The reader who has followed our argument this far will understand that we are seldom willing to think of the body as separate from the mind. The body is a machine, to be sure, but it is a machine that has a driver, and while it is possible for a sound machine to have a drunken and irresponsible driver, such a machine is not apt to remain sound very long. Frequently, when there is trouble with the machine, we find the fault to be with the driver; in other words, we find that what is needed for the body is a change in the mind.

If you wish to have a sound body, and to keep it sound as long as possible, the first problem for you to settle is what you want to make of your life; you must have a purpose, and confront the tasks of life with energy and interest. What is the use of talking about health to a man who has no moral purpose? He may answer—indeed, I have heard victims of alcoholism answer—"Let me alone. I have a right to go to hell in my own way."

I am aware, of course, that the opposite of the proposition is equally true. A man cannot enjoy much mental health while he has a sick body. It is a good deal like the old question, Which comes first, the hen or the egg? The mind and the body are bound up together, and you may try to deal with each by turn, but always you find yourself having to deal with both. Most physicians have a tendency to overlook the mind, and Christian Scientists make a religion of overlooking the body, and each pays the penalty in greatly reduced effectiveness.

My first criticism of medical science, as it exists today, is that it has a tendency to concentrate upon organs and functions, and to overlook the central unity of the system. You will find a doctor who specializes in the stomach and its diseases, and is apt to talk as if the stomach were a thing that went around in the world all by itself. He will discuss the question of what goes into your stomach, and overlook to point out to you that your stomach is nourished by your blood-stream, which is controlled by your nervous system, which in turn is controlled by hope, by ambition, by love, by all the spiritual elements of your being. A single pulse of anger or of fear may make more trouble with the contents of your stomach than the doctor's pepsins and digestive ferments can remedy in a week.

Of course, you may do yourself some purely local injury, and so for a time have a purely local problem. You may smash your finger, and that is a problem of a finger; but neglect it for a few days, and let blood poison set in, and you will be made aware that the human body is one organism, and also that, in spite of any metaphysical theories you may hold, your body does sometimes dominate and control your mind.

Some one has said that the blood is the life; and certainly the blood is both the symbol and the instrument of the body's unity. The blood penetrates to all parts of the body and maintains and renews them. If the blood is normal, the work of renewal does not often fail. If there is a failure of renewal—that is, a disease—we shall generally find an abnormal condition of the blood. The distribution of the blood is controlled by the heart, a great four-chambered pump. One chamber drives the blood to the lungs, a mass of fine porous membranes, where it comes into contact with the air, and gives off the poisons which it has accumulated in its course through the body, and takes up a fresh supply of oxygen. By another chamber of the heart the blood is then sucked out of the lungs, and by the next chamber it is driven to every corner of the body. It takes to every cell of the body the protein materials which are necessary for the body's renewal, and also the fuel materials which are to be burned to supply the body's energy; also it takes some thirty million millions of microscopic red corpuscles which are the carriers of oxygen, and an even greater number of the white corpuscles, which are the body's scavengers, its defenders from invasion by outside germs.

There are certain outer portions of the body, such as nails and the scales of the skin, which are dead matter, produced by the body and pushed out from it and no longer nourished by the blood. But all the still living parts of the body are fed at every instant by the stream of life. Each cell in the body takes the fuel which it needs for its activities, and combines it with the oxygen brought by the red corpuscles; and when the task of power-production has been achieved, the cell puts back into the blood-stream, not merely the carbon dioxide, but many complex chemical products—ammonia, uric acid, and the "fatigue poisons," indol, phenol and skatol. The blood-stream bears these along, and delivers some to the sweat glands to be thrown out, and some to the kidneys, and the rest to the lungs.

All of this complicated mass of activities is in normal health perfectly regulated and timed by the nervous system. You lie down to sleep, and your muscles rest, and the vital activities slow up, your heart beats only faintly; but let something frighten you, and you sit up, and these faculties leap into activity, your heart begins to pound, driving a fresh supply of blood and vital energy. You jump up and run, and these organs all set to work at top speed. If they did not do so, your muscles would have no fresh energy; they would become paralyzed by the fatigue poisons, and you would be, as we say, exhausted.

