4. INTRODUCTION. 
or, a great catalogue, in which all created beings have suitable names, may 
be recognised by distinctive characters, and be arranged in divisions and 
subdivisions, themselves named and characterised, in which they may be 
found. 
In order that each being may be recognised in this catalogue, it must 
be accompanied by its character: habits or properties, which are but mo- 
mentary, cannot, then, furnish characters—they must be drawn from the 
conformation. 
There is scarcely a single being which has a simple character, or can be 
recognised by one single feature of its conformation; a union of several of 
these traits are almost always required to distinguish one being from those 
that surround it, who also have some but not all of them, or who have them 
combined with others of which the first is destitute. The more numerous 
the beings to be distinguished, the greater should be the number of traits ; 
so that to distinguish an individual being from all others, a complete de- 
scription of it should enter into its character. 
It is to avoid this inconvenience, that divisions and subdivisions have 
been invented. A certain number only of neighbouring beings are com- 
pared with each other, and their characters need only to express their dif- 
ferences, which, by the supposition itself, are the least part of their con- 
formation. Such a re-union is termed a genus. 
The same inconvenience would be experienced in distinguishing genera 
from each other, were it not for the repetition of the operation in uniting 
the adjoining genera, so as to form an order, the orders to form a class, &c. 
Intermediate subdivisions may also be established. 
This scaffolding of divisions, the superior of which contain the inferior, 
is called a method. It is in some respects a sort of dictionary, in which 
we proceed from the properties of things to arrive at their names; being 
the reverse of the common ones, in which we proceed from the name to 
arrive at the property. - 
When the method is good, it does more than teach us names. If the 
subdivisions have not been established arbitrarily, but are based on the true 
fundamental relations, on the essential resemblances of beings, the method 
is the surest means of reducing the properties of beings to general rules, of 
expressing them in the fewest words, and of stamping them on the memory. 
To render it such, we employ an assiduous comparison of beings, di- 
rected by the principle of the subordination of characters, which is itself 
derived from that of the conditions of existence. The parts of a being pos- 
sessing a mutual adaptation, some traits of character exclude others, while, 
on the contrary, there are others that require them. When, therefore, we 
perceive such or such traits in a being, we can calculate before hand those 
that co-exist in it, or those that are incompatible with them. The parts, 
