pression in a new form under the conception of cosmic evolution. This conception, though specially associated with Spencer's work, is greater and more fundamental than the personal doctrines of any individual however eminent. Whatever hostile critics may think of Spencer's special treatment, it is not possible to deny to him the great credit of upholding and revivifying this principle at the time when it was in danger of being forgotten in the discovery of the enormous variety of new detailed fact. More than that, it was precisely these new discoveries which Spencer found most useful in the building of his own scheme of unification.
Granting the validity of the principle of universal evolution, there remains the more special question as to how far Spencer has succeeded in formulating and expressing it in a manner likely to be of present and of permanent value. One fact alone will predispose us to give this question the most careful attention. The remainder of his philosophical work was intended primarily as an application of his evolutionary ideas to all orders of phenomena. To this work it is impossible for anyone not hopelessly biased to deny very great merit. Yet First Principles is the coördination of the whole, and, whatever the other volumes of his philosophy may have accomplished incidentally, they were written to illustrate the applicability of his main ideas, and particularly of his famous formula of evolution, to all branches of knowledge, and particularly to those connected with life and mind.
Again, it is not possible to doubt that, in his hands, these principles have proved remarkably fertile in unravelling complexities and in solving problems presented by many diverse branches of knowledge. This is not a proof of the validity of the formula. It is possible to thread priceless pearls on worthless string; but we must not assume too hastily that the present is a case in point.
In attempting to formulate fundamental unifying principles, the philosopher who is acquainted with the trend of modern science will find part of his work already accomplished. Modern developments of chemistry and physics have elucidated two comprehensive generalizations, of which philosophy must take
