 Perdurance theorists, as Quine puts it, reject the point of view inherent in the tenses of our natural language. From that point of view persisting things endure and change through time, but do not extend through time, but only through space. Thus persisting things are to be sharply distinguished from events or processes, which precisely do extend through time. One way of describing the position of the perdurance theorist, then, is to say that he denies the existence of a distinct ontological category of persisting things, or substances. Thus, Quine writes, “physical objects, conceived thus four-dimensionally in space-time, are not to be distinguished from events, or, in the concrete sense of the term, processes. Each comprises simply the content, however heterogeneous, of some portion of space-time, however disconnected and gerrymandered” (1960:171).