INDUCTIVE EPOCH OF NEWTON. 41 i 



into many elements, such as can be separated ; to invent artifices for 

 dealing \vith each of these ; and then to recompound the laws thus ob- 

 tained into one common conception. The moon's motion cannot be 

 conceived without comprehending a scheme more complex than the 

 Ptolemaic epicycles and eccentrics in their worst form ; and the com- 

 ponent parts of the system are not, in this instance, mere geometrical 

 ideas, requiring only a distinct apprehension of relations of space in 

 order to hold them securely ; they are the foundations of mechanical 

 notions, and require to' be grasped so that we can apply to them sound 

 mechanical reasonings. Newton's successors, in the next generation, 

 abandoned the hope of imitating him in this intense mental effort ; 

 they gave the subject over to the operation of algebraical reasoning, in 

 which symbols think for us, without our dwelling constantly upon their 

 meaning, and obtain for us the consequences which result from the re- 

 lations of space and the laws of force, however complicated be the con- 

 ditions under which they are combined. Even Newton's countrymen, 

 though they were long before they applied themselves to the method 

 thus opposed to his, did not produce any thing which showed that 

 they had mastered, or could retrace, the Newtonian investigations. 



Thus the Problem of Three Bodies, 19 treated geometrically, belongs 

 exclusively to Newton ; and the proofs of the mutual action of the sun, 

 planets, and satellites, which depend upon such reasoning, could not be 

 discovered by any one but him. 



But we have not yet done with his achievements on this subject ; 

 for some of the most remarkable and beautiful of the reasouino-s which 



O 



he connected with this problem, belong to the next step of his geuer 

 alizatiou. 



5. Mutual Attraction of all Particles of Mutter. That all the parts 

 of the universe are drawn and held together by love, or harmony, or 

 some affection to which, among other names, that of attraction may 

 have been given, is an assertion which may very possibly have been 

 made at various times, by speculators writing at random, and taking 

 their chance of meaning and truth. The authors of such casual dog- 

 ~nas have generally nothing accurate or substantial, either in their con- 

 ception of the general proposition, or in their reference to examples of 

 it ; and, therefore, their doctrines are no concern of ours at present. 

 But among those who were really the first to think of the mutual at- 



10 See the history of the Problem of Three Hodies, ante, in Book vi. Chop. TU 

 Sect. 7. 



