UNIVERSAL CHARACTERS OBJECTIONABLE. 239 
characters from the same organs, or from the same 
premises. And, indeed, if we consider the subject 
for a moment, it is impossible they should ; because 
such divisions rest only upon individual opinion, 
without reference to any common standard by 
which such opinions can be judged. It is clear, 
also, that the same organs will have different degrees 
of consequence in different classes. By taking the 
form, number, and disposition of the teeth into 
consideration, we bring the quadrupeds into large 
but very natural divisions; but to carry on the same 
set of characters to fish, and make their dentation 
the chief guide in their arrangement, would be 
manifestly absurd, if not impossible. Hence it 
follows, that not only in a natural, but also in an 
artificial system, there are no organs in animals 
which can be universally employed to furnish 
generic characters, and to which we must exclu- 
sively direct our attention. The question, then, 
arises, by what rules are we to be guided in defining 
such divisions, and in giving them a stability which 
artificial groups have not ? 
(165.) When, therefore, the naturalist, following 
the principles already detailed, has before him a 
generic group, whose affinities, more or less, appear 
to be circular, he is next to seek for those charac- 
ters which are most prevalent in all the forms or 
species which compose it. It is a matter of perfect 
indifference, what organ, or what set of organs, fur- 
nish these characters, provided they are more com- 
prehensive than others, and are of such a nature as 
to be readily detected. His great object, in fact, 
is to point out, with clearness and precision, how 
