Amazingly good results from teeth-hygiene have been shown in a Boston asylum, which cares for over 300 children. Before the introduction of a dental clinic into this asylum, infectious diseases--diphtheria, mumps, scarlet fever, pneumonia, measles, whooping cough, tonsillitis, chicken-pox, croup, etc.--had been occurring for four years at the rate of over 80 cases per year, but for three years after the dental clinic was established the average was only 3 per year. CHAPTER IV ACTIVITY Section I--Work, Play, Rest and Sleep In order to live a hygienic life it is not only necessary, as shown in the foregoing three chapters, to supply the body with wholesome substances and to exclude unwholesome substances, but it is also necessary that the body should at times act, and at other times be inactive. There are two great forms of activity, work and play; and two great forms of inactivity, rest and sleep. All four of these are needed in the healthy life and in due relation to each other. [Sidenote: The Daily Rhythm] The whole personality should be utilized and energized in a daily rhythm. When, as too often happens, the equilibrium and mutual proportions of the various wholesome elements in a well-rounded life have been lost, the balance should be restored if possible the next day. If a physician has had his sleep broken, he should aim to make it up at the earliest opportunity. If the afternoon exercise has had to be omitted, an extra amount should be taken as soon as possible. Some people find that while it is difficult to live a complete life every single day, it is quite within their power to give every element its due proportion in each week, taken as a whole. To go a step farther, when the balance has not been kept even in a week as a whole, the next week should be modified to compensate. But it is ideal to make the day, not the week, the unit. It is almost as absurd to relegate all our exercise to Saturday afternoon as to do all our eating on Sunday. [Sidenote: Adjusting the Proportion of Work and Play] It is distinctly unhealthful either to overdo or to underdo work, play, rest, or sleep. "Moderation in all things" is a rule that is particularly important in this realm. Not all people are in need of exercise, nor are all in need of rest; but almost every one needs to change his proportion between the two. To-day many people are suffering from too much or too little work. For instance, the increase in diseases of the heart is often due to nervous overstrain combined with either too much or too little physical exertion.