宾尝闻之孙真人曰∶不知易，不足以言太医。每窃疑焉。以谓易之为书，在开物成务，
知来藏往；而医之为道，则调元赞化，起死回生。其义似殊，其用似异。且以医有内经，何
借于易？舍近求远，奚必其然？而今也年逾不惑，茅塞稍开；学到知羞，方克渐悟。乃知天
地之道，以阴阳二气而造化万物；人生之理，以阴阳二气而长养百骸。易者，易也，具阴阳
动静之妙；医者，意也，合阴阳消长之机。虽阴阳已备于内经，而变化莫大乎周易。故曰天
人一理者，一此阴阳也；医易同原者，同此变化也。岂非医易相通，理无二致，可以医而不
知易乎？予因默契斯言，潜心有日，管窥一得，罔敢自私，谨摭易理精义，用资医学变通，不
揣鄙俚而为之论曰∶易有太极，是生两仪，两仪生四象，四象生八卦。天尊地卑，乾坤定矣；
卑高以陈，贵贱位矣；动静有常，刚柔断矣；方以类聚，物以群分，吉凶生矣；在天成象，在地
成形，乾坤设位而易行乎其中矣。是故天生神物，圣人格之；天地变化，圣人效之；天垂象，
见吉凶，圣人象之；河出图，洛出书，圣人则之。于是乎近取诸身，远取诸物，作八卦以通神
明之德，以顺性命之理，八卦成列，象在其中矣；因而重之，爻在其中矣；刚柔相摩，八卦相
荡，变在其中矣；系辞焉而命之，动在其中矣；吉凶悔吝生乎动，而天地鬼神之为德，万物一
体之为能，森乎昭着而无所遁乎易矣。伟哉人生，禀二五之精，为万物之灵；得天地之中
和，参乾坤之化育；四象应天，四体应地；天地之合辟，即吾身之呼吸也；昼夜之潮汐，即吾
身之脉息也；天之北辰为群动之本，人之一心为全体之君也。由是观之，天之气，即人之
气；人之体，即天之体。故康节曰∶思虑未起，鬼神未知，不由乎我，更由乎谁？盖谓一念方
萌，便达乎气，神随气见，便与天地鬼神相感通。然则天人相与之际，精哉妙矣，诚可畏矣；
人身小天地，真无一毫之相间矣。今夫天地之理具乎易，而身心之理独不具乎易乎？矧天
地之易，外易也；身心之易，内易也。内外孰亲？天人孰近？故必求诸己而后可以求诸人，
先乎内而后可以及乎外；是物理之易犹可缓，而身心之易不容忽。医之为道，身心之易也，
医而不易，其何以行之哉？然易道无穷，而万生于一，一分为二，二分为四，四分为八，八分
为十六，自十六而三十二，三十二而六十四，以至三百八十四爻，万有一千五百二十策，而
交感之妙，化生之机，万物之数，皆从此出矣。详而言之，则其所谓一者，易有太极也。太
极本无极，无极即太极，象数未形理已具，万物所生之化原。故曰∶五行不到处，父母未生
前。又曰∶杳杳冥冥，其中有精，其精甚真，其中有信。是为造物之初，因虚以化气，因气以
造形，而为先天一气之祖也。医而明此，乃知生生化化，皆有所原，则凡吾身于未有之初，
便可因之以知其肇基于父母，而预占其禀受之象矣。所谓一分为二者，是生两仪也。太极
动而生阳，静而生阴；天生于动，地生于静；阳为阴之偶，阴为阳之基；以体而言为天地，以
用而言为乾坤，以道而言为阴阳；一动一静，互为其根，分阴分阳，两仪立焉。是为有象之
始，因形以寓气，因气以化神，而为后天体象之祖也。医而明此，乃知阴阳气血，皆有所钟，
则凡吾身之形体气质，可因之以知其纯驳偏正，而默会其禀赋之刚柔矣。所谓二分为四
者，两仪生四象也。谓动之始则阳生，动之极则阴生；静之始则柔生，静之极则刚生。太少
阴阳，为天四象；太少刚柔，为地四体；耳目口鼻以应天，血气骨肉以应地。医而明此，乃知
阳中有阴，阴中有阳，则凡人之似阳非阳、似阴非阴，可因之以知其真假逆顺，而察其互藏
之幽显矣。所谓四分为八者，四象生八卦也。谓干一、兑二、离三、震四、巽五、坎六、艮七、
坤八也。干，健也；坤，顺也；震，动也；巽，入也；坎，陷也；离，丽也；艮，止也；兑，
说也。伏羲八卦，分阴阳之体象；文王八卦，明五行之精微。医而明此，方知阴阳之中，复有阴阳，刚
柔之中，复有刚柔，而其对待之体，消息之机，交感之妙，错综之义，昭乎已备；则凡人之性
理神机，形情病治，可因之以得其纲领，而会通其变化之多矣。自兹而四象相交，成十六
事，八卦相荡，为六十四，分内外以配六爻，推九六以成蓍数，人物由之而大成，万象因之以
毕具。前阅圆图，即其精义，是图虽象乎万有，尤切夫人之一身。故曰先天图者，环中也；
环中者，天之象也。六十四卦列于外，昭阴阳交变之理也；太极独运乎其中，象心为一身之
主也。干南坤北者，象首腹之上下也；离东坎西者，象耳目之左右也。自复至同人，当内卦
震离之地，为阴中少阳之十六，在人为二八；自临至干，当内卦兑干之地，为阳中太阳之十
六，在人为四八；自 至师，当内卦巽坎之地，为阳中少阴之十六，在人为六八；自遁至坤，
当内卦艮坤之地，为阴中太阴之十六，在人为八八。阳生于子而极于午，故复曰天根，至干
为三十二卦，以应前之一世；阴生于午而极于子，故 曰月窟，至坤为三十二卦，以应后之
半生。前一世始于复之一阳，渐次增添，至干而阳盛已极，乃象人之自少至壮；后半生始于
之一阴，渐次耗减，至坤而阳尽以终，乃象人之自衰至老。纵观之，则象在初爻，其干尽
于午，坤尽于子，当二至之令，为天地之中而左右以判。左主升而右主降，升则阳居东南，
主春夏之发生，以应人之渐长；降则阴居西北，主秋冬之收敛，以应人之渐消。横观之，则
象在二爻，其离尽于卯，坎尽于酉，当二分之中，为阴阳之半而上下以分。上为阳而下为
阴，阳则日出于卯，以应昼之为寤；阴则日入于酉，以应夜之寐焉。即此一图，而天人之妙，
运气之理，无不具矣。再阅方图，其义象地，干始于西北，坤尽于东南。天不足西北，故圆
图之阳在东南；地不满东南，故方图之刚在西北。是皆伏羲之卦也。又若文王八卦，位有
不同。伏羲出自然之象，故干上坤下，离左坎右；文王合河图之数，故火南水北，木东金
西。（此节自方图以下并河洛数义，详方隅、气数二论。） 质诸人身，天地形体也，乾坤情性也，
阴阳气血也，左右逢原，纤毫无间，详求其道，无往不然。故以爻象言之，则天地之道，以六为节，三
才而两，是为六爻，六奇六偶，是为十二。故天有十二月，人有十二脏；天有十二会，人有十
二经；天有十二辰，人有十二节。知乎此，则营卫之周流，经络之表里，象在其中矣。以藏
象言之，则自初六至上六为阴为脏，初六次命门，六二次肾，六三次肝，六四次脾，六五次
心，上六次肺；初九至上九为阳为腑，初九当膀胱，九二当大肠，九三当小肠，九四当胆，九
五当胃，上九当三焦。知乎此，而脏腑之阴阳，内景之高下，象在其中矣。以形体言之，则
干为首，阳尊居上也；坤为腹，阴广容物也；坎为耳，阳聪于内也；离为目，阴明在外也；兑为
口，拆开于上也；巽为股，两垂而下也；艮为手，阳居于前也；震为足，刚动在下也。天不足
西北，故耳目之左明于右；地不满东南，故手足之右强于左。知乎此，而人身之体用，象在
其中矣。以生育言之，则天地 ，万物化醇，男女媾精，万物化生。天尊地卑，干父坤母，
干道成男，坤道成女，震坎艮是为三男，巽离兑是为三女。欲知子强弱，则震巽进而前，艮
兑退而止；欲辨脉息候，则干健在东南，坤顺向西北；欲为广嗣谋，则蓄坎填离宫，借兑为干
计；欲明布种法，则天时与地利，亏盈果由气，冬至始阳强，阴胜须回避。知乎此，而胎孕交
感之道，存乎其中矣。以精神言之，则北一水，我之精，故曰肾藏精；南二火，我之神，故曰
心藏神；东三木，我之魂，故曰肝藏魂；西四金，我之魄，故曰肺藏魄；中五土，我之意，故曰
脾藏意。欲知魂魄之阴阳，须识精神之有类。木火同气，故神魂藏于东南，而二八、三七同
为十；金水同原，故精魄藏于西北，而一九、四六同为十；土统四气，故意独居中，其数惟五，
而脏腑五行之象，存乎其中矣。以动静言之。则阳主乎动，阴主乎静；天圆而动，地方而
静；静者动之基，动者静之机。刚柔推荡，易之动静也；阴阳升降，气之动静也；形气消息，
物之动静也；昼夜兴寝，身之动静也。欲详求夫动静，须精察乎阴阳，动极者镇之以静，阴
亢者胜之以阳。病治脉药，须识动中有静；声色气味，当知柔里藏刚。知刚柔动静之精微，
而医中运用之玄妙，思过其半矣。以升降言之，则阳主乎升，阴主乎降；升者阳之生，降者
阴之死。故日在于子，夜半方升，升则向生，海宇俱清；日在于午，午后为降，降则向死，万
物皆鬼。死生之机，升降而已。欲知升降之要，则宜降不宜升者，须防剥之再进；宜升不宜
降者，当培复之始生。畏剥所从衰，须从观始；求复之渐进，宜向临行。此中有个肯綮，最
在形情气味。欲明消长之道，求诸此而得之矣。以神机言之，则存乎中者神也，发而中者
机也；寂然不动者神也，感而遂通者机也；蕴之一心者神也，散之万殊者机也。知乎此，则
财原其始，直要其终，我之神也；挥邪如匠石之斤，忌器若郢人之鼻，我之机也。见可而进，
知难而退，我之神也；疾徐如轮扁之手，轻重若庖丁之刀，我之机也。神之与机，互相倚伏。
故神有所主，机有所从；神有所决，机有所断；神为机之主，机为神之使。知神知机，执而运
之，是即医之神也矣。以屈伸言之，如寒往则暑来，昼往则夜来，壮往则衰来，正往则邪来。
故难易相成，是非相倾，刚柔相制，冰炭相刑。知乎此，则微者甚之基，盛者衰之渐；大由小
而成，远由近而遍。故安不可以忘危，治不可以忘乱；积羽可以沉舟，群轻可以折轴。是小
事不可轻，小人不可慢，而调和相济，以一成功之道，存乎其中矣。以变化言之，则物生谓
之化，物极谓之变；阴可变为阳，阳可变为阴。只此一二，交感生成，气有不齐，物当其会，
而变化之由，所从出矣。故阳始则温，阳极则热；阴始则凉，阴极则寒。温则生物，热则长
物，凉则收物，寒则杀物，而变化之盛，于斯着矣。至若夷父羌母，蛮男苗女，子之肖形，虬
髯短股；杏之接桃，梨之接李，实必异常，多甘少苦。迨夫以阴孕阳，以柔孕刚，以小孕大，
以圆孕方，以水孕火，以紫孕黄，以曲孕直，以短孕长。知乎此，则可以和甘苦，可以平
香，可以分经纬，可以调宫商，可以为蛇蝎，可以为鸾凰，可以为尧桀，可以为彭殇，庶胸次
化同大象，而应用可以无方矣。以常变言之，则常易不易，太极之理也；变易常易，造化之
动也。常易不变，而能应变；变易不常，靡不体常。是常者易之体，变者易之用；古今不易
易之体，随时变易易之用；人心未动常之体，物欲一生变之用。由是以推，则属阴属阳者，
禀受之常也；或寒或热者，病生之变也。素大素小者，脉赋之常也；忽浮忽沉者，脉应之变
也。恒劳恒逸者，居处之常也；乍荣乍辱者，盛衰之变也。瘦肥无改者，体貌之常也；声色
顿异者，形容之变也。常者易以知，变者应难识。故以寒治热得其常，热因热用为何物？
痛随利减得其常，塞因塞用为何物？检方疗病得其常，圆底方盖为何物？见病治病得其
常，不治之治为何物？是以圣人仰观俯察，远求近取，体其常也；进德修业，因事制宜，通其
变也。故曰不通变，不足以知常；不知常，不足以通变。知常变之道者，庶免乎依样画瓠
卢，而可与语医中之权矣。以鬼神言之，则阳之灵曰神，神者伸也；阴之灵曰鬼，鬼者归也。
鬼神往来，都只是气。故曰鬼神者，二气之良能也。阳为天地之神，阴为天地之鬼，春夏为
岁候之神，秋冬为岁候之鬼；昼午为时日之神，暮夜为时日之鬼。推之于人，则仁义礼智，
君子之神；奸盗诈伪，小人之鬼。乐天知命，道德之神；阿谀谄容，势利之鬼。推之于医，则
神圣工巧，得其神也；凡庸浅陋，类乎鬼也。精进日新，志惟神也；苟且殃人，心犹鬼也。察
