In the second edition of his book, Mr. Spencer supplemented his first formula by a unifying addition, meant to be strictly mechanical. "Evolution," he now said, "is the progressive integration of matter and dissipation of motion," during which both the matter and the motion undergo the previously designated kinds of change. But this makes the formula worse instead of better. The "dissipation of motion" part of it is simple vagueness,--for what particular motion is "dissipated" when a man or state grows more highly evolved? And the integration of matter belongs only to stellar and geologic evolution. Neither heightened specific gravity, nor greater massiveness, which are the only conceivable integrations of matter, is a mark of the more evolved vital, mental, or social things. It is obvious that the facts of which Spencer here gives so clumsy an account could all have been set down more simply. First there is solar, and then there is geological evolution, processes accurately describable as integrations in the mechanical sense, namely, as decrease in bulk, or growth in hardness. Then Life appears; and after that neither integration of matter nor dissipation of motion play any part whatever. The result of life, however, is to fill the world more and more with things displaying _organic unity_. By this is meant any arrangement of which one part helps to keep the other parts in existence. Some organic unities are material,--a sea-urchin, for example, a department store, a civil service, or an ecclesiastical organization. Some are mental, as a "science," a code of laws, or an educational programme. But whether they be material or mental products, organic unities must _accumulate_; for every old one tends to conserve itself, and if successful new ones arise they also "come to stay." The human use of Spencer's adjectives "integrated," "definite," "coherent," here no longer shocks one. We are frankly on teleological ground, and metaphor and vagueness are permissible. This tendency of organic unities to accumulate when once they are formed is absolutely all the truth I can distill from Spencer's unwieldy account of evolution. It makes a much less gaudy and chromatic picture, but what there is of it is exact. Countless other criticisms swarm toward my pen, but I have no heart to express them,--it is too sorry an occupation. A word about Spencer's conception of "Force," however, insists on being added; for although it is one of his most essential, it is one of his vaguest ideas.