2p13ax2a.md (536B)
1 When a body in motion impinges on another body at rest, which it is unable to 2 move, it recoils, in order to continue its motion, and the angle made by the 3 line of motion in the recoil and the plane of the body at rest, whereon the 4 moving body has impinged, will be equal to the angle formed by the line of 5 motion of incidence and the same plane. 6 7 So far we have been speaking only of the most simple bodies, which are only 8 distinguished one from the other by motion and rest, quickness and slowness. We 9 now pass on to compound bodies. 10 11