Yin and Yang of the Eight Principles

Yin and yang are two general principles used to categorize the other six principles, i.e., exterior, heat and shi belong to the category of yang, while interior, cold, and xu belong to yin.Yang syndromes and yin syndromes can be detailed as the collapse of yin,collapse of yang, yin xu (yin deficiency ), yang xu (yang deficiency),etc.

Yin xu and yang xu syndromes:Yin xu indicates consumption or loss of yin fluid.Yang xu manifests as the insufficiency of yang qi.Yin xu syndromes are afternoon fever, malar flush,feverish sensation in the palms and soles, irritability, insomnia,night sweating, dry mouth and throat, scanty and yellowish urine, dry stool, red tongue proper with little coating,and thread and rapid pulse.Since yin xu syndromes include internal heat,they are also known as xu heat syndrome.

Yang xu syndromes are manifested by chills,cold extremities,tastelessness in the mouth,absence of thirst,pale complexion,spontaneous sweating,profuse and clear urine,loose stool,and pale tongue proper.Thus while yang xu syndromes indicate inadequate yang qi,they are also termed syndromes of xu cold.

Generally, symptoms characterized by excitation, restlessness,hyperactivity, and optimism belong to yang syndromes, while those characterized by inhibition,quietude, decline, and gloominess are yin.

Yang collapse and yin collapse syndromes: Yang and yin collapse syndromes are dangerous signs during the progress of a disease. Yin collapse indicates an excessive loss of vital essence and nutrient fluid. Yang collapse causes pathological changes and symptoms due to the profuse consumption of body yang qi.Both may occur at the final stage of some chronic diseases or may appear in the crisis stage of some acute diseases. Because of the interdependent relationship of yin and yang, a collapse of one could lead to the collapse of the other. Therefore, the occurrence of these syndromes might be simultaneous with only the difference of early or late appearance.

Besides the symptoms of primary disease, collapses of yang and yin are both manifested by different degrees of persperation.The perspiration in yin collapse is characterized by a type of sticky hot sweat,accompanied by hot skin, warm hands and feet, thirst with preference for drinks , malar flush, and a thready, rapid, forceless pulse.These are signs of yin fluid exhaustion.Yang collapse perspiration is notable for dripping sweat, thin cold sweats, accompanied by aversion to cold, lying with the body curled up, cold extremities,listlessness,pale complexion, and feeble pulse, all of which are signs of yang qi prostration.

The syndromes of each of the eight principles are varied , but are closely related to each other in clinical application.For example , when differentiating syndromes of exterior and interior, the syndromes of cold, heat, xu, and shi are also involved;the differentiation of xu and shi syndromes is also involved with syndromes of cold, heat, exterior, and interior.

During the process of disease development, sometimes there will be non-conformity between the nature and the manifestation of a disease; for example, in syndromes of pseudo-cold and real heat,syndromes of real cold and pseudo-heat, etc.So attention should be paid to the pseudo-phenomena when a disease has developed to a serious stage.Differentiation of syndromes according to the eight principles should be used actively to prevent deception by the pseudo-phenomena of a disease.