The child is not alone in the danger from want of air and exercise. In the higher as well as the lower schools these essentials to health are still too often neglected. Many a student sits day after day in a close room bending over his books, his chest so contracted that he can not take a full, deep breath, his blood moving sluggishly, his feet cold, his head hot. The body not being sufficiently nourished, the muscles are weakened, and the whole system is enervated and diseased. Often such students become lifelong invalids. They might have come from school with increased physical as well as mental strength, had they pursued their studies under proper conditions, with regular exercise in the sunlight and the open air. [Sidenote: _Mental Effect_] The student who with limited time and means is struggling to gain an education should realize that time spent in physical exercise is not lost. He who continually pores over his books will find, after a time, that the mind has lost its freshness. Those who give proper attention to physical development will make greater advancement in literary lines than they would if their entire time were devoted to study. By pursuing one line of thought exclusively, the mind often becomes unbalanced. But every faculty may be safely exercised if the mental and physical powers are equally taxed, and the subjects of thought are varied. [Sidenote: _Moral Effect_] Physical inaction lessens not only mental but moral power. The brain nerves that connect with the whole system are the medium through which heaven communicates with man, and affects the inmost life. Whatever hinders the circulation of the electric current in the nervous system, thus weakening the vital powers and lessening mental susceptibility, makes it more difficult to arouse the moral nature. Again, excessive study, by increasing the flow of blood to the brain, creates morbid excitability that tends to lessen the power of self-control, and too often gives sway to impulse or caprice. Thus the door is opened to impurity. The misuse or nonuse of the physical powers is largely responsible for the tide of corruption that is overspreading the world. “Pride, fulness of bread, and abundance of idleness,” are as deadly foes to human progress in this generation as when they led to the destruction of Sodom. Teachers should understand these things, and should instruct their pupils in these lines. Teach the students that right living depends on right thinking, and that physical activity is essential to purity of thought. [Sidenote: _Gymnastic Exercises_] The question of suitable recreation for their pupils is one that teachers often find perplexing. Gymnastic exercises fill a useful place in many schools; but without careful supervision they are often carried to excess. In the gymnasium many youth, by their attempted feats of strength, have done themselves lifelong injury. [Sidenote: _Tendency of Sports_]