（此图本附十八难后。今移置此）
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男子面南背阳向阴。如天之覆。离为阳 \r图\pt40a12.bmp\r 坎为阴北
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\r太阴少阴厥阴\pt40a14.bmp\r
南离为阴\r图\pt40a15.bmp\r 坎为阳 女子面北背阴向阳如地之仰
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二十难曰。经言脉有伏匿。伏匿于何脏而言伏匿耶。然。谓阴阳更相乘更相伏也。脉居阴部而反阳脉见者。为阳乘
阴也。
丁曰。其部非独言寸为阳尺为阴也。若以前后言之。即寸为阳部。尺为阴部。若以上下言之。曰肌肉上为阳部。肌
肉下为阴部。今阴虚不足。阳入乘之。故阴部见阳脉。其脉乘时见沉涩而短。（按此乘字疑衍。）此是阳中伏阴也。杨曰。
谓尺中浮滑而长。
脉虽时沉涩而短。此谓阳中伏阴也。脉居阳部而反阴脉见者。为阴乘阳也。
丁曰。寸口之内。肌肉之上。时见沉涩短也。杨曰。尺中已浮滑而长。又时时沉涩而短。故曰阳中伏阴。寸口关中
沉短而涩也。
脉虽时浮滑而长。此谓阴中伏阳也。
丁曰。寸口之内。肌肉之下。脉时见浮滑而长者。是阴中伏阳也。杨曰。寸关已沉短而涩。而时时浮滑而长。故曰
阴中伏阳也。
重阳者狂。重阴者癫。脱阳者见鬼。脱阴者目盲。
丁曰。重阳者狂。谓脉浮滑而长。加于实数。所以狂言大事。自高自贤。狂越弃衣。其脱阴者目盲。视物卒失。故
言盲也。盲、犹荒也。重阴者癫。癫者、蹶也。其脱阳者、视其暗中见鬼。是故经言重阳者狂。重阴者癫。脱阳者见鬼。
脱阴者目盲也。虞曰。寸口曰阳。又今重见阳脉三倍以上。故曰重阳。其病狂惑。自高贤智。登高而歌。弃衣而走。骂
詈不避亲疏。故曰狂。尺中曰阴。而尺脉重见阴。故曰重阴。其为病也。名曰癫疾。谓僵仆于地。闭目不醒。阴极阳复。
良久却醒。故曰癫也。今天吊之类是也。人之所禀者阴与阳。阴阳平则权衡等。今阴气已脱。阳气独盛。五脏属阴。五
脏行气血溉灌。上荣于目。今阴气已脱。五脏之气不荣于目。故目盲无所见。故曰脱阴者目盲也。杨曰。重阳者、阳气
并于上也。谓关以前既浮滑而长。兼实强。复喘数。是谓重阳也。重阴者、谓尺中既沉短而涩。而又盛实。是谓重阴。
脱阳者、无阳气也。谓关以前细微甚也。故目中妄见而睹鬼物焉。脱阴者、谓尺中微细甚也。阴者。精气也。精气脱故
盲。盲脱之言失也。谓亡失阴阳之气也。
二十一难曰。经言人形病脉不病曰生。脉病形不病曰死。何谓也。
丁曰。此者五脏各有所主也。肺主气心主脉。脾主肌肉。肝主筋。肾主骨。其心肺主息脉。为通天气。邪不可中。
邪中则息脉不相应。形虽不病。当知死矣。肾肝脾皆主其形。皆通地气。邪中则害其形。其脉不病者皆生。形脉皆病者
不可理。此是五脏各主其形脉。故言大法也。
然。人形病脉不病。非有不病者也。谓息数不应脉数也。此大法。
吕曰。形病者。谓五脏损形体羸瘦。气微。脉反迟。与息不相应。其脉不相应。为形病也。脉病者。谓数诸至。脉
已病。人虽未头痛寒热。方病不久病。病则死。虞曰。人形病脉不病者。谓形苦而志乐。或劳形于事以致肌体瘦羸。脉
息俱。呼吸大小虽合常经。息数必违此大法。故曰形病脉不病也。脉病患不病者。其人必外多眷慕。内结想思。脉病形
安。形乐志苦。以致伤。脉息反常。不及有余。乍迟乍数。及乎病而不死爰焉。故曰。脉病患不病也。
二十二难曰。经言脉有是动。
虞曰。言反常之动也。
有所生病。
虞曰。脉动反常。故云有所生病。
一脉辄变为二病者。何也。然。经言是动者气也。所生病者血也。
虞曰。气病传血。此乃一脉变为二病。
邪在气。气为是动。
虞曰。脉动反常。邪在气也。
邪在血。血为所生病。
虞曰。气受邪传之与血。故血为所生病。
气主 之。
虞曰。 之、气流行之貌也。
血主濡之。
丁曰。气主 之。 谓吹嘘往来之象。血主濡之。濡谓濡软也。气行则血行。气止则血止。虞曰。濡者、濡润之
貌。言人身所禀者气血也。气血通行。沮润人身。其为病也。乃如下说也。
气留而不行者。为气先病也。血壅而不濡者。为血后病也。故先为是动。后所生病也。
丁曰。人一身经脉。通行气血。或居一经脉中。气留不行。故血壅不濡。其气先病。名曰是动。血壅不濡后病。名
曰所生。此是一脉辄变为二病也。虞曰。上文言脉有是动。动为阳。谓气先受热。热亦传于血。气血皆受热。则津液妄
行。是知脉有是动。此言留而不行。谓气血津液妄行。贼风薄之。故不行也。气传之与血。故血壅而不濡润。复受贼风。
故血亦住而病也。杨曰。经言手太阴之脉。起于中焦。下络大肠。还循胃口。上膈属肺。从肺系横出腋下。循 内行。
少阴心主之。前下肘臂。内上骨下廉入寸口。上循鱼际。出大指之端。其支者。从腕后直出次指。内廉出其端。是动则
病肺胀满。膨膨而喘咳。故缺盆中痛甚。则交两手而瞀。是为臂厥。是主肺。所生病者。咳。上气喘。渴。心烦。胸满
。臂内前廉痛厥。掌中热气有余。则肩背痛也。（按灵枢经脉篇、背作臂。下同。）、汗出中风。小便数而欠。气虚则肩
背痛。寒少。气不足以息。溺色变。略举此一经为例。余经皆可知也。凡人所以得主命者。气与血也。气为阳。阳为卫。
血为阴。阴为荣。二气常流。所以无病也。邪中于阳。阳为气。故气先病。阳气在外故也。若在阳不治。则入于阴中。
阴为血。故为血后病。血在内故也。气实则热。气虚则寒。血实则为寒。血虚则为热。阴阳之道理其然也。凡一脏之病。
有虚有实。有寒有热。有内有外。皆须知脏腑之所在。识经络之流行。随其本原以求其疾。则病形可辨。而针药无失矣。
如其不委斯道。（今委字疑当作悉。）则虽命药投针。病难愈也。故黄帝曰。夫十二经脉者。所以调虚实。处百病。决生
死。不可不通哉。此之谓也。虞曰。凡人血流据气。气动根据血。凝留而不行。壅而不濡。是知为病也。
二十三难曰。手足三阴三阳脉之度数。可晓以不。然。手三阳之脉。从手至头长五尺。五六合三丈。
杨曰。一手有三阳。两手合为六阳。故曰。五六合三丈也。虞曰。手太阳之脉。自两手小指之端。循臂上行。之耳
