The 16th and 17th centuries witnessed a philosophical shift that would help pave the way for modern science, a shift from metaphysical theories of material objects to other views embracing only the empirically-accessible parts of material things. One much-debated topic in the course of this shift was regarding prime matter. The late scholastic Jacobus Zabarella (1533-1589) arrived upon his views about prime matter via his version of the regressus method, a program for a sort of scientific reasoning. In his De (...) rebus naturalibus, Zabarella defends the position that prime matter is extended. However, it is less clear how he accounts for its extension. There is an important text where he apparently suggests that prime matter is extended in and of itself. However, there are two other texts apparently stating that matter is extended in virtue of a distinct accident in the category of quantity. I argue that a decisive reading based solely upon any particular texts is not available. Nevertheless, examining Zabarella’s writing on the topic as a whole, the trajectory of his overall argument is remarkably sympathetic to Averroes, who famously took the accidentally quantified position. Thus, from this systematic feature, the accidentally quantified reading is more reasonable. (shrink)