The lung belongs to metal. It is in charge of breathing and governs the qì of the body. The lung governs the skin and body hair. Its outer orifice is the nose, and its humor is snivel (nasal mucus). It governs the voice. It is the receptacle that hold phlegm. Its mind is worry, and its voice is wailing. It stands in exterior-interior relationship with the large intestine. The lung holds the Office of Minister-Mentor.

Metal

Metal as a material refers to any kind of metal, but notably the hardest of metals known to early medical scholars, iron.

Metal is the working of change (金曰从革 jīn yuē cóng gé). This originally signified the process of removing hair from animal hides to make leather and later denoted change in general. Being hard, sharpenable, heat resistant at the burning point of wood, malleable when red hot, and moldable when superheat forces it into a liquid state, metal is the most versatile of materials for making all manner of tools, utensils, and instruments, such as knives, scythes, axes, hoes, spades, and numerous weapons, as well as hooks, nails, pots, pans, pipes, and bells. It is especially associated with blades used to harvest grains, slaughter animals, and kill enemies.

Metal comes from ores dug out of the earth. Ore is smelted at high temperature to release the metal from the other minerals. The best metals are those that are freest of impurities, and so the concept of metal is closely associated with purity.

West, evening: Evening is the time when the power of the sun wanes, nature rests, and humans cease their toil and withdraw to their homes. Since the sun sets in the West, the westerly position is also associated with metal.

Autumn, withdrawal: Autumn in the yearly cycle corresponds to evening in the daily cycle. It is the time when frost causes trees to lose their leaves and when grasses and insects die, in other words, the time when nature withdraws into itself. The destructive action of frosts and cold weather on nature can be naturally likened to a knife. This notion of autumn is captured in the expression 肃杀 sù shā, purification and killing or ruthless purification, in which 肃 connotes the harsh purging quality of the bleak cold and stillness of autumn, and 杀 means to kill. Autumn is also a time when humans harvest their crops and slaughter animals to provide stores of food for the winter. Harvesting and slaughter require the use of metal scythes and knives. In Chinese, these ideas are summed up in the abstract concept of 收 shōu, which means both withdrawal (of nature) and gathering (of winter supplies). Thus, the association between metal and autumn revolves around the working of change, purification, the withdrawal of nature, and the gathering of sustenance.

Dryness is the environmental qì associated with metal because metal is unable to absorb water and hence is totally dry. Dryness prevails in many parts of China in the autumn. It is closely associated with cleanliness and purity. The modern Chinese word for clean is 干净 gān jìng, literally meaning dry [and] clean.

White is the color associated with metal. The color white corresponds to autumn, the time when the white frost comes. Although white could also be associated with the snow of winter, autumn marks the arrival of whiteness in nature. White is particularly associated with the west since the western mountains of China are snow-clad for much of the year. White is also the color of clothing worn at Chinese funerals to this day. It is the color that symbolizes grief and sorrow, presumably by association with the frosts to which nature succumbs in the fall.

Acridity, also called pungency, is associated with metal because iron gives off a sharp, acrid smell during the smelting process.

Five-phase cycles: In the engendering cycle, metal is engendered by earth, since ores form in the earth. Metal engenders water, which seems to be a reference to the tendency of water to condense and not be absorbed by metal. A less likely argument that has been proposed is that water wells in arid areas, where the ground is hard and dry, can only be dug with metal tools.

In the restraining cycle, metal restrains wood, since metal tools are needed to fell trees and fashion timber. Metal is restrained by fire, since fire melts metal.

The Lung

Since we are aware of air (qì) going in and out of our body, we observe the function of breathing directly. The chest expands and contracts with inhalation and exhalation. Simple dissection reveals the lung to be a spongy organ where inhaled air collects. Because we die when we cease to breathe, it follows that air is necessary for life.

The lung is in charge of breathing (肺司呼吸 fèi sī hū xī) and lung governs qì (肺主气 fèi zhǔ qì). According to Chinese medical knowledge, air inhaled is clear qì, which combines with nutrients extracted by the spleen from food to form the yáng qì that powers all bodily functions. Hence, the lung governs qì. What is exhaled is referred to as turbid qì, indicating that it was regarded as unclean waste, in contrast to clear qì, which is something good and necessary for the body.

