It follows therefore that, in the greater part of life, we act, not from demonstration, but from a proof in which faith is a constituent element.
Whence arises this trust in the uniformity of the phenomena of the Universe? We can hardly give any other answer except that we could not get on without it. Having been found to "work" by ourselves, and by many generations of our forefathers, this faith is possibly by this time an inherited instinct as well as the inbred result of our own earliest experiences. But when we analyse it we are forced to confess that we can give no logical account of it. Logically regarded, it savours of the most audacious optimism, arguing, or rather sentimentalizing, after this fashion: "It would be so immensely inconvenient if Nature were every moment changing her rules without notice! All forethought, all civilization would be at an end; nay, we could not so much as take a single step or move a limb with confidence, if we could not depend upon Nature!" Does not this personification of Nature, and trust or faith in Nature, somewhat resemble our trust or faith in God? I think it does; and it is very interesting to note that the very foundations of science are laid in a quasi-religious sentiment of which no logical justification can be given.
I might easily go further and shew that, even as regards the past, we act in our daily lives very often on the grounds of faith and very seldom on the grounds of demonstration. On this I have touched in a previous letter; but your dictum about the "immorality of believing what cannot be proved" makes it clear that you are hardly as yet aware of the nature of the ordinary "proofs" on which we act. How few there are who have any grounds but faith for believing in the existence of a Julius Cæsar or an Alexander! Yet they believe implicitly. Many have heard these two great men loosely spoken of, or alluded to; but they have
