七十四难曰。从其首。系其数。间象在表。五化叠元。并见前图。（拾遗）夫天元法者
。谓
之五化叠元。当从其首。系其数。首者寅方春也。在人为肝。是从东方。顺天轮数至所主之
处。计从几数却于所受病一方。倒叠回去数至根据前数尽处便于元受病一方穴内泻所止之方来
路穴也。不得于所主之方内经中泻之勿误。
假令病者闻香臭二者。心主五臭也。入脾为香臭。从东数至所主之处。所主五臭者心也
。东
一南二计得二数。却当于受病之方倒叠回去。脾一心二元数二也。是数至心。心者荣火也。
当
于受病之方内泻荣火。是脾经泻火都是也。或曰何以倒叠数对曰此从地出为天轮所载。右
迁于天不当于所显之虚治之此舟行岸移之意也。
六十八难曰。元证脉合。复生五象。
在表间象以应望闻。（及肝胆各五法）并见前图。
人元法例（前图已载七象七法见前人元例后）并见前图。
足太阳膀胱经之脉。出于至阴小指外侧。去爪角如韭叶。为井金。足小指之端也（十呼）
。
足少阴肾之脉涌泉。足心也。起于小指之下斜趣（三呼）
手厥阴心包脉。其直者循中指出其端。去爪甲如韭叶陷中为井。中冲穴也。其支者别掌
中循小指次指出其端。
手少阳三焦之脉。起于小指次指之端。去爪甲如韭叶为井。（三呼）
足少阳胆之脉。起于窍阴小指次指之端。去爪甲如韭叶为井。其支者上入大指岐骨内出
其端还贯爪甲出三毛。（三呼二十呼）
足厥阴之脉。起于大指之端。入聚毛之际。去爪甲如韭叶为井。大敦穴也。及三毛中。
（十呼六呼）
手太阴肺之脉。起于大指之端。出于少商大指内侧也。去爪甲角如韭叶为井。其支者出
次指内
出其端。手阳明大肠之脉。起于大指次指之端。入次指之内。去爪甲角如韭叶为井。（一
呼）中指内交（三呼）
足阳明胃之脉。起于大指次指之端。去爪甲如韭叶为井。其支者大指间出其端。（一呼）
足太阴脾之脉。起于足大指端。循指内一侧。去爪甲角如韭叶为井。隐白也。（十呼）
手少阴心之脉。起于小指内出其端。循指内 之端。去爪甲角如韭叶为井。（三呼）
手太阳小肠之脉。起于小指之端。循指之端。去爪甲一分陷中为井。（五呼）
《难经》第七十四难说：顺着起始方位，推算其数理。表象在体表，五行化生层层叠加。（拾遗）所谓天元法，称为五化叠元，应当从起始方位开始，依据数理进行推演。起始方位是寅方（春季），在人体对应肝脏，这是从东方出发，顺应天体运行的顺序数到病变所在的部位，计算从起始处经过几个数位后，再从受病的方位倒着往回数，直到与之前数的数量相等的位置，然后在原发病的方位穴位中，泻去该止点方位来路方向的穴位之气。切勿在病变所在的方位经脉内部进行泻法操作，以免出错。
举例来说，如果病人对气味闻不到或异常，心主管五种气味，气味进入脾脏表现为香臭。从东方开始数到所主的部位，主管五种气味的是心脏。东方数为1，南方数为2，合计得到2个数。然后应当在受病的方位倒着往回数。脾对应的数是1，心对应的数是2，总数为2。这样数到了心脏。心属营火，应当在受病的方位内泻去营火之气。这就是在脾经中泻火的方法。有人问为什么要倒着数？回答说这是因为气从地出，被天轮承载，向右迁移于天，不应当在显现的虚损之处治疗，这就像船在行驶而岸在移动的道理一样。
《难经》第六十八难说：原始证候与脉象相合，又产生五种象。在表层的表象用于对应望诊和闻诊。（以及肝胆各五种方法）并见前图。人元法的条例（前图已记载七象七法，见前人元例之后）并见前图。
足太阳膀胱经的脉气，出于至阴穴，位于小指外侧，距离趾甲角如韭菜叶宽度处，是井穴，属金。位于足小指的末端（呼吸十次的时间）。
足少阴肾经的脉气出于涌泉穴，位于足心。起于小指之下，斜向行走（呼吸三次的时间）。
手厥阴心包经的脉气，其直行者沿中指指出端，距离趾甲角如韭菜叶宽度处的凹陷中，是井穴，名为中冲穴。其分支从掌中分出，沿无名指出端。
手少阳三焦经的脉气，起于无名指末端，距离趾甲角如韭菜叶宽度处，是井穴（呼吸三次的时间）。
足少阳胆经的脉气，起于窍阴穴，位于无名指末端，距离趾甲角如韭菜叶宽度处，是井穴。其分支上行进入大脚趾歧骨内，出端部，贯穿趾甲，出于丛毛处（呼吸三次，共二十次）。
足厥阴肝经的脉气，起于大脚趾末端，进入丛毛之际，距离趾甲角如韭菜叶宽度处，是井穴，名为大敦穴。也在丛毛中（呼吸十次，六次）。
手太阴肺经的脉气，起于大脚趾末端，出于少商穴，在大脚趾内侧，距离趾甲角如韭菜叶宽度处，是井穴。其分支出于食指内侧，出端部。手阳明大肠经的脉气，起于食指末端，进入食指内侧，距离趾甲角如韭菜叶宽度处，是井穴（呼吸一次）。在中指内侧交汇（呼吸三次）。
足阳明胃经的脉气，起于食指末端，距离趾甲角如韭菜叶宽度处，是井穴。其分支在大脚趾间出端部（呼吸一次）。
足太阴脾经的脉气，起于足大脚趾末端，沿指内侧，距离趾甲角如韭菜叶宽度处，是井穴，名为隐白（呼吸十次）。
手少阴心经的脉气，起于小指内侧出端部，沿指内侧之端，距离趾甲角如韭菜叶宽度处，是井穴（呼吸三次）。
手太阳小肠经的脉气，起于小指末端，沿指之端，距离趾甲一分的凹陷中，是井穴（呼吸五次）。
The seventy-fourth difficulty of the *Nan Jing* states: Follow the starting direction and calculate its numerical sequence. The superficial manifestations are on the exterior, with the five transformations overlapping and stacking. (Supplementary notes) The so-called Tianyuan method is called "five transformations overlapping and stacking." One must start from the initial direction and rely on numerical calculation. The initial direction is Yin (Spring), which corresponds to the Liver in the human body. This proceeds from the East, following the celestial wheel's rotation to the location where the disease manifests. Calculate how many numerical steps are taken from the start, then reverse-count back from the affected side until reaching a point equal to the previous count. Then, at the acupoint on the original diseased side, drain the qi from the pathway of the stopping direction's acupoint. Do not mistakenly perform draining methods within the meridian of the affected side.
