165 



CHAP. II. 



ON THE PRINCIPLES ON WHICH NATURAL HISTORY, 

 AS A BRANCH OF PHYSICAL SCIENCE, IS TO BE 

 STUDIED. 



(103.) There are two modes by which our know- 

 ledge of natural history can be successfully pro- 

 secuted. The first of these is to commence with 

 investigating the forms and properties of species; 

 combining them, according to their degrees of 

 similarity, into groups or assemblages of different 

 magnitudes ; and then attempting to discover what 

 general inferences can be drawn from such com- 

 binations, or, in other words, what are the principles 

 by which their variations are regulated. This is 

 the analytical method, by which we commence, as 

 with an alphabet ; and from letters determine words ; 

 from words proceeding to sentences ; and, combining 

 these, again, to chapters. By the second mode, we 

 proceed quite differently. We begin by taking for 

 granted the correctness of certain given principles, 

 and apply them to the investigation and arrange- 

 ment of some particular group. This is the synthetic 

 mode. By the first, we commence as if all general 

 laws were yet to be discovered ; by the latter, as if 

 they were already known, and only required a more 

 particular or extended application. 



(104.) As all true knowledge of the combin- 

 m 3 



