六十二难曰∶脏井荥有五，腑独有六者。何谓也？然腑者阳也，三焦行于诸阳，故置一
俞，名曰原。腑有六者，亦与三焦共一气也。
滑氏曰∶脏之井荥有五，谓井荥俞经合也。腑之井荥有六，以三焦行于诸阳，故又置一
俞而
名曰原。所以腑有六者，与三焦共一气也。虞氏曰∶此篇疑有缺误，当与六十六难参考。
六十四难曰∶十变又言阴井木，阳井金，阴荥火，阳荥水，阴俞土，阳俞木，阴经金，
阳经火，阴合水，阳合土。
滑氏曰∶十二经起于井穴，阴井为木，故阴井木生阴荥火，阴荥火生阴俞土，阴俞土生
阴经
金，阴经金生阴合水。阳井为金，故阳井金生阳荥水，阳荥水生阳俞木，阳俞木生阳经火，
阳经火生阳合土。
阴阳皆不同其意何也？然是刚柔之事也。阴井乙木，阳井庚金，阳井庚金者，乙之刚也
；阴井乙木者，庚之柔也。乙为木，故言阴井木也；庚为金，故言阳井金也。余皆仿此。
滑氏曰∶刚柔者，乙庚之相配也。十干所以自乙庚而言者，盖诸脏腑穴，皆始于井，而
阴脉
之井始于乙木，阳脉之井始于庚金，故自乙庚而言刚柔之配，而其余五行之配，皆仿此也。
丁氏曰∶刚柔者，谓阴井木，阳井金，庚金为刚，乙木为柔，阴荥火，阳荥水，壬水为刚，
丁火为柔，阴俞土，阳俞木，甲木为刚，己土为柔。阴经金，阳经火，丙火为刚，辛金为柔
。阴合水，阳合土，戊土为刚，癸水为柔。盖五行之道，相生者母子之义，相克相制者夫妇
之类。故夫道皆刚，妇道皆柔，自然之理也。易曰∶分阴分阳，迭用柔刚，其是之谓欤。
《难经》第六十二难说：五脏的井、荥穴只有五个，而六腑却独有六个，这是为什么呢？回答说：六腑属阳，三焦之气运行于各阳经之中，所以在五输穴之外增设一个穴位，称为原穴。六腑之所以有六个输穴，是因为它们与三焦同属一气。
滑寿（滑氏）说：五脏的井、荥穴共有五个，指的是井、荥、俞、经、合这五种类型。六腑的井、荥穴有六个，因为三焦之气运行于各阳经，所以又增设一个穴位并命名为原穴。六腑之所以有六个，是因为与三焦共有一气。虞氏说：这一篇恐怕有脱漏或错误，应当参考《难经》第六十六难来理解。
《难经》第六十四难说：《十变》篇中又说，阴经的井穴属木，阳经的井穴属金；阴经的荥穴属火，阳经的荥穴属水；阴经的俞穴属土，阳经的俞穴属木；阴经的经穴属金，阳经的经穴属火；阴经的合穴属水，阳经的合穴属土。
滑寿说：十二经脉都起始于井穴。阴经的井穴属木，所以阴井木生阴荥火，阴荥火生阴俞土，阴俞土生阴经金，阴经金生阴合水。阳经的井穴属金，所以阳井金生阳荥水，阳荥水生阳俞木，阳俞木生阳经火，阳经火生阳合土。
阴阳五行配属为何不同呢？这是因为涉及刚柔的关系。阴井为乙木，阳井为庚金，阳井庚金是乙的刚性表现；阴井乙木是庚的柔性表现。乙属木，所以说阴井属木；庚属金，所以说阳井属金。其余类推。
滑寿说：所谓刚柔，是指天干中乙与庚的相配关系。之所以从乙、庚开始论述，是因为所有脏腑的穴位都始于井穴，而阴脉的井穴始于乙木，阳脉的井穴始于庚金，所以从乙、庚来说明刚柔的配合，其余五行的配合也都仿照这个规律。
丁氏说：所谓刚柔，是指阴井属木，阳井属金，其中庚金为刚，乙木为柔；阴荥属火，阳荥属水，其中壬水为刚，丁火为柔；阴俞属土，阳俞属木，其中甲木为刚，己土为柔；阴经属金，阳经属火，其中丙火为刚，辛金为柔；阴合属水，阳合属土，其中戊土为刚，癸水为柔。大概五行的道理中，相生体现的是母子之义，相克相制体现的是夫妇之类。所以夫道皆刚，妇道皆柔，这是自然的道理。《易经》说：“分阴分阳，迭用柔刚”，说的就是这个意思吧。
Chapter 62 of the *Nan Jing* (Classic of Difficult Issues) states: The Well and Ying-Spring points of the Zang organs number five, whereas the Fu organs have six. What is the reason for this? The answer is: The Fu organs belong to Yang. The Sanjiao (Triple Burner) Qi circulates through all the Yang meridians; therefore, an additional Shu point is added, named the Yuan-Source point. The Fu organs have six points because they share one Qi with the Sanjiao.
