The yawn is similar to the stretch. The yawn is a stretch of the lungs as the stretch is a yawn of the muscles. Both of these exercises express a hunger for oxygen. Whenever anyone is sitting in a cramped position or even in one position for a long time, the stretch or yawn is instinctive. The extension of the muscles of the body as illustrated in the stretch is one of the most necessary steps in normal adjustment. To speak of only one point: when a man sits his knees are bent, and the muscles in front of the leg are elongated and the muscles back of the knee are shortened. A stretch means simply the extension of these shortened muscles. All over the body we find a tendency to elongate certain muscles too much. This is true in the chest; true also of the face, at the corners of the mouth. The active use of the too elongated muscles will produce extension in those that are too much shortened. By doing this we bring about certain normal conditions and relations of parts. Again we find that the stretch is activity of the extensor muscles. It is the action of the extensor muscles upon which health especially depends. At any rate, the extensor muscles are much more important to bring about the right relation of all parts and the right balance of sensitive muscles and the equalization of circulation than the activity of the flexor muscles. Normal emotions, as we shall find later, are expressed through activity of the extensor muscles. Abnormal emotions, such as anger, affect the flexor muscles of the body more. Since nature has provided the stretch seemingly as the antidote for abnormal position, and especially abnormal position during sleep, in the programme of exercises it would seem most necessary to centre around some careful and scientific use of stretches. Have you ever noticed a dog or cat wake up? Observe their instinctive movements: the gradual but vigorous stretch in every direction, the deep breathing, the sympathetic extension and staying of the limbs at the climax, then the gradual giving up of the activity and the moment of restful satisfaction. Stretching in this way is one of the primitive instincts in all animals. He who will observe the animals will feel that the time for practicing the exercises is on awakening, and the primary exercise to be taken is the stretch. How can we best occupy a part at least of the half hour or more that is usually wasted in worrying and fretting or in sluggish indifference, between the time when we first awake and the time we begin to dress? With all the knowledge of the human organism which has been revealed to us by modern science, with our truer understanding of the nature of men, of the effect of the mind upon the body, with our observation of the instinctive actions of the animals at such an hour, why can we not so occupy a few of these most precious moments of the day as to add to our vitality and enjoyment?