珠子前。长五尺。两手合一丈。手阳明之脉。起于两手大指次指之侧。上循臂络于鼻左之右。右之左。长五尺。两手合
一丈。手少阳之脉。起于两手小指次指之端。上臂终于耳前。长五尺。两手合一丈。故曰。五六合三丈也。
手三阴之脉。从手至胸中。长三尺五寸。三六一丈八尺。五六三尺。合二丈一尺。
杨曰。两手各有三阴。合为六阴。故曰三六一丈八尺。虞曰。手太阴之脉。起于中焦。下络大肠。还循胃口。属肺。
出腋下。下肘入寸口。上鱼际。出乎大指之端。长三尺五寸。两手合七尺。手少阴之脉。起于心中。出属心系。下络小
肠。上肺出腋下。循臂出手小指之端。长三尺五寸。两手合七尺。手厥阴之脉。起于胸中。属心包络三焦。出胁腋下。
循入肘下。出小指次指之端。长三尺五寸。两手合长七尺。故曰二丈一尺。
足三阳之脉。从足至头。长八尺。六八四丈八尺。
杨曰。两足各有三阳。故曰六八四丈八尺也。按此脉度数。七尺五寸。中人之形。而云长八尺。理则难解。然足之
六阳。从足指而向上行。由其纡曲。故曰八尺也。虞曰。足太阳之脉。起于两足小指之侧。上循膝交 。中背上头。下
入目内 。长八尺。两足上行。合一丈六尺。足阳明之脉。起于足大指次指之端。循足胫。上挟脐左右各二寸。终于额
角发际。长八尺。两足合一丈六尺。足少阳之脉。起于足小指次指之端。上循两膝外廉。入季胁。上循目外 。长八尺。
两足合一丈六尺。故曰四丈八尺也。
足三阴之脉。从足至胸。长六尺五寸。六六三丈六尺。五六三尺。合三丈九尺。
杨曰。两足各有三阴。故曰六六三丈六尺也。按足太阴少阴。皆至舌下。足厥阴至于顶上。今言至胸中者。盖据其
相接之次也。虞曰。足太阴之脉。起于足大指内侧。循足胫内廉上。交出厥阴脉之前。上循入腹。属肝络胃。连舌本。
长七尺五寸。两行合长一丈五尺。足厥阴之脉。起于足大指聚毛之上。循足跗上廉去内踝一寸。上踝八寸。交出足太阴
之后。循股入阴毛。中环阴器抵少腹。挟胃。属肝。络胆。循喉咙。入颃颡。连目系。出额。长六尺五寸。两行合长一
丈三尺。足少阴之脉。起于足小指之下。斜趣足心。上 股内。贯脊。属肾。络膀胱。贯肝入肺。循喉咙挟舌本。长六
尺五寸。合长一丈三尺。故云三丈九尺。
人两足跷脉。从足至目。长七尺五寸。二七一丈四尺。二五一尺。合一丈五尺。
杨曰。人长七尺五寸。而跷脉从踝至目。不得有七尺五寸也。今经言七尺五寸者。是脚脉上于头而行焉。言至目者
举其纲维也。虞曰。人有阴跷阳跷二脉。两足合四脉。阳跷者、起于跟中。循外踝上行。入风池。阴跷者、亦起于跟中。
乃是足少阴之别络也。自然骨之后。上内踝之上。直上循阴股入阴。循腹（按原本误作股。根据二十八难注改正。）上胸里。
入缺盆。上出人迎之前。入 内廉。（按灵枢脉度篇。无内廉二字。）属目内 。合太阳脉。长七尺五寸。两行合一丈五
尺。准此推之。至目者、推尺是两足阴跷脉也。故经言从足至目。长七尺五寸。以合一丈五尺是也。
督脉。任脉。各长四尺五寸。二四八尺。二五一尺。合九尺。凡脉长一十六丈二尺。此所谓十二经脉长短之数也。
丁曰。此篇云十二经脉长短。又言阴跷从足至目。又言督任二脉。何独不言阳跷。阳跷亦起于跟中。循外踝上入风
池。亦长一丈五尺。言之则据经。丈尺有剩。不言有此阙漏。更俟后贤。其脉上云八尺者。其中庸之人。以省尺言之。
皆得四尺。今尺者、非黍尺也。皆以同身寸之为尺大小言之。皆八尺。杨曰。督脉起于脊KT 。上于头。下于面。至口
齿缝。计此不止长四尺五寸。今言四尺五寸者。当取其上极于风府而言之也。手足各十二脉（按原本各误合。根据史记正
义改。）为二十四脉。并督任两跷四部。合为二十八脉。以应二十八宿。凡长一十六丈二尺。荣卫行周此数。则为一度也。
故曰长短之数也。虞曰。经言督脉起于下极之俞。并于脊里。上至风府。入属于脑。长四尺五寸。任脉者。起于中极之
下。以上毛际。循复上关元。至咽喉。长四尺五寸。督任计之。长合九尺也。以上十二经。合二十四脉。合长一十三丈
八尺。兼之督任阴跷三脉。合长二丈四尺。共二十七脉。合长一十六丈二尺。以法三九之数。应漏水下二刻。杨氏言二
十八脉。乃阳跷亦系其数推之。二跷四行。则尺寸有余也。杨氏言二十八脉。误矣。
经脉十二。络脉十五。何始何穷也。然。经脉者。行血气。通阴阳。以荣于身者也。其始从中焦注手太阴阳明。阳
明注足阳明太阴。太阴注手少阴太阳。太阳注足太阳少阴。少阴注手心主少阳。少阳注足少阳厥阴。厥阴复还注手太阴。
别络十五。皆因其原。如环无端。转相溉灌。朝于寸口人迎。以处百病而决死生也。
丁曰。此者天地阴阳一岁终始于二十四气。日月晓昏。终始于二十四时。人之荣卫行经络二十四条。故复会于寸口
人迎。其言寸口者。手太阴脉口也。其穴名曰太渊。故脉会于太渊。其十二经十五络。皆辅三焦而生。故始从中焦注手
太阴阳明。所以处百病决死生也。杨曰。行手太阳讫。即注手阳明。行手阳明讫。即注足阳明。输转而行。余皆仿此也。
虞曰。其始从中焦者。谓直两乳间。名曰膻中穴。亦名气海。言气从此而起注太阴肺也。肺行讫。传之与手阳明也。素
问曰。膻中为臣使之官。谓胃化味为气。自此上传于肺也。杨曰。经脉十二。络脉十五。凡二十七气。以法三九之数。
天有九星。地有九州。人有九窍是也。其经络流行。皆朝会于寸口人迎。所以诊寸口人迎。则知其经络之病。死生之候
矣。虞曰。厥阴还注手太阴。如此推寻丈尺。则前后经义相违。离圣久远。难为粗述。
经曰。明知终始。阴阳定矣。何谓也。然。终始者、脉之纪也。寸口人迎阴阳之气通于朝。使如环无端，故曰始也。
杨曰。经脉流行。应于天之度数。周而复始。故曰如环无端也。
终者。三阴三阳之脉绝。绝则死。死各有形。故曰终也。
杨曰。阴阳气绝。其候亦见于寸口人迎。见则死矣。其死各有形诊。故曰终也。丁曰。所言三阴三阳之脉绝。绝则
死。死各有形。其义本经自解在二十四难中。
（此图原本附在第十八难之后。现在移置于此）
太阴、少阴、厥阴 [图片]
男子面南背阳向阴。如同天覆盖大地。离卦为阳 [图片] 坎卦为阴，位于北方
太阳、阳明、少阳 [图片]
太阴、少阴、厥阴 [图片]
南方离卦为阴 [图片] 坎卦为阳。女子面北背阴向阳，如同大地仰承天空
太阳、阳明、少阳 [图片]
