J 8 A VIS INERTIAE &C.

impulse of other matter, he affirms a directcontradiction: for both the kinds of matter inhis supposition (the matter impelling, and thematter impelled) must be supposed to rests inthis very impulse, or to resist internally, other-wise the impulse could have no effect. Thusit appears it is not in an adversary’s power tosuppose matter resisting otherwise than byits internal constitution, or as it is a solidextended substance. And if we shouldsuppose the power of an immaterial Beingconstantly exerted upon matter, to makeit a resisting substance ; this can be no otherway than as his power is constantly exert-ed upon it, to make it a solid substance.Therefore I conclude, as before, sihat re-sistance, or a vis inertiæ, is inseparable frommatter ; or is as efj'ential a property of it assolidity. And therefore all the reasoningfrom the beginning of the section hitherto,*so far as it was conditional, or depended up-on proving that the vis inertiæ was essen-tial to matter becomes now absolute and de-monstrative. And whatever other truths,or consequences, can be fairly drawn fromthis principle hereafter, must be such as wemay confidently rely upon.

SECT.