之形声，则坚凝深邃，形之神也；轻薄娇柔，形之鬼也。长洪圆亮，声之神也；短促轻微，声
之鬼也。诊之脉色，则绵长和缓，脉之神也；细急休囚，脉之鬼也。清苍明净，色之神也；浅
嫩灰颓，色之鬼也。是皆鬼神之征兆也。至若鬼神之原，尚有所谓。夫天地之鬼神，既不
能出天地之外；而人物之鬼神，又安能外乎人心？是以在天地则有天地之鬼神，在人物则
有人物之鬼神。善恶出之吾衷，良心自然难泯；强弱皆由阳气，神鬼判乎其中。以故多阳
多善者，神强而鬼灭；多阴多恶者，气戾而鬼生。然则神鬼从心，皆由我造；灵通变幻，匪在
我曾听孙真人说：“不懂《易经》，就不足以谈论高深的医学。”我对此一直心存疑惑。我认为，《易经》这部书，在于开启智慧、成就事务，预知未来、藏纳过往；而医学这门道术，则是调理元气、辅助造化，起死回生。它们的义理似乎不同，功用似乎各异。况且医学已有《内经》，何必借助于《易经》？舍近求远，为什么一定要这样呢？如今我已年过四十，茅塞稍开；学问到了知道羞耻的地步，才逐渐领悟。才知道天地之道，依靠阴阳二气来化育万物；人生的道理，依靠阴阳二气来滋养百骸。易，就是变易，具备阴阳动静的奥妙；医，就是意会，契合阴阳消长的机理。虽然阴阳的道理已在《内经》中备具，但变化没有比《周易》更大的了。所以说，天人一理，就是这个阴阳；医易同源，就是这个变化。难道不是医与易相通，道理没有两样，可以懂医学却不懂《易经》吗？我因此心领神会这番话，潜心研究多日，如管中窥豹所得的一得之见，不敢私藏，谨选取《易经》原理的精义，用来资助医学的变通，不顾自己浅陋而作此论述说：《易经》有太极，由此生出两仪（阴阳），两仪生出四象（少阳、太阳、少阴、太阴），四象生出八卦。天尊贵地卑贱，乾卦和坤卦的位置就确定了；卑高排列，贵贱的地位就确立了；动静有常规，刚柔就分辨清楚了；事物以类聚集，万物以群区分，吉凶就产生了；在天形成天象，在地形成地形，乾坤设立位置而《易》理就在其中运行了。所以天生神物（蓍草、龟甲），圣人效法它；天地变化，圣人模仿它；天垂示天象，显示吉凶，圣人模拟它；黄河出图，洛水出书，圣人取法它。于是就近取象于自身，远取象于万物，创作八卦以通达神明之德，以顺应性命之理。八卦排列成列，象就包含在其中了；因而重叠它们，爻就包含在其中了；刚柔相互摩擦，八卦相互激荡，变就包含在其中了；系上辞语并命名它，动就包含在其中了；吉凶悔吝产生于动，而天地鬼神作为德行，万物一体作为能力，森然显著而没有能逃避《易》理的。人生伟大，禀受阴阳五行之精，成为万物之灵；得到天地中和之气，参赞乾坤的化育；四象对应天，四肢对应地；天地的开合，就是人的呼吸；昼夜的潮汐，就是人的脉息；天的北辰是众动的根本，人的一心是全体的君主。由此看来，天的气，就是人的气；人的形体，就是天的形体。所以康节先生邵雍说：“思虑未起时，鬼神也不知道，如果不通过我，还能通过谁呢？”大概是指念头刚刚萌发，就通达于气，神随着气显现，便与天地鬼神相感通。既然这样，天人相交之际，真是精妙啊，确实令人敬畏；人身小天地，真是一点间隙都没有啊。现在天地之理具备于《易》，难道身心之理唯独不具备于《易》吗？况且天地之易，是外易；身心之易，是内易。内外哪个更亲近？天人哪个更近？所以必须从自身探求然后才能探求他人，先注重内在然后才能顾及外在；物理之易还可以暂缓，而身心之易不容忽视。医学这门道术，就是身心之易，医学如果不通晓《易》理，怎么能施行呢？然而易道无穷，而万生于一，一分化为二，二分为四，四分为八，八分为十六，从十六到三十二，三十二到六十四，以至三百八十四爻，一万一千五百二十策，而交感的奥妙，化生的机理，万物的数量，都从此出发了。详细来说，那个所谓的“一”，就是《易》中的太极。太极本无极，无极就是太极，形象数还没有形成时理已具备，这是万物所生的化源。所以说：“五行不到的地方，父母未生之前。”又说：“幽深渺茫之中，其中有精，这精非常真实，其中有信。”这是造物之初，因虚而化气，因气而造形，成为先天一气的祖始。医学如果明白这一点，就知道生生不息都有本源，那么凡是我身体在未形成之初，就可以据此知道它在父母那里肇基的情况，从而预先占测其禀受的征兆了。所谓“一分为二”，就是生出两仪。太极动而生阳，静而生阴；天生于动，地生于静；阳是阴的配偶，阴是阳的基础；从体来说叫天地，从用来说叫乾坤，从道来叫阴阳；一动一静，互为其根，分阴分阳，两仪就确立了。这是有形象的开始，因形以寄托气，因气以化神，成为后天体象的祖始。医学如果明白这一点，就知道阴阳气血都有汇聚之处，那么凡是我身体的形体气质，就可以据此知道它的纯杂偏正，从而默会其禀赋的刚柔了。所谓“二分为四”，就是两仪生四象。说动之始则阳生，动之极则阴生；静之始则柔生，静之极则刚生。太少阴阳，是天四象；太少刚柔，是地四体；耳目口鼻对应天，血气骨肉对应地。医学如果明白这一点，就知道阳中有阴，阴中有阳，那么凡是人的似阳非阳、似阴非阴的情况，就可以据此知道真假逆顺，从而察知互藏的幽显了。所谓“四分为八”，就是四象生八卦。说是干一、兑二、离三、震四、巽五、坎六、艮七、坤八。干，是健；坤，是顺；震，是动；巽，是入；坎，是陷；离，是附丽；艮，是止；兑，是悦。伏羲八卦，分阴阳的体象；文王八卦，明五行的精微。医学如果明白这一点，才知道阴阳之中，又有阴阳，刚柔之中，又有刚柔，而其对待的体貌，消息的机理，交感的奥妙，错综的意义，都已明显具备；那么凡是人的性理神机，形情病治，就可以据此得其纲领，从而融会贯通其变化的多了。从此四象相交，成十六事，八卦相荡，成六十四卦，分内外以配六爻，推九六以成蓍数，人物由之大成，万象因之而毕具。前看圆图，就是其中的精义，这个图虽然象征万物，尤其切近人的身体。所以说先天图，是环中；环中，是天的象。六十四卦列于外，昭示阴阳交变的道理；太极独运于其中，象征心是一身之主。干在南坤在北，象征首腹的上下；离在东坎在西，象征耳目的左右。自复卦至同人卦，位于内卦震离之地，为阴中少阳的十六卦，在人为二八岁；自临卦至乾卦，位于内卦兑乾之地，为阳中太阳的十六卦，在人为四八岁；自姤卦至师卦，位于内卦巽坎之地，为阳中少阴的十六卦，在人为六八岁；自遁卦至坤卦，位于内卦艮坤之地，为阴中太阴的十六卦，在人为八八岁。阳生于子时而极于午时，所以复卦叫天根，至乾卦共三十二卦，以应前半生；阴生于午时而极于子时，所以姤卦叫月窟，至坤卦共三十二卦，以应后半生。前半生始于复卦的一阳，渐次增添，至乾卦而阳盛已极，乃象征人从少年到壮年；后半生始于姤卦的一阴，渐次耗减，至坤卦而阳尽告终，乃象征人从衰老到死亡。纵观之，则象在初爻，乾尽于午，坤尽于子，当冬至夏至之时，为天地之中而左右判分。左主升而右主降，升则阳居东南，主春夏的发生，以应人的渐长；降则阴居西北，主秋冬的收敛，以应人的渐消。横观之，则象在二爻，离尽于卯，坎尽于酉，当春分秋分之中，为阴阳之半而上下分。上为阳而下为阴，阳则日出卯时，以应白昼为醒；阴则日入酉时，以应夜晚为睡。仅这一张图，而天人的奥妙，运气之理，无不具备。再看方图，其义象征地，乾始于西北，坤尽于东南。天不足西北，所以圆图的阳在东南；地不满东南，所以方图的刚在西北。这都是伏羲的卦。又如文王八卦，位置有所不同。伏羲出于自然之象，所以乾上坤下，离左坎右；文王合河图之数，所以火南水北，木东金西。（此节自方图以下并河洛数义，详方隅、气数二论。） 质之于人身，天地是形体，乾坤是性情，阴阳是气血，左右逢源，纤毫无间，详细探求其道，无往而不正确。所以从爻象来说，天地的道，以六为节制，三才各两，是为六爻，六奇六偶，是为十二。所以天有十二月，人有十二脏；天有十二时辰，人有十二经脉；天有十二辰，人有十二关节。懂得这些，营卫的周流，经络的表里，象就包含在其中了。从藏象来说，从初六至上六为阴为脏，初六对应命门，六二对应肾，六三对应肝，六四对应脾，六五对应心，上六对应肺；初九至上九为阳为腑，初九对应膀胱，九二对应大肠，九三对应小肠，九四对应胆，九五对应胃，上九对应三焦。懂得这些，脏腑的阴阳，内景的高下，象就包含在其中了。从形体来说，乾为首，阳尊居上；坤为腹，阴广容物；坎为耳，阳聪于内；离为目，阴明在外；兑为口，拆开于上；巽为股，两垂而下；艮为手，阳居于前；震为足，刚动在下。天不足西北，所以耳目的左边比右边明亮；地不满东南，所以手足的右边比左边强壮。懂得这些，人身的体用，象就包含在其中了。从生育来说，天地氤氲，万物化醇，男女媾精，万物化生。天尊地卑，乾父坤母，乾道成男，坤道成女，震坎艮是三男，巽离兑是三女。想知道子女的强弱，则震巽进而前，艮兑退而止；想辨别脉息候诊，则乾健在东南，坤顺向西北；想为繁衍后代谋划，则蓄坎填离宫，借兑为乾计；想明白布种方法，则天时与地利，盈亏果由气，冬至开始阳强，阴胜须回避。懂得这些，胎孕交感之道，就存在于其中了。从精神来说，北一水，是我的精，所以说肾藏精；南二火，是我的神，所以说心藏神；东三木，是我的魂，所以说肝藏魂；西四金，是我的魄，所以说肺藏魄；中五土，是我的意，所以说脾藏意。想知道魂魄的阴阳，须识精神有类似。木火同气，所以神魂藏于东南，而二八、三七同为十；金水同原，所以精魄藏于西北，而一九、四六同为十；土统四气，所以意独居中，其数惟五，而脏腑五行之象，存在于其中了。从动静来说。阳主乎动，阴主乎静；天圆而动，地方而静；静是动的根基，动是静的机理。刚柔推荡，是易的动静；阴阳升降，是气的动静；形气消长，是物的动静；昼夜起居，是身的动静。想详细探求动静，须精察阴阳，动极者镇之以静，阴亢者胜之以阳。治病脉药，须识动中有静；声色气味，当知柔里藏刚。知刚柔动静之精微，而医中运用之玄妙，思过半矣。从升降来说，阳主乎升，阴主乎降；升者是阳的生，降者是阴的死。所以日在子时，夜半方升，升则向生，海宇俱清；日在午时，午后为降，降则向死，万物皆鬼。死生之机，升降而已。想知道升降的要领，则宜降不宜升者，须防剥卦的再进；宜升不宜降者，当培复卦的始生。畏惧剥卦所从衰，须从观卦开始；寻求复卦的渐进，宜向临卦行进。这里有个关键，最在形情气味。想明消长之道，求于此而得之了。从神机来说，则存乎中者是神，发而中者是机；寂然不动者是神，感而遂通者是机；蕴之一心者是神，散之万殊者是机。懂得这些，则财原其始，直要其终，是我的神；挥邪如匠石之斤，忌器若郢人之鼻，是我的机。见可而进，知难而退，是我的神；疾徐如轮扁之手，轻重若庖丁之刀，是我的机。神之与机，互相倚伏。所以神有所主，机有所从；神有所决，机有所断；神为机之主，机为神之使。知神知机，执而运之，这就是医的神了。从屈伸来说，如寒往则暑来，昼往则夜来，壮往则衰来，正往则邪来。所以难易相成，是非相倾，刚柔相制，冰炭相刑。懂得这些，则微者是甚的基，盛者是衰的渐；大由小而成，远由近而遍。所以安不可以忘危，治不可以忘乱；积羽可以沉舟，群轻可以折轴。是小事不可轻，小人不可慢，而调和相济，以一成功之道，存在于其中了。从变化来说，物生谓之化，物极谓之变；阴可变为阳，阳可变为阴。只此一二，交感生成，气有不齐，物当其会，而变化的由来，所从出发了。所以阳始则温，阳极则热；阴始则凉，阴极则寒。温则生物，热则长物，凉则收物，寒则杀物，而变化的盛大，于此显著了。至于夷父羌母，蛮男苗女，子女肖形，虬髯短股；杏接桃，梨接李，果实必异常，多甘少苦。