But if, instead of occupying ourselves with that which has no foundation, unless in ordinary usage, we desire to know what ought to be understood by motion according to the truth of the thing, we may say, in order to give it a determinate nature, that it is the transporting of one part of matter or of one body from the vicinity of those bodiesthat are in immediate contact with it, or which we regard as at rest, to the vicinity of other bodies. By a body as a part of matter, I understand all that which is transferred together, although it be perhaps composed of several parts, which in themselves have other motions; and I say that it is the transporting and not the force or action which transports, with the view of showing that motion is always in the movable thing, not in that which moves; for it seems to me that we are not accustomed to distinguish these two things with sufficient accuracy. Farther, I understand that it is a mode of the movable thing, and not a substance, just as figure is a property of the thing figured, and repose of that which is at rest.
- When are two things are really distinct? How can we know that they are distinct?
- What kind of distinction holds between a substance and its essence—real, conceptual (a distinction of reason), or modal?
- Aristotle gave several criteria for substance-hood. What criterion does Descartes give? Is it the same as Aristotle’s?