第二难说：医经中说脉象有潜伏隐匿的情况。潜伏隐匿于哪个脏腑而言呢？回答说：这是指阴阳互相乘袭、互相潜伏。脉象处于阴部（尺部），却反而出现阳脉，这是阳邪乘袭阴位。
丁氏说：其部位不仅仅指寸为阳、尺为阴。如果以前后来划分，即寸为阳部，尺为阴部。如果以上下来划分，肌肉之上为阳部，肌肉之下为阴部。如今阴虚不足，阳气进入并乘袭它，所以在阴部见到阳脉。这种脉象有时表现为沉、涩、短。（按：此处“乘”字疑为衍文。）这叫做阳中伏阴。杨氏说：是指尺部脉浮滑而长。
脉虽然有时沉涩而短，这叫做阳中伏阴。脉象处于阳部（寸部），却反而出现阴脉，这是阴邪乘袭阳位。
丁氏说：在寸口之内，肌肉之上，时常见到沉、涩、短的脉象。杨氏说：尺部已经浮滑而长，又时时沉涩而短，所以叫阳中伏阴。寸关部沉短而涩。
脉虽然有时浮滑而长，这叫做阴中伏阳。
丁氏说：在寸口之内，肌肉之下，脉象时而见浮滑而长的，是阴中伏阳。杨氏说：寸关部已沉短而涩，而时时浮滑而长，所以叫阴中伏阳。
重阳则狂，重阴则癫。脱阳者见鬼，脱阴者目盲。
丁氏说：重阳则狂，是指脉象浮滑而长，加上实数，所以胡言乱语，自视甚高，狂妄越礼，弃衣奔走。其脱阴者目盲，视物突然丧失，所以说盲。盲，也就是荒废的意思。重阴则癫，癫就是蹶倒。其脱阳者，在暗处看见鬼怪。所以医经说重阳则狂，重阴则癫，脱阳者见鬼，脱阴者目盲。虞氏说：寸口称为阳。如今重见阳脉三倍以上，所以叫重阳。其病表现为狂惑，自视贤智，登高唱歌，弃衣奔走，骂詈不避亲疏，所以叫狂。尺中称为阴，而尺脉重见阴脉，所以叫重阴。其病名为癫疾，谓僵仆在地，闭目不醒。阴极阳复，很久才醒，所以叫癫。如今天吊之类的病就是如此。人所禀受的是阴与阳，阴阳平衡则权衡相等。如今阴气已脱，阳气独盛。五脏属阴，五脏运行气血以灌溉身体，上荣于目。如今阴气已脱，五脏之气不能荣养于目，所以目盲无所见，所以说脱阴者目盲。杨氏说：重阳，是阳气并于上部。指关前既浮滑而长，兼实强，又喘数，这叫重阳。重阴，指尺中既沉短而涩，而又盛实，这叫重阴。脱阳，是没有阳气。指关前脉细微至极。所以眼中妄见而睹鬼物。脱阴，指尺中脉微细至极。阴，是精气。精气脱失所以盲。盲和脱的意思是失去。指亡失阴阳之气。
第二十一难说：医经说人形体有病而脉象无病曰生，脉象有病而形体无病曰死。这是什么意思？
丁氏说：这是因为五脏各有所主。肺主气，心主脉，脾主肌肉，肝主筋，肾主骨。心肺主管呼吸和脉象，与天气相通，邪气不易侵入。邪气侵入则呼吸和脉象不相适应，形体虽无病，应当知道会死。肾、肝、脾都主管形体，与地气相通，邪气侵入则伤害形体。其脉象无病的都能生，形脉都有病的不可治疗。这是五脏各主其形脉，所以说是大法。
回答说：人形病脉不病，并非没有不病的情况，而是指呼吸次数与脉搏次数不相适应。这是大法。
吕氏说：形病，是指五脏受损，形体消瘦，气微弱，脉象反而迟，与呼吸不相适应。其脉象不相应，称为形病。脉病，是指脉象至数异常，脉已病，人虽然尚未头痛寒热，但不久将病，病则死。虞氏说：人形病脉不病，是指形体受苦而志意快乐，或因劳作导致肌体瘦弱，脉息俱平，呼吸大小虽合常经，但呼吸次数必违背此大法，所以说形病脉不病。脉病患不病，是指其人必定外多眷恋，内结相思，脉病形安，形乐志苦，以致受伤，脉息反常，不及或有余，忽迟忽数，等到发病而不死，所以说脉病患不病。
第二十二难说：医经说脉有是动。
虞氏说：指反常的变动。
有所生病。
虞氏说：脉动反常，所以说有所生病。
一脉辄变为二病，为什么呢？回答说：医经说“是动”是气病，“所生病”是血病。
虞氏说：气病传血，这就是一脉变为二病。
邪在气，气为是动。
虞氏说：脉动反常，邪在气。
邪在血，血为所生病。
虞氏说：气受邪传给血，所以血为所生病。
气主呴之。
虞氏说：呴，是气流行之貌。
血主濡之。
丁氏说：气主呴之。呴谓吹嘘往来之象。血主濡之。濡谓濡软也。气行则血行，气止则血止。虞氏说：濡，是濡润之貌。言人身所禀受的是气血。气血通行，滋润人身。其为病，乃如下所说：
气留而不行的，是气先病。血壅而不濡的，是血后病。所以先为是动，后为所生病。
丁氏说：人一身经脉，通行气血。或居一经脉中，气留不行，故血壅不濡。其气先病，名叫是动。血壅不濡后病，名叫所生。这是一脉辄变为二病。虞氏说：上文说脉有是动，动为阳，谓气先受热，热亦传于血，气血皆受热，则津液妄行。是知脉有是动，此言留而不行，谓气血津液妄行，贼风薄之，故不行也。气传之于血，故血壅而不濡润，复受贼风，故血亦住而病也。杨氏说：医经说手太阴之脉，起于中焦，下络大肠，还循胃口，上膈属肺，从肺系横出腋下，循臑内行，少阴心主之，前下肘臂，内上骨下廉入寸口，上循鱼际，出大指之端。其支者，从腕后直出次指内廉出其端。是动则病肺胀满，膨膨而喘咳，故缺盆中痛甚，则交两手而瞀，是为臂厥。是主肺所生病者，咳，上气喘，渴，心烦，胸满，臂内前廉痛厥，掌中热气有余，则肩背痛。（按《灵枢·经脉篇》背作臂，下同。）汗出中风，小便数而欠，气虚则肩背痛，寒少，气不足以息，溺色变。略举此一经为例，余经皆可知也。凡人所以得主命者，气与血也。气为阳，阳为卫；血为阴，阴为荣。二气常流，所以无病也。邪中于阳，阳为气，故气先病，阳气在外故也。若在阳不治，则入于阴中，阴为血，故为血后病，血在内故也。气实则热，气虚则寒；血实则为寒，血虚则为热。阴阳之道理其然也。凡一脏之病，有虚有实，有寒有热，有内有外，皆知脏腑之所在，识经络之流行，随其本原以求其疾，则病形可辨，而针药无失矣。如其不委斯道（今委字疑当作悉），则虽命药投针，病难愈也。故黄帝曰：夫十二经脉者，所以调虚实，处百病，决生死，不可不通哉。此之谓也。虞氏说：凡人血流据气，气动根据血，凝留而不行，壅而不濡，是知为病也。
第二十三难说：手足三阴三阳脉的长度，可以知晓吗？回答说：手三阳之脉，从手至头长五尺，五六合三丈。
杨氏说：一手有三阳，两手合为六阳，所以说五六合三丈。虞氏说：手太阳之脉，自两手小指之端，循臂上行，之耳珠子前，长五尺，两手合一丈。手阳明之脉，起于两手大指次指之侧，上循臂络于鼻左之右，右之左，长五尺，两手合一丈。手少阳之脉，起于两手小指次指之端，上臂终于耳前，长五尺，两手合一丈。所以说五六合三丈。
