CHAPTER ONE

Corollary 1.

3. Therefore, when a body original: "corpus" encounters an obstacle in its motion and, for that reason, cannot maintain the direction in which it is tending, it must then either come to rest or continue its motion in another direction.

Corollary 2.

4. In what direction the body proceeds after encountering the obstacle must be judged from the circumstances of both the motion and the position of the obstacle itself.

Scholion 2.

A "scholion" is an explanatory note or commentary used in historical scientific texts to provide further context for a definition or theorem.

5. It might appear that this doctrine pertains to the motion of bodies resulting from impact original: "ex percussione"; refers to the physics of bodies colliding and bouncing off one another, a subject which will not be dealt with in this book. In this volume, we assume obstacles of a different kind that do not require that specific knowledge of impact. These obstacles are continuous, restricting the motion of a point without allowing for any reflection meaning the body does not "bounce" off, but follows the surface; an example of this is a tube or a channel, whether straight or curved, in which a small body original: "corpusculum" must continue its motion. In this case, the path the body will follow is completely prescribed, and because of the firmness of the tube, it will be unable to exit from it. Therefore, since we are considering a point original: "punctum" in place of a body here, by this arrangement, the point must move along a given line and will not be able to depart from it.

Scholion 3.

6. In this book, we shall treat two species of impeded or restricted motion, the first of which
mo- Catchword for the next page, likely continuing "motus" (motion).