SUCCESSION OF CHARACTERS. 271 



It is not accidentally that I have been led to these in- 

 vestigations, but by necessity. As often as I tried to 

 compare higher or more limited groups of animals of the 

 present period with those of former ages, or early stages 

 of growth of higher living animals with full-grown ones of 

 lower types, I was constantly stopped in my progress by 

 doubts as to the equality of the standards I was applying, 

 until I made the standards themselves the object of direct 

 and very extensive investigations, covering indeed a much 

 wider ground than would appear from these remarks ; for 

 upon these principles I have already remodelled, for my 

 own convenience, nearly the whole animal kingdom, and 

 introduced into almost every class very unexpected changes 

 in the classification. 



I have already expressed above 1 my conviction that the 

 only true system is that which exists in nature; and as, 

 therefore, no one should have the ambition of erecting a 

 system of his own, I will not now even attempt to present 

 these results in the shape of a diagram, but remain satis- 

 fied to express my belief that all we can really do is, at 

 best, to offer imperfect translations, in human language, 

 of the profound thoughts, the innumerable relations, the 

 unfathomable meaning of the plan actually manifested in 

 the natural objects themselves; and I should consider it 

 as my highest reward, should I find, after a number of 

 years, that I had helped others on in the right path. 



SECTION IX. 



THE CATEGORIES OF ANALOGY. 



Thus far we have Considered those relations only among 

 animals, which are founded upon strictly homological 



1 See Chap. I, Sect, 1, p. 13. 



