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lished by the laborious investigations of the last fifty years, and as a result it is an accepted fact of anatomy that while the neurons of the cerebro-spinal system are directly subordinate to the brain, those of the sympathetic are so linked up with the other as to be indirectly subordinate to it. In other words, the whole nervous system is subject to the control of the brain, which is the seat of the human intelligence.
The brain itself consists of nerve cells which have fibres linking up every cell and every group of cells with each other, and also with every organ and every part of the body. They have an exquisitely fine internal structure, and their minuteness can be faintly imagined by their amazing number, which, according to Dr. Ford Robertson, may be computed at 3,000,000,000 in an average human brain: if all the telegraph batteries in the world with all their wires were thrown together and worked as one system, they would form a mechanism not to compare in numbers or complexity with the cells which are packed, together with their food-supply and drainage apparatus and the connecting tissue that holds them all in place, within the space of a single human skull.2
What are the nerves? Their vast number and the minuteness of their fibres may well excite astonishment; but this is not the real wonder of them. What makes them so mysterious, so incomprehensible, is that they are the link between matter and spirit.
1 See pp. 108, 111. 2 Dr. T. S. Clouston, The Hygiene of Mind, 4th ed., 1907, D.
We do not know how this is. Phrases about molecular action, such as Herbert Spencer used, only serve to make our ignorance appear learned, as indeed no one knew better than he. We not only do not know, we cannot even imagine, how a thought can be registered in a speck of protoplasm, or how a sensation can travel along a fibre. How can matter think? Or how can a syllogism store itself in a cell? There is no analogy to help us in the understanding of this. We could understand a ghost thinking, perhaps, because thought is a spiritual process. But how can a combination of carbon, hydrogen, oxygen, and nitrogen think, or feel, or aspire, or be sorry? We look at some minute filament of a neuron under the microscope, and we ask, How can the sensation of pain be carried along this, and how can pain be felt by the cell to which it runs? We look at the grey matter of the brain and we ask, How can millions of memories be impressed upon its millions of cells? And all such questions resolve themselves into the one mystery that spirit is incarnate in matter, that a brain cell is not merely what we can see, but is also something else and something infinitely more important. The Christian belief about God is certainly of a piece with the phenomena of life, for every neuron is itself an incarnate word.
This part at least of the human anatomy, therefore, the nervous system, is not merely body; it is equally spirit. To revert to the terms of our last chapter, it is a sacrament, having a mixed nature.
1 See, for instance, Herbert Spencer, First Principles of Psychology, 2nd ed., 1870, pp. 63–7.
We may regard it as physiology or we may regard it as psychology, for it is both: in the terrible language of the scientists, it belongs to physiological psychology
And I think we are both clearest to the understanding and truest of the facts when we say that the nervous system is the link between the two worlds, so different in their nature, of spirit and matter. There are various degrees in the psychical world, it is true, various stages in the mind, and these have their centres clearly defined in the body. It is now generally agreed that consciousness is practically limited to the outermost layer of the upper part of the brain — the cortex - which is thus the
of voluntary actions and conscious sensations; while below this are the mid-brain, and the medulla extending down the spinal cord to be linked up with the sympathetic system. A nervous stimulus may produce an action that is purely “reflex," and does not pass through the brain at all, as when by tapping below the knee-cap you make a man kick out his leg. But the nerve-force is of the same nature, and all belongs to the realm of “mind," that which we commonly call the mind being merely nerve-force in its highest form, conscious, and therefore connected with the cortex, the crown of the brain.
We need not pursue this farther for the present. It is enough to say that the life of the body is due to the fact that there exists in every part of it nerve fibres which connect it with another world, and infuse into it a psychic force which physiology shows to be of the same nature as that of the intelligent brain, since it uses the same organs, acts in the same
way, and is interchangeable with that of the brain. The whole nervous system of the body is in fact joined up with the brain cortex, by innumerable fibres; and thus is subordinate to it — the Cerebrospinal system directly, and the sympathetic system indirectly, subordinate to the seat of conscious will and intelligence. The brain is thus connected with every organ of the body, because it is itself the principal organ of the mind, and mind is the director - not only of the conscious acts of the body, but of the unconscious acts also. Being in a material environment, mind uses this nervous mechanism, just as the British Government uses the telegraph, and is connected by these channels of communication with every part of the Empire. The British Empire is not for this reason created by the telegraph, but is itself the creator, owner, and user of it. So is it, we think, with mind,
THE EFFECT OF MIND ON BODY
Thus we reach a conclusion of profound importance without passing into the regions of controversy, without leaving that world of security where things can be weighed and measured and seen under the microscope, without even troubling to deny the assumptions of the materialist. We might even allow him to assume for the sake of argument that matter is the one and only substance, and that thought is a secretion of the brain, since the fact remains that mind has a close and intimate control over every part of the body.
And if it be answered that this important conclusion is so generally accepted as to have become a truism, the answer is, on the one hand that the general public does not know it, and on the other that the profession which is most immediately concerned with the physical well-being of man has hitherto largely ignored it. It is new knowledge resulting largely on the tracing of the nerves made possible by the method of Golgi - and like most new knowledge it has not yet been assimilated. Dr. Schofield is surely well within the mark when he says
“The most recent physiologies agree in dealing solely with apparatus, structure, mechanism, and function on a