经云∶人之所受气者，谷也；谷之所注者，胃也；胃者，水谷血气之海也。海之所行云气者，天下也，胃
之所出血气者，经隧也。经隧者，五脏六腑之大络也。是脏腑受水谷之精气，由胃腑之大络，通于脏腑之经。
麦门冬主伤中伤饱，胃络脉绝，以其根须从中而贯，如络脉之贯于募原之中，是通胸络之气，藉中心之贯通
也。麦冬经冬不凋，能启阴气，上滋于心肺，故主心腹结气，咳嗽虚劳。肾脉上贯肝膈，入肺中，从肺出
络心，是肾气之上交于心肺。心肺之痰热，欲从下解者，又咸藉麦冬之心而导引于脉中也。盖凡物之寒凉
者，其心必热，热者，阴中之阳也。人但知去热，而不知用阳，得其阳，而后能通阴中之气。
经云∶水道不行，则形气消索。是水有随气而营运于肤表者，有水火上下之相济者，如气滞而水不行，
则为水病痰病矣。防己生于汉中者，破之纹作车辐，茎蔓空通，主通气行水，以防己土之制，故有防已之名，
《金匮》方治水病，有防己黄 汤、防己茯苓汤；治痰饮，有木防己汤、防己加茯苓芒硝汤。孙思邈治小便
闭涩，有三物木防己汤。盖气运于上，而水能就下也。今相沿为下部之药，缘前人创论于前，后人随文附会
尔！杲曰∶防己如险健之人，幸灾乐祸，首为乱阶，若善用之，亦可敌凶突险，此瞑眩之药也，故圣人存而
不废。如上焦气分之病，皆不可用，乃下焦血分之药耳！噫，如此议论，不知从何处参出？夫气化而后水
行，防己乃行气利水之品，反云上焦气分不可用。《神农本草》分上、中、下三品，以养生补益、延年不老
者为上品，治病者次之，毒药为下。防己能营运去病，是运中有补，故本经列于中品之前，奚为存而不废？且
气味辛平无毒，奚为瞑眩之药？如此议论，不能枚举，无裨治道，反疑惑后学。予观今世惟卢子田先生，学
识渊博，惟宗圣经，独不为前人所愚。
《黄帝内经》说：人摄取的气，来源于饮食水谷；水谷注入的地方，是胃；胃，是水谷化生的血气的海洋。海洋中运行的云气，对应于天下（指全身经络气血的运行），胃所输出的血气，通过经隧（经脉隧道）运行。经隧，是连接五脏六腑的大络脉。因此，脏腑接受水谷的精微之气，通过胃腑的大络脉，通达于脏腑的经脉。
麦门冬主治因饮食不节导致的内伤和饱食过度，以及胃络脉气血阻滞不通。这是因为它根须从中贯穿生长，如同络脉贯穿在募原（胸腹间的膜原组织）之中，能够疏通胸中络脉的气机，借助其中心贯通的特性来实现。麦冬经历冬天而不凋谢，能够激发阴气，向上滋润心肺，所以主治心腹部的结聚之气、咳嗽和虚劳。肾脉向上贯穿肝脏和膈肌，进入肺中，从肺出来联络心脏，这体现了肾气向上交合于心肺。心肺中的痰热，想要从下部排出时，又必须借助麦冬入心的特性，引导邪气从脉道中排出。大凡性质寒凉的药物，其中心往往偏热，热属于阴中之阳。人们只知道用药物去除热邪，却不知道利用其中的阳气，只有得到了这种阳气，才能疏通阴分中的气机。
《黄帝内经》说：水道运行不畅，就会导致形体和正气消损枯竭。水有随着气机运行而布散到皮肤表面的，也有水火上下相互济助的。如果气机阻滞导致水液不行，就会形成水病或痰病。生长在汉中的防己，折断后纹理像车轮的辐条，茎蔓中空通畅，主要功效是通气行水。因为防己具有克制土湿的作用，所以得名“防己”（防止湿气泛滥）。《金匮要略》中治疗水病的方剂，有防己黄芪汤、防己茯苓汤；治疗痰饮的方剂，有木防己汤、防己加茯苓芒硝汤。孙思邈治疗小便闭塞不通，使用了三物木防己汤。大概是因为气机运行于上，而水性趋下。现在世人沿袭旧说，将其作为治疗下部的药物，这是因为前人创立了某种理论，后人便顺着文字进行牵强附会的解释！李杲（东垣）说：防己就像险恶健讼之人，幸灾乐祸，首先制造混乱的开端，但如果善于使用它，也可以抵御凶险，这是一种产生瞑眩反应（服药后出现剧烈反应以驱除病邪）的药物，所以圣人保留它而不废除。如果是上焦气分的病症，都不可使用，它只是下焦血分的药物罢了！唉，这样的议论，不知道是从哪里参悟出来的？气机气化之后水液才能运行，防己明明是行气利水的药物，反而说上焦气分不可用。《神农本草经》将药物分为上、中、下三品，以养生补益、延年不老者为上品，治疗疾病的为次之，有毒的为下品。防己能够营运气血以祛除疾病，是运中有补，所以《本经》将其列在中品之前，为什么说它是被保留而不废除的毒药？况且它气味辛平无毒，为什么说是产生瞑眩反应的毒药？这样的议论不胜枚举，无助于治病之道，反而迷惑后学。我看当今世上只有卢子田先生，学识渊博，只尊崇经典圣经，唯独不被前人所愚弄。
The *Classic of Difficult Issues from the Lushan Hall* states: The Qi received by humans comes from grain and water; the place where grain and water are deposited is the Stomach; the Stomach is the sea of blood and Qi generated from grain and water. Just as clouds and Qi circulate in the ocean, corresponding to the whole world (the circulation of meridians and Qi-blood throughout the body), the blood and Qi outputted by the Stomach travel through the Jing-Sui (meridian tunnels). The Jing-Sui are the large collaterals connecting the Zang and Fu organs. Thus, the Zang and Fu organs receive the essence-Qi from grain and water, which, via the large collaterals of the Stomach, connects to the meridians of the Zang and Fu organs.
