古者，每方各有主药，用其主而进退其余，可云从古某方加减；如用其余而去其主，即
不得
称某方矣。仲景理中汤，一名治中汤，盖取《别录》人参“调中”两字，是人参乃其主药也
。桃花汤取赤石脂一名桃花石为义，是赤石脂乃其主药也。若去人参、赤石脂，用其术、干
等，而称理中、桃花，则失其义而袭其名，陋乎不陋？非独经方为然也，虽后世亦有之。丹
溪治六郁越鞠丸方，以川芎、山栀为主，缘川芎即《左传》鞠穷，山栀《本草》一名越桃，
故各摘取一字以名之，以见能治郁者之全在乎此。若不用芎、栀，用余四味，尚能再称越鞠
乎？《本草》经用之药，仅四、五百种，而自汉至明，方以亿万计，随举数味以成方，皆当
有合于古，举其相似者，反遗其相同者矣。昔徐灵胎诮叶天士，用《局方》逍遥散而去柴胡
，非以此哉？学人可以类推。
诸泻心皆从小柴胡来。小柴胡以柴、姜治半表；芩、参、甘、半治半里。兹则去其治半
表者，参用陷胸法，而随建主药，故当分数类观之。
半夏泻心汤，即小柴胡去柴、姜之治表，加干姜、黄连以和胃也。其生姜泻心汤与甘草
泻心
汤，皆即半夏泻心汤原方，而主药略增（从《金匮》有人参。）三方不外干姜、黄连者，以此
祛心下痞，乃胃虚上逆所致，与表陷之痞不同，故重在和胃也。其主药皆在小柴胡中，自为
一类。
其干姜黄连黄芩人参汤，则截半夏泻心之半而为之。其黄连汤，又即半夏泻心去黄芩加
桂枝者。但二方皆重用黄连，使与干姜并视半夏泻心为小变也。
黄芩汤，即截小柴胡之半而加芍药，以治腹痛。其黄芩加半夏生姜汤，即小柴胡去柴、
参加芍药也。二方皆主小柴胡中之黄芩，自为一类。
旋复代赭汤，即小柴胡去柴、芩，加旋、代，增姜、减参者，故以旋代命名。浓朴生姜
甘草
半夏人参汤，即小柴胡去柴、芩，加朴，增姜、减参者。二方皆主小柴胡中之生姜，自为一
类。
其橘皮竹茹汤，即浓朴生姜甘草半夏人参汤去朴、半，加橘皮、竹茹、大枣，增甘草，
故以橘皮竹茹命史。其橘皮汤，即取其方中二味为之。二方自为一类。
小半夏汤乃抽小柴胡方中治呕之品，而倍其分者。其生姜半夏汤，即半夏之法，而小半
夏加
茯苓汤属焉。其半夏干姜散，即生姜半夏汤去生姜加干姜者，意固重在温胃，与生姜温经略
殊。而大半夏汤，即半夏干姜散之变焉者也。其干姜人参半夏丸，即半夏干姜散加人参，倍
半夏者。六方皆从小半夏汤来，主小柴胡中之半夏，自为一类。
泻心汤，自大、小陷胸来。大黄黄连泻心汤，即泻心汤原方去黄芩。附子泻心汤，即泻
心汤
原方加附子。三方不外大黄、黄连者，以此处心下痞，乃表邪内陷所致，与结胸之义相同，
而与半夏等三方痞症不同，故重在下实，乃由泻心而将入承气也。
古代方剂，每一方都有主药，使用主药并随证加减其余药物，可以说是在古方的基础上进行加减；如果去掉主药而只保留其他药物，就不能再称为某方了。张仲景的理中汤，又名治中汤，大概是取自《名医别录》中人参“调中”二字的意思，这说明人参是它的主药。桃花汤取赤石脂又名“桃花石”的含义，说明赤石脂是它的主药。如果去掉了人参、赤石脂，却使用白术、干姜等药，还称之为理中汤、桃花汤，那就失去了本义而袭用了其名，这难道不浅陋吗？不仅仅是经方如此，即使是后世的方剂也有这种情况。朱丹溪治疗六郁的越鞠丸方，以川芎、山栀为主药，因为川芎即《左传》中的“鞠穷”，山栀在《本草》中又名“越桃”，所以各摘取一字来命名，以此表明能治疗郁证的关键全在于此。如果不使用川芎、山栀，而使用其余四味药，还能再称之为越鞠丸吗？《神农本草经》记载的药物仅有四五百种，而从汉代到明代，方剂数以亿计，随意选取几味药组成方剂，都应当符合古法，只举出相似者，反而遗漏了相同者。从前徐灵胎嘲笑叶天士，在使用《太平惠民和剂局方》的逍遥散时去掉了柴胡，不就是这个道理吗？学者可以由此类推。
所有的泻心汤类方剂都源于小柴胡汤。小柴胡汤用柴胡、生姜治疗半表证；黄芩、人参、甘草治疗半里证。现在的这些方剂去掉了治疗半表证的药物，参用陷胸汤的方法，并根据病情确立主药，因此应当分门别类地观察。
半夏泻心汤，就是小柴胡汤去掉柴胡、生姜以不再解表，加入干姜、黄连以调和胃气。生姜泻心汤与甘草泻心汤，都是基于半夏泻心汤的原方，只是主药略有增加（参考《金匮要略》，原方含有人参）。这三方不离干姜、黄连，是因为它们用来消除心下痞满，这是由胃虚气逆引起的，与表邪内陷导致的痞满不同，所以重在调和胃气。它们的主药都包含在小柴胡汤中，自然归为一类。
干姜黄连黄芩人参汤，则是截取半夏泻心汤的一半变化而来。黄连汤，又是半夏泻心汤去掉黄芩加入桂枝而成。但这两方都重用黄连，使其与干姜并重，相对于半夏泻心汤来说是小变。
黄芩汤，就是截取小柴胡汤的一半并加入芍药，用来治疗腹痛。黄芩加半夏生姜汤，就是小柴胡汤去掉柴胡、人参，加入芍药而成。这两方都以小柴胡汤中的黄芩为主药，自成一类。
旋复代赭汤，就是小柴胡汤去掉柴胡、黄芩，加入旋复花、代赭石，增加生姜用量，减少人参用量的方子，所以以旋复花、代赭石命名。厚朴生姜甘草半夏人参汤，就是小柴胡汤去掉柴胡、黄芩，加入厚朴，增加生姜用量，减少人参用量的方子。这两方都以小柴胡汤中的生姜为主药，自成一类。
