The students of physical science are not unfrequently told that their pursuits unfit them for the estimation of moral probability. And it may be so, for I am afraid that to those who are accustomed to severe reasoning, either in the province of Science or in that of Law, reasoning from 'moral probability' is apt to be regarded as a process of accumulating inconclusive arguments, in the hope that a great heap of them may, at least, look as firm as one good demonstration.