4 INTRODUCTION. 



either directly or by the principle of the conditions of existence, would 

 complete the system of the natural sciences, in rendering sensible in all 

 its parts the mutual influence of every being. To this end, should 

 those who cultivate these sciences direct all their efforts. 



All researches of this nature, however, presuppose means of distin- 

 guishing clearly, and enabling others to distinguish, the bodies they are 

 occupied with ; otherwise we should be continually confounding them. 

 .Natural History then should be based on what is called a System of 

 Nature ; 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 the character which distinguishes it from every 

 other : habits or properties which are but momentary cannot furnish 

 this character they must then be drawn from its 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 is almost always required to distinguish one 

 being from those which resemble it in some, but not in all its pecu- 

 liarities, or who have some of 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, it would be necessary, without some 

 concise method, to enter into a complete description of its character. 

 It is to avoid this inconvenience, that divisions and subdivisions 

 have been invented. A certain number only of neighbouring beings 

 are compared with each other, and their characters need only express 

 their differences, which, by the supposition itself, are the least part of 

 their conformation. Such a combination of beings is termed a genus. 



The same inconvenience would be experienced in distinguishing 

 genera from each other, were it not for the repetition of the oj>eration 

 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 infe- 

 rior, 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 much more than teach us names. If 

 thp subdivisions have not been established arbitrarily, but are based on 



