  In this paper we discuss various problems, associated to temporal phenomena.
These problems include persistence and change, the integration of objects and
processes, and truth-makers for temporal propositions. We propose an approach
which interprets persistence as a phenomenon emanating from the activity of the
mind, and which, additionally, postulates that persistence, finally, rests on
personal identity. The General Formal Ontology (GFO) is a top level ontology
being developed at the University of Leipzig. Top level ontologies can be
roughly divided into 3D-ontologies, and 4D-ontologies. GFO is the only top
level ontology, used in applications, which is a 4D-ontology admitting
additionally 3D objects. Objects and processes are integrated in a natural way.