橘皮竹茹汤，就是厚朴生姜甘草半夏人参汤去掉厚朴、半夏，加入橘皮、竹茹、大枣，增加甘草用量的方子，所以以橘皮、竹茹命名。橘皮汤，就是取其方中的两味药组成。这两方自成一类。
小半夏汤是抽取小柴胡汤中治疗呕吐的药物，并加倍其剂量而成。生姜半夏汤，即是半夏的方法，而小半夏加茯苓汤属于此类。半夏干姜散，就是生姜半夏汤去掉生姜加入干姜，用意固然重在温胃，与生姜温通经络略有不同。而大半夏汤，就是半夏干姜散的变方。干姜人参半夏丸，就是半夏干姜散加入人参，并将半夏用量加倍。这六方都源于小半夏汤，以小柴胡汤中的半夏为主药，自成一类。
泻心汤类方，自大、小陷胸汤演变而来。大黄黄连泻心汤，就是泻心汤原方去掉黄芩。附子泻心汤，就是泻心汤原方加入附子。这三方不离大黄、黄连，是因为它们用于治疗心下痞满，这是由表邪内陷引起的，与结胸病的含义相同，而与半夏泻心汤等三方所治的痞症不同，所以重在攻下实邪，是由泻心汤向承气汤过渡的阶段。
In ancient times, each prescription had a principal herb. Using the principal herb while adjusting the remaining herbs according to the syndrome could be described as modifying an ancient formula; however, if the principal herb is removed and only the remaining herbs are used, it can no longer be called that specific formula. Zhang Zhongjing's Lizhong Tang (Regulate the Middle Decoction), also known as Zhizhong Tang (Regulate the Middle Decoction), likely derives its name from the phrase "regulate the middle" (Tiao Zhong) in *Bencao Jingjiu Jiazhu* regarding Ginseng Radix et Rhizoma (Renshen, 人参), indicating that Ginseng is its principal herb. Taohua Tang (Peach Blossom Decoction) takes its name from Chishizhi (Red Halloysite), which is also called "Taohua Shi" (Peach Blossom Stone), indicating that Red Halloysite is its principal herb. If one removes Ginseng and Red Halloysite but uses Atractylodis Rhizoma (Baizhu, 白术) and Zingiberis Rhizoma Recens (Ganjiang, 干姜), yet still calls it Lizhong Tang or Taohua Tang, one loses the original meaning and merely appropriates the name. Is this not shallow? This applies not only to classical formulas but also to later prescriptions. Zhu Danxi's Yueju Wan (Solve Depression Pill) for treating six types of depression uses Chuanxiong Rhizoma (Chuanxiong, 川芎) and Gardeniae Fructus (Zhizi, 山栀子) as principal herbs. This is because Chuanxiong corresponds to "Ju Qiong" mentioned in *Zuo Zhuan*, and Gardeniae Fructus is named "Yue Tao" in *Bencao*. Thus, one character from each was extracted to form the name, demonstrating that the ability to treat depression lies entirely in these two herbs. If Chuanxiong and Gardeniae Fructus were not used, but the other four ingredients were, could