28. The craft of medicine.¹⁴⁶The craft of medicine

is needed in settled areas and cities but

not in the desert.

This craft is necessary in towns and cities because of its recognized usefulness. Its fruit is the preservation of health among those who are healthy, and the repulsion of illness among those who are ill, with the help of medical treatment, until they are cured of their illnesses.

It should be known that the origin of all illnesses is in food, as Muhammad said in the comprehensive tradition on medicine, that is reported among physicians but suspected by the religious scholars. ¹⁴⁷ He said: "The stomach is the home of disease. Dieting is the main medicine. The origin of every disease is indigestion." The statement "The stomach is the home of disease," is obvious. The statement: "Dieting is the main medicine," is to be understood in the sense that himyah "dieting" means "going hungry," since hunger means refraining (ihtima') from food. Thus, the meaning is that hunger is the greatest medicine, the origin of all medi­cines. The statement: "The origin of every disease is in­digestion," is to be understood in the sense that baradah "indigestion" is the addition of new food to the food already in the stomach before it has been digested.

(The statement lends itself to) the following comment. God created man and preserves his life through nourishment. He gets it through eating, and he applies to it the digestive and nutritive powers, until it becomes blood fitting for the flesh and bone parts of the body. Then, the growing power takes it over, and it is turned into flesh and bones. Digestion means that the nourishment is boiled by natural heat, stage by stage, until it actually becomes a part of the body. This is to be explained as follows. The nourishment that enters the mouth and is chewed by the jaws undergoes the influence of the heat of the mouth, which boils it slightly. Thus, its composition is slightly altered. This can be observed in a bit of food that is taken and chewed well. Its composition then can be observed to be different from that of the (original) food.

The food then gets into the stomach, and the heat of the stomach boils it, until it becomes chyme, that is, the essence of the boiled (food). ¹⁴⁸ (The stomach) sends (the chyme) on into the liver, and ejects the part of the food that has become solid sediment in the bowels, through the two body openings. The heat of the liver then boils the chyme, until it becomes fresh blood. On it, there swims a kind of foam as the result of the boiling. (That foam) is yellow bile. Parts of it become dry and solid. They are black bile. The natural heat is not quite sufficient to boil the coarse parts. They are phlegm. The liver then sends all (these substances) into the veins and arteries. There, the natural heat starts to boil them. The pure blood thus generates a hot and humid vapor that sustains the animal spirit. ¹⁴⁹ The growing power acts upon the blood, and it becomes flesh. The thick part of it then becomes bones. Then, the body eliminates the (elements of the digested food) it does not need as the various superfluities, such as sweat, saliva, mucus, and tears. This is the process of nourishment, and the transformation of food from potential into actual flesh.

Now, illnesses originate from fevers, and most illnesses are fevers. The reason for fevers is that the natural heat is too weak to complete the process of boiling in each of those stages. The nourishment thus is not fully assimilated. The reason for that, as a rule, is either that there is a great amount of food in the stomach that becomes too much for the natural heat, or that food is put into the stomach before the first food has been completely boiled. In such a case, the natural heat either devotes itself exclusively to the new food, so that the first food is left in its (half-digested) state, or it divides itself between the old and the new food, and then is insufficient to boil and assimilate them completely. The stomach sends the (food) in that state into the liver, and the heat of the liver likewise is not strong enough to assimilate it. Often, an unassimilated superfluity, resulting from food that had been taken in earlier, has (also) remained in the liver. The liver sends all of it to the veins unassimilated, as it is. When the body has received what it properly needs, it eliminates the (unassimilated superfluity) together with the other super­fluities such as sweat, tears, and saliva, if it can. Often, (the body) cannot cope with the greater part of the (unassimilated superfluity). Thus, it remains in the veins, the liver, and the stomach, and increases with time. Any composite humid (sub­stance) that is not boiled and assimilated undergoes putre­faction. Consequently, the unassimilated nourishment-what is called khilt ¹⁵⁰ becomes putrefied. Anything in the process of putrefaction develops a strange heat. This heat is what, in the human body, is called fever.

This may be exemplified by food that is left over and eventually becomes putrefied, and by dung that has become putrefied. Heat develops in it and takes its course. This is what fevers in the human body mean. Fevers are the main cause and origin of illness, as was mentioned in the (Prophetic) tradition.¹⁵¹ Such fevers can be cured by not giving an ill person any nourishment for a certain number of weeks; then, he must take the proper nourishment until he is completely cured. In a state of health, the same procedure serves as a preventive treatment for this and other illnesses. ¹⁵²

Putrefaction may be localized in a particular limb. Then, a disease will develop in that limb, or the body will be affected either in the principal limbs or in others, because (that partic­ular) limb is ill and its illness produces an illness of its powers. This covers all illnesses. Their origin as a rule is in the nourishment.

All this is left to (the attention of) the physician.

The incidence of such illnesses is more frequent among the inhabitants of sedentary areas and cities (than elsewhere), because they live a life of. plenty. They eat a great deal and rarely restrict themselves to one particular kind of food. They lack caution in taking food, and they prepare their food, when they cook it, with the admixture of a good many things, such as spices, herbs, and fruits, (both) fresh and dry. They do not restrict themselves in this respect to one or even a few kinds. We have on occasion counted forty different kinds of vegetables and meats in a single cooked dish. This gives the nourishment a strange temper and often does not agree with the body and its parts.

Furthermore, the air in cities becomes corrupt through admixture of putrid vapors because of the great number of superfluities (in cities).¹⁵³ It is the air that gives energy to the spirit and thus strengthens the influence of the natural heat upon digestion.¹⁵⁴

Furthermore, the inhabitants of cities lack exercise. As a rule, they rest and remain quiet. Exercise has no part in their (life) and has no influence upon them. Thus, the incidence of illness is great in towns and cities, and the inhabitants' need for medicine is correspondingly great.

On the other hand, the inhabitants of the desert, as a rule; eat little. Hunger prevails among them, because they have little grain. (Hunger) eventually becomes a custom of theirs which is often thought to be something natural to them because it is so lasting. Of seasonings they have few or none, The preparation of food boiled with spices and fruits is caused by the luxury of sedentary culture with which they have nothing to do. Thus, they take their nourishment plain and without admixtures, and its temper comes close to being agreeable to the body. Their air has little putrescence, because there is little humidity and putrescence when they stay (anywhere), and the air is changing when they move around. Too, they take exercise, and there is a lot of movement when they race horses, or go hunting, or search for things they need, or occupy themselves with their needs. For all these reasons, their digestion is very good. There is no adding of new food when the old food (has not yet completely been digested). Thus, their temper is healthier and more remote from illness (than that of sedentary people). As a result, their need for medicine is small. Therefore, physicians are nowhere to be found in the desert. The only reason for this is the lack of need for them, because if physicians were needed in the desert they would be there. There would then be a livelihood for them to lead them to settle there.

This is how God proceeds with His servants. "And verily, you will not be able to change God's way." ¹⁵⁵