, has remained genuine for
more than four centuries in the district where it is believed to have
originated.[941]

* * * * *

In accordance with the views maintained by me in this work and elsewhere,
not only the various domestic races, but the {430} most distinct genera and
orders within the same great class,--for instance, whales, mice, birds, and
fishes--are all the descendants of one common progenitor, and we must admit
that the whole vast amount of difference between these forms of life has
primarily arisen from simple variability. To consider the subject under
this point of view is enough to strike one dumb with amazement. But our
amazement ought to be lessened when we reflect that beings, almost infinite
in number, during an almost infinite lapse of time, have often had their
whole organisation rendered in some degree plastic, and that each slight
modification of structure which was in any way beneficial under excessively
complex conditions of life, will have been preserved, whilst each which was
in any way injurious will have been rigorously destroyed. And the
long-continued accumulation of beneficial variations will infallibly lead
to structures as diversified, as beautifully adapted for various purposes,
and as excellently co-ordinated, as we see in the animals and plants all
around us. Hence I have spoken of selection as the paramount power, whether
applied by man to the formation of domestic breeds, or by nature to the
production of species. I may recur to the metaphor given in a former
chapter: if an architect were to rear a noble and commodious edifice,
without the use of cut stone, by selecting from the fragments at the base
of a precipice wedge-formed stones for his arches, elongated stones for his
lintels, and flat stones for his roof, we should admire his skill and
regard him as the paramount power. Now, the fragments of stone, though
indispensable to the architect, bear to the edifice built by him the same
relation which the fluctuating variations of each organic being bear to the
varied and admirable structures ultimately acquired by its modified
descendants.

Some authors have declared that natural selection explains nothing, unless
the precise cause of each slight individual difference be made clear. Now,
if it were explained to a savage utterly ignorant of the art of building,
how the edifice had been raised stone upon stone, and why wedge-formed
fragments were use