Chap. i. PHILOSOPHY.

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as to make any proof in form needless. But in philosophyno properties of bodies can be in this manner received for self-evident ; since it has been observed above, that we can con-clude nothing concerning matter by any reasonings upon itsnature and essence, but that we owe all the knowledge, wehave thereof, to experience. Yet when our observations onmatter have inform’d us of some of its properties, we may se-curely reason upon them in our farther inquiries into nature.And these laws of motion, of winch I am here to speak, arefound so universally to belong to bodies, that there is no mo-tion known, which is not regulated by them. These are bySir Isaac Newton reduced to three a .

4. T h e first law is, that all bodies have such an indifferenceto rest, or motion, that if once at rest they remain so, till di-sturbed by some power acting upon them : but if once putin motion, they persist in it; continuing to move right for-wards perpetually, after the power, which gave the motion,is removed; and also preserving the fame degree of velocityor quickness, as was first communicated, not stopping or re-mitting their course, till interrupted or otherwise disturbed bysome new power impressed.

5*. The second law of motion is, that the alteration of thestate of any body, whether from rest to motion, or from mo-tion to rest, or from one degree of motion to another, is al-ways proportional to the force impressed. A body at rest, when

* Princip. philos. pa'g. 13, 14.

acted