it still be called Yueju Wan? The *Shennong Bencao Jing* records only four to five hundred medicinal substances, yet from the Han to the Ming dynasty, prescriptions numbered in the hundreds of millions. Randomly selecting a few herbs to form a prescription should ideally align with ancient principles; highlighting similarities often leads to overlooking identities. In the past, Xu Lingtai mocked Ye Tianshi for using Xiaoyao San (Free and Easy Wanderer Powder) from *Tai Ping Hui Min He Ji Ju Fang* without Chai Hu (Bupleuri Radix). Was this not for the same reason? Scholars can infer similar cases.
All Xixin Tang (Drain the Epigastrium Decoctions) originate from Xiao Chaihu Tang (Minor Bupleurum Decoction). Xiao Chaihu Tang uses Chai Hu (Bupleuri Radix) and Sheng Jiang (Zingiberis Rhizoma Recens) to treat half-exterior syndromes; Huang Qin (Scutellariae Radix), Renshen (Ginseng Radix et Rhizoma), and Gan Cao (Glycyrrhizae Radix et Rhizoma) treat half-interior syndromes. These subsequent formulas remove the herbs treating the half-exterior, incorporate methods from Xiongxiong Tang (Chest Trap Decoctions), and establish principal herbs based on the condition; therefore, they should be observed by categorization.
Banxia Xiexin Tang (Pinellia Drain the Epigastrium Decoction) is Xiao Chaihu Tang minus Chai Hu and Sheng Jiang to cease exterior treatment, plus Ganjiang (Zingiberis Rhizoma) and Huanglian (Coptidis Rhizoma) to harmonize the Stomach. Shengjiang Xiexin Tang (Fresh Ginger Drain the Epigastrium Decoction) and Gancao Xiexin Tang (Licorice Drain the Epigastrium Decoction) are both based on the original Banxia Xiexin Tang formula, with slight increases in principal herbs (referencing *Jingui Yaolue*, which includes Renshen). These three formulas essentially rely on Ganjiang and Huanglian to dispel epigastric fullness (Pi, 痞), which is caused by Stomach deficiency and rebellious Qi, differing from fullness caused by exterior pathogens sinking inward; thus, the focus is on harmonizing the Stomach. Their principal herbs are all contained within Xiao Chaihu Tang, naturally forming one category.