等到以阴孕阳，以柔孕刚，以小孕大，以圆孕方，以水孕火，以紫孕黄，以曲孕直，以短孕长。懂得这些，则可以调和甘苦，可以平调香臭，可以分经纬，可以调宫商，可以为蛇蝎，可以为鸾凰，可以为尧桀，可以为彭殇，庶几胸次化同大象，而应用可以无方了。从常变来说，则常易不易，是太极之理；变易常易，是造化之动。常易不变，而能应变；变易不常，靡不体常。是常者是易之体，变者是易之用；古今不易是易之体，随时变易是易之用；人心未动是常之体，物欲一生是变之用。由此推之，则属阴属阳者，是禀受之常；或寒或热者，是病生之变。素大素小者，是脉赋之常；忽浮忽沉者，是脉应之变。恒劳恒逸者，是居处之常；乍荣乍辱者，是盛衰之变。瘦肥无改者，是体貌之常；声色顿异者，是形容之变。常者易以知，变者应难识。所以以寒治热得其常，热因热用为何物？痛随利减得其常，塞因塞用为何物？检方疗病得其常，圆底方盖为何物？见病治病得其常，不治之治为何物？是以圣人仰观俯察，远求近取，体其常也；进德修业，因事制宜，通其变也。所以说，不通变，不足以知常；不知常，不足以通变。知常变之道的人，庶几免于依样画葫芦，而可与谈论医中之权变了。从鬼神来说，阳之灵曰神，神者伸也；阴之灵曰鬼，鬼者归也。鬼神往来，都只是气。所以说鬼神者，是二气的良能。阳为天地之神，阴为天地之鬼，春夏为岁候之神，秋冬为岁候之鬼；昼午为时日之神，暮夜为时日之鬼。推之于人，则仁义礼智，是君子之神；奸盗诈伪，是小人之鬼。乐天知命，是道德之神；阿谀谄容，是势利之鬼。推之于医，则神圣工巧，得其神也；凡庸浅陋，类乎鬼也。精进日新，志惟神也；苟且殃人，心犹鬼也。察之形声，则坚凝深邃，是形之神也；轻薄娇柔，是形之鬼也。长洪圆亮，是声之神也；短促轻微，是声之鬼也。诊之脉色，则绵长和缓，是脉之神也；细急休囚，是脉之鬼也。清苍明净，是色之神也；浅嫩灰颓，是色之鬼也。这些都是鬼神的征兆。至于鬼神的本源，尚有所谓。夫天地之鬼神，既不能出天地之外；而人物之鬼神，又安能外乎人心？所以在天地则有天地之鬼神，在人物则有人物之鬼神。善恶出于吾衷，良心自然难泯；强弱皆由阳气，神鬼判乎其中。所以多阳多善者，神强而鬼灭；多阴多恶者，气戾而鬼生。然而神鬼从心，皆由我造；灵通变幻，不在……
I once heard Master Sun (Sun Simiao) say: "One who does not understand the *Yi Jing* (Book of Changes) is not qualified to speak of the Great Physician." I often harbored doubts about this. I reasoned that the *Yi Jing*, as a book, aims to open up things and accomplish affairs, knowing the future and storing the past; whereas medicine, as a Dao, regulates the primal qi and assists in transformation, bringing the dead back to life. Their principles seem different, their applications seem distinct. Moreover, since medicine already has the *Nei Jing* (Inner Canon), why borrow from the *Yi Jing*? To abandon the near for the far, why must it be so? Now, having passed forty years of age, my mind has slightly opened; having learned to feel shame in my ignorance, I have gradually attained enlightenment. Thus, I came to know that the Dao of heaven and earth creates all things through the two qi of Yin and Yang; the principle of human life nourishes the hundred bones through the two qi of Yin and Yang. *Yi* means change; it possesses the wonder of Yin-Yang, movement, and stillness. Medicine means mental intention; it aligns with the mechanism of Yin-Yang waxing and waning. Although the principles of Yin and Yang are fully prepared in the *Nei Jing*, no changes are greater than those in the *Zhou Yi*. Therefore, it is said that Heaven and Man share one principle, which is this Yin and Yang; Medicine and *Yi* share the same origin, which is this transformation. Is it not true that Medicine and *Yi* are interconnected, with no difference in principle? How can one practice medicine without understanding the *Yi*? I secretly agreed with these words and devoted myself to study for many days. With insights gained from a narrow view, I dare not keep them to myself. I have carefully selected the essence of the *Yi* principles to aid the flexibility of medicine. Presuming upon my own shallowness, I offer this discussion: The *Yi* has the Supreme Ultimate (Taiji), which generates the Two Modes (Liangyi, i.e., Yin and Yang); the Two Modes generate the Four Images (Sixiang, i.e., Shao Yang, Tai Yang, Shao Yin, Tai Yin); the Four Images generate the Eight Trigrams (Bagua). Heaven is high and Earth is low, thus Qian (Heaven) and Kun (Earth) are established; when high and low are arranged, noble and base positions are set; movement and stillness have constants, thus Hard and Soft are distinguished; things gather by class, entities divide by group, thus Auspiciousness and Inauspiciousness arise; in Heaven images are formed, on Earth shapes are formed, Qian and Kun set their positions, and the *Yi* operates within them. Therefore, Heaven produces divine objects (divining grass and tortoise shells), and the Sage models himself after them; Heaven and Earth undergo changes, and the Sage imitates them; Heaven displays images showing auspiciousness and inauspiciousness, and the Sage represents them; the River produces the Map, the Luo produces the Book, and the Sage takes them as his model. Thus, taking examples nearby from the body and remotely from things, he created the Eight Trigrams to communicate the virtue of Spirit and Intelligence, and to conform to the principles of Life and Destiny. When the Eight Trigrams are arranged, Images are contained therein; when doubled, Yao lines are contained therein; when Hard and Soft rub against each other, and the Eight Trigrams clash, Change is contained therein; when statements are attached and names given, Movement is contained therein; Auspiciousness, Inauspiciousness, Regret, and Slight Blame arise from movement, while the virtue of Heaven, Earth, Spirits, and Ghosts, and the ability of all things to form one