予尝读《易》而闻诸夫子曰∶数往者顺，知来者逆，是故《易》，逆数也。由是默会其
理，而知天人之道得以无穷无息者，无非赖此逆数耳。何也？盖自太极初分，两仪以判，一
动一静，阴阳见矣。阴阳之体为乾坤，阴阳之用为水火。乾坤定对待之交易，故一在上而一
在下；水火荡流行之变易，故一主降而一主升。夫如是，斯得循环无已。总之而为天道，散
之而为人道，而大《易》之义，所以无微不在也。姑无论其他，而但以性理明之，则总由变
易之数。夫变易之数，即升降之数也。变易之所以无穷者，降以升为主，是即所谓逆数也。
若无此逆，则有降无升，流而不返，而大道如环，何所赖乎？由是逆顺交变，则阳与阴对，
热与寒对。升与降对，长与消对，进与退对，成与败对，勤与惰对，劳与逸对，善与恶对，
生与死对，凡此一逆一顺，其变无穷。惟从逆者，从阳得生；从顺者，从阴得死。君如不信
，第详考伏羲卦气之圆图，其义昭然可见也。观其阳盛之极，自夏至一阴初 ，由五、
六、七、八，历巽、坎、艮、坤，天道从西右行，则阳气日降，万物日消者，此皆顺数也。
顺则气去，即从阴得死之道也。幸而阴剥之极，自冬至一阳得复，由四、三、二、一，历震
、离、兑、干，天道从东左旋，则阳气日升，万物日盛者，此皆逆数也。逆则气来，即从阳
得生之道也。此天道之征，固如是也。
若以人道言之，则人道本乎天道，天心即是人心。第天有阴霾，能蒙日月，人有愚昧，
能胜聪明。故每多从顺者，喜其易也，喜其逸也；每多避逆者，畏其难也，畏其劳也。彼大
人之见则不然，如尊贵莫若帝王，可以逸矣，可以纵矣，而尧舜之惟微惟危，顾何必谆谆乎
在念？智能莫若圣人，可无劳矣，可无畏矣。而孔子之戒慎恐惧，又何必卷卷乎在心？此无他
，惟其代天功，主人极，总知夫顺不可从，从顺则流，逆不可舍，舍逆则退也。由此观之，
乃知士而舍逆，则有屈而无伸；农而舍逆，则有种而无获；工而舍逆，则有粗而无精；商而
舍逆，则有散而无聚。再由此而推展之，则凡曰修身齐家，凡曰治国平天下，进一步则日以
就成，退一步则日以就败，有源有流，其可任其长逝而不思砥柱之良图乎！此人道之攸系，
又如是矣。
然言天言人，总言乎生道也。而保生之道，莫先于医，医欲保生，其堪违阳道乎？其堪
倍逆数乎？然医贵圆通，安容执滞，非曰尽不从阴也，从阴正以卫阳也；非曰尽不用顺也，
用顺亦以成逆也，性命玄关，此为第一。独念有医名丕着之辈，犹然昧此，而妄言左道，留
传至今，因致伤生遗害非浅者，谓非轩岐之魔不可也。嗟！嗟！有心哉其谁乎？苟得其人，可
与谈还悟道矣。傥亦以吾言为然不。
我曾经研读《易经》，并听孔子说过：“追溯过去是顺着时间顺序，预知未来则是逆向推演”，因此，《易经》的核心在于“逆数”。由此我默会其中的道理，了解到天地人之道之所以能够无穷无尽、生生不息，无非是依靠这种“逆数”的作用罢了。为什么呢？大概自从太极初分，两仪（阴阳）确立，一动一静之间，阴阳的本质就显现了。阴阳的本体表现为乾和坤，阴阳的功能表现为水和火。乾和坤确定了相对位置的交换规律，所以一个在上，一个在下；水和火体现了流动变化的规律，所以一个主降，一个主升。像这样，才能形成循环往复、永不停止的状态。总括起来这就是天道，分散开来就是人道，而《易经》的深意，因此无处不在。暂且不论其他，仅从性理方面阐明，这一切都源于变化的数理。所谓变化的数理，就是升降的数理。变化之所以无穷无尽，是因为以“升”为主导来配合“降”，这就是所谓的“逆数”。如果没有这种“逆”，就只有降没有升，气机流散而不返回，那么大道如环般的循环，又依靠什么呢？由于逆与顺相互交替变化，于是阳与阴相对，热与寒相对，升与降相对，长与消相对，进与退相对，成与败相对，勤与惰相对，劳与逸相对，善与恶相对，生与死相对。凡此种种，一逆一顺，变化无穷。凡是顺应“逆”道的人，顺应阳气而得生；凡是顺应“顺”道的人，顺应阴气而得死。如果您不相信，只需详细考察伏羲卦气圆图，其意义便清晰可见。看那阳气极盛之时，从夏至开始，一阴初生，经过五、六、七、八的位置，历经巽、坎、艮、坤卦位，天道从西向右运行，阳气日渐下降，万物日渐消减，这些都是“顺数”。顺则气去，这是顺应阴气而走向死亡的道路。幸好到了阴气剥蚀至极点时，从冬至开始，一阳复生，经过四、三、二、一的位置，历经震、离、兑、乾卦位，天道从东向左旋转，阳气日渐上升，万物日渐兴盛，这些都是“逆数”。逆则气来，这是顺应阳气而获得生命的道路。这是天道的验证，本来就是这样。
如果从人道来说，人道本于天道，天心即是人心。只是天有阴霾，能遮蔽日月；人有愚昧，能掩盖聪明。所以人们大多喜欢顺从（顺道），因为那样容易、安逸；大多回避逆从（逆道），因为那样艰难、劳累。然而君子（大人）的看法则不然。尊贵莫过于帝王，可以安逸放纵了，但尧舜帝王的治国之道微妙而危险，为何还要念念不忘地谨慎呢？智能莫过于圣人，可以无需辛劳恐惧了，但孔子的戒慎恐惧，为何还要时刻挂在心头呢？这没有别的原因，只是因为他们代天行功，主持人的极致，深知顺道不可随从，随从顺道就会随波逐流；逆道不可舍弃，舍弃逆道就会退步不前。由此看来，士人如果舍弃逆道，就只能受屈而不能伸展；农夫如果舍弃逆道，就只播种而无收获；工匠如果舍弃逆道，就只粗糙而无精细；商人如果舍弃逆道，就只散乱而无聚集。再由此推广开来，凡是修身齐家，凡是治国平天下，进一步则日益成功，退一步则日益败坏，既有源头又有流向，难道可以任由生命流逝而不思考做中流砥柱的良好规划吗？这就是人道的关键所在，又是如此重要。
然而，谈论天和人都归结于生存之道。而保全生命的方法，没有比医学更重要的了。医生想要保全生命，岂能违背阳道？岂能背离逆数？然而医学贵在圆融通达，怎能固执僵化？并不是说完全不顺从阴，顺从阴正是为了护卫阳；并不是说完全不用顺，使用顺也是为了成就逆。性命的关键玄关，以此为第一要义。只是想到有些医者名声不显，却仍然不明白这个道理，妄言邪道，流传至今，导致伤害生命、遗留祸害非浅，称他们为轩辕岐伯（中医始祖）的魔障也不为过。唉！唉！谁是有心之人呢？如果遇到合适的人，就可以与他谈论还元悟道的大法了。倘若您也认为我的话是对的。
I once studied the *Book of Changes* (*Yijing*) and heard from Confucius that: "Tracing the past follows the sequence (Shun), while knowing the future involves reverse deduction (Ni); therefore, the *Book of Changes* is based on reverse numbers (Ni Shu)." From this, I silently comprehended its principle and realized that the reason why the Dao of Heaven and Humanity remains endless and unceasing lies entirely in this reliance on "reverse numbers." Why is this? Generally