While our youth often need to be restrained rather than encouraged to cultivate their muscles, yet they should be told to play when the opportunity is theirs. You ought to take the lead in their games. Your eye should be as bright, your sight as true, your cheeks as rosy, your step as elastic and your physical prowess the equal at least of any lad in school. All the text-books in the land are less effective than a few timely words from you. Occasions are continually presenting themselves which should be utilized. When a boy has been playing too violently, or when he neglects play, when he is careless as to his clothing or shows evidence of falling into any bad habit, a kind but pointed warning will accomplish more than weeks of study. There are other dangers to which boys are peculiarly exposed, and which obviously cannot be referred to in these pages, concerning which it would be criminal for you to remain silent, but in all such cases, your warning must be uttered to the offender in private, or by the father to whom you may make the suggestion. Of course you will see that the school-room is properly warmed and ventilated; that the pupils are kept out of all drafts; and that the air is as pure as possible. The faithful teacher will find almost hourly opportunities for impressing these vital truths upon the children, and, only by doing so to the fullest extent, can he approach a proper fulfillment of his own mission as the friend, counselor, and guide of the coming generations. TO THE FEMALE TEACHER. What has been said to your co-laborer about assuming the lead in observing the laws of health, applies with equal force to you. Your experience and knowledge give you invaluable opportunities for instructing the girls in what is truly the great question of life and death. Cleanliness, clothing, food, and all the subjects treated of in the following pages, should be supplemented by the practical illustrations which the girls themselves continually present. No observant teacher can have failed to become acquainted with the rudimentary laws of her being, and to none is given so golden an opportunity to make that knowledge a living truth as to her whose calling it is to instruct the future mothers of our country. CHAPTER I. WHY THE LAWS OF GOOD HEALTH SHOULD BE STUDIED. Every boy and girl ought to live a hundred years. When worn out at last by old age, death will come like sweet sleep, without pain, or suffering. No one can live very long, unless he obeys the laws of health. These laws are so simple that all can learn them. Many people remain ignorant of them until they grow to be men and women, when they find it too late to escape the penalty which nature visits on those who break her laws.