The four diagnostic methods, namely inspection, auscultation and olfaction,?inquiry, and pulse-taking and palpation, refer to the four basic procedures used?in diagnosing a disease, They are the presuppositions of correct differentiation?and effective treatment in TCM.

TCM.四診即望、聞、問、切，指的是用于診斷疾病的四個基本步驟，它們是中醫正確辨證和有效治療的前提。

When a disease occurs, there must be its abnormal outward manifestations from?which the pathological changes may be inferred, as is stated in Danxi's?Experience on Medicine （ DanxiXin Fa） , "To want knowing the internal conditions?of the body, the external manifestations of the body should be observed ; to?diagnose the external parts of the body may also know the internal conditions.

That is because the internal conditions of the body are always reflected on the?exterior of the body".The four diagnostic methods examine and learn about the?pathological conditions from different angle and aspect and find out the?etiology and pathogenesis, thereby providing the basis for TDS. The four methods?are related to and supplement one another. They cannot be separated from one?another, each having its specific function that cannot be substituted for the?others. In clinical practice, only when the four techniques are organically?combined can a disease be understood all-sidedly. Thus, a correct diagnosis can?be?made.

疾病發生時必有相關的病理改變引起的異常外在表現，正如《丹溪心法》所指出的：“欲知其內者，當以觀乎外，診于外者，斯以知其內，蓋有諸內者形諸外。”四診可以從不同角度檢查和了解病理狀態，找出病因和病機，從而為辨證論治提供基礎。四診相互聯系、相互補充，不能相互分離，每一部分都有其特殊的功能，不可代替。在臨床實踐中，只有將四診有機聯系，才能全面了解疾病，因此，才能做出正確的診斷。

1. Inspection?

Inspection is the first diagnostic procedure by which the?physician may observe the patient's vitality, complexion, physical build, head,neck, five sense organs, skin, tongue, external genitalia and anus on purpose so?as to understand the condition of a disease. TCM holds that the human body is an?organic whole. The exterior of the body is closely related to the internal?organs. Take observation the vitality and complexion for examples, the vitality?refers to the general external manifestations of life activity of the human?body, including spirit, consciousness and thinking. And it is the outward sign?of the conditions of qi and blood, yin and yang, or the zang-fu organs. The?vitality is manifested in manifold aspects, such as eyesight, complexion, facial?expressions, physical build, behavior and so on, among which the expression of?the eyes is the most important. This is because "all the vital essence from the?five zang and six fu organs converges into the eyes." From the observation of?vitality the physician may infer the abundance or inadequacy of the vital?essence, analyze mildness or the severeness of the disease and predict the?prognosis of disease. It is quite evident that the observation of vitality is of?an important significance in diagnosing a disease. The manifestations of?vitality are as follows; being of vitality, pseudo-vitality, and loss of?vitality.

1.望

望診是診斷的首要程序，通過望診，醫生可以有目的的觀察病人的神、色、體質、頭、頸、五官、皮膚、舌頭、前后二陰，以了解疾病的狀況。中醫認為人體是一個有機整體，體表和內臟是緊密聯系的。以觀察神色為例，神指的是人體生命活動的外在表現，包括精神和意識。它是氣血、陰陽、臟腑狀態的外在征象。神體現于多方面，如眼、面色、表情、體質、行為等，這之中，眼神是最重要的。這是由于“五臟之精上注于目”。通過對神的觀察，醫生可以了解正氣的充足與否，分析疾病的嚴重程度和預測疾病的預后。很明顯察神是診斷疾病的一個重要指征。神有如下表現：得神、假神和失神。