Ill SCIENCE AND PSEUDO-SCIENCE 105 



unconnected facts." There is hardly a line in 

 these paragraphs which appears to me to be in- 

 disputable. But, to confine myself to the matter 

 in hand, I cannot conceive that any one who had 

 taken ordinary pains to acquaint himself with the 

 real nature of either Kepler's or Newton's work 

 could have written them. That the labours of 

 Kepler, of all men in the world, should be called 

 " mere observation and record,' 7 is truly wonderful. 

 And any one who will look into the " Principia," 

 or the " Optics," or the " Letters to Bentley," will 

 see, even if he has no more special knowledge of 

 the topics discussed than I have, that Newton 

 over and over again insisted that he had nothing 

 to do with gravitation as a physical cause, and 

 that when he used the terms attraction, force, and 

 the like, he employed them, as he says, " mathe- 

 maticb " and not " physicb" 



How these attractions [of gravity, magnetism, and electricity] 

 may be performed, I do not here consider. "What I call attrac- 

 tion may be performed by impulse or by some other means un- 

 known to me. I use that word here to signify only in a general 

 way any force by which bodies tend towards one another, what- 

 ever be the cause. 1 



According to my reading of the best authorities 

 upon the history of science, Newton discovered 

 neither gravitation, nor the law of gravitation ; 

 nor did he pretend to offer more than a conjecture 

 as to the causation of gravitation. Moreover, his 



1 Optics, query 31. 



