The medieval church had always been concerned about superstition. In the late fourteenth and early fifteenth centuries—the waning years, as some would have it, of the European Middle Ages—certain theologians and other clerical authorities became obsessed with it. Authors from Iberia to the Low Countries and from Paris to Vienna turned their attention to this topic, and particularly in the first half of the 1400s a wave of tracts and treatises explicitly de superstitionibus issued from their pens. For these men, superstition was a serious error, not the typically harmless foolishness that modern use of the term tends to convey. In the theology of the age, superstitio meant most basically an excess of religion, literally “religion observed beyond proper measure.” Since human beings could not possibly offer a superabundance of proper worship beyond what God, in his perfection, de-served, this excess necessarily implied improper religious rites and observances. Superstition meant either performing elements of the divine cult incorrectly or, worse still, offering worship to entities other than the Deity.