All bodies are either in motion or at rest. Every body is moved sometimes more slowly, sometimes more quickly. Bodies are distinguished from one another in respect of motion and rest, quickness and slowness, and not in respect of substance . The first part of this proposition is, I take it, self-evident. It is brought out still more clearly from E1P15N .
All bodies agree in certain respects.
Further, in the fact that they may be moved less or more quickly, and may be absolutely in motion or at rest. A body in motion or at rest must be determined to motion or rest by another body, which other body has been determined to motion or rest by a third body, and that third again by a fourth, and so on to infinity. And this body again can only have been set in motion or caused to rest by being determined by a third body to motion or rest. This third body again by a fourth, and so on to infinity. This is indeed self-evident.