 But while such developments mark a break with the Aristotelian tradition of a purely qualitative physics, they remain largely theoretical. While the discussions giving rise to the mean speed theorem emerged from everyday observations of falling bodies, the theorem itself was proven arithmetically and geometrically (Clagett 1959: 256, 259–60). The principles developed were not “operationalized,” that is to say, expressed in forms that would allow for experimental testing (Clagett 1959: 206). Their experimental testing had to await Galileo’s inclined plane experiments (Crombie 1961: 153–54).