For example, if a patient has disorders regarding smell and odor, the Heart governs the five odors, which enter the Spleen as fragrant and foul smells. Counting from the East to the governed location, the organ governing the five odors is the Heart. The number for East is 1, and for South is 2, totaling 2. Then, one should reverse-count from the affected side. The Spleen corresponds to 1, and the Heart to 2, summing to 2. Thus, the count reaches the Heart. The Heart belongs to Ying-Fire (Nutritive Fire). Therefore, one should drain Ying-Fire within the affected side. This constitutes draining fire in the Spleen Meridian. Someone might ask why we count backwards? The answer is that Qi emerges from the Earth and is carried by the Heavenly Wheel, moving rightward toward Heaven; it should not be treated at the apparent void or deficiency. This is analogous to the meaning that when the boat moves, the shore appears to shift.
The sixty-eighth difficulty states: The primary symptoms and pulse correspond, generating five images again. The superficial images respond to observation and listening. (And five methods each for the Liver and Gallbladder) See the preceding diagram. The principles of the Renyuan method (the preceding diagram already records seven images and seven methods, see the previous Renyuan examples after) See the preceding diagram.
The Foot-Taiyang Bladder Meridian originates at Zhiyin (BL67), on the lateral side of the little toe, about the width of a leek leaf away from the nail corner, serving as the Jing-Well metal point. It is located at the tip of the foot little toe (ten breaths).
The Foot-Shaoyin Kidney Meridian originates at Yongquan (KI1), in the center of the sole. It begins below the little toe and slants forward (three breaths).
The Hand-Jueyin Pericardium Meridian: Its straight branch follows the middle finger to its tip, into the depression about the width of a leek leaf away from the nail, forming the Jing-Well point, Zhongchong (PC9). Its branch separates from the palm and follows the ring finger to its tip.
The Hand-Sanjiao Triple Energizer Meridian originates at the tip of the ring finger, about the width of a leek leaf away from the nail, forming the Jing-Well point (three breaths).
The Foot-Shaoyang Gallbladder Meridian originates at Qiaoyin (GB44), at the tip of the ring finger, about the width of a leek leaf away from the nail, forming the Jing-Well point. Its branch ascends into the space between the bones of the big toe, exits the tip, passes through the nail, and emerges among the hair (three breaths, twenty breaths total).
The Foot-Jueyin Liver Meridian originates at the tip of the big toe, entering the area where hairs gather, about the width of a leek leaf away from the nail, forming the Jing-Well point, Dazhun (LR14). It is also among the hair (ten breaths, six breaths).
The Hand-Taiyin Lung Meridian originates at the tip of the thumb, exiting Shaoshang (LU11) on the medial side of the thumb, about the width of a leek leaf away from the nail corner, forming the Jing-Well point. Its branch exits the medial side of the index finger to its tip. The Hand-Yangming Large Intestine Meridian originates at the tip of the index finger, entering the medial side of the index finger, about the width of a leek leaf away from the nail corner, forming the Jing-Well point (one breath). It intersects at the medial side of the middle finger (three breaths).
The Foot-Yangming Stomach Meridian originates at the tip of the second toe, about the width of a leek leaf away from the nail, forming the Jing-Well point. Its branch exits between the toes to the tip (one breath).
The Foot-Taiyin Spleen Meridian originates at the tip of the foot big toe, following the medial side of the toe, about the width of a leek leaf away from the nail corner, forming the Jing-Well point, Yinbai (SP1) (ten breaths).
The Hand-Shaoyin Heart Meridian originates at the medial tip of the little finger, following the medial end of the finger, about the width of a leek leaf away from the nail corner, forming the Jing-Well point (three breaths).
The Hand-Taiyang Small Intestine Meridian originates at the tip of the little finger, following the end of the finger, into the depression one fen away from the nail, forming the Jing-Well point (five breaths).