It is an often stated truth that medicine is one of the world’s oldest professions, but medical theory and practice have gone through significant changes in the past thousands of years. An interesting example for such a change can be seen in the concept of the “six natural forces”, one of the best known ideas in Arab medicine during its height in the Middle Ages. The “natural forces” are almost unknown today, certainly under this name, but references to them were ubiquitous in Chinese, Indian and Greek medical literature in antiquity. This term received many interpretations throughout history, but its basic meaning remained the same: the “natural forces” were those elements of daily life affecting our health, and manipulating them could help preserve health, or restore it if lost. These are all the elements in our life that today fall in the somewhat neglected category of “healthy lifestyle”, but in the past they stood on the frontlines of the medical battle over human health. An ancient Chinese medical text ranks physicians according to the importance of their specializations – surgeons and those who dispense drugs are ranked lowest, while the most important physicians are determined to be those who specialize in lifestyle, nutrition, and the maintenance of a healthy balance.

The six forces

In Middle Ages medical texts, the forces affecting a person are divided into three groups:

1. The “internal forces” – forces working within the body and affecting its normal functioning, according to Humorism. These include the elements, temperaments and humours.

2. The “natural forces” – six forces naturally affecting a person’s life and health. These six forces, as described by Arab physicians and philosophers during the Middle Ages, are:

– environment

– nutrition

– patterns of rest and movement

– sleep and alertness cycles

– patterns of restraint and release

– the psyche

3. “Forces departing from the natural course of things” – forces that are not normally part of the natural course of our lives, unlike the natural forces, and constitute external interference. In medicine, the goal of using these forces is to help restore the body to balance if the manipulation of the natural forces isn’t enough. This category includes all external medical intervention, at the time consisting of treatments such as the prescription of medicinal herbs, acupuncture, and bloodletting, and today focused on surgery and drug prescriptions.

In today’s world, we tend to skip over the use of the natural forces directly to the use of the “forces departing from the natural course of things”: a headache is immediately treated with an aspirin, wounds with antiseptic cream or a herbal balm. If a nutritional deficiency is detected, we turn to nutritional supplements.

Out of the three groups, the unnatural forces (medical intervention) are by far the best researched. Despite the misgivings expressed by the ancient physicians, modern researchers focus on what we understand best – powerful drugs and surgical intervention. But in the past, the internal and natural forces were of greater interest for physicians and philosophers. I have written about the internal forces elsewhere, so here I will concentrate on the natural ones.


This includes local climate (weather, humidity, etc.), as well as air and soil quality, type of community (urban/rural), and any other factor affected by our physical location. All of these play a central role in our physical state. It’s no accident that patients suffering from respiratory illnesses are sometimes prescribed a vacation in a dry place, but it should be remembered that a vacation is no cure. In this case, it resembles taking medication to treat the symptoms, while moving to live in a more suitable climate could eliminate the illness.


Nutrition was, and remains, one of the most important of the natural forces, and its significance increases as our food becomes more complex and more dependent on artificial ingredients. Our nutrition has a direct influence on our health and out of the natural forces it’s the one most used as clinical treatment, both in antiquity and today. A significant nutritional change designed to strengthen the body can have a decisive effect on healing from any illness.

Nutrition pertains to more than just the ingredients of the food we consume. Another important consideration is the way food enters the digestive system (combination of foods, , time of intake, and amounts eaten), and as a result, what the body can extract from it. Additionally, our food today often contains various substances that have no nutritional value and affect our digestive system in harmful ways. Although they cannot be considered “food”, they too are part of our diet and their consumption deserves our attention.

Patterns of rest and movement

Physical activity was a central and natural part of most people’s lives throughout history. Before the advance of agriculture, the whole tribe constantly moved in search of food and shelter. In agricultural societies, the central workforce – comprising the vast majority of society – preformed physically demanding work, either in the field or in the house. Travel was mostly done on foot, and people generally moved around a lot. Today, most of us travel from place to place by car and work at jobs that don’t demand much movement. This pattern generates two main problems: lack of physical activity is the better known of the two. This problem affects many people who work long hours sitting in the same position at a desk, and need rest upon arrival at home. Such a pattern doesn’t allow for nearly enough physical activity. The second and lesser known problem is the opposite – excess of physical activity where people are addicted to strenuous physical activity, carried out daily in an intensive and repetitive manner. This sort of intensive activity can be very harmful. For people suffering from lack of physical activity, it’s a good idea to add some element of movement to every task preformed – for example, parking farther away from the store, doing the housework ourselves, and traveling short distances by bicycle instead of by car.

