CONTRARIETY OF OPINION. 153 
by every one, few prejudices of sense can arise re- 
specting them. But when we proceed further, and 
attempt, from these facts, to draw inferences, the 
case is different. No principles having been yet 
established, by which the facts we know from ex- 
perience can be generalised in such a way as to es- 
tablish their mutual relation and dependence. Every 
naturalist therefore thinks he is at liberty to draw his 
own inferences, and to apply them to the systematic 
arrangement of the objects by which they are fur- 
nished. One, for instance, arguing from the flight 
of the bat, looks on it as that animal which constitutes 
the true passage from quadrupeds to birds. Another, 
looking to its general aspect, is disposed to place it 
among the mice, fortified by the general name given 
by the French to the whole tribe of chauve souris. 
A third, chiefly influenced by the peculiarity of its 
teeth, arranges it in the same group as the monkeys: 
and each, acting upon his respective inferences, 
fashions his system accordingly. Now, as to the 
facts connected with the individual structure and 
the economy of the bat, all these naturalists would 
agree ; because such facts can be verified by 
their personal observation, and there would be no 
room for prejudice. But here unanimity ceases. 
They proceed to inferences; and each, laying a 
peculiar stress upon some one fact more than upon 
others, makes it a principle of his own arrangement. 
This is the true cause of the number and the muta- 
bility of zoological systems. In respect to the bat, 
it is very clear, that if there is an order or progression 
in nature, — which no one ever thinks of doubting, — 
this quadruped can hold but ove station in the scale 
