1 88 0« Cnjstdllograpfnj, 



flower and the fruit in the individuals of the two species, 

 keeping separate in my iniaginalion all the parts which 

 tlifler; and in order to adapt the nomenclature to this 

 resemblance, which alone occupies my mind, I shall extend 

 the name of oak to both the sj)e.cies. Reierring my mind 

 afterwards to the differences which I have left on one side, 

 1 shall keep an acconnl of them in language, distinguish- 

 ing by ibe name of common oak the individuals of the 

 first species, and by the name of green oak those oF the 

 second. I shall then have a genus, of which the common 

 oak and the green oak will he two species. 



By a new abstraction I can consider in the two oaks no- 

 thing but their size, ligneous consistence, and the faculty 

 which they have of existing a certain nnmber of years ; and 

 observing that several kinds of productions, different from 

 oaks, hare also a great consistency and are very long lived, 

 while a multitude of other species are of lower stature, 

 more pliant, and exist a year or two only, I shall unite, un- 

 der one and the same idea, the first by the name of trees y 

 and I shall designate in common all the others by the 

 name of skrubs. I shall thus have two great classes*, each 

 of which may be subdivided into a certain number of genera, 

 which will be groups of species. Finally, if I have no 

 longer any regard but to the faculty which all these ob- 

 jects have of vegetating, and of being nourished from the 

 juices of the earth, 1 shall include them under the general 

 denomination plant, and I shall thus attain, by a scries of 

 ideas alwavs more abstract, the most elevated point of view 

 of the vegetable kingdom. 



Human languages present a host of examj)les of similar 

 abstractions, which a natural spirit of analysis has suggested 

 even to the vulgar; and it is by directing their views in the 

 same manner that the learned have formed their systems 

 and methods. They have merely subjected these luethodical 

 arrangements to more precise and more rational principles; 

 tliey have multiplied their divisions and subdivisions, and 

 have in some measure arranged them by the indication of 

 the characters peculiar to the objects which each division 

 contains. 



We see from what precedes, that in proportion as we 

 ascend into the course of .abstractions, we connect together 

 a greater number of beings, according to the relation or 

 character analogous to the degree of abstraction. Thus the 



* I do not pretend to establish rigorous limits here between the divisions 

 of bodies, hut merely to give a sketch of the progress of ideas by examples 

 taken from fanxiliar objecis. 



idea 



