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nature of the asserted conclusion. It may be merely the 
result of some measurement — astronomical, suppose — carried 
out by certain and definite methods, though subject, of course, 
to the inevitable errors of observation. Though unacquainted, 
it may be, with the particular process employed, we know 
enough of the general nature of such processes to give us 
confidence in the asserted conclusion, especially if several men 
qualified to judge concur in it. It may be, however, that what 
we are asked to accept on authority is some speculative theory, 
the arguments in favour of which depend on observed facts 
in great detail with which we are not acquainted. Still, even 
in such a case, we may usually form some sort of notion of 
the general character of the evidence, and of the degree to 
which speculation, which enters more or less into every theory, 
is checked by actual fact. 
There are one or two other considerations which must not 
be wholly left out of sight in estimating the value of autho- 
rity. There is apt to be a tendency to attach undue import- 
ance to what one has oneself made out. Perhaps the most 
straightforward seeker after truth is not wholly exempt from 
some slight bias in this direction ; but different individuals 
will vary immensely in the degree in which they are led by 
it. It may often happen that, though we are unable to 
follow a person whose conclusions we wish to weigh in the 
particular subject to which those investigations relate, we are 
able to follow him in some other investigations. We can 
thereby form some sort of rough gauge of the strictness of 
the man’s impartiality with respect to his own investigations. 
Again, an original investigator is gradually led to adopt 
some theory, after years, it may be, of patient labour, as 
representing the most probable conclusion from his long- 
continued study. In estimating the probability, he has the 
whole of the evidence before him, adverse as well as favour- 
able; and though, it may be, the latter, in his judgment, 
immensely preponderates, he does not leave out of sight the 
former. But one who has merely learned from him is not 
able to take, at least for a long time, an equally comprehen- 
sive view ; he is predisposed by the great name of his 
master to adopt his conclusion, and is apt to express himself 
in a tone of confidence which his master would hardly have 
employed. The public are thus led to suppose that the 
conclusion is a thing about which there cannot be any 
manner of doubt. 
In case scientific evidence should seem to point towards a 
conclusion different from that which we should naturally have 
been disposed to draw from what we accept as revelation, we 
