Gassendi bases natural philosophy on three principles, as many Aristotelian philosophers did. However, for the three Aristotelian principles matter, form, and privation, he substitutes space, time, and the atoms that constitute material bodies and whose motion constitutes their causality. The claim that space exists independently of bodies is necessary for Gassendi's atomism: Atoms move through the void, so independent space was a feature of both Democritean and Epicurean atomism. Gassendi also holds that time has a “remarkable parallelism” (1.133a) with space, and hence construes time as well as space as having an absolute existence independent from bodies or their motion. This is rather more novel, and it is nowhere near as clear that Gassendi's atomism requires absolute time. I begin by discussing space, time, and the void; in the next chapter, I move on to the world and the atoms that compose it.

Space, Place, and Vacuum

The terms space, place, and vacuum or void were widely used in ancient and medieval philosophy. Aristotle takes place as the primary notion and defines void as “place with nothing in it.” Because he concludes that the void is impossible, space and place end up being the same thing. Gassendi reverses the direction of argument, first arguing for the possibility and existence of space distinct from the place of any body and then for the existence of void space.