I.] INTRODUCTORY. 23 



explain, and such is the reception it has met with in the 

 world. A few words now as to the reasons for the very 

 wide-spread interest it has awakened, and the keenness 

 with which the theory has been both advocated and com- 

 bated. 



The important bearing it has on such an extensive 

 range of scientific facts, its utility, and the vast knowledge 

 and great ingenuity of its promulgator, are enough to ac- 

 count for the heartiness of its reception by those learned 

 in natural history. But quite other causes have concurred 

 to produce the general and higher degree of interest felt 

 in the theory besides the readiness with which it harmonizes 

 with -biological facts. These latter could only be appreci- 

 ated by physiologists, zoologists, and botanists ; whereas 

 the Darwinian theory, so novel and so startling, has found 

 a cloud of advocates and opponents beyond and outside 

 the world of physical science. 



In the first place, it was inevitable that a great crowd 

 of half-educated men and shallow thinkers should accept 

 with eagerness the theory of " Natural Selection," or rath- 

 er what they think to be such (for few things are more re- 

 markable than the way in which it has been misunder- 

 stood), on account of a certain characteristic it has in com- 

 mon with other theories ; which should not be mentioned 

 in the same breath with it, except, as now, with the accom- 

 paniment of protest and apology. We refer to its remark- 

 able simplicity, and the ready way in which phenomena 

 the most complex appear explicable by a cause for the 

 comprehension of which laborious and persevering efforts 

 are not required, but which maybe represented by the sim- 

 ple phrase " survival of the fittest." With nothing more 

 than this, can, on the Darwinian theory, all the most intri- 

 cate facts of distribution and affinity, form and color, be 

 accounted for ; as well the most complex instincts and the 

 most admirable adjustments, such as those of the human 



