Allah ﷻ says in the Qur'aan-ul-Kareem:

"We have created pairs (opposites) of everything (such as male and female, hot and cold, sweet and sour etc) so that you may take heed (realise our tremendous powers)" - [Translation as per Quran Made Easy]

From this ayat of Qur'aan and its explanation by the Mufassireen it is established that Allah created this entire world, in fact entire universe in a system of pairs, each and every thing that exists as a creation of Allah exists in two aspects that are opposite to each other while also dependant on each other for their very existence.

Simple examples that are before us every day are aspects such as night and day, they are opposite, yet one cannot exist without the other, hot and cold, again opposite but interdependant. The internal organs of the body and the outer surface aspect, the heavens and the earth, sweet and sour, wet and dry, male and female, down and up, passive and active etc

Like this every phenomenon, creation and "thing" whether material or abstract can be described in terms of two aspects that oppose each other, are dependant on each other, are mutually engendering, mutually controlling and mutually transforming.

In Chinese philosophy this principle is called the Yin-yang theory, but it is not something exclusive to Chinese philosophy as we see from Qur'aan. An amazing thing about this verse is that it is the 49th verse of the 51st Surah which in my humble opinion is an allusion to this principle of pairs and the harmony that is present between them in all things. Even in yin-yang theory it is said that yin and yang are not a static 50-50 balance but rather it is a dynamic relationship that together defines the whole, day is ever changing into night and night into day, the moon is constantly waxing or waning and so forth

This principle therefore also indicates the movement of yin and yang and it in fact represents a way of thinking that is necessary to the practice of Islamic Medicine. Because this concept is not exclusive to taoist or confucian philosophy I choose to use the same terms of yin and yang in Islamic Medicine as I cannot yet find an arabic word that captures the same meaning.

Yin in Chinese originally referred the shady side of a slope and is associated with qualities such as inwardness, cold, rest, passivity, darkness, tranquility, the end of things, completion and fruition.

Yang originally referred to the sunny side of a slope and is associated with qualities such as brightness, activity, motion, heat, stimulation, activity, upwardness, outwardness, increase, beginning and dynamic potential.

The two ayaat preceding the one above also allude to these opposing qualities:

The heavens are yang, strength is yang, expanding is yang.

The earth is yin (relative to the heavens) and spreading out is a yin quality. In other translations the last word is expressed as "place of rest" which is a yin quality.

So we can see that the phenomena of yin-yang opposites are all around us and it is in fact a very part of our life and existence and has also been alluded to in Qur'aan.

Rules governing the yin-yang relationship

Yin and yang display 7 basic principles that can be seen in nature and is also alluded to in the same ayaat of Qur'aan above though that discussion is of a highly technical nature involving the analysis of the grammar and use of arabic words which when done reveals much deeper insight into yin and yang. I will however leave that discussion for the Ulamaa and a later time Insha'Allah

1. Everything has a yin and yang aspect

The first rule, which is the literal meaning of the verse quoted first is that everything has both a yin and yang aspect. This does indeed apply to every single thing. The glory of Allah ﷻ is being displayed here through this method of His creating the universe and all that exists. Those who will ponder will understand that the whole of creation is inviting to Tauheed (oneness of Allah) by all having an opposite pair.

Upon the tapestry of the multitude of His paired creations, solely His Oneness is gloriously evident ﷻ

Only Allah Himself is one. Everything else is in pairs, and everything else is dependant on its pair to exist, whereas Allah ﷻ is independant of everything and anything and there is none like Allah ﷻ.

Sometimes we may not understand how an object, an idea or concept can have both yin and yang aspects so let us take for example the liver. As a whole we see that the liver has attached to it the gallbladder, in this relationship the liver is yin and the gallbladder is yang. When looking at the liver alone in terms of its structure it has both a left and a right lobe of different sizes, these are also the yin and yang of the liver, then the liver has both form and function, the structure of the liver will be it's yin, the function of the liver will be its yang. In terms of root syndrome differentiation, if liver function is deficient (characterised by pains along the liver meridian etc) we can say that liver yang is deficient, if liver function is excessive we could say that liver yang is hyperactive (characterised by migraine headaches etc), keep in mind that when I am describing these liver syndromes it is apparent that in Islamic Medicine just as in Chinese Medicine the liver is more than just the organ.

Let us take another example, depression. As one individual phenomena in the realm of mental disorders depression can be said to be a yin disorder since it is identified in western medicine by the lack of desire to do anything, more than normal sleeping, maybe even not wanting to meet people etc which are clearly "yin" signs. But even within depression there are yin-yang types such manic depression which is more yang, and seasonal affective disorder which is more yin.

This leads us to the next principle..

Any yin or yang aspect can be further divided into yin and yang

This principle was described in the previous discussions but as a further example take the case of cold water versus hot water. Each can be further divided into yin and yang, cold water can be divided into tap water (yang) versus fridge water (yin). This also means that yin and yang are relative, there is no absolute in nature, there can always be something that is more yin or more yang which the makes the original aspect the opposite quality in comparison.

