Philosophy, in order to adapt itself to the spirit of the age, must welcome and cultivate the freest critical inquiry into its own methods and results, and must cheerfully submit itself to the demand for evidences which has its roots in the common and essential experience of the race. Moreover, the growth of the spirit of democracy, which, on the one hand, is distinctly unfavorable to any system of philosophy whose tenets and formulas seem to have only an academic validity or a merely esoteric value, and which, on the other hand, requires for its satisfaction a more tenable, helpful, and universally applicable theory of life and reality, cannot fail, in my judgment, to influence favorably the development of philosophy. In the union of the speculative and the practical; in the harmonizing of the interests of the positive sciences, with their judgments of fact and law, and the interests of art, morality, and religion, with their value-judgments and ideals; in the synthesis of the truths of Realism and Idealism, as they have existed hitherto and now exist in separateness or antagonism; in a union that is not accomplished by a shallow eclecticism, but by a sincere attempt to base philosophy upon the totality of human experience;--in such a union as this must we look for the real progress of philosophy in the coming century. Just now there seem to be two somewhat heterogeneous and not altogether well-defined tendencies toward the reconstruction of systematic philosophy, both of which are powerful and represent real truths conquered by ages of intellectual industry and conflict. These two, however, need to be internally harmonized, in order to obtain a satisfactory statement of the development of the last century. They may be called the evolutionary and the idealistic. The one tendency lays emphasis on mechanism, the other on spirit. Yet it is most interesting to notice how many of the early workmen in the investigation of the principle of the conservation and correlation of energy took their point of departure from distinctly teleological and spiritual conceptions. "I was led," said Colding,--to take an extreme case,--at the Natural Science Congress at Innsbruck, 1869, "to the idea of the constancy of national forces by the religious conception of life." And even Moleschott, in his _Autobiography_, posthumously published, declares: "I myself was well aware that the whole conception might be converted; for since all matter is a bearer of force, endowed with force or penetrated with spirit, it would be just as correct to call it a spiritualistic conception." On the other hand, the modern, better instructed Idealism is much inclined, both from the psychological and from the more purely philosophical points of view, to regard with duly profound respect all the facts and laws of that mechanism of Reality, which certainly is not merely the dependent construction of the human mind functioning