INTRODUCTION. 9 



it does not limit itself to teaching us names only; 

 if the subdivisions have not been capriciously esta- 

 blished, but rest upon true fundamental distinc- 

 tions, upon the essential resemblance of the objects 

 subdivided, such a system will prove the surest 

 means of generalizing the properties of such ob- 

 jects, of expressing them in the fewest, most com- 

 prehensive, and most significant terms, and of im- 

 pressing them most successfully upon the memory. 



To invent a system at once rational and serviceable 

 to science, it is necessary to make an assiduous 

 comparison of the works of nature, under the 

 guidance of that principle which is termed the 

 subordination of characters, a principle which is it- 

 self derived from that of the conditions of existence 

 already alluded to. The separate parts of every 

 being must also possess a mutual adaptation ; there 

 are, therefore, certain peculiarities of conformation 

 which exclude others, and some again which ne- 

 cessitate the existence of others. When we know 

 any given peculiarities to exist in a particular being, 

 we may calculate what can and what cannot exist 

 in conjunction with them. The most obvious, 

 marked, and predominant of these ; those which 

 exercise the greatest influence over the totality of 

 such a being are denominated its important or lead- 

 ing characters, others . of minor consideration are 

 termed subordinate. 



The degree of influence of the peculiarities or 

 characters of any given being, may be frequently 

 determined by considering the nature of the organ 



