The Ontological Category is the fundamental concept for understanding the nature of physical (as opposed to merely formal) being. This category—here called Force—is parsed in terms of the quantum mechanical complementarity of Energy and Time, and represents that "je ne se qua" that is tantamount to the impermeability of physicality. In terms of the categorial triad (and in accord with modern Physics), Force is defined as "the time rate-of-change of energy" (that is, as the Transformation of Energy through Time). And analogously in Ontology, Force represents the active, dynamic physical aspect of Being: that which allows for (and is tantamount to) that mysterious quality of "the tangibility of specific beings".
The complementarity of Energy and Time, then, permits the free creativity of Nature or Physis, in which of course any actuality of Energy is possible if it occurs quickly enough, but which is less likely the longer the aspect of Time comes into play. For instance, any of the particle/anti-particle pairs of standard Physics may spontaneously erupt from Energy "borrowed" from the Void and manifest as virtual particles, but they must quickly anihilate each other before symmetry-laws (conservation-laws) are broken. In fact, under this scenario, whole "Universes" may spontaneously erupt into Time-reversible existence, as long as they do so very briefly (to put it mildly). And ultimately even "permenant" universes—Universes that involve Time-irreversible processes, as is the case for our universe—may be produced in this way, as long as the total Energy borrowed from the Void amounts to zero (as Physics defines this). And this is precisely the case for our own universe.