Hi. everyone. From this class on, we'll discuss final part of the chapter: theory of medicinal property. We will discuss it from three aspects, including the theory of property and flavour of TCM, the floating and settling theory of TCM and finally the theory of toxicity of TCM. In this lecture, the theory of property and flavour of TCM will be discussed in detail. Ginseng is a kind of TCM drug which many of you are familiar with. In the Chinese Pharmacopoeia (CP), China's national medical standard, there is such a description saying "[Ginseng is gan, weiku, ping] sweet, a little bitter and even in flavour. It is often used in the treatment of spleen, lung and heart." Well, who can tell what does this description really mean? "Gan"in the Chinese has similar meaning with "sweet". 那么“甘、微苦”应该就是药材的味道。 Therefore "Gan, weiku (sweet with slight bitter)" should be the flavor of ginseng. It is not very clear what "ping (even)" means here. The old often say that ginseng is both slightly sweet and bitter. So people would often add some sugar when stewing ginseng. Well, now "gan" means sweet and ginseng is both sweet and bitter. You might wonder how indeed such a mix of flavours tastes. I brought some samples of ginseng with me. You can try by yourself. Have you got any sense of how it tastes like? astringent? Somewhat astringent? But still a little bit sweet? Yes, also sweet. So it is both sweet and bitter. Does it really taste bitter? A bit. A little bit. Ok. So your taste just now implies that "Gan, weiku (Sweet with slight bitter)" accords with the flavour of a drug. Actually, the "property and flavour" of TCM does not necessarily behave so compatibly like ginseng. It has something to do with the theory of drug properties of TCM. Drug properties refer to the properties and performance of a drug, which are innate qualities of TCM. Xu Lingtai in the Qing Dynasty had made classical remarks that "When using a certain drug, we are actually using its property or its flavours. Different drugs should be applied to corresponding diseases with their features, so that these drugs could help treatment by balancing internal organs." This quotation tells the principles of the drug properties. The message that Xu Lingtai actually conveyed is that drug properties indeed build a bridge between "medical treatment" and "medicine". That is to say, if you know little about the knowledge of drug properties, you can hardly dispense medicines according to the TCM symptoms. Well now, the theory of drug properties include the four kind of properties, five kinds of flavors, floating and settling, channel tropism and toxicity. Just now we have discussed about "gan, weiku, ping (sweet with slight bitter, and its efficacy is even)". What does that mean after we have introduced the theory? It refers to the property and flavour of the drug, which is categorized into "four kinds of properties and five kinds of flavours" in TCM. What are the four kinds of properties? They are referring to the warm, heating, cold and cool properties of drug. You might think that warm, heating, cold and cool, all these words are used often to describe weather. Does TCM has a distinction of being "cold and heating" just like weather? Of course not. "Warm, heating, cold and cool" here refers not to the temperature of drug itself, but rather drug's effects on human body's metabolism and temperature change. As early as in the Western Han Dynasty about 2000 years ago, people had realized drugs' different effects on human body's temperature changes. As in the "Book of Han Dynasty: Art and Literature", it said, "classical prescriptions, which are warm or cool temperature of the herbs, can be used to measure the severity of sickness, through the properties and flavours of drugs." This implies that drugs have the properties of being warm and cool. Does that mean we can judge the drug properties by our own bodies? This is a rough understanding. More accurately speaking, drug properties are observed and summarized according to human bodies' reactions and responses after taking the drugs. For example a man who has a cold. Visual symptoms include fever with aversion to cold, and that aversion to cold means serious fear of cold. Even if you warm him or her by a fire or cover that person with thick quilt, he/she will still feel cold. Symptoms may also include nasal discharge and slightly yellow urine. The patient's nasal discharge is clear and transparent. and coating on the tongue is white. All these are symptoms caused by cold factors. If, at this time, you use decoction of perilla frutescens or ginger for the treatment, the patient shall be eased or recovered after diaphoresis. Accordingly, we can say perilla frutescens and ginger both possess the warm drug property. Likewise, when a patient shows symptoms of furunculosis, local swelling, or even yellow urine and yellow coating on the tongue, which are all symptoms caused by heating factors you can use honeysuckle and chrysanthemum for effective treatment. This illustrates honeysuckle and chrysanthemum's cool drug property. Eating ginger often makes people feel "warm" or "heating", and you might