Take the case, for example, of a boy who stoops very much, and combines a sinking above and below the clavicles with abnormal protrusion of the shoulder-blades. If he is told to “stand up straight” he will at once make undue physical effort to carry out the order thus crudely given, with the result that the shoulders will be thrown backward and upward, the shoulder-blades still further protruded, and the front and upper parts of the chest unduly elevated and expanded. There will also be a narrowing, a sinking, and a flabbiness of the lower dorsal and posterior thoracic region, with corresponding fixed protrusion and rigidity of the front chest wall, undue arching of the lumbar spine, shortening of the body and harmful stiffening of the arms and neck, instead of a fulness, broadness, and firmness of the back, with free mobility of the chest walls, resulting in normal curve of the lumbar region and comparative lengthening of the spine. With the arms hanging vertically, the relative position of that part of the thorax where the lungs are situated will be seen to be in front of the arms, instead of being, as it should be, behind them. In such a position, the boy feels helpless and tires rapidly, owing to the imperfect co-ordination, and any attempt to accustom him to this erect posture will ultimately result in deterioration rather than improvement. Now the narrowing and arching of the back already referred to is exactly opposite to what is required by nature, and to that which is obtained in re-education, co-ordination, and re-adjustment, viz., _widening of the back and a more normal and extended position of the spine_. Moreover, if these conditions of the back be first secured, the neck and arms will no longer be stiffened, and the other faults will be eradicated. In order to obviate the evils enunciated in the last two postulates the teacher must himself place the pupil in a position of mechanical advantage,[20] from which the pupil, by the mere mental rehearsal of orders which the teacher will dictate, can _ensure the posture specifically correct for himself_, although he is not, as yet, conscious of what that posture is. I further elaborated the same point in _Why We Breathe Incorrectly_ (November, 1909), and from this pamphlet I will now quote another passage which bears directly on some important points involved, viz.: