68 A VIS INERTIAS I

I fay, upon this supposition, from one place Ito another; for if we went on all four, as the Iquadrupeds do, there is manifestly a fujhing , Iand rejijianpe , to advance the center of gra-1vity of the body, in that cafe as in the former*»Or if we successively thrust forward our head,and the fore parts of our bodies and draggedup the feet and hind parts of them, as mubtipedous insects and worms do; besides theformer resistance between the earth and thematter of our bodies, this supposes a resistancebetween the parts of our bodies themselves*When the lumbricus thrusts forward thefore part of its body, it is by the resistance be^tween it and the hind part. How could thi*he, if matter were unresisting matter ? Theparts counteracting each other, must sink in,and penetrate into one another’s dimensions)or else remain in that state, motionless, andwithout possibility of advancing. In that cafe,when we thrust forward our hand (ifcould thrust it forward) to catch any thin$fixed and prominent, to help to drag up tlfjrest of the body, every thing must yield >

num super glacUfy. Prop. 168, Anlmalla sexttpediamodel incedant ; & prop, 13. part 2. £hto artiscionico lumbrici repere pojsint. It is evident also from ^seasoning, that fpwjs could not fly, nor fishes swim, 'the air and water did not afford them resistance- " ,

prop, 190 & 214- pqrt 1, astO