手三阴之脉，从手至胸中长三尺五寸，三六一丈八尺，五六三尺，合二丈一尺。
杨氏说：两手各有三阴，合为六阴，所以说三六一丈八尺。虞氏说：手太阴之脉，起于中焦，下络大肠，还循胃口，属肺，出腋下，下肘入寸口，上鱼际，出乎大指之端，长三尺五寸，两手合七尺。手少阴之脉，起于心中，出属心系，下络小肠，上肺出腋下，循臂出手小指之端，长三尺五寸，两手合七尺。手厥阴之脉，起于胸中，属心包络三焦，出胁腋下，循入肘下，出小指次指之端，长三尺五寸，两手合长七尺。所以说二丈一尺。
足三阳之脉，从足至头长八尺，六八四丈八尺。
杨氏说：两足各有三阳，所以说六八四丈八尺。按此脉度数，七尺五寸，是中人之形，而云长八尺，理则难解。然而足之六阳，从足指而向上行，由其纡曲，故曰八尺。虞氏说：足太阳之脉，起于两足小指之侧，上循膝交腨中背上头，下入目内眦，长八尺，两足上行，合一丈六尺。足阳明之脉，起于足大指次指之端，循足胫，上挟脐左右各二寸，终于额角发际，长八尺，两足合一丈六尺。足少阳之脉，起于足小指次指之端，上循两膝外廉，入季胁，上循目外眦，长八尺，两足合一丈六尺。所以说四丈八尺。
足三阴之脉，从足至胸长六尺五寸，六六三丈六尺，五六三尺，合三丈九尺。
杨氏说：两足各有三阴，所以说六六三丈六尺。按足太阴少阴，皆至舌下，足厥阴至于顶上，今言至胸中者，盖据其相接之次也。虞氏说：足太阴之脉，起于足大指内侧，循足胫内廉上，交出厥阴脉之前，上循入腹，属肝络胃，连舌本，长七尺五寸，两行合长一丈五尺。足厥阴之脉，起于足大指聚毛之上，循足跗上廉去内踝一寸，上踝八寸，交出足太阴之后，循股入阴毛，中环阴器抵少腹，挟胃，属肝，络胆，循喉咙，入颃颡，连目系，出额，长六尺五寸，两行合长一丈三尺。足少阴之脉，起于足小指之下，斜趣足心，上腨股内，贯脊，属肾，络膀胱，贯肝入肺，循喉咙挟舌本，长六尺五寸，合长一丈三尺。所以说三丈九尺。
人两足跷脉，从足至目长七尺五寸，二七一丈四尺，二五一尺，合一丈五尺。
杨氏说：人长七尺五寸，而跷脉从踝至目，不得有七尺五寸也。今经言七尺五寸者，是脚脉上于头而行焉，言至目者举其纲维也。虞氏说：人有阴跷阳跷二脉，两足合四脉。阳跷者，起于跟中，循外踝上行，入风池。阴跷者，亦起于跟中，乃是足少阴之别络也，自然骨之后，上内踝之上，直上循阴股入阴，循腹（按原本误作股，根据二十八难注改正。）上胸里，入缺盆，上出人迎之前，入目内廉（按《灵枢·脉度篇》无内廉二字。）属目内眦，合太阳脉，长七尺五寸，两行合一丈五尺。准此推之，至目者，推尺是两足阴跷脉也。故经言从足至目，长七尺五寸，以合一丈五尺是也。
督脉、任脉，各长四尺五寸，二四八尺，二五一尺，合九尺。凡脉长一十六丈二尺。此所谓十二经脉长短之数也。
丁氏说：此篇云十二经脉长短，又言阴跷从足至目，又言督任二脉，何独不言阳跷？阳跷亦起于跟中，循外踝上入风池，亦长一丈五尺。言之则据经，丈尺有剩，不言有此阙漏，更俟后贤。其脉上云八尺者，其中庸之人，以省尺言之，皆得四尺。今尺者，非黍尺也，皆以同身寸之为尺大小言之，皆八尺。杨氏说：督脉起于脊骶，上于头，下于面，至口齿缝，计此不止长四尺五寸。今言四尺五寸者，当取其上极于风府而言之也。手足各十二脉（按原本各误合，根据史记正义改。）为二十四脉，并督任两跷四部，合为二十八脉，以应二十八宿。凡长一十六丈二尺，营卫行周此数，则为一度也。故曰长短之数也。虞氏说：医经言督脉起于下极之俞，并于脊里，上至风府，入属于脑，长四尺五寸。任脉者，起于中极之下，以上毛际，循复上关元，至咽喉，长四尺五寸。督任计之，长合九尺也。以上十二经，合二十四脉，合长一十三丈八尺。兼之督任阴跷三脉，合长二丈四尺，共二十七脉，合长一十六丈二尺，以法三九之数，应漏水下二刻。杨氏言二十八脉，乃阳跷亦系其数推之，二跷四行，则尺寸有余也。杨氏言二十八脉，误矣。
经脉十二，络脉十五，何始何穷也？回答说：经脉者，行血气，通阴阳，以荣于身者也。其始从中焦注手太阴阳明，阳明注足阳明太阴，太阴注手少阴太阳，太阳注足太阳少阴，少阴注手心主少阳，少阳注足少阳厥阴，厥阴复还注手太阴。别络十五，皆因其原，如环无端，转相溉灌，朝于寸口人迎，以处百病而决死生也。
丁氏说：此者天地阴阳一岁终始于二十四气，日月晓昏，终始于二十四时。人之营卫行经络二十四条，故复会于寸口人迎。其言寸口者，手太阴脉口也。其穴名曰太渊，故脉会于太渊。其十二经十五络，皆辅三焦而生，故始从中焦注手太阴阳明，所以处百病决死生也。杨氏说：行手太阳讫，即注手阳明。行手阳明讫，即注足阳明。输转而行，余皆仿此也。虞氏说：其始从中焦者，谓直两乳间，名曰膻中穴，亦名气海，言气从此而起注太阴肺也。肺行讫，传之与手阳明也。《素问》曰：膻中为臣使之官，谓胃化味为气，自此上传于肺也。杨氏说：经脉十二，络脉十五，凡二十七气，以法三九之数，天有九星，地有九州，人有九窍是也。其经络流行，皆朝会于寸口人迎，所以诊寸口人迎，则知其经络之病，死生之候矣。虞氏说：厥阴还注手太阴，如此推寻丈尺，则前后经义相违，离圣久远，难为粗述。
医经说：明知终始，阴阳定矣。这是什么意思？回答说：终始者，脉之纪也。寸口人迎阴阳之气通于朝，使如环无端，故曰始也。
杨氏说：经脉流行，应于天之度数，周而复始，故曰如环无端也。
终者，三阴三阳之脉绝，绝则死，死各有形，故曰终也。
杨氏说：阴阳气绝，其候亦见于寸口人迎，见则死矣。其死各有形诊，故曰终也。丁氏说：所言三阴三阳之脉绝，绝则死，死各有形，其义本经自解在二十四难中。
(This diagram originally followed the Eighteenth Difficulty. It is now moved here.)
Taiyin, Shaoyin, Jueyin [Image]
For men, facing south with the back to yang and front to yin. Like heaven covering the earth. Li trigram represents Yang [Image] Kan trigram represents Yin, located in the North.
