of-hand
than Paley's 'Natural Theology.'

If, on the other hand, Mr. Darwin maintains natural selection to be a
cause of variation, this comes to saying that when an animal has varied
in an advantageous direction, the fact of its subsequently surviving in
the struggle for existence is the cause of its having varied in the
advantageous direction--or more simply still--that the fact of its
having varied is the cause of its having varied.

And this is what we have already seen Mr. Darwin actually to say, in a
passage quoted near the beginning of this present book. When writing of
the eye he says, "Variation will cause the slight alterations;"[349] but
the "slight alterations" _are_ the variations; so that Mr. Darwin's
words come to this--that "variation will cause the variations."

There does not seem any better way out of this dilemma than that which
Mr. Darwin has adopted--namely, to hold out natural selection as "a
means" of modification, and thenceforward to treat it as an efficient
cause; but at the same time to protest again and again that it is
not a cause. Accordingly he writes that "Natural Selection _acts
only by the preservation and accumulation_ of small inherited
modifications,"[350]--that is to say, it has had no share in inducing or
causing these modifications. Again, "What applies to one animal will
apply throughout all time to all animals--_that is, if they vary, for
otherwise natural selection can effect nothing_"[351]; and again, "for
natural selection only _takes advantage of such variations as
arise_"[352]--the variations themselves arising, as we have just seen,
from variation.

Nothing, then, can be clearer from these passages than that natural
selection is not a cause of modification; while, on the other hand,
nothing can be clearer, from a large number of such passages, as, for
instance, "natural selection may be _effective_ in _giving_ and
_keeping_ colour,"[353] than that natural selection is an efficient
cause; and in spite of its being expressly declared to be only a "means"
of modification, it will be accepted as cause by the great majority of
readers.

Mr. Darwin explains this apparent inconsistency thus:--He maintains that
though the advantageous modification itself is fortuitous, or without
known cause or principle underlying it, yet its becoming the predominant
form of the species in which it appears is due to the fact that those
animals which have been advantageously modified common