for the guidance of his practical affairs. It has taken long ages of
toilsome and often fruitless labour to enable man to look steadily at
the shifting scenes of the phantasmagoria of Nature, to notice what is
fixed among her fluctuations, and what is regular among her apparent
irregularities; and it is only comparatively lately, within the last few
centuries, that the conception of a universal order and of a definite
course of things, which we term the course of Nature, has emerged.

But, once originated, the conception of the constancy of the order of
Nature has become the dominant idea of modern thought. To any person who
is familiar with the facts upon which that conception is based, and is
competent to estimate their significance, it has ceased to be
conceivable that chance should have any place in the universe, or that
events should depend upon any but the natural sequence of cause and
effect. We have come to look upon the present as the child of the past
and as the parent of the future; and, as we have excluded chance from a
place in the universe, so we ignore, even as a possibility, the notion
of any interference with the order of Nature. Whatever may be men's
speculative doctrines, it is quite certain that every intelligent person
guides his life and risks his fortune upon the belief that the order of
Nature is constant, and that the chain of natural causation is never
broken.

In fact, no belief which we entertain has so complete a logical basis as
that to which I have just referred. It tacitly underlies every process
of reasoning; it is the foundation of every act of the will. It is based
upon the broadest induction, and it is verified by the most constant,
regular, and universal of deductive processes. But we must recollect
that any human belief, however broad its basis, however defensible it
may seem, is, after all, only a probable belief, and that our widest and