motion. This would involve an absolute break in the physical series, an annihilation of motion, and a virtual creation of something else. A completer denial of the conservation of energy could not be made. The natural scientist, therefore, has quite abandoned, on grounds that for him are imperative, the old position that the brain states are the cause of psychical states.

From the present standpoint of the natural scientist, therefore, we may not only say with Professor James,' that we have no need to assert a "productive function" of the brain in its relation to the psychical states, since we may equally well assume a "permissive" or "transmissive function"; but we may say, we cannot admit the possibility of a productive function of the brain, since it would deny the conservation of energy. To the strict logic of the position involved in the doctrine of the conservation of energy, naturalism must be held. That position only allows it to recognize two continuous mutually independent series-the one physical, the other psychical-equally justified as facts. And this necessary admission is quite sufficient for our present purpose, which was 1 Human Immortality, p. 15.

simply to show that physiological psychology does not preclude the conviction of a real and independent spiritual life.

That there are many reasons for questioning the absolute dualism of this conception of the relation of the physical and the psychical; that naturalism is itself most inconsistent in carrying out its position, since, as Ward points out, "though rejecting materialism" it "abandons neither the materialistic standpoint nor the materialistic endeavor to colligate the facts of life, mind and history with a mechanical scheme ";1 that the whole philosophy underlying it is hardly capable of any final defense;- all this need not now concern us. It is enough for the present that we are at liberty to speak in ordinary terms of the bodily conditions of the spiritual life, without any logically implied denial of the independent reality and significance of that spiritual life.

Returning, then, from this long digression, let us notice that these modern investigations do not allow us to forget that man-mind and body-is a real unity, two-sided and complex enough it may be, yet one and not two; they leave us no room to doubt the

1 Naturalism and Agnosticism, Vol. I, p. viii.

mysterious intimacy of the connection of the physical and the psychical. It is more than alliteration when Höffding1 insists on "the parallelism and proportionality," and Sully' insists on "the concomitance and covariation" of the nervous and mental processes.

CHAPTER V

THE UNITY OF MIND AND BODY—THE PSYCHOLOGICAL

EVIDENCE

I. THE LAW OF DIFFUSION

ONE of the clearest proofs of this intimate connection of the psychical with the physical -not in the case of the brain only, but in the whole body-is contained in what Bain has called the law of diffusion, and which James thus states: "Using sweeping terms, and ignoring exceptions, we might say that every possible feeling produces a movement, and that movement is a movement of the entire organism, and of each and all its parts. What happens patently when an explosion or a flash of lightning startles us, or when we are tickled, happens latently with every sensation we receive." These effects of feeling, even of the simplest kind, on the body, have been experimentally traced in the modification of the circulation of the blood, of respiration, of the activity of the sweat 1 1 Op. cit., Vol. II, p. 372.

glands, and of the voluntary muscles, and less accurately in movements of the viscera. To take but a single instance, the effect on circulation: every least mental activityfeeling or thought-affects the circulation of the blood. This is particularly striking in the brain.

Mosso's ingenious experiments here1 make the connection of thought and circulation of blood in the brain incontestable. He placed his subjects upon a table so carefully balanced that the slightest increase of weight at either extremity would turn the scale. He found that any active thinking by the subject, like the solving of a problem, would at once cause the head end of the table to go down, in consequence of the influx of blood to the head. Sometimes the subject went to sleep on this "scientific cradle," and it was found that even in sleep so slight a disturbance as the moving of a chair was enough to cause brain activity sufficient to call for such influx of blood as to make the head end of the table go down.

Henle has shown, also, that the depressing emotions increase the contraction of the

1 Cf., e. g., James, Op. cit., Vol. I, p. 98; Pedagogical Seminary, Vol. II, p. 12.