*Ophiopogonis Radix* (Maidong, 麦冬) primarily treats internal injury caused by improper diet or overeating, and the severance/blockage of Qi and blood in the stomach collaterals. This is because its rootlets penetrate vertically from the center, similar to how collaterals penetrate the Mu-Yuan (membranous origin in the chest and abdomen), thereby unblocking the Qi of the chest collaterals through its central penetrating nature. *Ophiopogonis Radix* does not wither in winter, enabling it to stimulate Yin Qi and nourish the Heart and Lungs upwards; thus, it treats knotting Qi in the chest and abdomen, cough, and deficiency consumption. The Kidney meridian ascends through the Liver and diaphragm, enters the Lung, and emerges from the Lung to connect with the Heart, illustrating the upward intersection of Kidney Qi with the Heart and Lungs. Phlegm-heat in the Heart and Lungs, wishing to resolve from below, relies on the Heart-entering property of *Ophiopogonis Radix* to guide the pathogenic factors out through the vessels. Generally, substances that are cold in nature have a hot core; heat is Yang within Yin. People only know how to use drugs to clear heat, but do not know how to utilize Yang; only by obtaining this Yang can one unblock the Qi within Yin.
The *Classic* states: If the water passages do not flow, the form and Qi will diminish and exhaust. Water circulates on the skin surface following Qi, and there is mutual assistance between Fire and Water above and below. If Qi stagnation causes water to fail to move, water diseases or phlegm diseases arise. *Stephaniae Tetrandrae Radix* (Fangji, 防己) grown in Hanzhong has a cross-section resembling chariot spokes, with hollow and smooth stems, primarily functioning to promote Qi movement and diuresis. Due to Fangji's ability to control damp-earth, it is named "Fangji" (preventing dampness). In the *Jin Gui Yao Lue*, formulas for treating water diseases include *Fangji Huangqi Tang* (Stephania and Astragalus Decoction) and *Fangji Fuling Tang* (Stephania and Poria Decoction); for treating phlegm-fluid retention, there is *Mufangji Tang* (Wood Stephania Decoction) and *Fangji Jia Fuling Mangxiao Tang* (Stephania with Poria and Mirabilite Decoction). Sun Simiao used *Sanwu Mufangji Tang* (Three-Ingredient Wood Stephania Decoction) to treat urinary obstruction. This is likely because Qi moves upward while water tends downward. Currently, it is conventionally used as a medicine for the lower part of the body; this stems from predecessors establishing theories and successors making forced interpretations based on text! Li Gao said: Fangji is like a treacherous and litigious person who delights in others' misfortune and initiates chaos; yet, if used skillfully, it can also counteract凶险 (peril), making it a drug that induces Mingxuan reactions (severe initial reaction to expel disease), so the Sages retained it without abolishing it. For diseases of the Upper Jiao Qi level, it should not be used; it is merely a medicine for the Lower Jiao Blood level! Alas, such discussions, from where were they derived? After Qi transformation, water flows; Fangji is clearly an agent for promoting Qi and promoting urination, yet it claims the Upper Jiao Qi level cannot use it. The *Shennong Bencao Jing* classifies herbs into Upper, Middle, and Lower grades. Those that nourish life, tonify, and prolong youth are Upper Grade; those treating diseases are next; toxic ones are Lower Grade. Fangji promotes circulation to remove disease, implying tonification within movement, so the *Bencao Jing* lists it before the Middle Grade. Why say it is retained but abolished? Moreover, its flavor is pungent and neutral, non-toxic; why call it a Mingxuan drug? Such arguments are too numerous to list, offering no benefit to therapeutic principles but rather confusing later learners. I observe that among scholars today, only Mr. Lu Zitian possesses profound learning, reveres only the classic scriptures, and alone is not deceived by predecessors.