In the Principles of Philosophy (1644), part II, Descartes introduces a distinction between “space or internal place,” which he equates with “the size and shape of a body” and “external place,” defined as “the surface immediately surrounding what is in the place.” The latter definition looks at first sight very similar to the one found in Aristotle's Physics IV, 4, where place is identified with the limiting surface of the surrounding body.

In the Rules for the Direction of the Mind (1628), Descartes had explicitly taken issue with the Aristotelian notion of place on the ground that “the surface of the surrounding body can change, even though I do not move or change my place; conversely, it may move along with me, so that, although it still surrounds me, I am no longer in the same place” (AT X 427, CSM I 49; cf. AT X 433, CSM I 53). In the Sixth Replies, Descartes endorsed the Aristotelian definition of place but avoided the difficulty raised in the Rules by defining “surface” not as a substance, but as a mode, which “cannot be a part of a body.” This means that “the place where a tower is does not change even though the air which surrounds it is replaced, or even if another body is substituted for the tower” (AT VII 433–34, CSM II 292–93).

Similarly, in the Principles II.15 one reads that “surface” does not mean “any part of the surrounding body, but merely the boundary between the surrounding and surrounded bodies, which is no more than a mode” and which “is always reckoned to be the same provided it keeps the same size and shape” (AT VIIIA 48–49, CSM I 229). But given that in Principles II.10 the “size and shape” of a body are identified with its internal place, it would seem as if the external place could change only if the internal place also changes. According to Thomas Lennon, Descartes maneuvers himself into an Eleatic position: “Motion occurs with change in external place; external place changes when there is change in internal place; but change in internal place is impossible…. Hence there is no real motion” (Lennon 2007, 37–38). In Principles II.10 and II.12, however, Descartes explains that there is a sense in which the internal place of a body can be said to change.