INTRODUCTION. 5 
the properties, or the traits of conformation, which have the greatest num- 
ber of these relations of incompatibility or of co-existence with others, or, 
in other words, that exercise the most marked influence upon the whole of 
the being, are called the important characters, dominating characters; the 
others are the subordinate characters, all varying in degree. 
This influence of characters is sometimes determined rationally, by the 
consideration of the nature of the organ. When this is impracticable, we 
have recourse to simple observation; and a sure mark by which we may 
recognise the important characters, and one which is drawn from their own 
nature, is their superior constancy, and that in a long series of different 
beings, approximated according to their degrees of similitude, these cha- 
racters are the last to vary. That they should be preferred for distin- 
guishing the great divisions, and that, in proportion as we descend to the 
inferior subdivisions, we can also descend to subordinate and variable char- 
acters, is a rule resulting equally from their influence and constancy. 
There can be but one perfect method, which is the natural method. We 
thus name an arrangement in which beings of the same genus are placed 
nearer to each other than to those of ihe other genera; the genera of the 
same order nearer than those of the other orders, &c. &c. This method 
is the zdeal to which natural history should tend; for it is evident that if 
we can reach it, we shall have the exact and complete expression of all 
nature. In fact, each being is determined by its resemblance to others, 
and difference from them; and all these relations would be fully given by 
the arrangement in question. Ina word, the natural method would be 
the whole science, and every step towards it tends to advance the science 
to perfection. 
Life being the most important of all the properties of beings, and the 
highest of all characters, it is not surprising that it has in all ages been 
made the most general principle of distinction; and that natural beings 
have always been separated into two immense divisions, the living and the 
inanimute. 
Of Living Beings, and Organization in general. 
If, in order to obtain a correct idea of the essence of life, we consider it 
in those beings in which its effects are the most simple, we quickly perceive 
that it consists in the faculty possessed by certain corporeal combinations, 
of continuing for a time and under a determinate form, by constantly at- 
tracting into their composition a part of surrounding substances, and ren- 
dering to the elements portions of their own. 
Life then is a vortex, more or less rapid, more or less complicated, the 
direction of which is invariable, and which always carries along molecules of 
similar kinds, but into which individual molecules are continually entering, 