These characterizations would have been supported by the observation that clear qì is depleted when humans and animals are confined to unventilated spaces. Although early medical scholars had no knowledge of oxygen and carbon dioxide, the terms they used indicate their understanding that inhalation contributes to the replenishment of the body’s qì, while exhalation cleanses the body of unwanted substances. This dual action of constant renewal was in all likelihood the main reason for associating the lung with the metal phase, which encapsulates the gathering of sustenance and the purification of nature in autumn.

Such ideas, far from lying within the exclusive purview of medical scholars, were widely understood among spiritual adepts. China has a tradition of breath control called tù-nà (吐纳) that developed in ancient times. Tù-nà involves breathing in through the nose and out through the mouth. Exhalation takes any one of six forms (吹 chuī, 呼 hū, 唏 xī, 呵 hē, 嘘 xū, 稲 dào), each of which has cleansing effects such as eliminating heat, wind, or vexation. Although these specific effects are not discussed in Chinese medicine, they may reflect notions widely held in early times that the lung was an organ of purification.

The same notion of purification is seen in nèi-dān, or internal elixir (内丹术) traditions, which developed among Daoists. Alchemy in China involved compounding elixirs of immortality by heating minerals, metals, and other natural substances. This tradition, which came to be known as wài-dān, or external elixir (外丹术), did not reach its height until the Táng Dynasty, but nevertheless developed before the time of the Nèi Jīng. Nèi-dān was a secondary development, founded on the belief that immortality could be achieved by cultivating the Three Treasures (三宝 sān bǎo), essence, qì, and spirit, by curbing desire and preserving essence, by controlling breath and the movement of qì through the body, and by practicing meditation. In both nèi-dān and medicine, breath and qì are barely distinguishable from each other and both fall within the jurisdiction of the lung. Viewed against this cultural background, it is likely that the functions of the lung were associated with the idea of purification and cultivation of qì in the pursuit of extending natural life and thus also with the alchemist’s cauldron (or crucible). Hence, the association of the lung with metal and the working of change would have been highly meaningful to early medical scholars.

The lung governs diffusion and depurative downbearing (肺主宣散、肃降 fèi zhǔ xuān sàn、sù jiàng): Breathing results from expansion and contraction of the chest powered by the lung’s own qì. Lung qì has two movements, one upward and outward, called diffusion, which expels air out of the body, and the other downward and inward, called depurative downbearing, which draws air into the body.

The two movements of the lung do more than merely draw in and expel air. Diffusion keeps the nose free of nasal mucus (snivel), while depurative downbearing keeps the lung free of phlegm. These actions therefore reinforce the assumption that the lung was regarded as an organ of purification, which again reflects the association with metal. In particular, the Chinese term we translate as depurative, 肃 sù, echoes the expression 肃杀 sù shā, used to describe the effect of autumn on nature.

Qì is an intangible substance that can pervade matter, so that the qì that drives the action of an organ also has the power to stretch well beyond the confines of the organ itself. Thus, lung qì, by its action of diffusion reaches upward through the airways and outward to the body’s exterior, to the skin and body hair. It helps defense qì reach the exterior to resist invading evils. By its action of depurative downbearing, lung qì not only carries phlegm out of the lung to keep the lung clean but also carries water down to the kidney and bladder. People who engage in breath cultivation practices can feel sensations in their body’s exterior on exhalation (though a scientific explanation would not involve the concept of qì), and people who practice qì-gōng learn to draw their qì down to the dān-tián (cinnabar field).

The diffusion and depurative downbearing actions of lung qì beyond the confines of the lung itself appear to derive, at least in part, from an analogy to the water cycle in nature. The Sù Wèn, whose authors were very much aware of how analogy influenced their thinking, describes this in Chapter 5 as follows: The qì of earth ascends to form clouds; the qì of heaven descends as rain. Rain produces the qì of earth; clouds produce the qì of heaven (地气上为云，天气下为雨，雨出地气，云出天气 dì qì shàng wèi yún, tiān qì xià wèi yǔ, yǔ chū dì qì, yún chū tiān qì). Chapter 21 of the Sù Wèn describes a corresponding process in the body: Imbibed liquids enter the stomach, are churned to spill essential qì, which is transported upward to the spleen and finally to the lung, which, by regulating the waterways, transports [fluid] down to the bladder and distributes the water essence to the four quarters [i.e., everywhere] through the five channels (饮入于胃，游溢精气，上输于脾，上归于肺，通条水道，下输膀胱，水精四布，五经并行 yǐn rù yú wèi, yóu yì jīng qì, shàng shū yú pí, shàng guī yú fèi, tōng tiáo shuǐ dào, xià shū páng guāng, shuǐ jīng sì bù, wǔ jīng bìng xíng). Fluids rise from spleen-earth, just as water evaporates from the earth and transpires from plants. They reach the lung, which is a light spongy organ in the upper body, corresponding to the planet’s atmosphere. From here, they spread all over the body, as moisture spreads through the atmosphere. They then descend to the bladder, as rain drains away in rivers and streams.

