Abstract
Process philosophy endeavors to replace the classical ontology of substances by a process ontology centered on the notions of change and transition. We argue that the substantial and processual approach are mutually complementary in the sense of a generalized quantum theory which is not limited to physical phenomena. From this point of view, restricting oneself to either substance ontology or process ontology would be as ill-advised as exclusively relying on position or momentum representations in physics. A new view on Zeno's paradox lends itself. The meaning of a 'mental energy' observable, complementary to 'internal time', and its relationship to acategorial states of the human mind will be tentatively discussed.