speaking, since the Great Ultimate (Taiji) was initially divided and the Two Modes (Liangyi, i.e., Yin and Yang) were distinguished, through movement and stillness, the nature of Yin and Yang became manifest. The substance of Yin and Yang manifests as Qian (Heaven) and Kun (Earth), while their function manifests as Water and Fire. Qian and Kun establish the exchange of opposing positions, thus one is above and one is below; Water and Fire demonstrate the changes of flowing circulation, thus one governs descent and one governs ascent. In this manner, a cycle without end is achieved. Summarized, this constitutes the Dao of Heaven; dispersed, it becomes the Dao of Humanity. Thus, the profound meaning of the *Great Changes* is present in every minute detail. Let us not discuss other aspects, but simply clarify it through the principles of nature and reason: everything stems from the numbers of change (Bian Yi). The numbers of change are essentially the numbers of ascending and descending. The reason why change is infinite is that ascent serves as the master for descent; this is what is referred to as "reverse numbers" (Ni Shu). Without this "reverse," there would only be descent and no ascent, with qi flowing away and never returning. How could the Dao, like a circle, rely on anything then? Due to the alternating transformation of reverse and forward, Yang pairs with Yin, Heat pairs with Cold, Ascending pairs with Descending, Growth pairs with Decline, Advancing pairs with Retreating, Success pairs with Failure, Diligence pairs with Laziness, Labor pairs with Rest, Goodness pairs with Evil, and Life pairs with Death. All these instances involve one reverse and one forward, resulting in infinite variations. Those who follow the "reverse" align with Yang and attain life; those who follow the "forward" align with Yin and meet death. If you do not believe this, merely examine carefully the Round Diagram of Fuxi’s Hexagram Qi, and its meaning will be clearly visible. Observe that when Yang energy reaches its peak, starting from the Summer Solstice, a single Yin line begins to emerge. Passing through positions five, six, seven, and eight, and traversing the Xun, Kan, Gen, and Kun trigrams, the Dao of Heaven moves from West to Right. Consequently, Yang energy descends daily, and all things decline daily; these are all "forward numbers" (Shun Shu). Following the forward leads to the departure of qi, which is the path of aligning with Yin to meet death. Fortunately, when Yin peeling reaches its extreme, starting from the Winter Solstice, a single Yang line recovers. Passing through positions four, three, two, and one, and traversing the Zhen, Li, Dui, and Qian trigrams, the Dao of Heaven rotates from East to Left. Consequently, Yang energy ascends daily, and all things flourish daily; these are all "reverse numbers" (Ni Shu). Following the reverse leads to the arrival of qi, which is the path of aligning with Yang to attain life. This is the evidence of the Dao of Heaven, and it is indeed so.
