154 STUDY OF NATURAL HISTORY. 
of being; and it therefore follows that only one of 
the opinions just glanced at can be true. Now, if 
we are unacquainted with any general laws of 
animal variation, by which the soundness of con- 
flicting inferences can be tested, how are we to 
decide in the case before us? It is clearly impos- 
sible: each opinion is supported by reasons, and 
each party appeals to and acknowledges the very 
same facts. In the infancy of science, such questions 
were generally decided by the authority and the in- 
fluence of a name. As knowledge increased, such 
arbitrary authorities also multiplied; but their in- 
fluences proportionally declined. Each, however, 
still continues to have its little circle of disciples, 
who, from having studied under, and imbibed the 
system and opinions of, their master, tenaciously 
adhere to what they have been taught to consider as 
truth. 
(94.) Here, then, lies that species of prejudice 
against which we would more especially caution the 
student; and which, if he will not conquer it, will 
incapacitate him, both from rising to the present 
level of science, and from extending its boundaries. 
He should ever bear in remembrance, that facts, 
authenticated by the experience of others, or falling 
under his own cognisance, are immutable, because 
nature is ever the same; but that the inferences 
from them may be so numerous, and so contradictory, 
that, until we are acquainted with some general laws 
whereby universal agreements can be established, 
one inference, in point of fact, is just as good as 
another. To illustrate our meaning more plainly, 
let us look to four of the greatest authorities on the 
ao 
