The Yellow Emperor's Classic of Internal Medicine, specifically Chapter 20, details a diagnostic system called the Three Divisions and Nine Indicators. This system uses pulse diagnosis at specific body points to assess the balance of qi and determine the severity and location of illness, distinguishing between life and death. The dialogue between the Yellow Emperor and Qibo explains the three divisions (Upper, Middle, Lower) and how each contains three indicators representing Heaven, Earth, and Humanity. The text further clarifies the interpretation of pulse characteristics, emphasizing the importance of observing imbalances and the timing of death based on these indicators. Finally, it offers treatment strategies based on the location and nature of the detected imbalances.