anything I know about the matter, it may be the way of Nature to be
unintelligible; she is often puzzling, and I have no reason to suppose
that she is bound to fit herself to our notions.

I shall place before you three kinds of evidence entirely based upon
what is known of the forms of animal life which are contained in the
series of stratified rocks. I shall endeavour to show you that there is
one kind of evidence which is neutral, which neither helps evolution nor
is inconsistent with it. I shall then bring forward a second kind of
evidence which indicates a strong probability in favour of evolution,
but does not prove it; and, lastly, I shall adduce a third kind of
evidence which, being as complete as any evidence which we can hope to
obtain upon such a subject, and being wholly and strikingly in favour of
evolution, may fairly be called demonstrative evidence of its
occurrence.




LECTURE II.

THE HYPOTHESIS OF EVOLUTION. THE NEUTRAL AND THE FAVOURABLE EVIDENCE.


In the preceding lecture I pointed out that there are three hypotheses
which may be entertained, and which have been entertained, respecting
the past history of life upon the globe. According to the first of these
hypotheses, living beings, such as now exist, have existed from all
eternity upon this earth. We tested that hypothesis by the
circumstantial evidence, as I called it, which is furnished by the