142 HERBERT SPENCER

the earlier changes which we can inductively establish; it
Is seen in the geologic and climatic evolution of the Earth,
and of every simple organism on its surface; it is seen in
the evolution of Humanity, whether contemplated in the
civilised individual, or in the aggregation of races; it is seen
in the evolution of Society in respect alike of its political,
its religious, and its economical organisation ; and it is seen
in the evolution of all those endless concrete and abstract
products of human activity which constitute the environment
of our daily life. From the remotest past which Science can
fathom up to the novelties of yesterday, that in which
Progress essentially consists is the transformation of the
homogeneous into the heterogeneous." This was written
in 1857.

As far back as 1852 Spencer contributed to the * Leader'
an essay on the * Development Hypothesis' which is one
of the most noteworthy of the pre-Darwinian presentations of
the general idea of evolution. Supposing that there are some
ten millions of species, extant and extinct, he asks " which
is the most rational theory about these ten millions of species ?
Is it most likely that there have been ten millions of special
creations ? or is it most likely that by continual modifications,
due to change of circumstances, ten millions of varieties have
been produced, as varieties are being produced still ? . . .•
Even could the supporters of the Development Hypothesis
merely show that the origination of species by the process of
modification is conceivable, they would be in a better position
than their opponents. But they can do much more than
this. They can show that the process of modification has
effected, and is effecting, decided changes in all organisms
subject to modifying influences. . . . They can show that
in successive generations these changes continue, until
ultimately the new conditions become the natural ones.
They can show that in cultivated plants, domesticated
animals, and in the several races of men, such alterations
have taken place. They can show that the degrees of
difference so produced are often, as in dogs, greater than
those on which distinctions of species are in other cases
founded. They can show, too, that the changes daily taking
pkce in ourselves—the facility that attends long practice,