share that feeling. But eating chrysanthemum won't let you feel any sense of "cold" or "cool". That is why the "four kinds of properties" could not be judged merely based on our own feelings, and they have to be summarized according to the drugs' clinical symptoms and efficacy. Another question is why drug properties can be called "the four kinds of flavours". That is only a habit of ancient Chinese, so we just follow the tradition. Li Shizhen has a famous saying that, "Mr. Kou said that "warm, heating, cool and cold are properties, while fragrant, smelly, stinking and foul are flavours. This accords with the descriptions in ”The Book of Rites“. Indeed, this saying accords with the descriptions in ”The Book of Rites“. However, since "Huangdi Neijing (The Inner Canon of Yellow Emperor)", TCM experts and theorists often spoke of only the flavours, while the four kinds of properties are neglected. That had formed a habit. Afterwards people just followed that tradition even though it is not very accurate. So that's how matters stand. Then how should we understand the relationship between the four drug properties of "warm, heating, cold and cool". Generally speaking, "warm and heating" stands for "Yang" while "cool and cold" for "Yin". They are contradictory. So they have quite adverse usage. "Warm and heating" drugs, with the thermogenous properties to fend off the cold and warming and activating meridian, are usually used for the treatment of cold-related diseases. On the contrary, "cold and cool" drugs, with the efficacy of heat-clearing and fire-purging, are often used for the treatment of heat-related diseases. So what's the difference between "warm" and heating", "cold" and "cool"? "warm" and heating" just differ in degree. Likewise, "cold" and "cool" have similar properties and only slight difference of degree. Will such a classification be oversimplified for so many Chinese medicine? Indeed, and ancient Chinese had been aware of such problems. So in order to better represent the differentiated properties, they add some qualifiers on the basis of the four drug properties of "warm, heating, cold and cool", such as "large, small, slight" and so on. Nonetheless, the strategy of qualifiers remained at qualitative analysis, instead of quantitative analysis. So such a strategy still has many limitations. Do there exist any Chinese medicine that is neither warm and heating, nor is cold and cool? Ginseng, which we have mentioned in the very beginning of the class, serves as good example. That is why we use "ping (even or flat)" to describe it. Ginseng has a weaker deviation (towards warm or cool), so that it might be more securely used. You have mentioned that there is another principle called "five kinds of flavours"in addition to "four kinds of properties" in terms of the theory of property and flavour of TCM. Yes, as early as in the Zhou Dynasty about 3000 years ago, people had realized that some drugs' efficacy are connected with their flavours. In "Zhouli: Tianguan (Rite System of Zhou Dynasty: Court Officials)", "As for flavour, sour drugs are for treatment of bone, spicy for tendon, salty for pulse, bitter for energy, sweet for flesh, smooth for joint." In the later Spring and Autumn Period and Warring-States Period, with the popularity of thoughts of Yin and Yang and Wuxing (five elements), the theory of flavour had been gradually reformed. Till the emergence of "Huangdi Neijing (The Inner Canon of Yellow Emperor)", there had formed rather systematic theory of five kinds of flavours. Such a theory held that five kinds of flavours, colours and stink accord with the the five internal organs. For example, we would say that sour drugs are for treatment of liver, and bitter drugs for treatment of heart. The five kinds of flavors also accord with the concept of "Yin and Yang". Like when it comes to the five kinds of flavors, we would say, "Spicy, sweet and flat" belong to Yang; and "sour, bitter, salty" belong to Yin. Later on, there arose the principle of "Five Contraindications", and what does that mean? It says that when a person has overfeeding or partiality for a particular kind of food, his/her inner organs might be harmed. For example, when you excessively eat some sour food, your liver would be negatively influenced. Then do the five kinds of flavors correspond to different functions? Yes, essentially speaking, he five kinds of flavours are defined on the basis of the combination of functions and flavours. Well, take for example the "spicy" flavour. Spicy drugs are intended for "San" and "Xing". "San" means relieving exterior syndrome by dispersion, like ephedra, cassia twig and mint. "Xing" means promoting blood circulation, like rhizoma cyperi, costustoot and peach seed. sourness could induce astringency, and is effective in hidroschesis. When somebody sweats, you can use light wheat and radix et rhizoma ephedrae, for their efficacy of hidroschesis. Astringent, take for another example, is mainly for relieving diarrhea with astringents, like fructus mume and cornus officinalis. Ok, we will stop here. Next class we will talk about the floating and settling theory of TCM.