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.