CHAPTEE XXIX. 



EXCEPTIONAL PHENOMENA. 



IF science consists in the detection of identity and the 

 recognition of one uniformity existing in many objects, it 

 follows almost of necessity that the progress of science 

 depends upon the study of exceptional phenomena. Such 

 new phenomena are the raw material upon which we are 

 to exert our faculties of observation and reasoning, in 

 order to reduce the new facts beneath the sway of the 

 laws of nature, either those laws already weU known, or 

 those to be discovered. Not only are strange and inex- 

 plicable facts those which are on the whole most likely to 

 lead us to some novel and important discovery, but they 

 are also best fitted to arouse our attention. So long as 

 events happen in accordance with our anticipations, and 

 the routine of every-day observation is unvaried, there is 

 nothing to impress upon the mind the smallness of its 

 knowledge, and the depth of mystery, which may be 

 hidden in the commonest sights and objects. In early 

 times the myriads of stars which remained in apparently 

 fixed relative positions upon the heavenly sphere, re- 

 ceived far less notice from astronomers than those few 

 planets whose wandering and inexplicable motions formed 

 an unsolved riddle. Hipparchus was induced to prepare 

 the first catalogue of stars, because a single new star had 

 been added to those nightly visible ; and in the middle 



