cience of a giddy metaphysician. One of the urgent needs of modern physical science is a thorough investigation of the nature, methods, and aids of scientific cognition, and thus of the nature of its real limits, chiefly in the light of the teachings of comparative philology and comparative psychology. Max Müller has happily designated the tendency to "reify" intellectual concepts (or, as Mill expresses it in nominalist phrase, to mistake names for things), as "modern mythology." But this mythology is not at all confined to ordinary language; it extends to all the formularies, including those employed in scientific research, which serve as the intellectual net-work for the delineation of physical phenomena and for the exact mathematical determination of the laws of their interdependence.
The most pressing need of modern physical science, however, is the disengagement of the facts of observation and induction from their present theoretical complications. Most of the scientific theories of our day have their root in the metaphysics of three centuries ago, and some of the materialistic speculations based upon them are redolent of the ancient culture of the Middle Kingdom. Both in physics and in chemistry (not to speak of the biological sciences), the facts have long since transcended the narrow bounds of the prevailing scientific hypotheses, and have thus been either ignored or misinterpreted. On the remaining pages of this paper I desire to direct attention to some of the facts connected with the main subject of my present inquiry—the concept force.
Physical forces are distributed by modern science into two classes, molecular and molar forces. Molecular forces are those which determine the internal changes of a body, while molar forces cause the motion of the entire mass. Molecular forces, therefore, are the agencies which determine the particular state of the body in its physical relations, considering it as an independent whole—or, as it is termed in modern mechanics, as an independent conservative system—while the molar forces determine the physical relations of the body to other bodies which, together with it, are integrant parts of a greater whole, i. e., of a more comprehensive conservative system.
Modern science teaches that all physical forces, molar as well as molecular, are mutually convertible. This fact is discussed and illustrated in scientific treatises without number, and its importance is duly appreciated. But there is another fact connected with it, equally well known, the significance of which is not, I think, at all realized: all force in its physical origin is molecular. The power which grinds the wheat in the mill on the stream, or which drives the steam-engines in a factory; the force which propels the cannon-ball on its path of destruction, or the vital juices in a vegetable or animal organism in their course of vital regeneration; the energy which causes the muscles of a man's arm or the vessels of his circulatory system to expand and contract—all are alike of helio-planetary origin,
