SUBJECTIVE AND OBJECTIVE METHODS 



there must be some unknown force acting in 

 composition with their momentum. What is 

 that unknown force ? That it was the same as 

 the force which causes apples to fall, that it va- 

 ried in amount in an inverse ratio to the square 

 of the distance between the sun and the planet, 

 and would therefore cause acceleration or re- 

 tardation of velocity according as the planet in 

 its elliptic path approached or receded from the 

 sun, — all this was a most brilliant hypothesis, 

 alleging no unverifiable agency, disposing of the 

 unexplained residual phenomena, and making 

 the Keplerian order of conceptions completely 

 congruous. According to the subjective method, 

 this was quite enough. And doubtless if New- 

 ton's mind had been constructed like Hegel's, 

 he would at once have announced his discovery 

 on the strength of its presumed subjective ne- 

 cessity, and would have left it for some other 

 more patient inquirer to verify its truth. But 

 Newton, rigorously adhering to the objective 

 method, saw that this was not enough. No 

 matter how perfectly congruous the subjective 

 order of conceptions may be in itself, it must be 

 confronted with the observed order of pheno- 

 mena and be shown to be congruous with that. 

 According to the hypothesis the moon must be 

 deflected on the average fifteen feet each minute 

 from its natural rectilinear path. But Newton's 

 own observations showed that this is not the 

 163 



