CONTEAST BETWEEN NEWTON AND KEPLER. 251 



true. And while that demonstration would have been 

 alone sufficient to give him an imperishable renown, it was 

 his still greater glory to divine the profound truth, that the 

 fall of the moon towards the earth that is, the deflection 

 of her path from a tangential line to an ellipse is a 

 phenomenon of the same order as the fall of a stone to the 

 ground ; and thus to show that the mutual attraction of 

 all masses of matter which we call gravitation, pervades the 

 whole universe and everywhere follows the same law.' 1 The 

 discovery of Kepler's laws, however, was, as far as it went, 

 a part of the explanation of the motions of the planets. 

 A generalised statement is also a partial explanation of 

 nature, so far as it justifies the conclusion that a common 

 cause acts in all the instances ; but it is of course a less 

 complete explanation than a statement of the cause itself 

 and its law of action. 2 



The exercise of the reasoning faculty in an unusually 

 high degree is a chief characteristic of great scientific 

 discoverers ; and the difference between such men and 

 barren reason ers is, that the former exercise their minds 

 upon an extensive knowledge of facts and truthful prin- 

 ciples, whilst the latter employ them on uncertain data. 

 According to Nichol : ' When you see a man in the 

 midst of his contemporaries not contesting opinions, not 

 quarrelling, but quietly, and without ostentation or fear, 

 proceeding to resolve by reason subjects which had hitherto 

 been in possession of ' f common belief," depend on it that 

 a signal accession of knowledge is awaiting us, for the 

 freshest stamp of divinity is upon that man. Herschel's 

 first remarkable paper gave a promise of this description, 

 and abundantly was it soon fulfilled.' 3 According to 



1 Carpenter, Mental Physiology, p. 501. 2 Compare p. 176. 



3 Architecture of the Heavens, p. 6. 



