PREFACE. Vli 



from than conduct us to useful conclusions. The 

 importance of the natural sciences ought to be too 

 evident to require demonstration. Geology and 

 mineralogy render daily services to industry, by 

 enabling us better to explore the wealth buried in the 

 bowels of the earth ; Botany makes us acquainted 

 with the plants, so varied and so beautiful, which 

 supply our wants in magnificent prodigality ; Zoo- 

 logy gives a knowledge of those animals which pro- 

 duce wool, silk, and honey, and those that assist us 

 in our toils with their strength, as well as of those 

 which, instead of being useful to us, destroy our 

 crops. How important a guide natural m'story may 

 be made to agriculture, the great pursuit in the 

 United States ! Besides, let us remember the long 

 list of diseases by which the human machine is 

 afflicted, and bear in mind the fact that the practice 

 of medicine is blind in action when it does not rest 

 on a scientific knowledge of the nature of man. 



The practical importance of the study of natural 

 history, we repeat, requires no proof, and must be 

 felt, no matter what may be our career. But its 

 influence does not stop here ; the influence it can be 

 made to exert over our faculties themselves, is 

 worthy of the most serious attention. In fact, the 

 natural sciences, by reason of the routine system 

 peculiar to them, accustom the mind to go back from 

 effects to causes, and at the same time invariably 



