THE MOTION OF THE EARTH. 9 



Motion depends upon certain external disturbing and 

 directing forces acting upon all matter; and, conse- 

 quently, as every. mode of action is determined by some 

 excitement external to the body moved, motion cannot, 

 philosophically, be regarded otherwise than as a pecu- 

 liar affection of matter under determinable conditions. 

 " We find," says Sir Isaac Newton, " but little motion 

 in the world, except what plainly flows from either the 

 active principles of nature, or from the command of the 

 wilier."* 



" I demand how there comes to bo local motion in the world ? 

 For either all the portions of matter that compose the universe 

 have motion belonging to their natures, which the Epicureans 

 affirmed for their atoms, or some parts of matter have this motive 

 power, and some have not, or else none of them have it; but all 

 of them are naturally devoid of motion. If it be granted that 

 motion does naturally belong to all parts of matter, the dispute is 

 at an end, the concession quite overthrowing the hypothesis. 



" If Mr. Hobbes should reply that the motion is impressed 

 upon any of the parts of matter by God, he will say that which 

 I most readily grant to be true, but will not serve his turn, if he 

 would speak congruously with his own hypothesis. For I demand 

 whether this Supreme Being that the assertion has recourse to, be 

 a corporeal or an incorporeal substance ? If it be the latter, and 

 yet the efficient cause of motion in bodies, then it will not be uni- 

 versally true that whatever body is moved is so by a body conti- 

 guous and moved. For, in our supposition, the bodies that God 

 moves, either immediately or by the intervention of any other 

 immaterial being, are not moved by a body contiguous, but by an 

 incorporeal spirit." Some Considerations about the Reconcile able- 

 ness of Reason and Religion : Boyle, vol. iii. p. 520. 



* Boyle has some ingenious speculations on this point : 



" That there is local motion in many parts of matter is manifest 

 to sense, but how matter came by this motion was of old, and is 

 still, hotly disputed of: for the ancient Corpuscularian philoso- 

 phers (whose doctrine in most other points, though not in all, we 

 are the most inclinable to), not acknowledging an author of the 

 universe, were thereby reduced to make motion congenite to 

 matter, and consequently coeval with it. But since local motion, 

 or an endeavour at it, is not included in the nature of matter, 

 which is as much matter when it rests as when it moves ; and 

 since we see that the same portion of matter may from motion be 



