13. Special care should be taken to have regular movements of the bowels that carry off the impurities of the body. It is an axiom in medicine, that so long as evacuations are absent, or difficult, or require strong efforts, the individual is liable to serious disease. Every medical means should be taken to overcome constipation in order to escape its dangers. For this purpose young people should be given salty food, materials that have been soaked in olive oil, salt itself, or certain vegetable soups with olive oil and salt. Older people should take honey mixed with warm water early in the morning and four hours later should take their breakfast. This proceeding should be followed up from one to four days until the constipation is overcome.
14. Another axiom of medicine is that so long as a man is able to be active and vigorous, does not eat until he is over-full, and does not suffer from constipation, he is not liable to disease. Even such men, however, are much safer if they do not take food that may disagree with them.
15. Whoever gives himself up to inactivity, or puts off evacuations of the bowels, or suffers from constipation, will be sure to suffer from many diseases and will see his strength disappear even should he eat the best food in the world and make use of all the remedies that physicians have. Immoderate eating is a poison for men and the cause of many diseases which attack them. Most diseases come from either eating too much or partaking of unsuitable food. That was what Solomon meant with his proverb: "He who puts a guard over his mouth and his tongue protects himself from many evils," that is to say, whoever protects his mouth from the overindulgence in food and his tongue from unsuitable speech protects himself from many evils.
16. Every week at least a man should take a warm bath. One should not bathe when hungry, nor after eating until the food is digested, and bathe the whole body in warm but not too hot water and the head in hot water. Afterwards the body should be washed in lukewarm and cool water until finally cold water is used. One should pour neither cold nor even lukewarm water on the head, nor bathe in cold water in the winter time, nor when the body is tired and in perspiration. At such times the bath should be put off for a while.
17. As soon as one leaves the bath one should cover oneself, and especially cover the head, so that no draught may strike it. Even in summer, care must be taken to observe this rule. After this one should rest for a while until the heat of the body passes off and then should go to table. If one could sleep a little just before a meal it is often very beneficial. Neither during the bath nor immediately after it should cold water be drunk, and if there is an inappeasable thirst a little wine and water or water and honey should be taken. In winter it is beneficial to rub the body with oil after the bath.
18. Venesection should not be practised frequently, for it is only meant for serious illness. It should not be permitted in winter or summer, nor during the months of April or September (the "r" months). After passing his fiftieth year an individual should abstain from venesection. Venesection should not be practised on the day when one takes a bath or goes on a journey or returns from it. On the day when it is practised less than usual should be eaten and drunk, and the patient should give himself to rest, undertake no work nor bothersome occupation, and take no walk.
19. Whoever observes these rules of life faithfully I guarantee him a long life without disease. He shall reach a good old age, and when he comes to die will not need a physician. His body will remain always strong and healthy, unless of course he has been born with a weak nature, or has had an unfortunate bringing up, or should be attacked by epidemic disease or by famine.
20. Only the healthy should keep these rules. Whoever is ill or a sufferer from any injuries, or has lost his health through bad habits, for him there are special rules for each disease, only to be found in the medical books. Let it be remembered that every change in a life habit is the beginning of an ailment.
21. If no physician can be secured, then ailing people may use these rules as well as the healthy.
These rules are, of course, full of the common sense of medicine that endures at all times. For the tropical climate of the Eastern countries they probably represent as good advice as could be given even at the present time. With them before us it is not surprising to find that on other subjects Maimonides was just as sensible. Perhaps in nothing is this more striking than in his complete rejection of astrology. Considering how long astrology, in the sense of the doctrine of the stars influencing human health and destinies, had dominated men's minds, and how universal was the acceptance of it, Maimonides' strong expressions show how much genius lifts itself above the popular persuasions of its time, even among the educated, and how much it anticipates subsequent knowledge.