cosmic and organic evolution. Let us examine this distinction more closely. We know that an organism develops, much like a world, out of an homogeneous and diffused state of its elements. Throughout its course the organic aggregate behaves like other aggregates. From the imperceptible it becomes perceptible. From the diffuse it becomes concentrated. From the indefinite it becomes definite. From the homogeneous it becomes heterogeneous. From the unstable it approaches the stable condition. Segregation, which is the selective process, is more marked in the organic than in the inorganic aggregate. Its parts are differentiated and rendered distinct and definite, while through an increasing dependence between them the whole aggregate becomes more and more firmly integrated or consolidated. Growth, which is increase of bulk, is simply the absorption of diffuse gaseous or liquid materials, which may theoretically be regarded as having originally belonged to the aggregate in its most widely diffused condition. Development, which is increase of structure, is the same process which all aggregates undergo in their transition from the homogeneous and indefinite toward the heterogeneous and definite, under the laws of segregation and the multiplication of effects. Finally, equilibration in organic aggregates is distinct and universal.
Every organism must reach this stage, and that in a comparatively brief period—so brief as to be capable of repeated and easy observation. So plain does this stage of its progress become that it is feared that the predication of a stage of equilibration, not to say dissolution, for inorganic aggregates, is an argument from analogy, where the analogy is taken from a very subordinate class of phenomena, viz., from the observed equilibration of organic aggregates. A universal conclusion is deduced from a particular case; the law of the whole is assumed from that of a part. This, according to Mr. Spencer's own showing in his "Principles of Psychology," is the weakest form of reasoning. It should be admitted, however, that while the doctrine of the ultimate disintegration and dissolution of the celestial bodies rests on very insufficient inductive evidence, there are strong a priori grounds, beyond the domain of science, but clearly within the range of philosophy, which make it a legitimate object for the exercise of the "constructive imagination."
The most important truth which can be called in to aid us in this difficulty and apparent confusion of phenomena is that of the perpetual competitive operation of both the forces of evolution and of dissolution. Both these influences are at all times and in all kinds of aggregates simultaneously at work. The history of every aggregate is that of its struggle with these opposite contending influences. The final equilibration implies this. It is the establishment of equilibrium between just these forces. In the evolution of a star the forces of dissolution are mostly within the aggregate. In that of a star-system they seem to be wholly so. The process of evolution goes on against