  (1) As we noted above, the physics of the TMA assigns to bodies no  resistance to motion, and thus predicts that under idealized  conditions it should be no harder to move something massive than  something minuscule. In distancing himself from this early view,  Leibniz comes to argue that, in fact, matter “resists being  moved through a certain natural inertia it has … so  that it is not indifferent to motion and rest, as is commonly  believed, but requires more active force for motion in proportion to  its size” (G IV.510/AG 161). In short, Leibniz came to maintain that bodies have an intrinsic power resistant to motion, which he  calls, following Kepler, “natural inertia.”  Significantly, Leibnizian natural inertia is a force which is opposed to motion itself, and not merely, as Newton held, to changes in  velocity. Thus, while Newton maintains that no active force is  required to keep a body moving with a constant velocity under  idealized conditions, Leibniz maintains that a body in motion in the  absence of any countervailing active force will naturally come to  rest. 