626 THE PRINCIPLES OF SCIENCE. [CH. xxvn. 



dulum and a planet, true in substance though mistaken in 

 some details. All the advances of modern science rise 

 from the conception of Galileo, that in the heavenly 

 bodies, however apparently different their condition, we 

 shall ultimately recognise the same fundamental principles 

 of mechanical science which are true on earth. 



Generalisation is the great prerogative of the intellect, 

 but it is a power only to be exercised safely with much 

 caution and after long training. Every mind must gene- 

 ralise, but there are the widest differences in the depth of 

 the resemblances discovered and the care with which the 

 discovery is verified. There seems to be an innate power 

 of insight which a few men have possessed pre-eminently, 

 and which enabled them, with no exemption indeed from 

 labour or temporary error, to discover the one in the 

 many. Minds of excessive acuteness may exist, which 

 have yet only the powers of minute discrimination, and of 

 storing up, in the treasure-house of memory, vast accumu- 

 lations of words and incidents. But the power of dis- 

 covery belongs to a more restricted class of minds. La- 

 place said thab, of all inventors who had contributed the 

 most to the advancement of human knowledge, Newton 

 and Lngrange appeared to possess in the highest degree 

 the happy tact of distinguishing general principles among 

 a multitude of objects enveloping them, and this tact 

 he conceived to be the true characteristic of scientific 

 genius. 1 



1 Young's IKorJb. vol. ii. ]>. 564 