Taiyang, Yangming, Shaoyang [Image]
Taiyin, Shaoyin, Jueyin [Image]
South Li trigram represents Yin [Image] Kan trigram represents Yang. For women, facing north with the back to yin and front to yang, like earth receiving heaven.
Taiyang, Yangming, Shaoyang [Image]
The Nineteenth Difficulty states: The classic texts mention that pulses may be hidden or latent. Hidden or latent in which zang-fu organ does this refer? The answer is: This refers to yin and yang mutually overacting (Cheng) and mutually hiding. When a pulse is located in the yin portion (Chi position) but instead shows a yang pulse, this is called Yang overacting on Yin.
Ding says: The term "portion" does not solely refer to Cun as Yang and Chi as Yin. If speaking of anterior and posterior, then Cun is the Yang portion and Chi is the Yin portion. If speaking of superior and inferior, the area above muscle is the Yang portion, and below muscle is the Yin portion. Now, due to Yin deficiency and insufficiency, Yang enters and overacts upon it. Therefore, a yang pulse is seen in the yin portion. The pulse may occasionally appear deep (Chen), choppy (Se), and short (Duan). (Note: The character "Cheng" here is suspected to be an interpolation.) This is called "Yang containing hidden Yin." Yang says: This refers to the Chi pulse being floating (Fu), slippery (Hua), and long (Chang).
Although the pulse is occasionally deep, choppy, and short, this is called "Yang containing hidden Yin." When a pulse is located in the yang portion (Cun position) but instead shows a yin pulse, this is called Yin overacting on Yang.
Ding says: Within the Cun Kou, above the muscle, one occasionally sees deep, choppy, and short pulses. Yang says: The Chi pulse is already floating, slippery, and long, yet also occasionally deep, choppy, and short; hence it is called "Yang containing hidden Yin." The Cun and Guan positions are deep, short, and choppy.
Although the pulse is occasionally floating, slippery, and long, this is called "Yin containing hidden Yang."
Ding says: Within the Cun Kou, below the muscle, when the pulse occasionally appears floating, slippery, and long, this is "Yin containing hidden Yang." Yang says: The Cun and Guan positions are already deep, short, and choppy, yet occasionally floating, slippery, and long; hence it is called "Yin containing hidden Yang."
Extreme Yang leads to mania (Kuang); Extreme Yin leads to epilepsy (Dian). Loss of Yang leads to seeing ghosts; Loss of Yin leads to blindness.
