We now reach the heart of clinical practice: diagnosis — the gathering of signs from the living patient. You have learned the body, its channels, the causes of disease and its mechanisms; now you must learn to read them in a real person. The classical method for this is the four examinations (si zhen): four complementary ways of collecting information, which together give the physician everything needed to distinguish the pattern.
The four ways of gathering
The four examinations are, quite simply, the four channels through which a physician perceives a patient — one for each of the main senses used in diagnosis:
- Looking (Inspection) — what the physician sees: the patient's spirit and vitality, the complexion, the body and its movement, and — supremely important — the tongue.
- Listening and Smelling — what the physician hears and smells: the voice, the breath, the cough and other sounds; and the odours of the body and its secretions.
- Asking (Inquiry) — what the physician learns by questioning: the history, and a systematic set of questions about how the patient feels and functions (the "ten questions").
- Touching (Palpation) — what the physician feels: palpation of the body and channels for tenderness or temperature, and, above all, the pulse at the wrist.
These four correspond to seeing, hearing/smelling, asking and touching — a complete method for perceiving the state of a person, requiring no instruments beyond the trained senses.
Every sign is a window on the interior
Why can these outward observations reveal an inner imbalance? Because of the principle you learned at the very beginning: in Chinese medicine, the interior shows on the exterior. The state of the deep organs and substances is reflected outwardly — in the colour of the face, the vitality of the eyes, the coating of the tongue, the quality of the pulse, the sound of the voice. Each sign is a window onto the interior. The four examinations are simply the disciplined art of reading these windows.
The cardinal rule: combine the four
Here is the single most important principle of diagnosis, and you must hold it above all others: no single sign, and no single examination, is ever enough. A pale tongue, a rapid pulse, a bitter taste, a poor appetite — each alone is ambiguous, consistent with several different patterns. Diagnosis is not the matching of one sign to one conclusion; it is the assembling of all the signs, from all four examinations, into a single coherent picture.
The four examinations must therefore be cross-checked against one another. The signs should agree — and when they do, they confirm the pattern. And when one sign disagrees with the others, that disagreement is itself vital information: it may reveal a complex or mixed condition, or a "false" sign (recall true-cold-false-heat), which is precisely why the whole picture, not the single sign, makes the diagnosis. The physician who reads only the pulse, or only the tongue, will be misled; the physician who weighs all four together sees the truth.
From signs to pattern
The purpose of all this gathering is a single act you already know: distinguishing the pattern (bian zheng). The four examinations supply the raw material — the full set of signs; the physician then weighs them by the frameworks you have learned (Yin-Yang, the substances, the organs, Excess and Deficiency, the mechanisms) and assembles them into the one pattern that best explains the whole. Diagnosis is where all your knowledge comes together and becomes usable.
In this course we take each examination in turn, learning what to look for and how to read it — the inspection and the tongue, the listening and smelling, the art of asking, and the pulse. Throughout, remember the two governing ideas: every outward sign is a window on the interior, and the diagnosis is made not by any single window but by all of them together. We begin with what the physician sees.
