Man lives in nature and takes nature as his vital conditions for living. In the meantime, he is influenced directly or indirectly by the movements and changes in nature, to which he is bound to make corresponding physiological and pathological responses. For example, as the climate varies with the four seasons in a year, the normal pulse conditions (including pulse rate, rhythm, volume, tension, etc.) are also varied. The pulse becomes string-like in spring, full in summer, floating in autumn and sunken in winter. This provides a basis for doctors to distinguish abnormal pulse conditions from the normal ones during the clinical diagnosis. The occurrence, development and changes of many diseases are seasonal. For example, spring witnesses more epidemic febrile diseases; summer more sunstroke; fall more cases with symptoms of dryness and winter more cold-stroke syndromes. Of course, people can certainly reduce or eliminate some seasonal diseases by doing physical exercises, transforming nature and taking active measures of prevention. TCM physicians also have observed that along with alternation of early morning, late afternoon, daytime and night in a day, a disease may become severer or milder. For instance, the monograph entitled "Ling Shu Shun Qi Yi Ri Fen Wei Si Shi Pian" (Regarding a Day as a Year Consisting of the Four seasons, a chapter of Miraculous Pivot) says, "There are various diseases, most of which become milder in the morning, better during the daytime, worse again in the late afternoon and even severer at nigh". This is because "In the morning the vital energy of the human body begins to grow stronger, while the pathogenic factors weaker; at midday the vital energy of the human body is predominant and lords it over the pathogenic factors; in the late afternoon the vital of the human body begins to become weaker; while the pathogenic factors stronger; at midnight, the vital energy of human body returns to the internal organs, while the pathogenic factors come into leading place". In modern times, someone has also noticed that human pulse condition, temperature, the amount of oxygen consumed, carbon dioxide released and hormone have biorhythms during the 24 hours of a day. This finding may promote the round-the-clock exploration of the physiological and pathological changes of the human body

Based on the theory of the circulation of qi characteristic of TCM, the pathogenesis of the human body is often influenced by the periodic changes of the climate, which take place every 12 years or every sixty years. In recent years, scientists have realized that the law of these periodic changes has something to do with the cycle of sunspots, which is formed every 1l to 12 years. Their movements bring about periodic changes in the radiation of sunlight, interfere with the magnetic field of the earth, and change the climate around the earth, thus exerting impact upon the physiology and pathology of the human body.

TCM believes that different geographical surroundings produce different effects on the physiology and pathology of the human body. The effects are even so great as to extend or shorten human lives. For instance, "Su Wen Wu Chang Zheng Da Lun" (On Conventions of the Five Circuit Phases, a chapter of Plain Questions) says: "People who live in the high areas have a long life, while those who live in the low ones die young. Living areas differ in altitude. A little difference in height causes a little difference in life, while a great difference in height results in a great difference in life. Therefore, physicians have to know the law of nature and geographical conditions". Modern researches have shown that the mountain area between 1,500 and 2,000 meters above the sea level is the ideal geographical surroundings for a long life, because it is a place where hydrogen anions are concentrated.