body, are manifest and clear, leaving nothing hidden from the *Yi*. Great is human life! Endowed with the essence of Yin and Wu Xing (Five Phases), humans are the spirit of all things; receiving the harmony of Heaven and Earth, they participate in the creative work of Qian and Kun. The Four Images correspond to Heaven, and the four limbs correspond to Earth. The opening and closing of Heaven and Earth are equivalent to human respiration; the tides of day and night are equivalent to human pulse and breath. The North Star of Heaven is the root of all movement, and the single Heart of man is the ruler of the whole body. From this perspective, the Qi of Heaven is the Qi of Man; the Body of Man is the Body of Heaven. Thus, Master Kangjie (Shao Yong) said: "When thoughts have not yet arisen, Spirits and Ghosts do not know; if not through me, then through whom?" This refers to the fact that as soon as a thought arises, it reaches the Qi; Spirit appears with Qi, and thus connects and resonates with Heaven, Earth, Spirits, and Ghosts. Therefore, the interaction between Heaven and Man is truly subtle and wonderful, indeed awe-inspiring; the human body is a small Heaven and Earth, with absolutely no gap. Now, the principles of Heaven and Earth are contained in the *Yi*; how could the principles of Mind and Body not be contained in the *Yi*? Moreover, the *Yi* of Heaven and Earth is External *Yi*; the *Yi* of Mind and Body is Internal *Yi*. Which is closer, internal or external? Which is nearer, Heaven or Man? Therefore, one must seek within oneself before seeking in others; prioritize the internal before attending to the external. The *Yi* of physical principles can be delayed, but the *Yi* of Mind and Body cannot be neglected. Medicine is the Dao of Mind and Body; if Medicine does not utilize the *Yi*, how can it be practiced? However, the Dao of *Yi* is infinite, yet all things originate from One. One divides into Two, Two into Four, Four into Eight, Eight into Sixteen, from Sixteen to Thirty-Two, Thirty-Two to Sixty-Four, up to three hundred and eighty-four Yao lines and eleven thousand five hundred and twenty calculating sticks. The wonders of interaction, the mechanisms of generation, and the numbers of all things all emerge from here. Specifically speaking, that so-called 'One' is the Taiji of the *Yi*. The Taiji originally was Wuji (Non-Limit); Wuji is Taiji. Before images and numbers took shape, principles were already present; this is the source of transformation for all things. Thus it is said: "Where the Five Phases do not reach, before parents were born." It is also said: "Dark and obscure, there is Essence; this Essence is very true, there is Trustworthiness." This is the beginning of creation, where Void transforms into Qi, and Qi forms Shape, becoming the ancestor of the Pre-Heaven One Qi. If Medicine understands this, it knows that continuous generation has its source. Then, regarding our bodies before formation, we can use this to know their foundation in parents and predict the signs of their endowment. The so-called 'One dividing into Two' is generating the Two Modes. Taiji moves to generate Yang, and is still to generate Yin; Heaven is born from movement, Earth from stillness; Yang is the companion of Yin, Yin is the foundation of Yang. Speaking of Substance, it is called Heaven and Earth; speaking of Function, it is called Qian and Kun; speaking of Principle, it is called Yin and Yang. One movement and one stillness, mutually serving as roots, dividing Yin and Yang, the Two Modes are established. This is the beginning of visible forms, where Form houses Qi, and Qi transforms into Spirit, becoming the ancestor of Post-Heaven physical manifestations. If Medicine understands this, it knows that Yin, Yang, Qi, and Blood all have their gathering points. Then, regarding the physical constitution and temperament of our bodies, we can use this to know their purity, impurity, bias, and correctness, and silently comprehend the hardness and softness of their endowments. The so-called 'Two dividing into Four' is the Two Modes generating the Four Images. It says: At the beginning of movement, Yang is born; at the extreme of movement, Yin is born; at the beginning of stillness, Softness is born; at the extreme of stillness, Hardness is born. Shao Yang, Tai Yang, Shao Yin, Tai Yin are the Four Images of Heaven; Shao Gang, Tai Gang, Shao Rou, Tai Rou are the Four Bodies of Earth. Ears, eyes, mouth, and nose correspond to Heaven; Blood, Qi, Flesh, and Bones correspond to Earth. If Medicine understands this, it knows that Yang contains Yin, and Yin contains Yang. Then, regarding