174 ELEMENTARY PROPERTIES 



causes by which the effects are produced, 

 which he has described. 



SIR ISAAC NEWTON supposed, " that the ori- 

 ginal construction of matter was solid, massy, 

 impenetrable ; that these solid primitive parti- 

 cles are incomparably harder than any porous 

 bodies composed of them, and that they were 

 so hard, as never to break in pieces. While 

 the particles continue entire, they may com- 

 pose bodies of one and the same nature and 

 texture, in all ages ; but should they wear 

 away, or break in pieces, the nature of all 

 things, depending on them, would be changed. 

 Water and earth composed of old worn-out 

 particles, and fragments of particles, would 

 not now be of the same texture with water and 

 earth composed of. entire particles in the be- 

 ginning; and, therefore, in order that nature 

 may be lasting, the change of corporeal things 

 is to be placed in the various separations, and 

 new associations and motions of these perma- 

 nent particles ; compound bodies being apt to 

 break, not in the midst of solid particles, but 

 when these particles are laid together, and 

 touch in a few parts. These particles have not 

 only a vis inertia accompanied with such laws 

 of motion as naturally result from that force, 

 but also are moved by certain active principles ; 

 a.s gravity, and that which causes the fermenta- 



