26 HISTORY OF MECHANICS. 



faculties by which such science is rendered possible, 

 and suitable to man's intellectual nature. 



The induction by which the First Law of Mo- 

 tion is established, consists, as induction consists 

 in all cases, in conceiving clearly the Law, and in 

 perceiving the subordination of Facts to it. But 

 the Law speaks of bodies not acted upon by any 

 external force, a case which never occurs in fact; 

 and the difficulty of the step consisted in bringing 

 all the common cases in which motion is gradually 

 extinguished, under the notion of the action of a 

 retarding force. In order to do this, Hooke and 

 others showed that, by diminishing the obvious 

 resistances, the retardation also became less; and 

 men were gradually led to a distinct apprecia- 

 tion of the Resistance, Friction, &c., which, in all 

 terrestrial motions, prevent the Law from being 

 evident; and thus they at last established by ex- 

 periment a Law which cannot be experimentally 

 exemplified. The natural uniformity of motion was 

 proved by examining all kinds of cases in which 

 motion was not uniform. Men culled the abstract 

 Rule out of the concrete Experiment ; although 

 the Rule was, in every case, mixed with other 

 Rules, and each Rule could be collected from the 

 Experiment only by supposing the others known. 

 The perfect simplicity which we necessarily seek 

 for in a law of nature, enables us to disentangle 

 the complexity which this combination appears at 

 first sight to occasion. 



