 The fact that the force of movement can be applied to different bodies appears as the crucial point in La Forge’s argument. However, it might be asked why we should grant that the force is separable from the body and can be transferred. In the end, what prevents us from claiming that even the force is a modification of the body and thus cannot be separated from it? La Forge seems well aware of this problem and proposes a reductio ad absurdum to support this point: