These include the nerves of touch, sight, pain, hearing, temperature, taste and smell. Motor nerves are those that carry messages from the brain and spinal cord on the one hand to the muscles on the other. They are the lines along which flash all orders resulting in bodily movements.

[Sidenote: Nerve Systems]

Another broad division of nerves is into two great nerve systems. There are the _cerebro-spinal_ system and the _sympathetic_ system. The first, the cerebro-spinal system, includes all the nerves of _consciousness_ and of _voluntary action_; it includes all nerves running between the brain and spinal cord on the one hand and the voluntary muscles on the other. The second, the sympathetic nerve system, consists of all the nerves of the unconscious or functional life; it therefore includes all nerves running between the brain and sympathetic or involuntary nerve centers on the one hand and the involuntary muscles on the other.

Every bodily movement or function that you can start or stop at will, even to such seemingly unconscious acts as winking, walking, etc., is controlled through the cerebro-spinal system. All other functions of the body, including the great vital processes, such as heart pulsation and digestion, are performed unconsciously, are beyond the direct control of the will, and are governed through the sympathetic nerve system.

[Sidenote: Organs of Consciousness and Subconsciousness]

It is obvious that the cerebro-spinal nerve system is the organ of consciousness, the apparatus through which the mind exercises its conscious and voluntary control over certain functions of the body. It is equally obvious that the _sympathetic system is not under the immediate control of consciousness, is not subject to the will, but is dominated by mental influences that act without, or even contrary to, our conscious will and sometimes without our knowledge._

Yet you are not to understand that these two great nerve systems are entirely distinct in their operations. On the contrary, they are in many respects closely related.

[Ill.u.s.tration: SEPARATE NERVE CENTERS, PLEXUSES AND GANGLIA, THE "LITTLE BRAINS" OF THE HUMAN BODY]

Thus, the heart receives nerves from both centers of government, and besides all this is itself the center of groups of nerve cells. The power by which it beats arises from a ganglionic center within the heart itself, so that the heart will continue to beat apart from the body if it be supplied with fresh blood. But the rapidity of the heart"s beating is regulated by the cerebro-spinal and sympathetic systems, of which the former tends to r.e.t.a.r.d the beat and the latter tends to accelerate it.

In the same way, your lungs are governed in part by both centers, for you can breathe slowly or rapidly as you will, but you cannot, by any power of your conscious will, stop breathing altogether.

Your interest in the brain and nerve system is confined to such facts as may prove to be of use to you in your study of the mind. These anatomical divisions interest you only as they are identified with conscious mental action on the one hand and unconscious mental action on the other.

It is, therefore, of no use to you to consider the various divisions of the sympathetic nerve system, since the sympathetic nerve system in its entirety belongs to the field of unconscious mental action. It operates without our knowledge and without our will.

[Sidenote: Looking Inside the Skull]

The cerebro-spinal system consists of the spinal cord and the brain. The brain in turn is made up of two princ.i.p.al subdivisions. First, there is the greater or upper brain, called the cerebrum; secondly, there is the lower or smaller brain, called the cerebellum. The cerebrum in turn consists of three parts: the convoluted _surface_ brain, the _middle_ brain and the _lower_ brain. So that in all we have the _surface_ brain, the _middle_ brain, the _lower_ brain and the _cerebellum_. All these parts consist of ma.s.ses of brain cells with connecting nerve fibers.

[Sidenote: Brains Parts and Functions]

And now, as to the functions of these various parts. Beginning at the lowest one and moving upward, we find first that the _spinal cord_ consists of through lines of nerves running between the brain and the rest of the body. At the same time it contains within itself certain nerve centers that are sufficient for many simple bodily movements.

These bodily movements are such as are instinctive or habitual and require no distinct act of the will for their performance. They are mere "reactions," without conscious, volitional impulse.

Moving up one step higher, we find that the _cerebellum_ is the organ of equilibrium, and that it as well as the spinal cord operates independently of the conscious will, for no conscious effort of the will is required to make one reel from dizziness.

As to the divisions of the greater brain or cerebrum, we want you to note that the _lower brain_ serves a double purpose. First, it is the channel through which pa.s.s through lines of communication to and from the upper brain and the mid-brain on the one hand and the rest of the body on the other. Secondly, it is itself a central office for the maintenance of certain vital functions, such as lung-breathing, heart-beating, saliva-secreting, swallowing, etc., all involuntary and unconscious in the sense that consciousness is not necessary to their performance.

The next higher division, or _mid-brain_, is a large region from which the conscious will issues its edicts regulating all voluntary bodily movements. It is also the seat of certain special senses, such as sight.

Lastly, the _surface brain_, known as the cortex, is the interpretative and reflective center, the abode of memory, intellect and will.

[Sidenote: Drunkenness and Brain Efficiency]

The functions of these various parts are well ill.u.s.trated 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 mid-brain 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 a.s.sault 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 const.i.tute together the organ of consciousness and will. Consciousness and will disappear with the deadening or paralysis of these two organs.

[Sidenote: Secondary Brains]

Yet these two organs const.i.tute but a small proportion of the entire ma.s.s 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._

[Sidenote: Dependence of the Subconscious]

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 const.i.tute 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.

[Sidenote: Unconsciousness and Subconsciousness]

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 const.i.tutes 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 "_sub_conscious."

[Sidenote: Synthesis of the Man-Machine]

[Sidenote: Subserviency of the Body]

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 a.s.sociation; 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, const.i.tuting the organ of a central governing intelligence with the important business of receiving, cla.s.sifying, 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.

The Supremacy of Consciousness

CHAPTER VI

THE SUPREMACY OF CONSCIOUSNESS

CONCLUSIONS DRAWN FROM STUDIES IN HUMAN PSYCHOLOGY, ANATOMY AND PHYSIOLOGY

[Sidenote: Striking off the Mental Shackles]

Stop a moment and mark the conclusion to which you have come. You have been examining the human body with the scalpel and the microscope of the anatomist and physiologist. In doing so and by watching the bodily organs in operation, you have learned that _every part of the body, even to those organs commonly known as involuntary, is ultimately subject to the influence or control of consciousness_, that part of the human intelligence which is popularly known as "the mind."

Prior to this, as a matter of direct introspective knowledge, we had come to the conclusion that the influence of the mind over all the organs of the body was one of the most obvious facts of human life.