190 HISTORY OF PHYSICAL ASTRONOMY. 



to generals, and from one generalization to another; 

 that we have, in short, successive steps of induc- 

 tion. As Newton's laws assumed Kepler's, Kepler's 

 laws assumed as facts the results of the planetary 

 theory of Ptolemy ; and thus the theories of each 

 generation in the scientific world are (when tho- 

 roughly verified and established,) the facts of the 

 next generation. Newton's theory is the circle of 

 generalization which includes all the others ; the 

 highest point of the inductive ascent ; the catas- 

 trophe of the philosophic drama to which Plato had 

 prologized; the point to which men's minds had 

 been journeying for two thousand years. 



Character of Newton. It is not easy to anato- 

 mize the constitution and the operations of the 

 mind which makes such an advance in knowledge. 

 Yet we may observe that there must exist in it, in 

 an eminent degree, the elements which compose the 

 mathematical talent. It must possess distinctness 

 of intuition, tenacity and facility in tracing logical 

 connexion, fertility of invention, and a strong tend- 

 ency to generalization. It is easy to discover indi- 

 cations of these characteristics in Newton. The dis- 

 tinctness of his intuitions of space, and we may add 

 of force also, was seen in the amusements of his 

 youth ; in his constructing clocks and mills, carts 

 and dials, as well as the facility with which he 

 mastered geometry. This fondness for handicraft 

 employments, and for making models and machines, 

 appears to be a common prelude of excellence in 



