 Some scholars might wish to describe what Galileo achieved in psychological terms, as an introduction of new mental models (Palmieri 2003) or a new model of intelligibility (Machamer 1994; Machamer, 1998a; Adams, et al. 2017). However phrased, Galileo’s main move was to dethrone the Aristotelian physical categories; namely, the one celestial element (aether, or quintessence—i.e., “fifth element”) and the four terrestrial ones (fire, air, water, and earth), along with their respective motive natures (circular, and up and down). In their place, he left only one element, corporeal matter, whose properties and motions he described using the mathematics of proportional relations typified by the Archimedian simple machines—the balance, the inclined plane, and the lever—to which Galileo added the pendulum (Machamer 1998a; Machamer and Hepburn 2004; Palmieri 2008). In doing so, Galileo changed the acceptable way of talking about matter and its motion, and so ushered in the mechanical tradition that characterizes so much of modern science, even today. See Dijksterhuis 1961; Machamer, et al. 2000; Gaukroger 2006; Roux and Garber 2013.