There is a wide gulf between the thing you cannot explain and the thing
that upsets you altogether. There is hardly any hypothesis in this
world which has not some fact in connection with it which has not been
explained, but that is a very different affair to a fact that entirely
opposes your hypothesis; in this case all you can say is, that your
hypothesis is in the same position as a good many others.

Now, as to the third test, that there are no other causes competent to
explain the phenomena, I explained to you that one should be able to
say of an hypothesis, that no other known causes than those supposed by
it are competent to give rise to the phenomena. Here, I think, Mr.
Darwin's view is pretty strong. I really believe that the alternative
is either Darwinism or nothing, for I do not know of any rational
conception or theory of the organic universe which has any scientific
position at all beside Mr. Darwin's. I do not know of any proposition
that has been put before us with the intention of explaining the
phenomena of organic nature, which has in its favour a thousandth part
of the evidence which may be adduced in favour of Mr. Darwin's views.
Whatever may be the objections to his views, certainly all others are
absolutely out of court.

Take the Lamarckian hypothesis, for example. Lamarck was a great
naturalist, and to a certain extent went the right way to work; he
argued from what was undoubtedly a true cause of some of the phenomena
of organic nature. He said it is a matter of experience that an animal
may be modified more or less in consequence of its desires and
consequent actions. Thus, if a man exercise himself as a blacksmith,
his arms will become strong and muscular; such organic modification is
a result of this particular action and exercise. Lamarck thought that
by a very simple supposition based on this truth he could explain the