justification and even their use, but which are now obviously
incompatible with the well-ascertained truths of palaeontology.
At present these truths leave room for only two hypotheses.
The first is that, in the course of the history of the earth,
innumerable species of animals and plants have come into
existence, independently of one another, innumerable times.
This, of course, implies either that spontaneous generation on
the most astounding scale, and of animals such as horses and
elephants, has been going on, as a natural process, through all
the time recorded by the fossiliferous rocks; or it necessitates
the belief in innumerable acts of creation repeated innumerable
times. The other hypothesis is, that the successive species of
animals and plants have arisen, the later by the gradual
modification of the earlier. This is the hypothesis of
evolution; and the palaeontological discoveries of the last
decade are so completely in accordance with the requirements of
this hypothesis that, if it had not existed, the palaeontologist
would have had to invent it.

I have always had a certain horror of presuming to set a limit
upon the possibilities of things. Therefore I will not venture
to say that it is impossible that the multitudinous species of
animals and plants may have been produced, one separately
from the other, by spontaneous generation; nor that it is
impossible that they should have been independently originated
by an endless succession of miraculous creative acts. But I must
confess that both these hypotheses strike me as so astoundingly
improbable, so devoid of a shred of either scientific or
traditional support, that even if there were no other evidence
than that of palaeontology in its favour, I should feel