THE GENESIS OF THE LAW OF GRAVITY 339 



What Newton accomplished in optics and in mathematics would 

 entitle him to high rank in the world of science. Of his work in 

 mathematics the German scholar, Leibnitz, said, " Taking mathematics 

 from the beginning of the world to the time when Newton lived, what 

 he had done was much the better half." 



The work included in the " Principia " was most of it done between 

 1680 and 1686. By far the greater part wa,8 done during the last two 

 years of this short period, or between the forty-second and forty-fourth 

 years of his age. This work, in its scope, in its far-reaching impor- 

 tance, and in the order of mind required for its accomplishment, raises 

 Newton not merely to the first rank of the world's great minds, but 

 compels the world to admit no second in his class. His genius shone 

 resplendent even in his own day. We have already quoted Leibnitz. 

 A French admirer wrote to an English correspondent, " Does Mr. 

 Newton eat, drink, sleep like other men? I picture him to myself 

 as a celestial genius, entirely removed from the restrictions of ordinary 

 matter." Says Lagrange (1736-1813), a great French mathematician, 

 " Newton was the greatest genius that ever existed, and the most 

 fortunate, for we can not find more than once a system of the world 

 to establish." The English writer, Whewell (1794-1866), writes, 

 " The (Law of Gravitation) is indisputably and incomparably the 

 greatest scientific discovery ever made, whether we look at the advance 

 which it involved, the extent of truth disclosed, or the fundamental 

 and satisfactory nature of this truth." Pope in a striking epigram 

 expresses the same thought : 



Nature and Nature's laws lay hid in night; 

 God said, Let Newton be, and all was light. 



La Place, who did much work along the lines laid down by Newton, 

 says of the " Principia " : " The universality and generality of the dis- 

 coveries it contains, the number of profound and original views respect- 

 ing the system of the universe it presents, and all presented with so 

 much elegance, will insure to it a lasting preeminence over all other 

 productions of the human mind." 



Sir Oliver Lodge says of Newton : " In science the impression he 

 makes upon me is only expressed by the words ' inspired,' * super- 

 human.' " 



Of his own work Newton says: "I know not what the world will 

 think of my labors, but to myself it seems that I have been but as a child 

 playing on the seashore; now finding some pebble rather more polished, 

 and now some shell rather more agreeably variegated than another, 

 while the immense ocean of truth extended itself unexplored before 

 me." "When asked how he made his discoveries, he replied : " By always 

 thinking unto them. I keep the subject constantly before me, and 