Ding says: Extreme Yang leads to mania, meaning the pulse is floating, slippery, and long, compounded by excess and rapidity. Thus, the patient speaks nonsense, considers themselves superior, acts wildly, discards clothes, and runs about. In cases of loss of Yin leading to blindness, vision is suddenly lost, hence the term "blind." Blind implies desolation. Extreme Yin leads to epilepsy; Dian means falling into convulsions. In cases of loss of Yang, the patient sees ghosts in the dark. Thus, the classics state: Extreme Yang leads to mania, Extreme Yin leads to epilepsy, Loss of Yang leads to seeing ghosts, and Loss of Yin leads to blindness. Yu says: Cun Kou is referred to as Yang. Now, if yang pulses are seen more than three times excessively, it is called "Extreme Yang." The disease manifests as madness, considering oneself wise and virtuous, singing while climbing high, discarding clothes and running, cursing without distinguishing relatives from strangers; thus it is called mania. Chi is referred to as Yin. If yin pulses are excessively repeated at Chi, it is called "Extreme Yin." The disease is named epilepsy (Dian Ji), characterized by stiffening and falling to the ground, eyes closed and unconscious. After extreme yin reaches its limit and yang recovers, consciousness returns after a long time; thus it is called epilepsy. Diseases like Tian Diao today are examples. Humans are endowed with Yin and Yang. When Yin and Yang are balanced, scales are equal. Now, if Yin Qi has departed, Yang Qi stands alone and excessive. The Five Zang organs belong to Yin; they circulate Qi and Blood to irrigate the body and nourish the eyes from above. Now, since Yin Qi has departed, the Qi of the Five Zang cannot nourish the eyes. Hence, blindness occurs with no sight; therefore, "Loss of Yin leads to blindness." Yang says: Extreme Yang means Yang Qi merges into the upper part. Referring to the area before Guan, where the pulse is floating, slippery, and long, combined with excess strength and panting rapidity, this is called Extreme Yang. Extreme Yin means the Chi pulse is deep, short, and choppy, yet also full and solid; this is called Extreme Yin. Loss of Yang means the absence of Yang Qi. Referring to the area before Guan, where the pulse is extremely fine and minute. Thus, the eyes see hallucinations and ghostly objects. Loss of Yin means the Chi pulse is extremely fine and minute. Yin refers to Essence and Qi. Since Essence and Qi are lost, blindness results. The terms blind and loss imply deprivation. It refers to the loss of Yin and Yang Qi.
The Twenty-First Difficulty states: The classic texts say that if the physical form is diseased but the pulse is healthy, the prognosis is survival; if the pulse is diseased but the physical form is healthy, the prognosis is death. What does this mean?
Ding says: This is because each of the Five Zang organs has its specific dominion. Lung governs Qi, Heart governs Pulse, Spleen governs Muscle, Liver governs Sinew, and Kidney governs Bone. Heart and Lung govern respiration and pulse, connecting with Heavenly Qi; pathogenic factors do not easily invade them. If pathogens invade, respiration and pulse become unresponsive. Although the form shows no disease, death should be anticipated. Kidney, Liver, and Spleen all govern the form and connect with Earthly Qi. If pathogens invade, they harm the form. If the pulse remains healthy, survival is possible; if both form and pulse are diseased, treatment is futile. This illustrates that each Zang governs its respective form and pulse, hence it is stated as a general principle.
The response is: "Physical form diseased, pulse healthy" does not mean there is absolutely no health issue, but rather that the respiratory rate does not correspond to the pulse rate. This is a general principle.
Lu says: "Form disease" refers to damage to the Five Zang organs, emaciation of the body, weak Qi, and a pulse that is unexpectedly slow, inconsistent with respiration. This inconsistency in pulse relative to form is called "form disease." "Pulse disease" refers to abnormal pulse frequency. The pulse is diseased, although the person has not yet experienced headache or fever/chills, they will soon fall ill, and if illness sets in, death will follow. Yu says: "Physical form diseased, pulse healthy" refers to a situation where the body suffers but the mind is content, or where labor causes emaciation. The pulse and respiration are harmonious, and breathing size conforms to normal standards, yet the respiratory count violates this general principle; hence it is called "form diseased, pulse healthy." "Pulse diseased, form healthy" refers to a person who is externally attached to desires and internally burdened by longing. The pulse is diseased while the form is safe. The body is comfortable but the mind is distressed, leading to injury. The pulse and respiration become abnormal, either deficient or excessive, sometimes slow, sometimes rapid. When the disease eventually manifests without immediate death, it is called "pulse diseased, form healthy."
The Twenty-Second Difficulty states: The classic texts mention that pulses have "Shi Dong" (Is Moving).
Yu says: This refers to abnormal movement.
And "You Suo Sheng Bing" (What is Produced).
Yu says: Because the pulse moves abnormally, it is said to produce diseases.
Why does one meridian transform into two types of disease? The answer is: The classic texts state that "Shi Dong" refers to Qi disease, and "You Suo Sheng Bing" refers to Blood disease.
Yu says: Qi disease transmitting to Blood is why one meridian transforms into two diseases.
Pathogens in Qi make Qi "Shi Dong."
Yu says: Abnormal pulse movement indicates pathogens in Qi.
Pathogens in Blood make Blood "You Suo Sheng Bing."
Yu says: Qi receives pathogens and transmits them to Blood; thus Blood becomes "You Suo Sheng Bing."
Qi primarily warms (Xu) it.
Yu says: Xu describes the flowing nature of Qi.
Blood primarily moistens (Ru) it.
Ding says: Qi primarily warms (Xu). Xu refers to the image of blowing and往来 (coming and going). Blood primarily moistens (Ru). Ru refers to softness and moisture. When Qi moves, Blood moves; when Qi stops, Blood stops. Yu says: Ru refers to the appearance of moistening. It means that what humans are endowed with is Qi and Blood. Qi and Blood circulate, moisturizing the human body. Their pathology is described as follows:
When Qi stagnates and fails to move, it is Qi disease occurring first. When Blood is obstructed and fails to moisten, it is Blood disease occurring later. Therefore, first comes "Shi Dong," followed by "You Suo Sheng Bing."
Ding says: The meridians throughout the body circulate Qi and Blood. If Qi stagnates within one meridian and fails to move, Blood becomes obstructed and fails to moisten. The Qi disease occurs first, named "Shi Dong." The Blood obstruction and lack of moisture occur later, named "You Suo Sheng Bing." This is how one meridian transforms into two diseases. Yu says: The previous text mentioned pulse "Shi Dong." Movement is Yang, implying Qi first heats up, and heat transmits to Blood. Both Qi and Blood receive heat, causing fluids to flow recklessly. Knowing this, pulse "Shi Dong" refers to stagnation and failure to move. It implies that Qi, Blood, and fluids flow recklessly, attacked by evil wind, thus failing to move. Qi transmits to Blood, so Blood becomes obstructed and fails to moisten. Repeated attack by evil wind causes Blood to stop and become diseased. Yang says: The classic texts state that the Hand Taiyin Meridian originates in the Middle Jiao, descends to connect with the Large Intestine, returns along the stomach opening, ascends through the diaphragm to belong to the Lung. From the lung system, it emerges horizontally under the armpit, follows the interior of the arm, passes the Shaoyin and Pericardium meridians, descends anterior to the elbow and forearm, enters the Cun Kou above the radial styloid process, ascends along the Thenar eminence, and exits at the tip of the thumb. Its branch goes straight from behind the wrist to the tip of the index finger, emerging at its inner side. "Shi Dong" causes lung distension, fullness, wheezing, and coughing. Severe pain in the supraclavicular fossa causes crossing of hands and dizziness, known as Arm Jue. This meridian governs Lung diseases. "You Suo Sheng Bing" includes cough, asthma, thirst, heart vexation, chest fullness, pain and coldness in the anterior medial aspect of the arm, excess heat in the palm, and shoulder/back pain. (Note: In *Ling Shu · Jing Mai*, "back" is written as "arm".) Sweating with wind-stroke, frequent urination with scantiness, Qi deficiency causing shoulder/back pain, slight chills, insufficient breath, and changes in urine color. Taking this one meridian as an example, others can be understood similarly. Humans derive life from Qi and Blood. Qi is Yang, Yang is Wei (Defensive); Blood is Yin, Yin is Ying (Nutritive). These two energies flow constantly, preventing disease. Pathogens strike Yang; Yang is Qi, so Qi disease occurs first because Yang Qi is external. If untreated in Yang, it enters Yin; Yin is Blood, so Blood disease occurs later because Blood is internal. Excess Qi leads to heat, deficiency of Qi leads to cold; excess Blood leads to cold, deficiency of Blood leads to heat. This is the principle of Yin and Yang. Any disease of a Zang organ involves deficiency or excess, cold or heat, internal or external. One must know the location of the Zang organs, understand the circulation of the meridians, and seek the origin of the disease to distinguish its form, ensuring acupuncture and herbal medicine are not mistaken. If one does not fully comprehend this way (the character "Wei" is suspected to be "Xi"), even prescribing herbs and applying needles, the disease will be difficult to cure. Thus, the Yellow Emperor said: The twelve meridians regulate deficiency and excess, treat hundreds of diseases, and determine life and death; they must not be left unexamined. This is what is meant. Yu says: Human blood flow relies on Qi; Qi movement depends on Blood. Stagnation and failure to move, obstruction and failure to moisten indicate disease.