people who appear Yang but are not Yang, or appear Yin but are not Yin, we can use this to know their truthfulness, falseness, reverse, and smooth conditions, and observe the hidden and manifest aspects of mutual containment. The so-called 'Four dividing into Eight' is the Four Images generating the Eight Trigrams. It refers to Qian 1, Dui 2, Li 3, Zhen 4, Xun 5, Kan 6, Gen 7, Kun 8. Qian is Strength; Kun is Compliance; Zhen is Movement; Xun is Penetration; Kan is Pitfall; Li is Clinging; Gen is Stillness; Dui is Joy. Fuxi's Bagua distinguishes the substance and image of Yin and Yang; King Wen's Bagua clarifies the subtleties of the Five Phases. If Medicine understands this, it realizes that within Yin and Yang, there is again Yin and Yang, and within Hard and Soft, there is again Hard and Soft. Their opposing substances, the mechanisms of waxing and waning, the wonders of interaction, and the meanings of complexity are clearly prepared. Then, regarding human nature, reason, spirit, machine, form, emotion, disease, and treatment, we can use this to grasp the outline and integrate their numerous changes. From here, the Four Images intersect to form sixteen matters, the Eight Trigrams clash to form sixty-four hexagrams. Dividing internal and external to match the six Yao lines, deducing Nine and Six to form the number of divining stalks, persons and things achieve great completion, and all phenomena are fully present. Previously viewing the Round Diagram, we see its essential meaning. Although this diagram symbolizes all existence, it is particularly relevant to the human body. Thus it is said: The Pre-Heaven Diagram is the center of the ring; the center of the ring is the image of Heaven. The sixty-four hexagrams are arranged outside, illuminating the principle of Yin-Yang interaction and change; the Taiji operates alone in the center, symbolizing the Heart as the master of the body. Qian in the South and Kun in the North symbolize the upper and lower parts of the head and abdomen; Li in the East and Kan in the West symbolize the left and right of the ears and eyes. From Fu Hexagram to Tong Ren Hexagram, located in the inner trigrams Zhen and Li, these are the sixteen hexagrams of Lesser Yang within Yin, corresponding to age sixteen (two eights) in humans. From Lin Hexagram to Qian Hexagram, located in the inner trigrams Dui and Qian, these are the sixteen hexagrams of Greater Yang within Yang, corresponding to age thirty-two (four eights) in humans. From Gou Hexagram to Shi Hexagram, located in the inner trigrams Xun and Kan, these are the sixteen hexagrams of Lesser Yin within Yang, corresponding to age forty-eight (six eights) in humans. From Dun Hexagram to Kun Hexagram, located in the inner trigrams Gen and Kun, these are the sixteen hexagrams of Greater Yin within Yin, corresponding to age sixty-four (eight eights) in humans. Yang is born at Zi hour and peaks at Wu hour; thus Fu is called the Root of Heaven. Up to Qian, there are thirty-two hexagrams, corresponding to the first half of life. Yin is born at Wu hour and peaks at Zi hour; thus Gou is called the Cave of the Moon. Up to Kun, there are thirty-two hexagrams, corresponding to the second half of life. The first half begins with the one Yang of Fu, gradually increasing until Qian, where Yang is extremely abundant, symbolizing human growth from youth to adulthood. The second half begins with the one Yin of Gou, gradually decreasing until Kun, where Yang is exhausted, symbolizing human decline from aging to death. Viewing longitudinally, the image is in the first Yao line. Qian ends at Wu, Kun ends at Zi, during the Solstices, representing the center of Heaven and Earth, with Left and Right distinguishing. The Left governs ascending, and the Right governs descending. Ascending places Yang in the Southeast, governing the generation of Spring and Summer, corresponding to gradual human growth. Descending places Yin in the Northwest, governing the harvesting of Autumn and Winter, corresponding to gradual human decline. Viewing horizontally, the image is in the second Yao line. Li ends at Mao, Kan ends at You, during the Equinoxes, representing half of Yin and Yang, with Upper and Lower dividing. The Upper is Yang and the Lower is Yin. Yang rises at Mao hour, corresponding to daytime wakefulness; Yin sets at You hour, corresponding to nighttime sleep. In this single diagram, the mysteries of Heaven and Man, and the principles of Luck and Qi, are all complete. Re-examining the Square Diagram, its meaning symbolizes Earth. Qian begins in the Northwest, Kun ends in the Southeast. Heaven is deficient