His life and that of the planet alike.] Moreover, it appears
that the order of development in the life of individual man and the
order of development in the life of the earth are the same, their common
features indicating a common plan. The one is the movement of a few
hours, the other of myriads of ages. This sameness of manner in their
progression points out their dependence on a law immutable and
universal. The successive appearance of the animal series in the endless
course of time has not, therefore, been accidental, but as predetermined
and as certain as the successive forms of the individual. In the latter
we do not find any cause of surprise in the assumption of states ever
increasing in improvement, ever rising higher and higher toward the
perfection destined to be attained. We look upon it as the course of
nature. Why, then, should we consider the extinctions and creations of
the former as offering any thing unaccountable, as connected with a
sudden creative fiat or with an arbitrary sentence of destruction?

[Sidenote: Progress of humanity is according to law.] In this book I
have endeavoured to investigate the progress of humanity, and found that
it shows all the phases of individual movement, the evidence employed
being historical, and, therefore, of a nature altogether different from
that on which our conclusions in the collateral instances rest. It may
serve to assure us that the ideas here presented are true when we
encounter, at the close of our investigation, this harmony between the
life of the individual, the life of society, and the life of the earth.

Is it probable that the individual proceeds in his movement of
development under law, that the planet also proceeds in its movements
under law, but that society does not proceed under law?

[Sidenote: Eternity and universality of that law.] Man, thus, is the
last term of an innumerable series of organisms, which, under the
domination of law, has, in the lapse of time, been evolving. Law has
controlled the inorganic world, and caused the earth to pass through
various physical conditions, gently and continuously succeeding one
another. The plastic forms of organic beings have been modelled to suit
those changing conditions. The invariability of that law is indicated by
the numberless ages through which it has been maintained, its
universality by its holding good in the life of the meanest individual.

But it is only a part of sociology that we have co