Yin and yang are relative opposites

This principle is evident from the discussion so far in that by nature yin and yang hold qualities which are relatively opposite to each other. This may not always be apparent and possibly the term opposite is very strong but we are able to differentiate between yin and yang based on qualities which we normally regard as opposite to each other. In the case of fridge versus tap water where we may find it difficult to characterise one as being "opposite" to the other in terms of temperature we can look at it this way that the molecules in the case of fridge water are moving faster than the slower molecules in the fridge water, because it is the movement of the molecules that determine the temperature of the water, the more the molecules move about being the cause of higher temperature. (There is a video that explains this in the supplementary material below)

Yin and yang are complementary

While yin and yang are opposite they are also complementary as they cannot exist without the other, they work together and produce harmony in the universe just as a husband and wife do in order to produce harmony in the family. From the coming together of yin and yang virtue is produced. Day and night are both needed, work and rest complement each other, the king and the servants both make up a kingdom, if one is missing then the whole cannot survive.

Yin and yang control each other

Because yin and yang are relative opposites they act to control one another. This control can also be regarded as a balance.

In the human body there are both yin and yang and if one is deficient it will not be able to control the other effectively. For example if there is a yin deficiency, yang will not be sufficiently controlled and therefore symptoms such as heat, restlessness etc can occur. If one of them are in excess this can also result in overcontrol. If yin is in excess then yang will be suppressed and this will result in signs such as feeling cold, inactivity, poor digestion etc.

Yin and yang are rooted in each other

This principle is important to understand as it can be confusing to many. we have described yin and yang so far as being opposite but complementary but here I am saying that yin is rooted in yang and yang is rooted in yin. This principle can also be termed this way: Yin and yang mutually engender

What is meant here, and what is observed in nature is that yin gives rise to yang and yang gives rise to yin, this is the constant changing of nature and there is also reference to this in various places in the Qur'aan-ul-Kareem, for example in Surah Alam Nashra Allah ﷻ says more or less to this meaning that after every difficulty there is ease, so in this case the ease is rooted in the difficulty, because there was a period of difficulty now an ease has come.

Another example is the english proverb that you have to be cruel to be kind, meaning that by being so to say cruel at times, you will engender the quality that you want which then turns out to be kindness. The kindness which is yin was rooted in the cruelty which is yang.

Another way this principle is described is that within yin and yang the seed (potential) for the opposing factor exists. This is why in the symbol for yin and yang there is a dot of the opposite color in each side and it is this seed that becomes the other as seen in the gif after the picture below:

and here is a representation of the dynamicity of yin and yang and in many ways all the principles I have mentioned so far:

Yin and yang transform into each other

The final principle that I want to speak about with regard to yin and yang is that yin and yang transform into one another, this can also be seen in the image above but what is meant specifically here is that double yin turns into yang, double yang turns into yin.

Let us take for example the case of a car that is speeding, which is yang, as the speed increases the yang keeps increasing, within yang there is the potential for yin, so eventually the speed increases to a point where an accident is inevitable, once this accident happens double yang has turned into yin (the accident)

Another example from the human body is that if fever which is yang continues increasing, eventually the person will die which is now a yin condition. This principle often refers to the extreme case and is applied especially where we see a reversal of symptoms in a patient.

These princples of yin and yang extend into the understanding of the human body as well and the nature of health and disease and once we begin to think in terms of yin and yang it becomes easy to understand many different illnesses that may at first be daunting to tackle.

For this reason I want to direct your attention to the two tables below that describe the nature of disease/illness in relation to yin yang concepts:

The first table below describes the 8 very basic types of yin-yang disharmony that may occur in the body. Keep in mind that this is a generalisation and often the condition is more complex and can include multiple patterns that can occur at the same time.

Eight Principal Disharmony Patterns

Disharmony Pattern Yin/Yang Manifestations 1 Exterior Yang An exterior pattern is generated by "external influences" such as wind and cold. (i.e. common cold) 2 Interior Yin An interior pattern is generated by internal disharmony such as a disorder of organ function. 3 Cold Yin A cold pattern is manifested by the signs such as a pale face, cold limbs, aversion to cold, clear urine, or watery stools. The signs are usually related to non-excitatory physiological functions. 4 Heat Yang A heat pattern is manifested by signs of a red face, high fever, dislike of heat, dark urine, or constipation. The signs are usually related to excitatory physiological functions. 5 Deficiency Yin Signs of frail and weak movements, tiredness, shortness of breath, low voice, or dizziness indicate a deficiency pattern. The signs are usually related to lack of energy of normal functions. 6 Excess Yang An excess pattern exhibits signs of heavy movements, heavy and coarse respiration, or discomfort when touched with pressure. The signs are usually related to an excess/accumulation of evils/metabolic waste. 7 Yin Yin General pattern groups for Yin manifestations include interior, cold and deficiency patterns. 8 Yang Yang General pattern groups for Yang manifestations include exterior, heat and excess patterns.

Yin and Yang signs in the body

Body signs Yang signs Yin signs Face Red face, fever, hot feeling, agitated and active manner Pale face, low spirit, feels cold, cold limbs, tired and weak, Voice Coarse and strong voice, coarse breath, dry moth, thirst Low voice, reduced appetite, no taste in mouth, little thirst Urine Constipation with awkward smell, dark urine Copious and clear urine Tongue Red and scarlet tongue or yellow and black moss present on tongue Pale and swollen tongue material Pulse Rapid and floating, flooded and strong, slippery and full pulse Slow and sinking, weak, frail pulse

This is the second level of diagnosis in Islamic Medicine, the first being identifying the constitution of the patient. The third is identifying the root syndrome/s and associated branch syndromes.