in the Northwest, so the Yang of the Round Diagram is in the Southeast; Earth is incomplete in the Southeast, so the Hardness of the Square Diagram is in the Northwest. These are all Fuxi's hexagrams. Furthermore, King Wen's Bagua has different positions. Fuxi derived natural images, so Qian is above and Kun below, Li on the left and Kan on the right; King Wen combined the numbers of the He Tu, so Fire is South and Water North, Wood East and Metal West. (This section from the Square Diagram onwards and the meanings of He Lu numbers are detailed in the discussions on Directions and Qi Numbers.) Applying this to the human body, Heaven and Earth are the physical form, Qian and Kun are the temperament, Yin and Yang are the Qi and Blood. They meet their sources on both sides, with no gap whatsoever. Seeking their way in detail, there is nowhere they are not correct. Thus, speaking of Yao images, the Dao of Heaven and Earth uses six as the measure. Three Realities each doubled make six Yao lines; six odd and six even make twelve. Therefore, Heaven has twelve months, Man has twelve Zang organs; Heaven has twelve double-hours, Man has twelve Meridians; Heaven has twelve Earthly Branches, Man has twelve joints. Understanding this, the circulation of Ying and Wei Qi, and the interior-exterior relationship of meridians, are contained in the images. Speaking of Zang-Xiang (Viscera and Manifestations), from Chu Liu to Shang Liu are Yin and Zang organs. Chu Liu corresponds to the Mingmen (Gate of Life), Liu Er to Kidney, Liu San to Liver, Liu Si to Spleen, Liu Wu to Heart, Shang Liu to Lung. From Chu Jiu to Shang Jiu are Yang and Fu organs. Chu Jiu corresponds to Urinary Bladder, Jiu Er to Large Intestine, Jiu San to Small Intestine, Jiu Si to Gallbladder, Jiu Wu to Stomach, Shang Jiu to San Jiao (Triple Burner). Understanding this, the Yin-Yang of Zang-Fu organs, and the high-low arrangement of internal scenery, are contained in the images. Speaking of physical form, Qian is the Head, Yang honored residing above; Kun is the Abdomen, Yin broadly containing things; Kan is the Ear, Yang hearing internally; Li is the Eye, Yin seeing externally; Dui is the Mouth, opening upwards; Xun is the Thigh, hanging down in pairs; Gen is the Hand, Yang residing forward; Zhen is the Foot, Hard moving below. Heaven is deficient in the Northwest, so the brightness of ears and eyes is greater on the left than the right; Earth is incomplete in the Southeast, so the strength of hands and feet is greater on the right than the left. Understanding this, the substance and function of the human body are contained in the images. Speaking of reproduction, Heaven and Earth interact, and all things transform thoroughly; men and women unite their essences, and all things are generated. Heaven is high, Earth is low; Qian is Father, Kun is Mother. The Dao of Qian completes the Male, the Dao of Kun completes the Female. Zhen, Kan, Gen are the Three Males; Xun, Li, Dui are the Three Females. To know the strength of children, Zhen and Xun advance forward, Gen and Dui retreat and stop. To distinguish pulse diagnosis, Qian's Strength is in the Southeast, Kun's Compliance faces the Northwest. To plan for progeny, store Kan and fill Li's palace, borrowing Dui to calculate for Qian. To understand sowing methods, consider Heavenly Timing and Earthly Advantage;盈亏 (fullness and emptiness) depend on Qi; Yang strengthens starting from Winter Solstice, avoid when Yin prevails. Understanding this, the Dao of conception and interaction is contained within. Speaking of Spirit and Mind, North One Water is my Essence, hence Kidney stores Essence; South Two Fire is my Spirit, hence Heart stores Spirit; East Three Wood is my Soul, hence Liver stores Soul; West Four Metal is my Corporeal Soul, hence Lungs store Corporeal Soul; Center Five Earth is my Intention, hence Spleen stores Intention. To know the Yin-Yang of Soul and Corporeal Soul, one must recognize that Spirit and Mind have similarities. Wood and Fire share the same Qi, so Soul and Hun are stored in the Southeast, and 2x8 and 3x7 both equal ten; Metal and Water share the same origin, so Essence and Po are stored in the Northwest, and 1x9 and 4x6 both equal ten; Earth commands the Four Qi, so Intention alone resides in the center, its number being five, and the images of Zang-Fu and Five Phases are contained within. Speaking of Movement and Stillness: Yang governs Movement, Yin governs Stillness; Heaven is round and moves, Earth is square and still; Stillness is the foundation of Movement, Movement is the mechanism of Stillness. Hard and Soft pushing and swinging are the