Matter--Dynamic and Inert

According to Kant's representation of Newtonian Physics, a body is both 1. 'dynamic', insofar as it is constituted by internal repulsive and attractive forces, and 2. 'inert', insofar as it can be moved only by an external force.  So, one challenge to Newton is to explain how his deus ex machina manages to function from within Matter, which the imparting to the latter of a repulsive force would seem to entail.  For, Kant, whether a fundamental particle is dynamic, or is inert, seems reducible to the question of whether there exists a further irreducible particle, i. e. to a dialectical antinomy.  However, to allow even the possibility of a particle moving itself would seem to disrupt the fundamental premise of his Freedom-Nature distinction.  An alternative resolution to the apparent dynamic-inertia conflict is to infer from the former that Matter is not essentially independent of Force, but is itself a product of it, e. g. of Repulsion and Attraction in equilibrium, with respect to which, Inertia is a derivative characteristic.  Subsequent developments in sub-atomic Physics have tended to confirm that alternative.