The Twenty-Third Difficulty states: Can the lengths of the Three Yin and Three Yang meridians of the hands and feet be explained? The answer is: The Hand Three Yang meridians extend from hand to head, measuring five chi. Six times five equals three Zhang.
Yang says: Each hand has three Yang meridians; two hands total six Yang meridians. Hence, six times five equals three Zhang. Yu says: The Hand Taiyang Meridian starts from the tips of the little fingers of both hands, follows the arm upward to the front of the ear珠 (Zhu), measuring five chi per hand, totaling one Zhang for both hands. The Hand Yangming Meridian originates from the sides of the index and middle fingers of both hands, ascends along the arm, connects to the nose crossing from left to right and right to left, measuring five chi per hand, totaling one Zhang for both hands. The Hand Shaoyang Meridian originates from the tips of the ring and little fingers of both hands, ascends the arm ending in front of the ear, measuring five chi per hand, totaling one Zhang for both hands. Hence, six times five equals three Zhang.
The Hand Three Yin meridians extend from hand to chest, measuring three chi and five cun. Three times six equals one Zhang and eight chi; five times six equals three chi; totaling two Zhang and one chi.
Yang says: Each hand has three Yin meridians; two hands total six Yin meridians. Hence, three times six equals one Zhang and eight chi. Yu says: The Hand Taiyin Meridian originates in the Middle Jiao, descends to connect with the Large Intestine, returns along the stomach opening, belongs to the Lung, emerges under the armpit, descends the elbow into the Cun Kou, ascends to the Thenar eminence, and exits at the tip of the thumb, measuring three chi and five cun per hand, totaling seven chi for both hands. The Hand Shaoyin Meridian originates in the Heart, emerges belonging to the Heart system, descends to connect with the Small Intestine, ascends to the Lung, emerges under the armpit, follows the arm exiting at the tip of the little finger, measuring three chi and five cun per hand, totaling seven chi for both hands. The Hand Jueyin Meridian originates in the Chest, belongs to the Pericardium and San Jiao, emerges from the hypochondrium and underarm, follows into the elbow, exits at the tip of the ring finger, measuring three chi and five cun per hand, totaling seven chi for both hands. Hence, two Zhang and one chi.
The Foot Three Yang meridians extend from foot to head, measuring eight chi. Six times eight equals four Zhang and eight chi.
Yang says: Each foot has three Yang meridians; hence six times eight equals four Zhang and eight chi. Note: Regarding these measurements, a medium-sized person is seven chi five cun tall, yet the text says eight chi, which is hard to explain logically. However, the six Yang meridians of the feet ascend from the toes via winding paths, hence stated as eight chi. Yu says: The Foot Taiyang Meridian originates from the sides of the little toes of both feet, ascends along the knees, crosses the calf muscles, goes up the back to the head, and descends into the inner canthus of the eye, measuring eight chi per leg, totaling one Zhang and six chi for both legs. The Foot Yangming Meridian originates from the tips of the second toes of both feet, follows the lower leg, ascends flanking the navel two cun on each side, ending at the hairline of the forehead, measuring eight chi per leg, totaling one Zhang and six chi for both legs. The Foot Shaoyang Meridian originates from the tips of the fourth toes of both feet, ascends along the lateral aspects of both knees, enters the costal region, ascends along the outer canthus of the eye, measuring eight chi per leg, totaling one Zhang and six chi for both legs. Hence, four Zhang and eight chi.
The Foot Three Yin meridians extend from foot to chest, measuring six chi and five cun. Six times six equals three Zhang and six chi; five times six equals three chi; totaling three Zhang and nine chi.
Yang says: Each foot has three Yin meridians; hence six times six equals three Zhang and six chi. Note: Foot Taiyin and Shaoyin both reach under the tongue, and Foot Jueyin reaches the vertex. The statement "reaching the chest" likely refers to their connection sequence. Yu says: The Foot Taiyin Meridian originates from the medial side of the big toe, follows the medial aspect of the lower leg upward, crosses anterior to the Jueyin meridian, ascends into the abdomen, belongs to the Liver and connects with the Stomach, connects to the root of the tongue, measuring seven chi and five cun per leg, totaling one Zhang and five chi for both legs. The Foot Jueyin Meridian originates above the pubic hair on the big toe, follows the medial aspect of the dorsum of the foot one cun from the medial malleolus, ascends eight cun above the ankle, crosses posterior to the Foot Taiyin, follows the thigh into the pubic hair, circles around the genitalia to reach the lower abdomen, flanks the Stomach, belongs to the Liver and connects with the Gallbladder, follows the throat, enters the pharynx, connects to the eye system, emerges at the forehead, measuring six chi and five cun per leg, totaling one Zhang and three chi for both legs. The Foot Shaoyin Meridian originates below the little toe,斜趣slopes toward the sole of the foot, ascends the medial calf, pierces the spine, belongs to the Kidney and connects with the Bladder, pierces the Liver and enters the Lung, follows the throat flanking the root of the tongue, measuring six chi and five cun per leg, totaling one Zhang and three chi for both legs. Hence, three Zhang and nine chi.
The two Foot Qiao meridians in humans extend from foot to eye, measuring seven chi and five cun. Two times seven equals one Zhang and four chi; two times five equals one chi; totaling one Zhang and five chi.