Movement and Stillness of Yi; Yin and Yang rising and falling are the Movement and Stillness of Qi; Form and Qi waxing and waning are the Movement and Stillness of Things; Day and Night waking and sleeping are the Movement and Stillness of the Body. To inquire in detail into Movement and Stillness, one must carefully observe Yin and Yang. Extreme Movement is stabilized by Stillness; Excessive Yin is overcome by Yang. In treating disease with pulse and herbs, one must recognize Stillness within Movement; in voice, color, smell, and taste, one must know Hardness hidden within Softness. Knowing the subtleties of Hard/Soft and Movement/Stillness, the mysteries of medical application are more than half understood. Speaking of Ascending and Descending: Yang governs Ascending, Yin governs Descending; Ascending is the birth of Yang, Descending is the death of Yin. Thus, when the sun is at Zi hour, it rises only at midnight; ascending leads to life, and the universe is clear. When the sun is at Wu hour, it descends after noon; descending leads to death, and all things become ghosts. The mechanism of life and death is merely Ascending and Descending. To know the key of Ascending and Descending, what should descend rather than ascend must guard against the progression of Bo (Peeling); what should ascend rather than descend should cultivate the initial birth of Fu (Return). Fearing the decline associated with Bo, one must start from Guan (Contemplation); seeking the gradual return of Fu, one should move towards Lin (Approach). There is a crucial point here, most lying in form, emotion, smell, and taste. To understand the Dao of Waxing and Waning, seek it here and find it. Speaking of Spirit Machine (Shen Ji): What resides in the center is Spirit (Shen); what emerges and hits the mark is Machine (Ji); What is silent and unmoving is Spirit; what responds and penetrates is Machine; What is gathered in one heart is Spirit; what scatters into myriad differences is Machine. Understanding this, tracing the origin to the beginning and aiming for the end is my Spirit; driving away evil like the craftsman Shi's axe, avoiding injury like the man of Ying's nose, is my Machine. Advancing when appropriate, retreating when difficult, is my Spirit; moving fast or slow like Lun Bian's hand, heavy or light like Cook Ding's knife, is my Machine. Spirit and Machine rely on each other. Thus, Spirit has its master, Machine has its follower; Spirit makes decisions, Machine executes them; Spirit is the master of Machine, Machine is the servant of Spirit. Knowing Spirit and Machine, grasping and operating them, this is the Spirit of Medicine. Speaking of Flexion and Extension: As Cold goes, Heat comes; as Day goes, Night comes; as Vigor goes, Decline comes; as Righteousness goes, Evil comes. Thus, Difficulty and Ease complement each other, Right and Wrong lean against each other, Hard and Soft constrain each other, Ice and Charcoal punish each other. Understanding this, the slight is the basis of the severe, the flourishing is the gradual decline; the large is formed from the small, the distant spreads from the near. Therefore, in safety, one must not forget danger; in order, one must not forget chaos; accumulating feathers can sink a boat, a pile of light weights can break an axle. Small matters must not be slighted, petty people must not be despised, and the way of harmonious assistance to achieve success lies within. Speaking of Change: The birth of things is called Hua (Transformation); the extremity of things is called Bian (Change); Yin can change to Yang, Yang can change to Yin. Just this one and two, interacting and generating, with Qi uneven, and things meeting their time, the source of change emerges. Thus, when Yang begins, it is Warm; when Yang peaks, it is Hot; when Yin begins, it is Cool; when Yin peaks, it is Cold. Warmth generates things, Heat grows things, Coolness gathers things, Cold kills things, and the greatness of change is manifested here. As for barbarian fathers and Qiang mothers, Man males and Miao females, children resembling forms, curly beards and short legs; grafting peach onto apricot, plum onto pear, fruits must be abnormal, mostly sweet and little bitter. Until Yin conceives Yang, Soft conceives Hard, Small conceives Large, Round conceives Square, Water conceives Fire, Purple conceives Yellow, Crooked conceives Straight, Short conceives Long. Understanding this, one can harmonize Bitter and Sweet, balance Fragrant and Foul, distinguish Warp and Weft, tune Gong and Shang, become a snake or scorpion, become a phoenix, become Yao or Jie, become Peng or Shang. Hopefully, the