466 HISTORY OF OPTICS. 



cidence; falsehood cannot. But the phenomena be- 

 came more numerous, more various, more strange : 

 no matter: the theory is equal to them all. It 

 makes not a single new physical hypothesis; but 

 out of its original stock of principles it educes 

 the counterpart of all that observation shows. It 

 accounts for, explains, simplifies, the most entangled 

 cases ; corrects known laws and facts ; predicts and 

 discloses unknown ones ; becomes the guide of its 

 former teacher, observation; and, enlightened by 

 mechanical conceptions, acquires an insight which 

 pierces through shape and colour to force and 

 cause (MA). 



We thus reach the philosophical moral of this 

 history, so important in reference to our purpose ; 

 and here we shall close the account of the discovery 

 and promulgation of the undulatory theory. Any 

 further steps in its developement and extension, 

 may with propriety be noticed in the ensuing chap- 

 ters, respecting its reception and verification. 