Yang says: A human is seven chi five cun tall, yet the Qiao meridian extends from the ankle to the eye; it cannot measure seven chi five cun. The text stating seven chi five cun implies the foot meridians ascend to the head, and "to the eye" highlights the main framework. Yu says: Humans have Yin Qiao and Yang Qiao meridians; two feet total four meridians. Yang Qiao originates in the heel, follows the lateral malleolus upward, entering Fengchi. Yin Qiao also originates in the heel, being a branch of the Foot Shaoyin. Behind the natural bone, above the medial malleolus, it ascends straight along the medial thigh into the yin region, follows the abdomen (Note: Original text mistakenly wrote thigh; corrected according to Twenty-Eighth Difficulty commentary) up to the chest interior, enters the Clavicle hollow (Que Pen), ascends anterior to Renying, enters the inner canthus (Note: *Ling Shu · Mai Du* lacks "inner canthus"), belongs to the inner canthus, combines with the Taiyang meridian, measuring seven chi and five cun, totaling one Zhang and five chi for both legs. Deduced from this, "to the eye" refers to the measurement of the two Yin Qiao meridians of the feet. Hence, the text states "from foot to eye, measuring seven chi five cun, totaling one Zhang and five chi."
The Du Mai (Governor Vessel) and Ren Mai (Conception Vessel) each measure four chi and five cun. Two times four equals eight chi; two times five equals one chi; totaling nine chi. The total length of all meridians is sixteen Zhang and two chi. This is the number of lengths of the twelve primary meridians.
Ding says: This chapter mentions the lengths of the twelve meridians, also mentions Yin Qiao from foot to eye, and Du and Ren vessels. Why is Yang Qiao not mentioned? Yang Qiao also originates in the heel, follows the lateral malleolus upward to Fengchi, also measuring one Zhang and five chi. Mentioning it would align with the classics, but the measurements exceed the total. Not mentioning it leaves a gap, awaiting future scholars. The "eight chi" mentioned for meridians refers to average people using provincial chi, all getting four chi. The current "chi" is not the millet grain chi, but based on "same-body inch" scaled to chi, all measuring eight chi. Yang says: The Du Mai originates from the sacrum, ascends to the head, descends to the face, reaching the teeth gap. Calculated this way, it exceeds four chi five cun. The statement of four chi five cun likely refers to its upper limit at Fengfu. The twelve meridians of hands and feet (Note: Original text mistakenly wrote "combined"; corrected according to *Shiji* commentary) total twenty-four meridians. Combined with Du, Ren, and the two Qiao meridians (four branches), they total twenty-eight meridians, corresponding to the twenty-eight lunar mansions. Total length sixteen Zhang and two chi. When Ying and Wei circulate this distance, it constitutes one cycle. Hence, it is called the number of lengths. Yu says: The classics state Du Mai originates from the lower extremity acupoint, runs parallel in the spinal column, ascends to Fengfu, and enters the brain, measuring four chi five cun. Ren Mai originates below Zhongji, ascends past the pubic hair, follows up to Guanyuan, reaching the throat, measuring four chi five cun. Du and Ren together total nine chi. The aforementioned twelve meridians total twenty-four meridians, combining to thirteen Zhang and eight chi. Adding Du, Ren, and Yin Qiao (three meridians), totaling two Zhang and four chi, makes twenty-seven meridians, combining to sixteen Zhang and two chi, conforming to the number of three times nine, corresponding to two ke of water clock drainage. Yang states twenty-eight meridians, deducing Yang Qiao into the count. Two Qiao meridians, four branches, result in excess measurements. Yang's statement of twenty-eight meridians is erroneous.
There are twelve meridians and fifteen collaterals. Where do they begin and end? The answer is: Meridians circulate Qi and Blood, connect Yin and Yang, and nourish the body. They begin at the Middle Jiao, flowing to Hand Taiyin and Yangming. Yangming flows to Foot Yangming and Taiyin. Taiyin flows to Hand Shaoyin and Taiyang. Taiyang flows to Foot Taiyang and Shaoyin. Shaoyin flows to Hand Jueyin (Pericardium) and Shaoyang. Shaoyang flows to Foot Shaoyang and Jueyin. Jueyin returns to flow to Hand Taiyin. The fifteen collateral vessels all follow their origins, forming a circle without beginning or end, irrigating each other, gathering at Cun Kou and Renying, to treat hundreds of diseases and determine life and death.
Ding says: Heaven and Earth Yin and Yang complete a year starting and ending at the twenty-four solar terms. Day and night start and end at the twenty-four hours. Human Ying and Wei circulate through twenty-four meridians, thus reuniting at Cun Kou and Renying. "Cun Kou" refers to the pulse point of the Hand Taiyin meridian. Its acupoint is named Taiyuan; thus pulses gather at Taiyuan. The twelve meridians and fifteen collaterals all assist San Jiao in generation, hence beginning at the Middle Jiao flowing to Hand Taiyin and Yangming, to treat diseases and determine life and death. Yang says: After circulating Hand Taiyang, it flows to Hand Yangming. After circulating Hand Yangming, it flows to Foot Yangming. It transfers and circulates; others follow this pattern. Yu says: "Beginning at the Middle Jiao" refers to the area between the breasts, named Danzhong acupoint, also called Qi Hai, indicating Qi rises from here and flows to the Lung. After Lung circulation, it transmits to Hand Yangming. *Su Wen* states: Danzhong is the official of the ministerial envoy, meaning the Stomach transforms flavors into Qi, transmitting this upward to the Lung. Yang says: Twelve meridians and fifteen collaterals constitute twenty-seven Qi, conforming to the number of three times nine. Heaven has nine stars, Earth has nine provinces, Humans have nine orifices. Their meridian circulation all gathers at Cun Kou and Renying. Thus, diagnosing Cun Kou and Renying reveals meridian diseases and life/death signs. Yu says: Jueyin returns to flow to Hand Taiyin. Deducting lengths this way contradicts previous and subsequent textual meanings, being far from the sages, making it difficult to elaborate roughly.
The classic states: Knowing the beginning and end, Yin and Yang are determined. What does this mean? The answer is: Beginning and End are the chronology of pulses. Yin and Yang Qi at Cun Kou and Renying connect to the court, forming a circle without beginning or end; hence it is called "Beginning."
Yang says: Meridian circulation corresponds to heavenly degrees, cycling repeatedly; hence "circle without beginning or end."
"End" refers to the severance of the Three Yin and Three Yang meridians. Severance means death. Death has different manifestations; hence it is called "End."
Yang says: Severance of Yin and Yang Qi is also manifested at Cun Kou and Renying. Appearance indicates death. Different deaths have different diagnostic forms; hence "End." Ding says: The severance of Three Yin and Three Yang meridians leading to death with different manifestations is explained within the Twenty-Fourth Difficulty itself.