166 HISTORY OF PHYSICAL ASTRONOMY. 



by the fall of an apple. The popular mind is caught 

 by the character of an eventful narrative which the 

 anecdote gives to this occurrence ; and by the anti- 

 thesis which makes a profound theory appear the 

 result of a trivial accident. How inappropriate is 

 such a view of the matter we shall soon see. The 

 narrative of the progress of Newton's thoughts, is 

 given by Pemberton (who had it from Newton him- 

 self) in his preface to his View of Newton s Philoso- 

 phy, and by Voltaire, who had it from Mrs. Conduit, 

 Newton's niece 5 . "The first thoughts," we are told, 

 " which gave rise to his Principia, he had when he 

 retired from Cambridge, in 1666, on account of the 

 plague, (he was then twenty-four years of age.) As 

 he sat alone in a garden, he fell into a speculation 

 on the power of gravity ; that as this power is not 

 found sensibly diminished at the remotest distance 

 from the center of the earth to which we can rise, 

 neither at the tops of the loftiest buildings, nor 

 even on the summits of the highest mountains, it 

 appeared to him reasonable to conclude that this 

 power must extend much further than was usually 

 thought : Why not as high as the moon ? said he to 

 himself; and if so, her motion must be influenced by 

 it ; perhaps she is retained in her orbit thereby." 



The thought of cosmical gravitation was thus 

 distinctly brought into being: and Newton's supe- 

 riority here was, that he conceived the celestial 

 motions as distinctly as the motions which took 



5 Etemens de Phil, de Newton, 3me partie, chap. iii. 