The lung opens at the nose: Air is drawn in via the nose, so naturally the nose is the outer orifice of the lung.

Snivel is the humor of the lung: Nasal mucus, or snivel, as we like to call it so as to reflect the homey flavor of the Chinese term 悌 tì, keeps the nose moist. When the lung is affected by an invading external evil, snivel tends to increase. Thin runny snivel indicates cold, while thick yellowish snivel that causes nasal congestion is a sign of heat.

The lung is the receptacle that holds phlegm (肺为贮痰之器 fèi wéi zhù tán zhī qì): Like the nose, the lung itself is kept moistened by fluid. In pathological conditions, fluid increases in volume and becomes sticky to form phlegm. Hence, it is said that the lung is the receptacle that holds phlegm. Phlegm results from the concentration of excessive water-damp arising when the spleen fails to deal adequately with fluids (the spleen is the source of phlegm formation). The development of phlegm from water-damp can also be fostered by heat or qì stagnation.

The lung is the delicate viscus (肺为娇脏 fèi wéi jiāo zàng) because its function is easily impaired by the presence of excess snivel and especially phlegm and by invading external evils.

The lung governs the skin and body hair (肺主皮毛 fèi zhǔ pí máo): Lung qì can flow beyond the lung itself to affect other parts of the body. Its diffusing action carries moisture and warmth to the exterior of the body, while its depurative downbearing action carries excesses of water away from the exterior. The exterior of the body is here represented by the skin and body hair, which has a distinct resonance with metal’s working of change, where the word for change is革 gé, which originally denoted the process of turning skin into leather. The lung has its bloom in the body hair is the same in meaning.

The lung governs regulation of the waterways (肺主通调水道 fèi zhǔ tōng tiáo shuǐ dào): Another aspect of lung qì’s ability to move outside the lung itself is its action of carrying water from the upper and outer body down to the lower body, eventually to be discharged. Three viscera are responsible for moving fluids in the body, the lung, the spleen, and the kidney. The lung, by its governance of qì, plays an overarching role in this process.

The lung belongs to metal: The association between metal and autumn revolves around the working of change, purification, the withdrawal of nature, and the gathering of sustenance. The lung’s association with metal is made on two accounts. One is that breathing, which involves inhalation of clear qì and exhalation of turbid qì, is a constant process of replenishment and purification. The other is that qì, which is governed by the lung, works all the changes in the body (metal is the working of change).

Qì has a considerable affinity with metal. Metal is a highly refined, pure, solid substance made from impure ores. The yáng qì of the body is a highly refined substance made from less pure substances entering the body. Although it is not hard like metal, it shares with metal the working of change, since qì is the substance said to drive all movement and transformations in the body. The lung draws in qì, which is converted into the various sorts of qì (true qì, ancestral qì, defense qì, provisioning qì, channel qì, etc.), just as metal is fashioned into all manner of artifacts specialized for different purposes. The versatility of metal derives from its ability to assume distinct forms at different temperatures (solid, malleable, molten). Thus, it is comparable to the forms of water qì in the environment (invisible vapor, visible mist, rain, running water, snow, and ice). Qì pervades matter as metal can cut through it. Lung qì, by its action of diffusion, spreads, just as metal can be flattened and extended when heated. By its action of downbearing, it draws qì downward into the body as molten metal flows down into a mold.

In accordance with the rain-cycle analogy described above, we might speculate that the lung may have been associated with metal because the cold qì of the atmosphere causes water to condense, just as condensation easily forms on metal. The function of the lung, conceived of as sending water to the kidney, thus reflects the notion of metal engendering water. A further expression of the relationship between the lung and kidney is seen in the kidney’s function of helping the lung’s depurative downbearing and governance of the waterways, whereby water flows from lung-metal to kidney water as autumn gives way to winter.

