THE UNDULATORY THEORY. 501 



is the same. In both we have many Laws of Phe- 

 nomena detected and accumulated by acute and 

 inventive men ; we have Preludial guesses which 

 touch the true theory, but which remain for a time 

 imperfect, undeveloped, unconfirmed: finally, we 

 have the Epoch when this true theory, clearly ap- 

 prehended by great philosophical geniuses, is recom- 

 mended by its fully explaining what it was first 

 meant to explain, and confirmed by its explaining 

 what it was not meant to explain. We have then 

 its Progress struggling for a little while with ad- 

 verse prepossessions and difficulties; finally over- 

 coming all these, and moving onwards, while its 

 triumphal procession is joined by all the younger 

 and more vigorous men of science. 



It would, perhaps, be too fanciful to attempt to 

 establish a parallelism between the prominent per- 

 sons who figure in these two histories. If we were 

 to do this, we must consider Huyghens and Hooke 

 as standing in the place of Copernicus, since, like 

 him, they announced the true theory, but left it to 

 a future age to give it developement and mecha- 

 nical confirmation; Malus and Brewster, grouping 

 them together, correspond to Tycho Brahe and 

 Kepler, laborious in accumulating observations, in- 

 ventive and happy in discovering laws of pheno- 

 mena ; and Young and Fresnel combined, make up 

 the Newton of optical science (OA). 



