If there is any truth in this molecular-force-theory of life, it is about time for us to discard some of the old categories respecting matter, motion, and life, and substitute new ones in their place. In the multiplicity of new scientific terms constantly springing up for recognition in these days, there ought to be no difficulty in expressing the true categories, and assigning to them their proper definitional value. To include physical force, chemical force, molecular force, and vital force all under one and the same category, and then interpret their several modes of action on any theory of force-correlation, is not emancipating language from the gross thraldom into which their "molecular machinery" has driven it. Besides, there is moral force, mental force, the force of will, the force of reason, the force of honesty, the force of fraud, etc., and any number of other forces, all possessing more or less impetus or momentum, and capable of binding or coercing persons and things, in all their diversified relations, correlations, incidences, coincidences, affinities, antagonisms, and so on through an interminable chapter of interchangeable predications. All these different expressions of force are to be tethered together--definitionally bound hand and foot--under the one explanatory head of "force-correlation." We protest against the labor of thus unifying all the natural forces of the universe, even if it were practicable under scientific methods. But Professor Tyndall denies that "molecular groupings" and "molecular motions" explain anything--account for anything--in the way of explicating life-manifestations, or determining what life is.[31] And it would be difficult to cite a stronger and more determined materialist as authority on the point we are considering. He says: "If love were known to be associated with a right-handed spiral motion of the molecules of the brain, and hate with the left-handed, we should remain as ignorant as before, as to the cause of motion." But there is no proof that the molecules of the brain manifest any other motions than those necessary for keeping up the normal condition of health and vital activity in the brain itself. No one can be certain that he has seen these molecules in a state of mental activity; for where portions of the human brain have been exposed to microscopic examination, even in perfect states of consciousness on the part of those whose brains have been laid bare, there can be no certainty that the molecular action, if any, is referable to one set of movements more than another. And even in the case of animalcules, as seen in the object glass of the microscope, there is no absolute certainty that their quick, darting or jerking movements are due to any life-manifestation, as heretofore assumed. Some quite as well defined forms are entirely motionless, and if all were so, it would be idle to predicate vitality of them.[32] These infinitessimal and constantly