y to the law of gravity, yet we ought to attribute
the course of each planet to the individual act of the will of the
Creator{306}. It is in every case more conformable with what we know of
the government of this earth, that the Creator should have imposed only
general laws. As long as no method was known by which races could become
exquisitely adapted to various ends, whilst the existence of species was
thought to be proved by the sterility{307} of their offspring, it was
allowable to attribute each organism to an individual act of creation.
But in the two former chapters it has (I think) been shown that the
production, under existing conditions, of exquisitely adapted species,
is at least _possible_. Is there then any direct evidence in favour <of> or
against this view? I believe that the geographical distribution of
organic beings in past and present times, the kind of affinity linking
them together, their so-called "metamorphic" and "abortive" organs,
appear in favour of this view. On the other hand, the imperfect evidence
of the continuousness of the organic series, which, we shall immediately
see, is required on our theory, is against it; and is the most weighty
objection{308}. The evidence, however, even on this point, as far as it
goes, is favourable; and considering the imperfection of our knowledge,
especially with respect to past ages, it would be surprising if evidence
drawn from such sources were not also imperfect.

{306} In the Essay of 1842 the author uses astronomy in the same
manner as an illustration. In the _Origin_ this does not occur; the
reference to the action of secondary causes is more general, _e.g._
Ed. i. p. 488, vi. p. 668.

{307} It is interesting to find the argument from sterility given
so prominent a place. In a corresponding passage in the _Origin_,
Ed. i. p. 480, vi. p. 659, it is more summarily treated. The author
gives, as the chief bar to the acceptance of evolution, the fact
that "we are always slow in admitting any great change of which we
do not see the intermediate steps"; and goes on to quote Lyell on
geological action. It will be remembered that the question of
sterility remained a difficulty for Huxley.

{308} Similar statements occur in the Essay of 1842, p. 24, note 1,
and in the _Origin_, Ed. i. p. 299.

As I suppose that species have been formed in an analogous manner with
the varieties of the domes