1566. The proper care of the body and of health is not merely a thing next to godliness; it is a moral duty, and so a part of godliness. God Himself on Sinai gave to the Chosen People of old a sanitary code, and the faithful observance by orthodox Jews of those regulations has had much to do with the superior health and longevity of their race. Moral Theology, therefore, is not digressing from its proper subject-matter, if it gives some attention to rules of health. The duties owed to physical well-being can be reduced to the following: (a) to secure for the body the things needed for the maintenance and replenishment of its substance and vigor, such as food, air, sleep and exercise; (b) to ward off or remove those things that are injurious to or destructive of health, such as excessive heat or cold, waste matter, poisons, and disease; (c) to assist these physical means by psychical or spiritual ones, such as cheerfulness and the will to keep well and fit.
1567. Food and drink are naturally a prime requisite for life, since they furnish the material from which the body is built and renewed. They should be used, however, in such a way as to serve their purpose.
(a) Thus, the quantity and quality have to be regulated according to the needs of the individual and circumstances, and so will vary with climate, age, health, and occupation. The distinction of clean and unclean foods does not exist in the New Law (Rom., xiv. 14; Matt., xv. 17-20), but it is clear that the same kinds or amounts of food and drink do not agree with all constitutions; that overeating, undereating, and want of variety in diet are not conducive to good health. Physicians recommend that something raw be eaten every day and something indigestible at every meal, and that a person watch his weight, keeping a little overweight up to middle life and a little underweight after that age.
(b) The manner of eating is of first-rate importance, since the digestion is harmed if one eats without appetite or with mental preoccupation on deep subjects, or bolts the food, or makes excessive use of relishes or condiments.
1568. Fresh air, on which the production of pure blood and the continuance of vitality depend, is another necessity of life. Hence, we may well heed the following rules which hygienists lay down on this point: (a) let in fresh air and sunshine to the places where you live and work, and exclude dust and smoke; (b) wear light, loose and porous clothing, so that the skin may have air; (c) get out of doors in the open air part of the time every day, even though the weather is uninviting, for sunshine or natural light is also a requisite of good health; (d) breathe through the nose, and not through the mouth. Breathing should be deep, slow and regular, and one should take deep-breathing exercises several times a day; (e) sleep in a well-ventilated room, or out-of-doors if possible.
1569. Rest and relaxation are needful for body and mind alike, that the burdens of life may not bear too heavily, and nature may be allowed to exercise her ministries of renewal and restoration. But here, as in other things, the guiding rule must be moderation.
(a) Through excess, some harm their health by indulging in too much repose. A strong, healthy individual who remains in bed from midnight till noon, or who gives most of the afternoon to a prolonged nap, is storing up more energy than he or she needs, and will feel the worse for it. Similarly, persons whose life is one round of vacations or diversions pay for their aimless existence in various kinds of mental or nervous disorders, to say nothing of the moral dangers to which they are exposed (Ecclus., xxxiii. 29).
(b) Through defect, on the other hand, some injure their health by depriving themselves of the sleep or rest they ought to take. The time that should be given to repose differs with the individual. The young, brain-workers and the feeble are in greater need than others; but there is no one who can dispense with his proper share of rest. It is sinful, therefore, to reduce needed sleep by late retiring or early rising, or to work unremittingly to such an extent that the bodily powers and resistance become unequal to the demands made on them and unfitted for duties. According to physicians, seven hours out of every twenty-four should be spent in bed, and the hours before midnight are much more precious for rest than the early morning hours. Some holidays and vacations are a necessity in these days of rapid and strenuous life.
1570. Physical exercise is a factor of good health, for it stirs up the circulation of the blood, assists digestion, and rids the body of surplus weight. Moreover, it has great value for the mind (to which it gives diversion and refreshment) and for the soul (since it promotes temperance and chastity). If taken in the form of sports, physical exercise is a training in cooperation with others, in loyalty, discipline, and fairness. But health is impaired by excess as well as by defect in exercise.
(a) Examples of over-exercise are athletes who carry on endurance tests to the point of exhaustion, devotees of violent forms of contests or matches that overtax the heart, etc.