I also apprehend that in all cases whatever,
in which any doubt may be urged as to the truth
of a fact, or as to its possessing those conditions
which determine it to be in reality that fact
which it purports to be, I apprehend that, in
all these cases, the worth of the aflSrmation of
any honest witness is always in proportion to



134 CONVICTION OF THE WITNESSES. CHAP. II.
the strength of the conviction with which that
same witness delivers his testimony. Suppose
the case of a man who has been stabbed in a
quarrel, and who dies a few days after receiving
the wound. The surgeon who attended him
may be merely inclined to believe that the wound
inflicted was the cause of his death j or he may
know it to have been that cause with the fullest
certainty. The measure of his conviction is
here the sole measure of the evidence.
Or suppose that an eruption of some volcano
takes place. We credit the account of the at-
tendant pbaenomena which may be given to us
by any particular witness, in the exact propor-
tion in which he is sure of his own accuracy.
