稍虚，邪便入于阴，故不可妄下以虚其阳。少阴为阴枢，阳有余邪，便伤其阴，故宜急下以存其阴。且少阳属
木，邪在少阳，惟畏其克土，故无下证。少阴主水，邪在少阴，更畏有土制，故当急下。盖真阴不可虚，强阳
不可纵也。
调胃承气汤∶
大黄（三两） 炙甘草（二两） 芒硝（半斤）
上三味， 咀，以水三升，煮取一升，去滓，内芒硝，更上火微煮令沸，少少温服。
亢则害，承乃制，承气所由名也。不用枳、朴而任甘草，是调胃之义。胃调则诸气皆顺，故亦以承气名之。
此方专为燥屎而设，故芒硝分两多于大承气。前辈见条中无燥屎字，便云未燥坚者用之，是未审之耳。
大承气汤∶
大黄（四两，酒洗） 浓朴（半斤） 枳实（五枚，炙） 芒硝（三合）
水一斗，先煮二物，取五升，去滓，内大黄，煮二升，去渣，再内芒硝，上火微一二沸，分温再服。得下，
余勿服。
小承气汤∶
大黄（四两） 浓朴（二两，去皮） 枳实（三枚）
水四升，煮取一升二合，分温三服。初服汤当大便，不尔者尽饮之。若得大便，勿服。
诸病皆因于气，秽物之不去，由气之不顺也。故攻积之剂，必用气分之药，故以承气名。汤分大小，有
二义焉∶浓朴倍大黄，是气药为君，味多性猛，制大其服，欲令大泄下也。大黄倍浓朴，是气药为臣，味少性缓，
制小其服，欲微和胃气也。前法更有妙义。大承气之先后作三次煎者，何哉？盖生者气锐而先行，熟者气纯而
和缓，欲使芒硝先化燥屎，大黄继通地道，而后枳、朴除其痞满也。若小承气三物同煮，不分次第，只服四合，
但求地道之通，而不用芒硝之峻，且远于大黄之锐，故称微和之剂云。
If the healthy qi is slightly deficient, pathogenic factors enter the Yin aspect; therefore, one must not recklessly use purgation to avoid damaging Yang Qi. Shaoyin (Lesser-Yang) serves as the pivot of Yin. If there is excess Yang-heat pathogen, it will injure Yin fluids; thus, urgent purgation is indicated to preserve Yin. Furthermore, Shaoyang belongs to Wood. When pathogens are in Shaoyang, one fears their overacting on Earth (Spleen/Stomach); hence, there are no indications for purgation. Shaoyin governs Water. When pathogens are in Shaoyin, one further fears Earth controlling Water; thus, urgent purgation is required. This is because True Yin must not be depleted, and hyperactive Yang must not be indulged.
Tiaowei Chengqi Decoction:
Rhei Radix et Rhizoma (3 liang), Prepared Glycyrrhizae Radix et Rhizoma (2 liang), Natrii Sulfas (0.5 jin).
The above three ingredients are cut into small pieces. Boil with 3 sheng of water until reduced to 1 sheng. Strain out the dregs, add Natrii Sulfas, and boil gently until boiling again. Take warm in small amounts frequently.
"Excess leads to harm, and succession brings control." This is the origin of the name "Chengqi" (Succession of Qi). The exclusion of Zhi Shi (Fructus Aurantii Immaturus) and Hou Po (Cortex Magnoliae Officinalis) in favor of Gan Cao (Radix Glycyrrhizae) embodies the meaning of "regulating the Stomach." When the Stomach is regulated, all Qi flows smoothly; hence, it is also named Chengqi Tang. This formula is specifically designed for dry feces; therefore, the dosage of Natrii Sulfas is greater than that in Dachengqi Tang. Previous scholars, noting the absence of the term "dry feces" in the text, claimed it was used when feces were not yet fully hardened. This reflects a lack of careful examination.
Dachengqi Tang (Major Order the Qi Decoction):
Rhei Radix et Rhizoma (4 liang, washed with wine), Cortex Magnoliae Officinalis (0.5 jin), Fructus Aurantii Immaturus (5 pieces, roasted), Natrii Sulfas (3 he).
Boil with 1 dou of water. First decoct the first two ingredients until reduced to 5 sheng. Strain out the dregs, add Rhei Radix et Rhizoma, and boil until reduced to 2 sheng. Strain out the dregs again, add Natrii Sulfas, and boil gently for one or two boils. Divide into two warm doses. If bowel movement occurs, do not take the remainder.
Xiaochengqi Tang (Minor Order the Qi Decoction):
Rhei Radix et Rhizoma (4 liang), Cortex Magnoliae Officinalis (2 liang, bark removed), Fructus Aurantii Immaturus (3 pieces).
Boil with 4 sheng of water until reduced to 1.2 sheng. Divide into three warm doses. After the first dose, bowel movement should occur. If not, consume the remaining liquid. If bowel movement has occurred, do not take further doses.
All diseases arise from Qi dysfunction; the retention of turbid matter is due to the obstruction of Qi flow. Therefore, formulas for attacking accumulation must utilize herbs that regulate Qi, which is why they are named "Chengqi." The distinction between Major and Minor versions lies in two aspects: In Dachengqi Tang, the dosage of Cortex Magnoliae Officinalis is double that of Rhei Radix et Rhizoma, making the Qi-regulating herb the Sovereign. With many ingredients and potent nature, the dosage is increased to induce severe purgation. In Xiaochengqi Tang, the dosage of Rhei Radix et Rhizoma is double that of Cortex Magnoliae Officinalis, making the Qi-regulating herb the Minister. With fewer ingredients and milder nature, the dosage is decreased to mildly harmonize Stomach Qi.
There is a subtle principle in the decoction method. Why does Dachengqi Tang involve three separate decoction steps? Raw herbs possess sharp Qi and act quickly, while cooked herbs have pure Qi and act gently. The purpose is for Natrii Sulfas to first soften dry feces, followed by Rhei Radix et Rhizoma to unblock the intestines, and finally Fructus Aurantii Immaturus and Cortex Magnoliae Officinalis to remove fullness and distension. In contrast, Xiaochengqi Tang decocts all three ingredients together without sequence, administered in smaller quantities (4 he). It seeks only to unblock the intestines, avoiding the harshness of Natrii Sulfas and the sharpness of Rhei Radix et Rhizoma; thus, it is termed a formula for mild harmonization.