All the rest of the body might be described as a shelter and accessory to the life-giving blood-stream; all the rest is the blood-stream's means of protecting itself and renewing itself. The stomach is to digest and prepare new blood material, the teeth are to crush it and grind it, the hands are to seize it, the eyes are to see it, the brain is to figure out its whereabouts. Man, in his egotism, imagines his little world as the center of the universe; but the wise old fellow who lives somewhere deep in our subconsciousness and looks after the welfare of our blood-stream—he has far better reason for believing that all our consciousness and our personality exist for him!

Now, disease is some failure of this blood-stream properly to renew itself or properly to protect itself and its various subsidiary organs. When you find yourself with a disease, you call in a doctor; and unless this doctor is a modern and progressive man, he makes the mistake of assuming that the disease is in the particular organ where it shows itself. You have, let us say, "follicular tonsilitis." (These medical men have a love for long names, which have the effect of awing you, and convincing you that you are in desperate need of attention.) Your throat is sore, your tonsils are swollen and covered with white spots; so the doctor hauls out his little black bag, and makes a swab of cotton and dips it, say in lysol, and paints your tonsils. He knows by means of the microscope that your tonsils are covered and filled with a mass of foreign germs which are feeding upon them; also he knows that lysol kills these germs, and he gives you a gargle for the same purpose, puts you to bed, and gradually the swelling goes down, and he tells you that he has cured you, and sends you a bill for services rendered. But maybe the swelling does not go down; maybe it gets worse and you die. Then he tells your family that nature was to blame. Nature is to blame for your death, but it never occurs to anyone to ask what nature may have had to do with your recovery.

I do not know how many thousands of diseases medical science has now classified. And for each separate disease there are complex formulas, and your system is pumped full of various mineral and vegetable substances which have been found to affect it in certain ways. Perhaps you have a fever; then we give you a substance which reduces the temperature of your blood-stream. It never occurs to us to reflect that maybe nature has some purpose of her own in raising the temperature of the blood; that this might be, so to speak, the heat of conflict, a struggle she is waging to drive out invading germs; and that possibly it would be better for the temperature to stay up until the battle is over. Or maybe the heart is failing; then our medical man is so eager to get something into the system that he cannot wait for the slow process of the mouth and the stomach, he shoots some strychnine directly into the blood-stream. It does not occur to him to reflect that maybe the heart is slowing up because it is overloaded with fatigue poisons, of which it cannot rid itself, and that the effect of stimulating it into fresh activity will be to leave it more dangerously poisoned than before.

We are dealing here with processes which our ancient mother nature has been carrying on for a long time, and which she very thoroughly understands. We ought, therefore, to be sure that we know what is the final effect of our actions; more especially we ought to be sure that we understand the cause of the evil, so that we may remove it, and not simply waste our time treating symptoms, putting plasters on a cancer. This is the fundamental problem of health; and in order to make clear what I mean, I am going to begin by telling a personal experience, a test which I made of medical science some twelve or fourteen years ago, in connection with one of the simplest and most external of the body's problems—the hair. First I will tell you what medical science was able to do for my hair, and second what I myself was able to do, when I put my own wits to work on the problem.

I had been overworking, and was in a badly run down condition. I was having headaches, insomnia, ulcerated teeth, many symptoms of a general breakdown; among these I noticed that my hair was coming out. I decided that it was foolish to become bald before I was thirty, and that I would take a little time off, and spend a little money and have my hair attended to. I did not know where to go, but I wanted the best authority available, so I wrote to the superintendent of the largest hospital in New York, asking him for the name of a reliable specialist in diseases of the scalp. The superintendent replied by referring me to a certain physician, who was the hospital's "consulting dermatologist," and I went to see this physician, whose home and office were just off Fifth Avenue.

He examined my scalp, and told me that I had dandruff in my hair, and that he would give me a prescription which would remove this dandruff and cause my hair to stop falling out. He charged me ten dollars for the visit, which in those days was more money than it is at present. Being of an inquiring turn of mind, I tried to get my money's worth by learning what there was to learn about the human hair. I questioned this gentleman, and he told me that the hair is a dead substance, and that its only life is in the root. He explained that barbers often persuade people to have their hair singed, to keep it from falling out, and that this was an utterly futile procedure, and likewise all shampooing and massage, which only caused the hair to fall out more quickly. It was better even not to wash the hair too often. All that was needed was a mixture of chemicals to kill the dandruff germs; and so I had the prescription put up at a drug store, and for a couple of years I religiously used it according to order, and it had upon my hair absolutely no effect whatever.

