Hi, Inertial mass can be understood as the resistance to change motion. Gravitational mass exerts a pull on every other object (and as a result of action-reaction force law also on itself). It has been shown by experiment that both mass concepts are the same. But it looks strange that one quantity is a resistance to motion and cause of motion at the same time. Would it not be more logical to assume that there exists a natural motion of scattering all things and that mass is a reverse motion (a kind of friction) that resists this natural motion of scattering.