PREFACE. 



submit results deduced from preceding observations 

 to the test of new facts ; their study leads to specu- 

 lations of the most elevated character, but never 

 leads the imagination astray, because it always 

 places material proof alongside of theory. And 

 beyond any other pursuit, natural history exercises 

 the mind in habits of method, a part of logic with- 

 out which every investigation is laborious, and 

 every exposition obscure. 



Natural History ought to constitute one of the 

 elements of every system of liberal education ; but 

 it is not necessary that every young man should be 

 a naturalist. To become a proficient in a science 

 so vast in its scope, w r ould require more time than 

 can be spared from other classical studies, and it 

 comprises a host of details useful only to those who 

 are desirous of devoting themselves especially- to it. 

 What every well-educated young man ought to 

 know is, not the characteristics which distinguish 

 this or that genus of plants or animals from another 

 genus, nor the exact course of every nerve, or every 

 artery in the human body : to charge his memory 

 with such details, would subject him to labour which 

 would be neither useful nor durable in its results ; 

 but what he ought to possess, are sound views on 

 all the great questions that it is the province of the 

 natural sciences to solve; those on the constitution 

 of the earth, and the physical revolutions that have 