Hua Shou (Master Hua) states: The Well and Ying-Spring points of the Zang organs are five in number, referring to the Well, Ying-Spring, Shu-Stream, Jing-River, and He-Sea points. The Well and Ying-Spring points of the Fu organs are six because the Sanjiao Qi circulates through all the Yang meridians; thus, an additional Shu point is added and named the Yuan-Source point. The reason the Fu organs have six points is that they share one Qi with the Sanjiao. Yu Shi states: This chapter likely contains omissions or errors and should be cross-referenced with Chapter 66 of the *Nan Jing*.
Chapter 64 of the *Nan Jing* states: The *Shi Bian* (Ten Transformations) also says: The Yin Well points correspond to Wood, and the Yang Well points to Metal; the Yin Ying-Spring points to Fire, and the Yang Ying-Spring points to Water; the Yin Shu-Stream points to Earth, and the Yang Shu-Stream points to Wood; the Yin Jing-River points to Metal, and the Yang Jing-River points to Fire; the Yin He-Sea points to Water, and the Yang He-Sea points to Earth.
Hua Shou states: The twelve meridians originate from the Well points. Since the Yin Well points correspond to Wood, Yin Well-Wood generates Yin Ying-Spring-Fire, Yin Ying-Spring-Fire generates Yin Shu-Stream-Earth, Yin Shu-Stream-Earth generates Yin Jing-River-Metal, and Yin Jing-River-Metal generates Yin He-Sea-Water. Since the Yang Well points correspond to Metal, Yang Well-Metal generates Yang Ying-Spring-Water, Yang Ying-Spring-Water generates Yang Shu-Stream-Wood, Yang Shu-Stream-Wood generates Yang Jing-River-Fire, and Yang Jing-River-Fire generates Yang He-Sea-Earth.
Why do Yin and Yang differ in their elemental associations? This concerns the matter of Gang (Firm/Hard) and Rou (Soft/Yielding). The Yin Well is Yi Wood, and the Yang Well is Geng Metal. The Yang Well Geng Metal represents the Gang aspect of Yi; the Yin Well Yi Wood represents the Rou aspect of Geng. Since Yi belongs to Wood, it is said that the Yin Well corresponds to Wood; since Geng belongs to Metal, it is said that the Yang Well corresponds to Metal. The rest follow this pattern.
Hua Shou states: "Gang and Rou" refers to the pairing of Yi and Geng. The reason the discussion begins with Yi and Geng is that all acupoints of the Zang and Fu organs start at the Well points. The Well points of the Yin meridians begin with Yi Wood, and the Well points of the Yang meridians begin with Geng Metal. Therefore, the pairing of Gang and Rou is explained starting from Yi and Geng, and the pairings of the remaining Five Elements follow this same logic.
Ding Shi states: "Gang and Rou" means that for the Yin Well (Wood) and Yang Well (Metal), Geng Metal is Gang and Yi Wood is Rou; for the Yin Ying-Spring (Fire) and Yang Ying-Spring (Water), Ren Water is Gang and Ding Fire is Rou; for the Yin Shu-Stream (Earth) and Yang Shu-Stream (Wood), Jia Wood is Gang and Ji Earth is Rou; for the Yin Jing-River (Metal) and Yang Jing-River (Fire), Bing Fire is Gang and Xin Metal is Rou; for the Yin He-Sea (Water) and Yang He-Sea (Earth), Wu Earth is Gang and Gui Water is Rou. Generally, in the principles of the Five Elements, mutual generation embodies the relationship of mother and child, while mutual restriction embodies the relationship of husband and wife. Thus, the way of the husband is always Gang, and the way of the wife is always Rou, which is the natural order. The *I Ching* (Book of Changes) states: "Yin and Yang are distinguished, and softness and firmness are used alternately." This is precisely what is meant.