 In the Metaphysical Foundations, in particular, Kant articulates a specific realization of the Analogies of Experience in terms of the Newtonian theory of universal gravitation. Kant’s three “laws of mechanics” (a version of the Newtonian laws of motion: compare notes  12  and  32  above) correspond to the three principles of the Analogies; the categories of substance, causality, and community are realized by the system of Newtonian massive bodies interacting with one another in the context of what Newton, in Book III of the Principia, calls the System of the World. The category of substance, that is, is realized by the conservation of the total quantity of matter (mass) in all interactions involving these bodies (compare  note 43  above, together with the sentence to which it is appended); the category of causality is realized by the gravitational forces through which these interactions take place (in accordance with the law of inertia); and the category of community is realized by the circumstance that precisely these forces are everywhere mutually equal and opposite. The temporal relation of duration is thereby realized by the progressive empirical procedure by which we successively correct our ordinary measure of time in light of our evolving astronomical knowledge (compare  note 44  above, together with the sentence to which it is  appended).[45]  The temporal relation of succession is realized by the deterministic evolution of the motions of the bodies (masses) in question described by the law of universal gravitation (according to which every later state of the system is uniquely determined by its earlier  states).[46]  The temporal relation of simultaneity, finally, is realized by the circumstance that gravitational forces instantaneously connect each body in the system with all other  bodies.[47]  It is in precisely this sense that the procedure of time determination Kant describes in the Analogies is intended to replace the conception of a pre-given absolute time.