The Greatest Benefit to Mankind: A Medical History of Humanity. Roy Porter

in supernatural disorders was to be eroded, however, and from the earliest systematic formulations of cosmological principles around 200 BC, sicknesses were regarded by physicians as determined by certain natural principles, rather as in the Hippocratic teachings. Chinese natural philosophy deals less in things than in relations, processes and cycles of transformation. The key to the natural world is qi (also rendered ch’i), variously translated as ‘air’ ‘vapours’ or ‘energy’, and somewhat resembling the pneuma or spiritus of Graeco-Roman medicine. In natural philosophy, qi, which permeates the cosmos, is something which stimulates a process of transformation, or is the medium through which such processes take place. In living beings, qi can be designated as ‘vital energies’ whose circulation sustains life itself. Life arises from a build-up of qi; its dissipation is marked by death. To preserve good health, a person must nurture the qi which sustains bodily functions. Qi can also be disruptive, however – ‘pathogenic’ qi brings illness on.

      A concept fundamental for understanding the distribution of qi is the yin yang pairing, crucial from the Yellow Emperor’s Inner Canon of Medicine onwards. Yin possesses the qualities which superficially seem the diametrical opposite of yang – pairings like lower-upper, inner-outer, cold-hot, feminine-masculine, dark-light, wet-dry, etc. But these must not be read as fixed contraries; they are always relational and complementary – in any particular situation, yin and yang are symbiotic and subject to continual cyclical change.

      Yin and yang are functions of space and time. Yang is more exterior, yin more interior. Once pathogenic qi penetrates the outer yang qi, which make up the body’s defences, it reaches the interior regions of yin qi which supply the body with nourishment and growth, and thereby turns more threatening. Like every other natural process, a malady will run through active yang phases and latent yin phases: once yang sickness has reached crisis point, it moves into a yin phase, which requires a distinctive treatment. Yin yang relations, in short, are complex, and must be appreciated from various viewpoints. In health and sickness alike, the body is in continual need of vigilant monitoring.

      Wu xing (Five Phases) has often been translated as ‘five elements’, but that is misleading as there is no true parallel to the Greek notion of elements; the term ‘phases’ better suggests the dynamic quality involved. The Five Phases are wood, fire, earth, metal and water, paralleling the five viscera (heart, liver, spleen, lungs and kidneys), and all the other corresponding ‘fives’ (tastes, climates, odours, emotions, sounds, etc.). Each phase represents a class of action or interaction. Physiologically speaking, wood denotes a growth phase and a branching development; fire a phase of rapid upward dispersal, and so forth. Each phase is characterized by a distinctive colour, odour, sensation, bodily secretion, etc. and definite chains of relations result. The liver, for instance, is identified with the phase of wood, and the spleen with the phase of soil. Wood, perhaps in the form of a wooden spade, could move soil; hence, a relationship between liver and spleen could be explained as resulting from the tendency of the liver to govern the functions of the spleen.

      The theory covering the patterning of these phases is known as ‘systematic correspondence’, embracing a vision of health as natural harmony within a holistic system. The Five Phases spontaneously beget each other in this sequence (the order of ‘mutual production’), while a sequence of ‘mutual restraint’ also applies – wood, earth, water, fire, metal. The body thus comprises a microcosm whose processes, healthy and pathological alike, are regarded as governed by the universal characteristics of qi, yin yang and the Five Phases.

      Within the body, qi has two aspects – these are not material but processual. The yang element, likewise called qi, represents the capacity for action and transformation; the yin component, called xue (literally ‘blood’), represents the capacity for circulation, nourishment and development. Another vital substance (jing), translated as ‘essence’, includes both the nourishment gained from food and also (via the Taoist tradition) the reproductive substances like semen necessary for procreation. The vital forces circulate through the body in regular cycles through the circulation passages. These circulation tracts linking the visceral systems include the anatomically identifiable blood vessels but also involve invisible pathways along which qi travels in its various incarnations.

      Before the systematic correspondence theory was elaborated, Chinese thinking about tracts and viscera seems to have conformed fairly closely with western anatomy. Early texts associate certain tracts with blood vessels, while others sketch in the location of the viscera. Chinese physicians were never interested in the mechanical models of the body promoted in the West after Descartes; nor, as medical theory became oriented from matter to processes, was close anatomical knowledge of the organs themselves expected.

      Classical medical theory teaches there are five yin visceral systems: the cardiac, hepatic, splenetic, pulmonary and renal. These create, transform, govern, and accumulate qi, xue and jing. There are also six yang systems: gall-bladder, stomach, large intestine, small intestine, urinary bladder and the san jiao (‘triple burner’). These process food to generate qi, xue and jing, and discharge waste. Despite apparent analogues with Western anatomical thinking about organs like the heart, lungs and liver, the emphasis is always upon functions – the Chinese body is above all a functional organism. The ‘triple burner’, which arose late in Chinese medicine, does not map onto any anatomical part of all, yet possesses a well-defined complement of functions. The connections between the visceral systems, and the sequences in which malfunctioning in one affects the others, are to be grasped in terms of the theory of systematic correspondence. Because the relationships between the viscera and the associated organs, senses, emotions and secretions are seen holistically, there can be no such thing in Chinese medical thinking as ‘Cartesian’ mind/body dualism, strict ‘localism’, or the aetiological specificity of ‘one cause, one symptom’ pathology.

      When qi is circulating in the proper manner through the body, external threats are held at bay, harmony prevails, and good health is enjoyed and maintained through temperate behaviour. There are many ways to produce healthy qi: through diet, exercise, preventative acupuncture, moxa cauterization, meditation or sexual self-control. Such methods not only reinforce health but aid longevity: some texts envisage a lifespan of over a hundred years, while others aspire, in the Taoist manner, to immortality.

      Illness (bing) by contrast results from imbalances of yin and yang, causing disturbance of qi circulation, which then impairs the normal operation of the visceral systems and the vital fluids. Obstruction, surplus or depletion of qi or xue in one of the visceral systems upset its functioning and distribution through the organism in ways determined by phase dynamics and modified in the individual case by the sufferer’s own constitution. If caught early in its yang (external) phase, the imbalance can be treated and health restored, but once the life-threatening yin phases are reached, the harm may be irreversible.

      In these theories, a disorder can be produced either by the invasion of an external threat (noxious qi) or by internally generated imbalance. ‘Excesses’ are the main danger, but deficiencies can also do harm – gynaecological disorders, for instance, are supposed common among widows deprived of sex. External pathogens include heat and cold, damp, poisons, fright (especially in the case of children), or sexual intercourse with ghosts.

      The presentation of a disorder in the particular case is shaped not only by the pathogen, but also by the sufferer’s constitution, which influences its phase dynamics. The state of disorders caused by any specific type of pathogen (cold damage disorders, for example) thus conforms to a general pattern but allows infinite variations. Though diagnostic handbooks tended to classify disorders for convenience’s sake by symptoms rather than causes, maladies could not truly be cured until their fundamental causes were fathomed.

      Classical Chinese medicine thus embraced a humoral and constitutional approach to illness – ‘biomedical’ concepts of disease are foreign to its basic thinking. In the seventeenth century, however, a wave of epidemics led physicians