Sleep and alertness cycles

We have evolved as a diurnal species, awake during the day and asleep during the night. During seasons with long hours of darkness some activity during the night is reasonable, but this activity should be followed returning to sleep. Our modern nighttime sky, flooded by light from street lamps, buildings, billboards and vehicles, is a rather new phenomenon. In the distant past the night was lit only by a few small camp fires that turned to softly glowing embers as the night proceeded, and even during more recent history the nights were mostly dark. Residential lighting was expensive and inefficient, and activity during nighttime was limited. When darkness fell, the limited light allowed the body to prepare for the night’s rest, and so people went to bed some time after sunset and rose again with the sun.

Going to bed at seven o’clock seems downright ridiculous in today’s world, but this is still the most natural thing for our bodies. Going to bed after eleven o’clock is, physically speaking, an extreme excess. We all heard from our parents that children grow in their sleep, and its true – during the night sleep the body carries out important maintenance and growth functions. Going to bed late confuses the biological rhythms of our bodies and disturbs these important functions, leading to tiredness during the day and potentially causing us enduring harm. It is therefore recommended to go to bed at least two hours before midnight.

The problem is even greater among children. Children need plenty of sleep in order to grow, and their biological rhythms are still intact. Their bodies are set to go to sleep when darkness falls, but when darkness doesn’t come, the lights in the home are all lit, and the light of the television is flickering, their bodies get confused and send conflicting messages of alertness and tiredness. It’s a good idea to provide children with a natural sleep environment during the evening – dimmed lights and calm activities, without many diversions. This is helpful to all children, but especially to those suffering from sleeping problems.

Patterns of release and restraint

In the past, medical writers used this category to discuss control and management of bodily waste (urine and feces). Now we might add other kinds of waste removal that used to be freer and are often constrained today, like sweating, sneezing, and vomiting.

Waste removal is an important function, especially in a world where basic functions such as eating, drinking and breathing bring with them many toxic substances into the body. The body’s ability to remove toxins efficiently is expressed through our bodily condition and can attest to our resistance. Various illnesses related to the waste removal systems are common today, among them diarrhea and constipation, psoriasis and respiratory illnesses. The ancient knowledge helps us understand that these are waste removal problems, so we can concentrate on this aspect when we try to come up with possible solutions.

The psyche

This category does not concern “psychological problems”, instead it treats the psyche as a factor naturally and normally effecting our health, in much the same way nutrition does. The psyche is indeed a major actor in our health, but it differs from the other forces by being overwhelmingly influenced by them. The climate, for example, isn’t affected by resting (although the reverse is sometimes true), but the psyche is directly affected by them both, as is physical health.

Today’s psychology is mostly concerned with psychological problems, and almost doesn’t touch on the physical and environmental influences on a patient’s psyche. Many physicians recognize the importance of sleep and fresh air for psychological health, but do not feel comfortable advising a new mother to take walks in order to avoid post-partum depression. (why not? Because it sounds too simple?) Additionally, the further our living conditions depart from those we evolved in, the more complex their affect on our psyche.

Our psyche plays a major role in our health, and our mental state affects it in various ways. One of the most complicated – and today, most common – problems arising from this relationship is chronic stress, a constant state of stress affecting the mind and often caused by the fast pace of modern life. Stress wreaks havoc in the functions of the natural forces. A person can choose to live in a clean environment, maintain a generally healthy lifestyle, and observe a nutritious diet, but a difficult mental state can undermine his health to the point that he may not be able to reach balance or heal.

Searching for the root of a problem, instead of treating symptoms, is central to the understanding of the natural forces in medical practice. Today we often tend to first treat the symptoms, and only if they don’t go away do we search for a deeper underlying problem. In the past the direction of enquiry was opposite – physicians looked first at the six natural forces, and only when treatment through the manipulation of these forces failed did they turn to medication. This medication was also geared to treat the basic underlying problem making the person susceptible to the illness, and not the symptoms themselves. Symptomatic medication was reserved for those who could no longer be cured.

In areas of the world where Humorism was present (more common word), physicians offered the population guidance on maintaining health through lifestyle. Physicians wrote cookbooks, philosophy texts, poetry and stories illustrating the importance of lifestyle to the health, and acted as advisers in royal courts and also as a service for the poor. A while back I received a medieval book of engravings presenting the natural forces in pictures, thus making them accessible to all in an effort to teach how to live in accordance with the forces affecting the health.

It proves just as difficult today as it was in antiquity to offer genuine recovery to another person without first understanding the whole of their body’s actions in sickness and in health, and self-healing, too, which can only occur when taking into account the forces affecting our lives by virtue of being human.