This section is from the book "Applications of Psychology to the Problems of Personal and Business Efficiency", by Warren Hilton. Also available from Amazon: Psychology and Achievement - Applied Psychology 12 Volume Set.
The functions of these various parts are well illustrated by the effects of alcohol upon the mind. If a man takes too much alcohol, its first apparent effect will be to paralyze the higher or cortical center. This leaves the midbrain without the check-rein of a reflective intellect, and the man will be senselessly hilarious or quarrelsome, jolly or dejected, pugnacious or tearful, and would be ordinarily described as "drunk." If in spite of this he keeps on drinking, the mid-brain soon becomes deadened and ceases to respond, and the cerebellum, the organ of equilibrium, also becomes paralyzed. All voluntary bodily activities must then cease, and he rolls under the table, helpless and "dead" drunk, or in language that is even more graphically appreciative of the physiological effects of alcohol, "paralyzed." However, the deep-seated sympathetic system is still alive. No assault has yet been made upon the vital organs of the body; the heart continues to beat and the lungs to breathe. But suppose that some playful comrade pours still more liquor down the victim's throat. The medulla, or lower brain, then becomes paralyzed, the vital organs cease to act and the man is no longer "dead" drunk. He has become a sacrifice to Bacchus. He is literally and actually dead.
It seems, then, that the surface brain and mid-brain constitute together the organ of consciousness and will. Consciousness and will disappear with the deadening or paralysis of these two organs.
Yet these two organs constitute but a small proportion of the entire mass of brain and nervous tissue of the body. In addition to these, there are not only the lower brain and the spinal cord and the countless ramifications of motor and sensory nerves throughout the body, but there are also separate nerve-centers or ganglia in every one of the visceral organs of the body. These ganglia have the power to maintain movements in their respective organs. They may in fact be looked upon as little brains developing nerve force and communicating it to the organs.
All these automatic parts of the bodily mechanism are dominated by departments of the mind entirely distinct from ordinary consciousness. In fact, ordinary consciousness has no knowledge of their existence excepting what is learned from outward bodily manifestations.
All these different organic ganglia constitute together the sympathetic nerve system, organ of that part of the mind which directs the vital operations of the body in apparent independence of the intelligence commonly called "the mind," an intelligence which acts through the cerebro-spinal system.
Yet this independence is far from being absolute. For, as we have seen, not only is the cerebro-spinal system, which is the organ of consciousness, the abode of all the special senses, such as sight, hearing, etc., and therefore our only source of information of the external world, but many organs of the body are under the joint control of both systems.
So it comes about that these individual intelligences governing different organs of the body, with their intercommunications, are dependent upon consciousness for their knowledge of such facts of the outer world as have a bearing on their individual operations, and they are subject to the influence of consciousness as the medium that interprets these facts.
It is unnecessary for us to go into this matter deeply. It is enough if you clearly understand that, in addition to consciousness, the department of mind that knows and directly deals with the facts of the outer world, there is also a deep-seated and seemingly unconscious department of mind consisting of individual organic intelligences capable of receiving, understanding and acting upon such information as consciousness transmits.
We have spoken of conscious and "seemingly unconscious" departments of the mind. In doing so we have used the word "seemingly" advisedly. Obviously we have no right to apply the term "unconscious" without qualification to an intelligent mentality such as we have described.
"Unconscious" simply means "not conscious." In its common acceptation, it denotes, in fact, an absence of all mental action. It is in no sense descriptive. It is merely negative. Death is unconscious; but unconsciousness is no attribute of a mental state that is living and impellent and constantly manifests its active energy and power in the maintenance of the vital functions of the body.
Hereafter, then, we shall continue to use the term consciousness as descriptive of that part of our mentality which constitutes what is commonly known as the "mind"; while that mental force, which, so far as our animal life is concerned, operates through the sympathetic nerve system, we shall hereafter describe as "subconscious."
Let us summarize our study of man's physical organism. We have learned that the human body is a confederation of various groups of living cells; that in the earliest stages of man's evolution, these cells were all of the same general type; that as such they were free-living, free-thinking and intelligent organisms as certainly as were those unicellular organisms which had not become members of any group or association; that through the processes of evolution, heredity and adaptation, there has come about in the course of the ages, a subdivision of labor among the cells of our bodies and a consequent differentiation in kind whereby each has become peculiarly fitted for the performance of its allotted functions; that, nevertheless, these cells of the human body are still free-living, intelligent organisms, of which each is endowed with the inherited, instinctive knowledge of all that is essential to the preservation of its own life and the perpetuation of its species within the living body; that, as a part of the specializing economy of the body, there have been evolved brain and nerve cells performing a twofold service - first, constituting the organ of a central governing intelligence with the important business of receiving, classifying, and recording all impressions or messages received through the senses from the outer world, and, second, communicating to the other cells of the body such part of the information so derived as may be appropriate to the functions of each; that finally, as such complex and confederated individuals, each of us possesses a direct, self-conscious knowledge of only a small part of his entire mental equipment; that we have not only a consciousness receiving sense impressions and issuing motor impulses through the cerebro-spinal nervous system, but that we have also a subconsciousness manifesting itself, so far as bodily functions are concerned, in the activity of the vital organs through the sympathetic nerve system; that this subconsciousness is dependent on consciousness for all knowledge of the external world; that, in accordance with the principles of evolution, man as a whole and as a collection of cell organisms, both consciously and unconsciously, is seeking to adapt himself to his external world, his environment; that the human body, both as a whole and as an aggregate of cellular intelligences, is therefore subject in every part and in every function to the influence of the special senses and of the mind of consciousness.