Zhu Xi didn’t feel the need to formulate a theory of motion as such either, because the factors were glossed in his commonsense grasp of the world and he didn’t see any advantage in explicating them. Importantly, he couldn’t conceive of their theoretical ramifications or especially of their practical implications, such as for engineering and technology. At the same time, Zhu did have a grasp of inertia and the relativity of motion, keys to solving the problems of motion, but it was not adequate