* INTRODUCTION. 



vegetable and animal, in all of which phenomena 

 may be observed varying- more or less from the 

 known laws of motion and of chemical attraction, as 

 well as from every other cause, the analysis of which 

 is appropriated to general physics. 



Hence it appears that mineralogy, botany, and 

 zoology form the principal divisions of natural his- 

 tory, as ordinarily understood. 



Natural history should, in strictness, be cultivated 

 by the same methods as are adopted in the various 

 branches of general science, and in fact it is so cul- 

 tivated, when the objects of it are sufficiently simple 

 to permit the usage of such methods. But this is 

 very far from being practicable in every instance. 

 There is this essential difference between the gene- 

 ral sciences and natural history: in the former the 

 student possesses a power of regulating the condi- 

 tions of the phenomena which he studies ; in the 

 latter, the phenomena are by no means subject to 

 his control. He cannot, like the experimental phi- 

 losopher, separate the elementary parts from each 

 other in the objects of his examination. Such objects 

 come under his view in a complex form, and he can 

 decompose them and analyze their component parts 

 only in thought. What a variety of conditions, for 

 example, are necessary to animal life ! If, in attempt- 

 ing to analyze the nature of that life, we were in 

 reality to separate from it any of those requisite 

 conditions, its duration must instantly cease, and 

 the object of our researches be frustrated. We 

 must, to use^the language of the poet, " lose it in the 



