INDUCTIVE EPOCH OF NEWTON. 415 



the five steps made at once, formed not a leap, but a flight,- not ai. 

 improvement merely, but a metamorphosis, not an epoch, but a ter- 

 mination. Astronomy passed at once from its boyhood to mature man- 

 hood. Again, with regard 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. Kep- 

 ler's laws were merely formal rules, governing the celestial motions ac- 

 cording to the relations of space, time, and number ; Newton's was a 

 casual law, referring these motions to mechanical reasons. It is no 

 doubt conceivable that future discoveries may both extend and further 

 explain Newton's doctrines ; may make gravitation a case of some 

 wider law, and may disclose something of the mode in which it oper- 

 ates ; questions with which Newton himself struggled. But, in the 

 mean time, few persons will dispute, that both in generality and pro- 

 fundity, both in width and depth, Xewton's theory is altogether with- 

 out a rival or neighbor. 23 



The requisite conditions of such a discovery in the mind of its author 

 were, in this as in other cases, the idea, and its comparison with facts ; 

 the conception of the law, and the moulding this conception in such 

 a form as to correspond with known realities. The idea of mechanical 



23 The value and nature of this step have long been generally acknowledged 

 wherever science is cultivated. Yet it would appear that there is, in one part of 

 Europe, a school of philosophers who contest the merit of this part of Newtoirs 

 discoveries. "Kepler," says a celebrated German metaphysician,* " discovered the 

 laws ot fv^e motion ; a discovery of immortal glory. It has since been the fashion 

 to say that Newton first found out the proof of these rules. It has seldom hap- 

 pened that the glory of the first discoverer has been more unjustly transferred to 

 another person." It may appear strange that any one in the present day should 

 hold such language ; but if we examine the reasons which this author gives, they 

 will be found, I think, to amount to this : that his mind is in the condition in which 

 Kepler's was ; and that the whole range of mechanical ideas and modes of concep- 

 tion which made the transition from Kepler' and Newton possible, are extraneous 

 to the domain of his philosophy. Even this author, however, if I understand him 

 rightly, recognizes Newton as the author of the doctrine of Perturbations. 



I have given a further account of these views, in a Memoir On Hegel's Criticism 

 of Newtorfs Principia. Cambridge Transactions, 1849. 



* Hegel, Encyclopedia, 270. 



