  One thing is certain: it is hard to resist comparing the scientific ideas of a medieval scholar to those of later thinkers, even when one is vehemently opposed to doing so. Another debate that has arisen over Marchia’s scientific theories further illustrates this. One of the most important innovations of the mature Galileo was the assertion that the celestial and terrestrial realms are made of the same fundamental matter and therefore follow the same basic natural laws. In the book that inaugurated the renaissance, or rather birth, of Marchia studies, Notker Schneider declared that Francis of Marchia put forth a hypothesis similar to Galileo’s in his commentary on book II of the Sentences, qq. 29–32 (Schneider 1991). On the basis of texts he himself edited, Schneider maintained that, contrary to contemporary Aristotelian theory, Marchia argues that the heavens are not made up of matter so completely different from terrestrial matter that it radically differentiates the supralunar realm from the sublunar one. On the contrary, the basic matter is the same everywhere, and just as Marchia considers the natural world to follow predictable patterns, he also thinks that those patterns are universally applicable. These two tenets have important implications for the practice of natural philosophy (Schneider 1991).