  Augustine’s position would remain ascendant among Christian philosophers for most of the Middle Ages. Thirteenth-century Franciscans, led by figures such as Bonaventure (c.1217–1274) and Matthew of Aquasparta (c.1237–1302), gave the theory a detailed and systematic defense, focusing on the changeability and hence uncertainty of the human mind and the sensory world (see Marrone 2001). Bonaventure characteristically argues, 