belief, however broad its basis, however defensible it may seem,
is, after all, only a probable belief, and that our widest and
safest generalisations are simply statements of the highest
degree of probability. Though we are quite clear about the
constancy of the order of Nature, at the present time, and in
the present state of things, it by no means necessarily follows
that we are justified in expanding this generalisation into the
infinite past, and in denying, absolutely, that there may have
been a time when Nature did not follow a fixed order, when the
relations of cause and effect were not definite, and when extra-
natural agencies interfered with the general course of Nature.
Cautious men will allow that a universe so different from that
which we know may have existed; just as a very candid thinker
may admit that a world in which two and two do not make four,
and in which two straight lines do inclose a space, may exist.
But the same caution which forces the admission of such
possibilities demands a great deal of evidence before it
recognises them to be anything more substantial. And when it is
asserted that, so many thousand years ago, events occurred in a
manner utterly foreign to and inconsistent with the existing
laws of Nature, men, who without being particularly cautious,
are simply honest thinkers, unwilling to deceive themselves or
delude others, ask for trustworthy evidence of the fact.

Did things so happen or did they not? This is a historical
question, and one the answer to which must be sought in the same
way as the solution of any other historical problem.

So far as I know, there are only three hypotheses which ever
have been entertained, or which well can be entertained,