Library

The *Nan Jing* (Classic of Difficult Issues) states: "For deficiency, tonify the mother; for excess, drain the child." This is also a rhetorical device to clarify that tonification and draining methods have flexible applications, and one should not rigidly adhere only to the direct tonification or draining of the affected Zang organ. Therefore, it is common to encounter cases where an excess condition is treated by draining the mother organ, and a deficiency condition is treated by tonifying the child organ. The use of Da Huang (Rhei Radix et Rhizoma) in Zhang Zhongjing's Xiexin Tang (Heart-Draining Decoction) indeed embodies the principle of "draining the child in excess conditions." This occurs because Fire Qi is obstructed by Earth Qi, with damp-heat stagnating and knotting in the chest, preventing the Fire Qi from performing its normal ascending and descending functions, thereby leading to wheezing, distension, fullness, palpable masses, and obstruction. Tonifying the mother and draining the child is a method employed when the primary Zang organ cannot be directly tonified or drained, serving as a roundabout approach to achieve completeness. In diseases requiring simultaneous tonification and draining, one cannot apply both methods to a single organ; thus, one weighs the mother-child relationship and applies them separately.

Dry stool results from the consumption and deficiency of body fluids, causing dryness and coagulation in the intestines and stomach, leading to the inability to pass stool; this represents an excess of Yang and a deficiency of Yin. Retained food results from cold-dampness in the Stomach, where water and grain remain stagnant for a long time without being digested; this represents an excess of Yin and a deficiency of Yang. Therefore, Zhang Zhongjing uses Chengqi Tang (Descending-the-Qi Decoction) to treat dry stool, employing Mang Xiao (Natrii Sulfas) to clear heat, Da Huang (Rhei Radix et Rhizoma) to moisten dryness, and Zhi Shi (Aurantii Fructus Immaturus) and Hou Po (Magnoliae Officinalis Cortex) to push the Qi downward. If retained food fails to undergo proper digestion and transformation, it must be resolved using warm agents such as Gan Jiang (Zingiberis Rhizoma), Dou Kou (Cardamomi Fructus), Shan Zha (Crataegi Fructus), and Mai Ya (Hordei Fructus Germinatus). Modern physicians fail to distinguish between dry stool and retained food; they often use Shan Zha and Mai Ya to treat dry stool, causing the stool to become harder and impossible to pass; they use Da Huang and Mang Xiao to purge retained food, often resulting in severe diarrhea with undigested food, loss of Yang Qi, and death. If one cannot differentiate and treat such superficial conditions, how can one claim to be a physician?

Li Dongyuan considers constipation to be caused by latent fire within the Blood. This refers to habitual constipation. There are also cases of sudden constipation occurring around the Spring Equinox, which are mostly caused by the initial rising of Liver Yang and the sudden movement of latent fire. However, if sudden constipation occurs around the Autumn Equinox, or during periods of prolonged drought and intense summer heat in midsummer, it mostly belongs to deficiency-dryness of Lung Qi. Summer heat and dryness have already dispersed Lung Qi, and excessive sweating further damages body fluids. Coupled with rapid and vigorous respiration through the mouth and nose, this leads to insufficient Lung Qi to descend and insufficient body fluids to moisten the Large Intestine. This is described as the Lung transferring dryness to the Large Intestine, unrelated to latent fire in the Blood. I often prescribe Sha Shen (Glehniae Radix) and Gua Lou Gen (Trichosanthis Radix), each in quantities of approximately 30 grams (one liang), with very rapid efficacy, without needing to use blood-invigorating herbs.