INDUCTIVE EPOCH OF NEWTON. 187 



Reflections on the Discovery. Such, then, is the 

 great Newtonian Induction of Universal Gravitation, 

 and such its history. It is indisputably and incom- 

 parably the greatest scientific discovery ever made, 

 whether we look at the advance which it involved, 

 the extent of the truth disclosed, or the funda- 

 mental and satisfactory nature of this truth. As to 

 the first point, we may observe that any one of the 

 five steps into which we have separated the doc- 

 trine, would, of itself, have been considered as an 

 important advance ; would have conferred distinc- 

 tion on the persons who made it, and the time to 

 which it belonged. All the five steps made at once, 

 formed not a leap, but a flight, not an improve- 

 ment merely, but a metamorphosis, not an epoch, 

 but a termination. Astronomy passed at once from 

 its boyhood to mature manhood. Again, with re- 

 gard to the extent of the truth, we obtain as wide a 

 generalization as our physical knowledge admits, 

 when we learn that every particle of matter, in all 

 times, places, and circumstances, attracts every 

 other particle in the universe by one common law 

 of action. And by saying that the truth was of a 

 fundamental and satisfactory nature, I mean that it 

 assigned, not a rule merely, but a cause, for the 

 heavenly motions; and that kind of cause which 

 most eminently and peculiarly we distinctly and 

 thoroughly conceive, namely, mechanical force* 

 Kepler's laws were merely formal rules, governing 

 the celestial motions according to the relations of 