iii) The Guiding function of the Concept of the Organism as a Whole

The concept of the organism as a whole not only embodies TCM's understanding of the human body itself and the relationship between it and nature, but also provides the medical workers with a necessary method of thinking in treating diseases. Such a concept penetrates through the entire theory concerning the physiology and pathology of TCM, and of great significance in guiding diagnosis and treatment. For example, TCM believes "The heart has its specific opening in the tongue proper", so the physiological functions and pathological changes of the heart can be known by observing the tongue. Pale tongue indicates the blood deficiency of the heart; purple tongue with petechiae, the blood stagnation of the heart. To cure these diseases, the first important thing of all is to find out where the key pathogenesis is according to the relationship between the heart and the tongue, by taking into consideration of the concept of the organism as a whole, and by making a comprehensive analysis of the case. Another example, acupuncture therapies of TCM, Zi Wu Liu Zhu (select the acupoint on the basis of "five shu points" of the twelve channels matching the "heavenly stems and earthly branches") and Ling Gui Ba Fa (select the acupoint according to the eight points in the eight extra-channels matching the "heavenly stems and earthly branches"), have obvious curative effects just because the acupoints and acutime are determined according to the relationship between the working of the channels, pulse, vital energy and blood of the human body on one side and time on the other. The most adequate time should be also chosen for taking herbal medicines. For instance, the Shi Zao Tang (Ten Jujube Decoction) in the book "Shang Han Lun" (Treatise on Febrile Diseases written by Zhang Zhongjing in 219 A. D.) is better to be taken on an empty stomach in the early morning; the Ji Ming San (Cock Crowing Powder); which is recorded in the book "Zheng Zhi Zhun Sheng" (Standards for Diagnosis and Treatment by Wang Kentang in 1,602 A. D.) should be taken at daybreak when cocks begin to crow. Modern medicine has also noticed that the effect of digitalis taken by the patient with heart failure at about 4 o'clock in the early morning is 40 times greater than that of it taken at any other time. And insulin, if taken at the time mentioned above, is most effective for the patients with diabetes, too. Why does the human body have so close relationship with nature, and why does the human body itself act in accordance with so strict time rhythm and regularity? In recent years, not few scholars have pointed out that these result both from the adaptation of all living things to the changes of physical surroundings such as the earth's revolution, rotation and so on, and from the domination of some structure within the body. Now it has been proved that in the nucleus suprachiasmaticus (SCH), epiphysis, pituitary bodies and adrenal gland, there exist such structures as control the time rhythm and regularity. From the foregoing it is easy to see that concept of "Tian Ren Xiang Ying" (relevant adaptation of the human body to natural environment in TCM) has its material base and a scientific basis as well.

2. Diagnosis and Treatment Based on a Overall Analysis of Signs and Symptoms

By "Bian Zheng" we mean analyzing the relevant information, signs and symptoms collected through the four methods of diagnosis (observation, listening and smelling, inquiring, pulse feeling and palpation) in the light of the theory of TCM, having a good idea of the cause, nature and location of a disease, and the relationship between pathogenic factors and the vital energy, and summarizing them into "Zheng" of a certain nature (syndrome). By "Shi Zhi" we mean determining the corresponding therapeutic method according to the conclusion of an overall differentiation of symptoms, signs and others.

In clinical treatment, TCM physicians do not focus their main attention on the similarities and dissimilarities between diseases but on the differences between the syndromes they have. Generally speaking, the same syndromes are treated in similar ways, while different syndromes are treated in different ways. Take cold for example, if manifests itself in more server chilliness, slight fever, a tongue with thin and white fur, then it belongs to the exterior symptom-complex caused by wind and cold, and should be treated with strong sudorific drugs, pungent in taste and warm in property, to dispel the wind and cold; if its manifestations are more server fever, milder chilliness, a tongue with thin and yellow fur, then it belongs to the exterior symptom-complex caused by wind and heat, and should be treated with mild diaphoretics, pungent in taste and cool in property, to dispel the wind and heat. This is called "treating the same diseases with different methods". Sometimes, different diseases have same syndromes in nature, so their treatment is basically the same. If clinical analysis and differentiation show that persistent dysentery, prolapse of the rectum, uterus and others belong to the syndrome of "sinking of the qi" (functional activities of the middle warmer, the middle portion of the body cavity housing the spleen and stomach), then their treating method should be the same one, lifting the qi of the middle warmer. This is called "treating different diseases with the same method".

In China, quite a number of colleges of medicine and pharmacy and scientific research institutes are undertaking the researches on the essence of "Zheng" (syndrome) in TCM. For example, Chongqing Medical College holds that "Zheng" is the comprehensive manifestation of the disorderly relations, resulting from the pathogen and pathogenic condition between the whole body and its reactive characteristics on one side and its surroundings (including nature and society) on the other, between viscera, bowels, channels and collaterals, between cells themselves and between cells and body fluid; that "Zheng" is a reaction of life substances characterized by time-phase and essentiality in the course of a disease; and that "Zheng" is a whole-finalized pattern of reaction which mainly manifests itself in the clinical functional changes. Other scholars believe, from the point of vague mathematics, which "Zheng" is a vague collectivity made up of such materials as symptoms, signs and characteristics.