CHAPTEE XXIX 



EXCEPTIONAL PHENOMENA. 



IF science consists in the detection of identity and the 

 recognition of uniformity existing in many objects, it 

 follows that the progress of science depends upon the study 

 of exceptional phenomena. Such new phenomena are the 

 raw material upon which we exert our faculties of obser- 

 vation and reasoning, in order to reduce the new facts 

 beneath the sway of the laws of nature, either those laws 

 already well known, or those to be discovered. Not only 

 are strange and inexplicable 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 appa- 

 rently fixed relative positions upon the heavenly sphere, 

 received less notice from astronomers than those few 

 planets whose wandering and inexplicable motions formed 

 a 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 ages 

 two brilliant but temporary stars caused more popular 

 interest in astronomy than any other events, and to one 

 of them we owe all the observations of Tycho Brahe, the 

 mediaeval Hipparchus. 



In other sciences, as well as in that of the heavens, 



