Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 1.djvu/32

Rh of univerals. the contitution of particular things is known by observations and experiments; and when that is done, it is by this rule that we judge univerally of the nature of uch things in general.

Since then all bodies, whether upon Earth or in the Heavens, are heavy, o far as we can make any experiments or obervations concerning them; we mut certainly allow that gravity is found in all bodies univerally. And in like manner as we ought not to uppoe that any bodies can be otherwie than extended, moveable or impenetrable; o we ought not to conceive that any bodies can be otherwie than heavy. The extenion, mobility and impenetrability of bodies become known to us only by experiments; and in the very ame manner their gravity becomes known to us. All bodies we can make any obervations upon, are extended, moveable and impenetrable; and thence we conclude all bodies, and thoe we have no obervations concerning, to be extended and moveable and impenetrable. So all bodies we can make obervations on, we find to be heavy; and thence we conclude all bodies, and thoe we have no obervations of; to be heavy alo. If any one hould ay that the bodies of the fixed Stars are not heavy becaue their gravity is not yet oberved; they may ay for the ame reaon that they are neither extended, nor moveable nor impenetrable, becaue thee affections of the fixed Stars are not yet oberved. In hort, either gravity mut have a place among the primary qualities of all bodies, or extenion, mobility and impenetrability mut not. And if the nature of things is not rightly explained by the gravity of bodies, it will not be Rh