sociological. It is evident that the student of society, if he accepts
fully the modern scientific spirit, must also assume evolution in this
second or universal sense.

The Different Phases of Universal Evolution.--It may be well, in order
to correlate our knowledge of social evolution with knowledge in
general, to note the different well-marked phases of universal
evolution.

(1) _Cosmic Evolution._ This is the phase the astronomer and the
geologist are particularly interested in. It deals with the evolution of
worlds. In this phase we are dealing merely with physical matter, and it
is supposed that the active principle which works in this phase of
evolution is the attraction of particles of matter for one another. This
leads to the condensation of matter into suns and their planets, and the
geological evolution of the earth, for example. Laplace's nebular
hypothesis is an attempt to give an adequate statement of the cosmic
phase of evolution. While this hypothesis has been much criticized of
late, in its essentials it seems to stand. We are not, however, as
students of society, concerned with this phase of evolution.

(2) _Organic Evolution._ This is the phase of evolution with which
Darwin dealt and which biology, as a science of evolution of living
forms, deals with. The great merit of Darwin's work was that he showed
that the active principle in this phase of evolution is natural
selection; that is, the extermination of the unadapted through death or
through failure to reproduce. Types unsuited to their environment thus
die before reproduction. The stronger and better fitted survive, and
thus the type is raised. Natural selection may be regarded, then, as
essentially the creative force in this phase of evolution.