165 
CHAP. i: 
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 
