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Deficiency and Excess (Xu-Shi) are also the guiding principles of pulse diagnosis. When the force is sufficient in all three positions (Cun, Guan, Chi) and nine examinations (Superficial, Middle, Deep at each position), it can be termed Excess; when the force is insufficient in all three positions and nine examinations, it can be termed Deficiency. Thus, whenever "Excess" is mentioned, it encompasses pulses such as Xian (Wiry), Jin (Forceful), Hong (Surging), and Jin (Taut); whereas whenever "Deficiency" is mentioned, it encompasses pulses such as Wei (Minute), Ruo (Weak), Chi (Slow), and Ruan (Soft). Originally, this was not intended to designate a specific morphological name exclusively for either Deficiency or Excess.

However, ancient practitioners often defined "floating with insufficient force" as Deficiency, attempting to distinguish it from the Ruo pulse characterized by "deep with insufficient force"; and they defined "deep with sufficient force" as Excess, attempting to distinguish it from the Ge pulse characterized by "floating with sufficient force". Although subdividing these domains is not without logical basis, I (Zhang Shanlei, courtesy name Shouyi) privately believe that the original meaning of the terms "Deficiency" and "Excess" should not be understood in this manner. Could it be that those lacking force at the middle and deep levels cannot be called Deficient, while those possessing force at the superficial and middle levels cannot be called Excessive? By considering the names and their meanings, one should gain sudden enlightenment.

Therefore, when an Excess pulse is diagnosed, unless it is due to robust physical constitution, it must indicate that the pathogenic process is excessive. However, if the pulse is excessively firm and hard, beating against the fingers without yielding, it signifies that the pathogenic force is rising vigorously, having lost its harmonious nature. When a Deficiency pulse is diagnosed, it may be due to innate constitutional weakness, reflecting merely an insufficiency of Yuan Qi (Original Qi); but if the deficiency is extreme, and the pulse feels spiritless under the fingers, it indicates that the root is deteriorating, resembling only the residual breath remaining in a corpse.

Consequently, in the case of a swelling ulcer (Zhong Yang), if the pulse is Deficient, although it suggests that the disease pathology is Excess while the pulse response is Deficient (a mismatch), if it is not a major condition and the patient's form and spirit have not yet collapsed, a slight appearance of Deficient and soft pulse does not necessarily lead to immediate grave harm. Only when the ulcerative condition is extremely severe, yet the pulse comes forth extremely weak, is this considered a contradiction between pulse and symptoms, which usually indicates untreatability. In the case of a swelling ulcer, if the pulse is Excess, although it suggests that the pathogen is Excess and the pulse matches the symptoms, if the pulse is indeed abnormally firm and wiry, it implies that a great toxin is entrenched with deep roots, which surely warrants concern.

In the case of an open ulcer (Kui Yang), a Deficient pulse indicates that Qi and Blood have recently been depleted, which is considered a favorable progression according to medical principles. However, recovery requires that the storm has passed and residual waves have subsided, followed by clear nourishment and support, to finally reach safety. If foul necrotic tissue has not yet detached and the flame of toxicity has not diminished, yet the pulse has already become weak and limp, one must fear that the Healthy Qi (Zheng Qi) will be unable to sustain itself, leading to mutual destruction. If an Excess pulse appears during the open ulcer stage, it must imply that residual toxins are still abundant and Qi and Blood are not yet harmonized; for instance, if too much pus has been discharged, yet the pulse remains firm and solid, it will be difficult to manage the aftermath successfully.