sweep aside this medieval way of thinking. First, the introduction of the printing press in 1451 made new philosophies about the world, as well as criticisms of the old philosophies, available to a larger audience. Second, in 1453 Muslims expelled Greek scholars from Constantinople who brought the classical Greek texts with them to Europe. These texts, including...