So here was the best that medical science could do. But still, I did not want to be bald, so I went among the health cranks—people who experiment without license from the medical schools. Also, I experimented upon myself, and now I know something about the human hair, something entirely different from what the rich and successful "consulting dermatologist" taught me, but which has kept me from becoming entirely bald:

First, the human hair is made by the body, and it is made, like everything else in the body, out of the blood-stream. It is perfectly true that the dandruff germ gets into the roots, and makes trouble, and that the process of killing this germ can be helped by chemicals; but it does not take a ten-dollar prescription, it only takes ten cents' worth of borax and salt from the corner grocery. (Put a little into a saucer, moisten it, rub it into the scalp, and wash it out again.) But infinitely more important than this is the fact that healthy hair roots are a product of healthy blood, and that unhealthy blood produces sick hair roots, which cannot hold in the hair. Most important of all is the fact that in order to make healthy hair roots the blood must flow fully and freely to these hair roots; whereas I had been accustomed for many hours every day of my life to clap around my scalp a tight band which almost entirely stopped the circulation of the life-giving blood to my sick hair roots. In other words, by wearing civilized hats, I was literally starving my hair to death.

As soon as I realized this I took off my civilized hat, and have never worn one since. As a rule, I don't wear anything. On the few occasions when I go into the city, I wear a soft cap. Now and then I experience inconvenience from this—the elevator boy in some apartment house tells me to come in by the delivery entrance, or the porter of a sleeping-car will not let me in at all. I remember discussing these embarrassments with Jack London, who went even further in his defiance of civilization, and wore a soft shirt. It was his custom, he said, to knock down the elevator boys and sleeping-car porters. I answered that that might be all right for him, because he could do it; whereas I was reduced to the painful expedient of explaining politely why I went about without the customary symbols of my economic superiority.

The "consulting dermatologist" had very solemnly and elaborately warned me concerning the danger of moving my hair too violently, and thus causing it to come out; but now my investigations brought out the fact that moving the hair, that is, massaging the scalp, increases the flow of blood to the hair roots, and further increases resistance to disease. As for causing the hair to fall out, I discovered that the more quickly you cause a hair to fall out, the greater is the chance of your getting another hair. If a hair is allowed to die in the root, it kills that root forever, but if it is pulled out before it dies, the root will make a new hair. Every "beauty parlor" specialist knows this; she knows that if a hair is pulled, it grows back bigger and stronger than ever, and so to pull out hair is the last thing you must do if you want to get rid of hairs!

I know a certain poet, who happens to have been well-endowed with physical graces by our mother nature. He finds it worth while to preserve them—they being accessory to those amorous experiences which form so large a part of the theme of poetry. Anyhow, this poet values his beautiful hair, and you will see him sitting in front of his fireplace, reading a book, and meanwhile his fingers run here and there over his head, and he grabs a bunch of hair and pulls and twists it. He has cultivated this habit for many years, and as a result his hair is as thick and heavy as the "fuzzy-wuzzies" of Kipling's poem. It is a favorite sport of this poet to lure some rival poet into a contest. He will mildly suggest that they take hold of each other's hair and have a tug of war. The rival poet, all unsuspecting, will accept the challenge, and my friend will proceed to haul him all over the place, to the accompaniment of howls of anguish from the victim, and howls of glee from the victor, who has, of course, a scalp as tough as a rhinoceros hide.

I am not a poet, and it is not important that I should be beautiful, and I have been too busy to remember to pull my hair; but by giving up tight hats, and by limiting the amount of my overworking, I have managed to keep what hair I had left when the hair specialist had got through with me. I tell this anecdote at the beginning of my discussion of health, because it illustrates so well the factors which appear in every case of disease, and which you must understand in seeking to remedy the trouble.

We have a phrase which has come down to us from the ancient Latins, "vis medicatrix naturae," which means the healing power of nature. So long ago men realized that it is our ancient mother who heals our wounds, and not the physician. Out of this have grown the cults of "nature cure" enthusiasts; and according to the fashion of men, they fly to extremes just as unreasonable and as dangerous as those of the "pill doctors" they are opposing. I have in mind a man who taught me probably more than any other writer on health questions, and with whom I once discussed the subject of typhoid, how it seemed to affect able-bodied men in the prime of their physical being. This, of course, was contrary to the theories of nature cure, and my friend had a simple way of meeting the argument—he refused to believe it. He insisted that, as with all other germ infections, it must be a question of bodily tone; no germ could secure lodgment in the human body unless the body's condition was reduced.