Ganjiang Huanglian Huangqin Renshen Tang (Ginger, Coptis, Scutellaria, and Ginseng Decoction) is derived by taking half of Banxia Xiexin Tang. Huanglian Tang (Coptis Decoction) is Banxia Xiexin Tang minus Huang Qin plus Guizhi (Cinnamomi Ramulus). However, both formulas heavily emphasize Huanglian, placing it on equal footing with Ganjiang, representing a minor variation from Banxia Xiexin Tang.
Huangqin Tang (Scutellaria Decoction) is derived by taking half of Xiao Chaihu Tang plus Shaoyao (Paeoniae Radix Alba) to treat abdominal pain. Huangqin Banxia Shengjiang Tang (Scutellaria, Pinellia, and Fresh Ginger Decoction) is Xiao Chaihu Tang minus Chai Hu and Renshen plus Shaoyao. Both formulas take Huang Qin from Xiao Chaihu Tang as the principal herb, forming their own category.
Xuanshu Daizhe Tang (Inula and Hematite Decoction) is Xiao Chaihu Tang minus Chai Hu and Huang Qin, plus Xuanshu (Inulae Flos) and Daizhe (Haematitum), increasing Sheng Jiang and decreasing Renshen; hence it is named after Inula and Hematite. Houpo Shengjiang Gancao Banxia Renshen Tang (Magnolia Bark, Fresh Ginger, Licorice, Pinellia, and Ginseng Decoction) is Xiao Chaihu Tang minus Chai Hu and Huang Qin, plus Houpo (Magnoliae Officinalis Cortex), increasing Sheng Jiang and decreasing Renshen. Both formulas take Sheng Jiang from Xiao Chaihu Tang as the principal herb, forming their own category.
Jupi Zhuru Tang (Citrus Peel and Bamboo Shavings Decoction) is Houpo Shengjiang Gancao Banxia Renshen Tang minus Houpo and Banxia, plus Jupi (Citri Reticulatae Pericarpium), Zhuru (Bambusae Caulis in Taeniam), and Dazao (Jujubae Fructus), increasing Gan Cao; hence it is named after Citrus Peel and Bamboo Shavings. Jupi Tang (Citrus Peel Decoction) consists of just these two ingredients from the previous formula. These two form their own category.
Xiao Banxia Tang (Minor Pinellia Decoction) extracts the anti-emetic components from Xiao Chaihu Tang and doubles their dosage. Shengjiang Banxia Tang (Fresh Ginger and Pinellia Decoction) follows the method of Pinellia, while Xiao Banxia Jia Fuling Tang (Minor Pinellia Plus Poria Decoction) belongs to this group. Banxia Ganjiang San (Pinellia and Ginger Powder) is Shengjiang Banxia Tang minus Sheng Jiang plus Ganjiang, intending to warm the Stomach, which differs slightly from Sheng Jiang's warming of meridians. Banxia Tang (Major Pinellia Decoction) is a variation of Banxia Ganjiang San. Ganjiang Renshen Banxia Wan (Ginger, Ginseng, and Pinellia Pill) is Banxia Ganjiang San plus Renshen and doubling the amount of Banxia. These six formulas all originate from Xiao Banxia Tang, taking Banxia (Pinelliae Rhizoma) from Xiao Chaihu Tang as the principal herb, forming their own category.
Xiexin Tang (Drain the Epigastrium Decoction) evolves from Da Xiongxiong Tang (Major Chest Trap Decoction) and Xiao Xiongxiong Tang (Minor Chest Trap Decoction). Dahuang Huanglian Xiexin Tang (Rhubarb and Coptis Drain the Epigastrium Decoction) is the original Xiexin Tang minus Huang Qin. Fuzi Xiexin Tang (Aconite Drain the Epigastrium Decoction) is the original Xiexin Tang plus Fuzi (Aconiti Lateralis Radix Praeparata). These three formulas essentially rely on Dahuang (Rhei Radix et Rhizoma) and Huanglian to treat epigastric fullness caused by exterior pathogens sinking inward. This mechanism is identical to Jie Xiong (Chest Trap) pathology and differs from the Pi symptoms treated by the Banxia-type formulas; thus, the focus is on purging interior excess, marking a transition from draining the epigastrium to using Chengqi Decoctions.