ic effects,
in vigour of motion, energy of life, intellectual power.

When, therefore, we notice such orderly successions, we must not at once
assign them to a direct intervention, the issue of wise predeterminations
of a voluntary agent; we must first satisfy ourselves how far they are
dependent on mundane or material conditions, occurring in a definite and
necessary series, ever bearing in mind the important principle that an
orderly sequence of inorganic events necessarily involves an orderly and
corresponding progression of organic life.

[Sidenote: Universal control of physical agents over organisms.]

To this doctrine of the control of physical agencies over organic forms
I acknowledge no exception, not even in the case of man. The varied
aspects he presents in different countries are the necessary
consequences of those influences.

[Sidenote: The case of man.]

He who advocates the doctrine of the unity of the human race is plainly
forced to the admission of the absolute control of such agents over the
organization of man, since the originally-created type has been brought
to exhibit very different aspects in different parts of the world,
apparently in accordance with the climate and other purely material
circumstances. To those circumstances it is scarcely necessary to add
manner of life, for that itself arises from them. The doctrine of unity
demands as its essential postulate an admission of the paramount control
of physical agents over the human aspect and organization, else how
could it be that, proceeding from the same stock, all shades of
complexion in the skin, and variety in the form of the skull, should
have arisen? Experience assures us that these are changes assumed only
by slow degrees, and not with abruptness; they come as a cumulative
effect. They plainly enforce the doctrine that national type is not to
be regarded as a definite or final thing, a seeming immobility in this
particular being due to the attainment of a correspondence with the
conditions to which the type is exposed. Let those conditions be
changed, and it begins forthwith to change too. I repeat it, therefore,
that he who receives the doctrine of the unity of the human race, must
also accept, in view of the present state of humanity on various parts
of the surface of our planet, its necessary postulate, the complete
control of physical agents, whether natural, or arising artificially
from the arts of civilization and the secular