A further reason why the lung is associated with metal concerns acridity. While the other four flavors (sourness of wood, bitterness of fire, sweetness of earth, and saltiness of water) are tastes registered by the tongue, acridity is an odor registered by the nose, the outer orifice of the lung. In Chinese, the word qì is often used to distinguish odors from tastes. Hence, a direct association also exists between acridity and qì, which is governed by the lung. It is no coincidence that the English word sharp not only describes metal objects formed to perform cutting but is also a synonym for acrid. Although Chinese does not describe these two qualities with a single word, the conceptual connection nevertheless exists.

Acrid medicinals have several actions, which include freeing the nasal orifices, transforming phlegm, resolving the exterior, and moving qì and are notably used to treat runny nose, nasal congestion, or coughing up phlegm. One has only to think of mint, which clears the nose and airways, and enables us to think more clearly when a stuffy nose makes our brain foggy.

The body can, in fact, produce the same effect naturally when breathing is optimized through breath control. People who engage in breathing exercises such as quiet slow breathing through the nose, as in tù-nà practice, can faintly detect a sharp acrid odor in the nostrils as their nasal passages free up. In scientific terms, this smell is from the nitric oxide (NO) released into the inhaled breath to increase the absorption of oxygen into the blood. Traditional practitioners of breath control methods did not know about nitric oxide but were evidently aware of the power to free the movement of qì through controlled breathing. This is reflected in the tù-nà prescription for inhalation through the nose.

A further reason for the attribution of the lung to metal lies in the image of the bellows. People in ancient times, who were much more likely than people in the modern age to witness the smelting and forging of iron, would have been aware of the need for bellows to create a fire of sufficient intensity for these processes. They may have been struck by the similarity of the lung, as the visibly most active organ, to the iron worker’s bellows. This similarity may have supported the association of the lung with the metal phase.

The lung governs the voice: The voice lies on the windpipe and is powered by exhalation produced by the diffusion action. Thus, it has a natural-cause relationship with the lung. However, the voice also provides a further reason for the lung’s association with metal.

Although sound is produced by many things, the clearest and most precise sounds in the past were produced by metal bells, the technology of whose production well before the Hàn dynasty reached untold heights in the development of the biān zhōng 编钟, a set of musical bells hung from a large frame, each of which could produce two distinct tones depending on where they were struck. Hence, the voice has a direct association with metal. The lung’s similarity to a bell in both its shape and its hollow quality provides a further reason for its pairing with metal.

The repletion and vacuity conditions of a hoarse voice have been described since the Míng Dynasty as solid metal failing to sound 金实不鸣 jīn shí bù míng and broken metal failing to sound 金破不鸣 jīn pò bù míng respectively. A bell must be empty of anything except qì to produce sound, and a broken bell is incapable of producing a clear sound.

Worry is the mind of the lung. The Chinese 忧 yōu has several meanings: worry, sadness, depression. All of these can be felt in the chest and can affect breathing. Among the seven affects, sorrow (悲 bēi) is unequivocal in meaning. Sorrow is the affect we feel when we experience the loss of a loved one, a valuable possession, or an opportunity for positive action. It is associated with the lung, probably because it is most strongly felt in the chest as a feeling of heaviness. Extreme feelings of grief and loss can result in an existential crisis that manifests in a sensation of being unable to breathe. Conversely, breathing difficulties can cause emotional changes where a psychological factor is absent. Sorrow accords with the lugubrious feelings evoked in autumn when life activity is in decline. Excessive sorrow damages the lung.

Wailing is the voice of the lung: Sorrow and grief are naturally expressed in crying and wailing. For this reason, wailing (哭 kū) is deemed to be the voice of the lung. Note that crying and wailing are associated with lacrimation. However, tears are associated with the liver, not with the kidney.

The lung is averse to cold: This is a classical phrase that is not frequently cited in modern textbooks because the lung is susceptible to both heat and cold. However, common cold affecting the lung is closely associated with cold weather. Interior repletion heat patterns can develop from the invasion of external cold evil.

The lung stands in exterior-interior relationship with the large intestine: The large intestine is said to govern conveyance and transformation of waste. The lung and large intestine appear to have little to do with one another, since the one’s main function is that of breathing, while the other’s is related to digestion. Nonetheless, the conveyance and transformation of waste can be construed as being comparable to the lung’s depurative downbearing function.