chest transforms into the Great Image, and application can be boundless. Speaking of Constant and Variable: The Constant Yi is Unchanging, the principle of Taiji; the Variable Yi is constantly changing, the movement of Creation. The Constant Yi does not change, yet can respond to change; the Variable Yi is not constant, yet embodies the Constant. Thus, the Constant is the Substance of Yi, the Variable is the Function of Yi; unchanging through ancient and modern times is the Substance of Yi, changing with the times is the Function of Yi; the unmoved human heart is the Substance of Constant, the arising of material desires is the Function of Variable. Deduced from this, belonging to Yin or Yang is the Constant of endowment; being Cold or Hot is the Variable of disease onset. Always large or always small is the Constant of pulse endowment; suddenly floating or sinking is the Variable of pulse response. Constant labor or rest is the Constant of dwelling; sudden glory or humiliation is the Variable of prosperity and decline. Unchanged thinness or fatness is the Constant of appearance; sudden difference in voice and color is the Variable of expression. The Constant is easy to know, the Variable is hard to recognize. Thus, treating Heat with Cold obtains the Constant; what is 'Treating Heat with Heat'? Pain relieved by benefit obtains the Constant; what is 'Treating Obstruction with Obstruction'? Checking prescriptions to treat disease obtains the Constant; what is 'Round bottom and square lid'? Seeing disease and treating disease obtains the Constant; what is 'Treating without treating'? Therefore, the Sage looks up and observes, seeks far and takes near, embodying the Constant; advancing virtue and cultivating business, adapting to circumstances, communicating with the Variable. Thus it is said: Without communicating with the Variable, one cannot know the Constant; without knowing the Constant, one cannot communicate with the Variable. Those who know the Dao of Constant and Variable will likely avoid copying gourds and can be spoken to regarding the flexibility of medicine. Speaking of Spirits and Ghosts: The spirit of Yang is called Shen (Spirit), Shen means extension; the spirit of Yin is called Gui (Ghost), Gui means return. The coming and going of Spirits and Ghosts are merely Qi. Thus it is said: Spirits and Ghosts are the good abilities of the two Qi. Yang is the Spirit of Heaven and Earth, Yin is the Ghost of Heaven and Earth; Spring and Summer are the Spirits of the yearly season, Autumn and Winter are the Ghosts of the yearly season; Noon is the Spirit of the day and time, Evening and Night are the Ghosts of the day and time. Extending to humans: Benevolence, Righteousness, Propriety, and Wisdom are the Spirits of the Gentleman; Treachery, Theft, Deceit, and Hypocrisy are the Ghosts of the Petty Man. Content with Heaven and knowing Destiny is the Spirit of Morality; Flattery and Sycophancy are the Ghosts of Power and Profit. Extending to medicine: Divine, Holy, Skillful, and Ingenious obtain its Spirit; Mediocre, Vulgar, Shallow, and Ignorant resemble Ghosts. Progressing daily and renewing, with will only in Spirit; being careless and harming others, with heart like Ghost. Observing form and sound: Firm, condensed, and profound is the Spirit of Form; light, thin, delicate, and soft is the Ghost of Form. Long, resonant, round, and bright is the Spirit of Sound; short, hurried, faint, and weak is the Ghost of Sound. Diagnosing pulse and color: Continuous, long, harmonious, and slow is the Spirit of Pulse; fine, rapid, resting, and imprisoned is the Ghost of Pulse. Clear, dark blue, bright, and clean is the Spirit of Color; pale, tender, gray, and decaying is the Ghost of Color. These are all omens of Spirits and Ghosts. As for the origin of Spirits and Ghosts, there is something more. The Spirits and Ghosts of Heaven and Earth cannot exist outside Heaven and Earth; and the Spirits and Ghosts of persons and things, how can they be outside the human mind? Therefore, in Heaven and Earth there are the Spirits and Ghosts of Heaven and Earth; in persons and things there are the Spirits and Ghosts of persons and things. Good and Evil come from our inner selves, conscience naturally hard to extinguish; Strength and Weakness all depend on Yang Qi, Spirits and Ghosts are judged within it. Thus, those with much Yang and much Good have strong Spirits and extinguished Ghosts; those with much Yin and much Evil have hostile Qi and generating Ghosts. However, Spirits and Ghosts follow the heart, all created by me; spiritual connection and transformation, not in...