"But how can you be sure of that?" I argued. "You know that if you go into the jungle, you are not immune against the scorpion or the cobra or the tiger. There is nothing in all nature that is safe against every enemy. What possible right have you to assert that you are immune against every enemy which can attack your blood-stream?"

We shall find here, as we find nearly always, that the truth lies somewhere between the extremes of two warring schools. Our race has been existing for a long time in a certain environment, and its very existence implies superiority to that environment. The weaklings, for whom its hardships were too severe, were weeded out; hostile parasites invaded their blood-stream and conquered and devoured them. But those who survived were able to make in their blood-stream the substances known as anti-bodies, the "opsonins," to help the white blood corpuscles devour the germs. As the result of their victory, we carry those anti-bodies in our system, which gives us immunity to those particular diseases, or at any rate gives us the ability to have the diseases without dying. Every time we go into a street car, we take into our throat and lungs the germs of tuberculosis. Examination proves that we carry around with us in our mouths the germs of all the common throat and nose diseases, colds, bronchitis, tonsilitis. No matter what precautions we might take, no matter if we were to gargle our throats every few minutes, we could never get rid of such germs. And they wage continual war upon the body's defenses; they batter in vain upon the gates of our sound health. But take us to some new environment to which we are not accustomed; take us to Panama in the old days of yellow fever, or take us to Africa, and let the tsetse fly bite us, and infect us with "sleeping sickness." Here are germs to which our systems are not accustomed; and before them we are as helpless as the ancient knights-at-arms, who had conquered everything in sight, and ruled the continent of Europe for many hundreds of years, but were wiped off the earth by a chemist mixing gunpowder.

In the Marquesas Islands, in the South Seas, there lived a beautiful and happy race of savages, believed to have been descended, long ages ago, from Aryan stock. From the point of view of physical perfection, they were an ideal race, living a blissful outdoor life, which you may read about in Melville's "Typee," and in O'Brien's "White Shadows in the South Seas." This race conformed to all the requirements of the nature enthusiast. They went practically naked, their houses were open all the time, they lived on the abundant fruits of the earth. To be sure, they were cannibals, but this was more a matter of religious ceremony than of diet. They ate their war captives, but this was only after battle, and not often enough to count, one way or the other, in matters of health. They had lived for uncounted ages in perfect harmony with their environment; they were happy and free; and certainly, if such a thing were possible to human beings, they should have been proof against germs. But a ship came to one of these islands, and put ashore a sailor dying of tuberculosis, and in a few years four-fifths of the population of this island had been wiped out by the disease. What tuberculosis left were finished by syphilis and smallpox, and today the Marquesans are an almost extinct race.

But there is another side to the argument—and one more favorable to the nature cure enthusiast. We civilized men, by soft living, by self-indulgence and lack of exercise, may reduce the tone of our body too far below the standard which our ancestors set for us; and then the common disease germs get us, then we have colds, sore throats, tuberculosis. The nature cure advocate is perfectly right in saying that there is no use treating such diseases; the thing is to restore the body to its former tone, so that we may be superior to our normal environment and its strains.

You know the poem of the "One Hoss Shay," which was so perfectly built in every part that it ran for fifty years and then collapsed all at once in a heap. But the human body is not built that way. It always has one or more places which are weaker than the others, and which first show the effects of strain. In one person it will take the form of dyspepsia, in another it will be headaches, in another colds, in another decaying teeth, in another hardening of the arteries or stiffening of the joints. But whatever the symptoms may be, the fundamental cause is always the same, an abnormal condition of the blood-stream, and a consequent lowering of the body's tone. Therefore, studying any disease and its cure, you have first the emergency question, are there any germs lodged in the body, and if so, how can you destroy them? As part of the problem, you have to ask whether your blood-stream is normal, and if not, what are the methods by which you can make it normal and keep it so? Also you have to ask, what are the reasons why your trouble manifests itself in this or that particular organ? Is there some weakness or defect there, and can the defect be remedied, or can your habits be changed so as to reduce the strain on that organ? Are there any measures you can take to increase the flow of blood to that organ, and to promote its activity? In the study of your health, you will find that circumstances differ, and the importance of one factor or the other will vary; but you will seldom find any problem in which all these factors do not enter, and you will seldom find an adequate remedy unless you take all the factors into consideration.