282 STUDY OF NATURAL HISTORY. 



CHAP. VI. 



ON THE IMPORTANCE OF ANALOGY WHEN APPLIED TO 

 THE CONFIRMATION OF THEORY. 



(191.) We have already explained, and familiarly- 

 illustrated, the two sorts of relations which natural 

 objects bear to each other, and which are distin- 

 guished by the terms Analogy and Affinity. The 

 prevalence of these relations is so universal through- 

 out nature, that there is no group of beings, however 

 small, which does not present them. Nay, we question 

 not that every individual species has its analogies, 

 as it certainly must have its affinities. In a future 

 volume we propose to enquire more particularly into 

 these relations, and to bring forward such instances 

 of their prevalence, as to sanction the hypothesis 

 that they are uniform, constant, and universal in 

 every part of the animal creation. In regard to 

 affinities, indeed, this truth is self-evident ; because, 

 whatever forms part of a series, must of necessity 

 have affinities, and these must be of different de- 

 grees. But, in regard to analogy, the case is differ- 

 ent, and calls for a much more extended enquiry. 

 On the present occasion, however, we shall merely 

 consider those arguments which may be used, a 

 priori, in favour of the supposition that analogies 

 are, in the most comprehensive sense of the word, 

 universal; and that they consequently assume an 

 importance of the highest order when applied to 

 illustrate, and to confirm, any theory on the vari- 

 ation of animal structure. 