If we speak of the Dao of Humanity, the Human Dao originates from the Heavenly Dao, and the Heart of Heaven is the Heart of Humanity. However, just as Heaven has haze that can obscure the sun and moon, humans have ignorance that can overshadow wisdom. Therefore, people often prefer to follow the "forward" because it is easy and comfortable; they often avoid the "reverse" because it is difficult and laborious. The perspective of the noble person (Junzi) is different. No one is more honorable than an emperor, who can enjoy ease and indulgence, yet Yao and Shun considered governance subtle and perilous, why must they constantly keep this in mind? No one is more intelligent than a sage, who should need no labor or fear, yet Confucius practiced caution and awe, why must he constantly hold this in his heart? There is no other reason; it is simply that they perform the functions of Heaven and preside over the ultimate standard of humanity. They fully understand that the forward path cannot be followed, for following it leads to drifting; the reverse path cannot be abandoned, for abandoning it leads to regression. From this, we see that if a scholar abandons the reverse, he suffers humiliation without extension; if a farmer abandons the reverse, he sows without harvest; if a craftsman abandons the reverse, he produces roughness without precision; if a merchant abandons the reverse, he disperses without gathering. Extending this further, regarding self-cultivation and family regulation, and governing the state and bringing peace to the world, advancing one step leads to daily success, while retreating one step leads to daily failure. Since there is both a source and a flow, how can one allow life to pass away endlessly without thinking of the good plan to act as a pillar against the current? This is the connection of the Human Dao, and it is thus significant.
However, whether speaking of Heaven or Humanity, it all concerns the Dao of Life. Among methods to preserve life, none is prior to medicine. If a doctor wishes to preserve life, how can he violate the Dao of Yang? How can he deviate from the reverse numbers? Yet medicine values flexibility and thorough understanding, allowing no rigidity. It does not mean completely ignoring Yin; following Yin is precisely to guard Yang. It does not mean completely avoiding the forward; using the forward is also to achieve the reverse. The mysterious gate of life and nature considers this the first priority. I only recall that some physicians of little renown remain ignorant of this, spreading heretical doctrines, which have been passed down to the present, causing harm to life and leaving deep repercussions. They cannot be described otherwise than as demons of Xuanyuan and Qibo (the mythical founders of Chinese Medicine). Alas! Alas! Who among us has a sincere heart? If such a person is found, one can discuss the Dao of returning to enlightenment with him. I hope you agree with my words.