Both organs help to keep the body free of unwanted substances. The intestines are considered part of the waterway system, which is regulated by the lung because they channel water downward to carry waste out of the body, as rivers carry mud out to sea. The large intestine is said to govern liquid, having the task of removing water from the stool to control defecation, just as rivers lose some of the water to the land on either side of them on the low-altitude plains. An obvious mechanical analogy of the intestines as tubular structures to metal pipes used to conduct liquids would also relate the conveyance and transformation action to the lung’s function of governing the waterways.

In therapy, interventions that enhance lung function are sometimes used in tandem with direct action on the large intestine to treat large intestinal problems such as constipation.

The Minister-Mentor

The lung holds the Office of Minister-Mentor, management and regulation arise from it. Here, Minister-Mentor (相傅 xiàng fù) refers to a dual government position held by a single person in the Hàn dynasty. Minister refers to the 宰相 zǎi xiàng, the prime minister, whose responsibility is to ensure the day-to-day running of the country in accordance with the sovereign’s orders. Mentor refers to 太傅 tài fù, the personal tutor/advisor to the emperor, who provides calm advice to temper any impulsiveness of the sovereign. In our modern world, this function has been transferred to institutions, which represent the accumulated sense of political wisdom and sobriety, preventing any elected leader from doing anything too outrageous.

The functions of the Minister-Mentor are reflected in the lung. The lung occupies a high position in the body and surrounds the heart (the sovereign). The image of prime minister reflects the lung’s governance of qì, which moves the blood around the body keeping the whole of the empire-body in integrated working order. In this, the prime minister is also like the qì of heaven that controls the whole of the ecological water cycle.

The mentor, who provides wise counsel, reflects the power of breathing to calm the emotions. Breathing is the only internal function that can be voluntarily controlled. We take a deep breath to brace ourselves for a shock or an injection. We calm our breath to deal with episodes of emotional stress. Depending on how we breathe, we can alter our heart rate and calm or excite the nervous system. Breath control has been shown to relieve asthma, worry, grief, depression, post-traumatic stress, and insomnia. Those who engage in breathing practices can become skilled not only in controlling their emotional and mental states, thoughts, and desires but also in developing mental focus. Controlled breathing is an antidote to all negative emotions and hence promotes joy, the mind of the heart.

The lung and the heart are said to be powered by ancestral qì (宗气 zōng qì), which gathers in the chest. Ancestral qì is therefore the force by which the lung breathes and by which the heart moves the blood. The word 宗 zōng means ancestor, but an extended meaning is gathering or convergence, reflecting the way in which the lines of a family tree converge on our ancestors. For this reason, zōng qì has sometimes been translated as gathering qì, which fits its definition as the qì that gathers in the chest. However, according to ancient belief, ancestors have an important moderating hand in human affairs. Thus, an adequate description of the body in terms of the way the world works could not exclude them.

Summary of Lung-Metal

The lung governs breathing and governs qì. It governs the skin and body hair, opens at the nose, and has its bloom in the body hair. Its fluid is snivel, and its mind is worry (and sorrow). Its government epithet is the Minister-Mentor. It has a special association with acridity.

• Breathing is a directly observable function of the lung.
• The lung’s governance of qì is derived from this.
• The lung’s belonging to metal, the phase associated with the purification of nature in autumn, is explained by the lung’s need to inhale clear qì and expel turbid qì and by its need to keep the airways free of nasal mucus and phlegm.
• Acridity is the smell of metal and acrid medicinals clear the airways.
• Lung qì has an upward and outward movement called diffusion that is responsible for exhalation. A complementary downward and inward movement called depurative downbearing is responsible for inhalation. Diffusion and depurative downbearing work together, not only to keep the airways free of nasal mucus and phlegm but also to control the wider movement of fluids in the body. The understanding of this function may have developed by an analogy to the rain cycle and may explain the connection with the skin and body hair (which are directly associated with metal among the five phases). Just as the rain cycle is governed by the qì of heaven, the lung, which is the governor of qì, controls the movement of water throughout the body.
• The voice is associated with the lung not only because it is located on the airway but also because the lung resembles a metal bell in that it rings clearly only when empty, i.e., when the airways are free of obstructions.
• Worry and sorrow are associated with the lung because they are felt in the chest and easily affect lung function. They also reflect the lugubriousness of the autumn.
• The lung holds the Office of Minister-Mentor because it controls the qì of the entire body. Breathing has a powerful regulatory impact on the heart rate and emotions, just as the Minister-Mentor, by his wise counsel, tempers the excesses of the sovereign.