INTRODUCTION, 



ractcrs^ which is itself derived from that of the; conditions of 

 existence. The parts of a being possessing a mutual adapta- 

 tion, some traits of character exclude others, while on the 

 contrary, there are others that ref^uire them. When, there- 

 fore, we perceive such or such traits in a being, we can calcu- 

 late before hand those that co-exist in it, or those that are 

 incompatible with them. The parts, the properties, or the 

 traits of conformation, which have the greatest number of 

 these relations of incompatibility or of co-existence with others, 

 or, in other words, that exercise the most marked influence 

 upon the whole of the being, are called the important charac- 

 ters^ dominating characters ; the others are the subordinate 

 characters, all varying in degree. 



This influence of characters is sometimes determined ration- 

 ally, by the consideration of the nature of the organ. When 

 this is impracticable, we have recourse to simple observation ; 

 and a sure mark by which wx may recognise the important 

 characters, and one which is drawn from their own nature, is 

 their superior constancy, and that in a long series of different 

 beings, approximated according to their degrees of similitude, 

 these characters are the last to vary. That they should be 

 preferred for distinguishing the great divisions, and that in 

 proportion as we descend to the inferior subdivisions, we can 

 also descend to subordinate and variable characters, is a rule 

 resulting equally from their influence and constancy. 



There can be but one perfect method, which is the natural 

 method. We thus name an arrangement in which beings of the 

 same genus are placed nearer to each other than to those of the 

 other genera ; the genera of the same order nearer than those 

 of the other orders, &c. &c. This method is the ideal to 

 which natural history should tend ; for it is evident that if we 

 can reach it, we shall have the exact and complete expression 

 of all nature. In fact, each being is determined by its resem- 

 blance to others, and difference from them ; and all these rela- 

 tions would be fully given by the arrangement in question. 

 In a word, the natural method would be the whole science, 

 and every step towards it tends to advance the science to per- 

 fection. 



