Not only is the simple act of walking carried on for us without mental effort on our part, but to a very large extent the guidance through the sense of sight becomes reflex also. Thus, as we go along the street, we step down from or up on to the curb at the crossings without noticing particularly what we are doing. The approach of the curb is registered through the eyes, and the sensory disturbances thus set up are carried into the brain and intermingled with those from the organs of muscle sense and equilibrium, so that the motions are adjusted to carry us safely down or up. This reflex guidance through the eye becomes so perfect that one who habitually walks over a certain course, as a man in going from his home to his place of business, ordinarily goes the entire distance with scarcely any conscious attention to what he is doing; in fact, persons who move from one locality to another frequently, when they start to walk home, unless they pay attention, find themselves going to the old home instead of the new. The reflex machinery which guided them to their old home works so well that only by conscious interference with it are they able to direct themselves to the new one. Whenever an act of locomotion is learned, it is carried on at first by nervous disturbances from the _cerebrum_, just as are muscular actions of all sorts; but, as time goes on, there seems to be a transference of the control from the _cerebrum_ to the _cerebellum_, and as this happens the act is more accurately performed. We have an amusing illustration of this in persons who are learning to ride a bicycle. So long as they are making movements of the handle bars and at the same time pedaling by pure acts of the will, they proceed with the very greatest difficulty; after these actions become habitual, they are carried on easily and skillfully. The great effort of athletic trainers is to develop what is called “form.” What this really means is that they try to teach the athlete the best way of making the desired motions, and then drill him in that particular way, so that it becomes completely reflex with him. The more fully this is done, the better will the athlete perform.