DISCORDANCE OF ARTIFICIAL SYSTEMS. 155 



classification of the Mammalia, namely, Linnaeus, 

 Cuvier, Illiger, and Hamilton Smith. Each of these 

 studied from the same models, — models which are 

 now the same as when they were first created ; and 

 each and all agree in the results of their respective 

 examinations ; that is, in the facts belonging to the 

 structure of these animals. So far, therefore, we 

 need not question their authority. But when they 

 began to reason upon these facts, each drew separate 

 inferences, and consequently produced different 

 systems or methods of classification. These systems, 

 however, make no reference to other parts of creation. 

 They treat of the class before them, as if it was the 

 only one in nature, and as if the principles by 

 which it was to be arranged had no connection with 

 those which governed other classes. We find, in 

 short, no allusion to mutual resemblances out of this 

 division of animals ; so that an ordinary reader would 

 suppose that nature had one system for quadrupeds, 

 another for birds, a third for fish, and a fourth for 

 insects. Did he turn to the best classifications of 

 each of these orders now in use, he would be still 

 further confirmed in this opinion, by seeing that 

 they were all treated of in the same isolated and dis- 

 connected manner. The ornithological systems of 

 the greatest naturalists in this department differ 

 from each other fully as much as those relating to 

 quadrupeds, and are calculated to produce the same 

 impressions. Seeing, therefore, that inferences may 

 be innumerably various and discordant; by what 

 rule, as the science now stands, are we to be guided 

 in choosing truth ? It is evident, that if there be 

 but one system in nature, there can be but one 



