32 ATTRACTION OF GRAVITATION. 



him to conjecture, that it might extend as far as the qjoon, 

 and be the means of retaining her in her orbit. Imagine 

 the moon, he reasoned, at the first moment of its creation, 

 to have been projected forward, with a certain velocity, in a 

 rectilinear direction ; then, as soon as it began to move, gra- 

 vity would act upon it, an<l impel it toward the centre of the 

 earth. But as a body, impelled by two forces, will follow the 

 direction of neither, the moon, so circumstanced, would 

 neither proceed directly forward, nor fall directly downward, 

 but keep a middle course, and move round the earth in a 

 curvilinear orbit. This may be more fully illustrated, by at- 

 tending to the motion of a shot, or any other projectile. A 

 ball, shot from the mouth of a cannon, in a horizontal direc- 

 tion, does not fall to the ground till it has proceeded to a 

 considerable distance ; and if it be discharged from the top 

 of a high mountain, it will fly still further before it comes to 

 the earth. Increase the force and the height, and the dis- 

 tance will be augmented accordingly. And thus, in imagi- 

 nation at least, we can suppose the ball to be discharged 

 with such velocity, that it will never come to the ground, 

 but return to the place whence it set out, and circulate con- 

 tinually round the earth, in the manner of a little moon. 

 Thus proceeding in his reflections, Newton discovered the 

 admirable provision of the great Creator to prevent the eva- 

 gation of the planets, and to retain them exactly within the 

 .bounds of tlieir orbits. This he has demonstrated to be ef- 

 fected by gravity^ and that gravity and motion completely 

 solve all the phenomena of the planetary revolutions, both 

 primary and secondary. By establishing this one principle 

 in philosophy he has fully explained the system of the world, 

 so far as it relates to this globe, and to all the rest of the pla- 

 nets that regard the sun as their centre. Such is the New^ 

 tonian system of universal gravitation or attraction. But 

 what is this principle, which gives life and motion to inani- 

 mate beings, and how does it act ? The effbcts are visible, 

 but the agent that produces them is hidden from our senses. 

 It eluded the search of Newton himself; he that soared to 

 the utmost regions of space, and looked through nature with 

 the eye of an eagle, was unable to discover it. This princi- 

 ple of gravitation, has been styled " The constant impression 

 of Divine power ;" — in every other sense the cause is likely 

 to continue unexplored by man. It is, however, pretty ge- 



