医家既知修德，又当爱惜自己精神，医之难者难于此也。倘精神昏耗，察识必不能精，方药必不能尝，
虽有济人之心，而势不能及
也。若夫病有服药针灸不能效者，以其不知保养之方。古云∶与其病后善服药，莫若病前善自防。是录《天真论
》于前者，保养之原也；录《茹淡》、《阴火论》于中者，保养不过节食与色而已；更为说于后者，黜邪崇正，
法颐之贞也。
黄帝曰∶余闻上古春秋皆度百岁，而动作不衰，今年半百而动作皆衰者，时世异耶？人将失之耶？岐伯
对曰∶上古之人，其知道者，（一阴一阳之谓道。）法于阴阳，（阴阳者，万物之终始，死生之本，逆之则
灾害生，从之则苛疾不起。）和于术数，（术者，阴阳所发；数者，阴阳节限也，和术数，即法阴阳也。饮食
起居，随时安分而不纵欲是也。）饮食有节、起居有常，不妄作劳，（人身欲得小劳，则气血不滞，过则伤人。）
故能形与神俱，而尽终其天年，度百岁乃去。今时之人不然也，以酒为浆，以妄（作劳）为常，醉以入房，以
欲竭其精，以耗散其真，不知持满，不时御神。（不知爱惜此身，如持盈满之器，惟恐其倾也∶不能时时制御
心神，如朽索之御六马。）务快其心（之所欲，）逆于（养）生（真）乐，起居无节，（房劳亦起居内事。）
故半百而（形神）衰也，夫上古圣人之教下也，皆谓之虚邪贼风，避之有时，恬澹虚无，真气从之，精
神内守，病安从来？是以志闲而少欲，心安而不惧，形劳而不倦，气（血相）从以顺（行），各从其欲，皆
得所愿，（志不贪，故所欲皆顺；心易足，故所愿必从；以不异求，故无难得也。）故美其食，（顺精粗也。）
任其服，（随美恶也。）乐其俗，（去倾慕也。）高下不相慕，其民故曰朴。（至无求也，是所谓心足也。）
是以嗜欲不能劳其目，淫邪不能惑其心，愚智贤不肖，不惧于物，（不惧为外物所夺。）故合于道，所以能年
皆度百岁，而动作不衰者，以其德全不危也。（不纵情恣欲，涉于危险之地。）帝曰∶人年老而无子者，材力
尽耶？将天数然也？岐伯曰∶女子七岁肾气盛，齿更发长；（老阳之数极于九，少阳之数极于七，女子为少阴
之气，故以少阳数偶之，明阴阳气和，乃能生成其形体。）二七而天癸至，任脉通，太冲脉盛，月事以时下，
故有子；（癸谓壬癸北方水，干名也。肾气全盛，冲任流通，天真气降，应时而下，故曰天癸，冲为血海，任
主胞胎，月事调匀，故能有子。）三七肾气平均，故真牙生而长极；（真牙，牙之最后生者，牙齿为骨之余。）四
七筋骨坚，发长极，身体壮盛；五七阳明脉衰，面始焦，发始堕；（阳明之脉气荣于面，故其衰也，面焦发
堕。）六七三阳脉衰于上，面皆焦，发始白；（三阳之脉，尽上于头，故三阳衰则面皆焦，发始白，所以衰者，
以其经月数泄脱之故。）七七任脉虚，太冲脉衰少，天癸竭，地道不通，（经水绝，是为地道不通矣。）故形
坏而无子也。（血气不荣其自身形容，而况可生人乎。）丈夫八岁肾气实，发长齿更；（老阴之数极于十，少
阴之数次于八，男子为少阳之气，故以少阴数配之。）二八肾气盛，天癸至，精气溢泻，阴阳和，故能有子；
（男女有阴阳之质不同，天癸则精血之形亦异，阴静海满而去血，阳动应血而泄精，二者通和，故能有子。
《易》曰男女构精，万物生化，此之谓也。）三八肾气平均，筋骨劲强，故真牙生而长极；四八筋骨隆盛，
肌肉满壮；五八肾气衰，发堕齿槁；（精无所养，故令发堕齿枯。）六八阳气衰竭于上，面焦，发鬓颁白；（阳气，阳
明之气也。）七八肝气衰，筋不能动，天癸竭，精少，肾衰，形体皆极；八八齿发去。（落也。）肾者主水，
受五脏六腑之精而藏之，故五脏盛乃能泻；（五脏各有精，随用而灌注于肾，此乃肾为都会关司之所，非肾一
脏而独有精，故曰五脏盛乃能泻也。）今五脏皆衰，筋骨解惰，天癸尽矣，故发鬓白，身体重，行步不正，
而无子耳。帝曰∶有其年已老而有子者，何也？岐伯曰∶此天寿过度，气脉常通，而肾气有余也。此虽有子，
男不过尽八八，女不过尽七七，而天地之精气皆竭矣。（虽老而生子，子寿亦不能过天癸之数。）帝曰∶夫
道者，年皆百数，能有子乎？岐伯曰∶夫道者，能却老而全角，身年虽寿，能生子也。
医家既然懂得修养品德，就应当爱惜自己的精神，医生的难点就在于此。如果精神昏沉耗损，诊察辨识必然不能精准，开方用药也必然不能恰当，虽然怀有救人的心，但形势上却无法达到效果。至于那些服药针灸无效的病症，是因为患者不懂得保养的方法。古话说：“与其病后善于服药，不如病前善于自我防范。”前面收录《天真论》，是保养的根本；中间收录《茹淡》、《阴火论》，说明保养不过是节制饮食和房事罢了；后面又加以论述，旨在排斥邪气崇尚正气，这是效法颐养正道的方法。
黄帝说：“我听说上古时代的人都能活过百岁，而动作依然不衰老，现在的人年过半百动作就都衰败了，这是时代不同呢？还是人们违背养生之道造成的呢？”岐伯回答说：“上古时代的人，那些懂得养生之道的人，遵循阴阳变化的规律（一阴一阳的规律叫做道），顺应阴阳的变化（阴阳是万物的开始与终结，生死的根本，违背它就会产生灾害，顺从它就不会发生重病），调和于各种养生方法之中（所谓‘术’，是阴阳的发用；所谓‘数’，是阴阳的节律限度，调和术数，就是效法阴阳。饮食起居，随顺时节安守本分而不放纵欲望，就是这个意思），饮食有节制，起居有规律，不妄自过度劳累（人体需要适度的劳动，这样气血才不会停滞，过度则会伤害身体），所以能够形体与精神协调统一，从而享尽天赋的自然寿命，度过百岁才离世。现在的人却不是这样，把酒当作汤水随意饮用，把妄作劳倦当作常态，醉酒后行房事，以纵欲来耗尽精气，以耗散来亏损真元，不知道保持精气的充盈，不能适时地调控心神（不知道爱惜身体，就像拿着装满水的容器，唯恐它倾覆；不能时时控制心神，就像用腐烂的缰绳驾驭六匹马）。只图满足内心的欲望，违背了养生的乐趣，起居没有节制（房事也是起居内部的事情），所以半百之年形体和精神就衰败了。上古圣人对百姓的教导，都是说要按时避开虚邪贼风，心境恬静淡泊、虚无宁静，真气就会顺从，精神内守，疾病从哪里产生呢？因此志向清闲而欲望少，内心安宁而无恐惧，形体劳作而不疲倦，气血顺从运行，各随其意愿，都能实现愿望（志向不贪婪，所以欲望都能顺遂；内心容易满足，所以愿望都能实现；因为没有非分的追求，所以没有什么难以得到的），所以觉得食物美味（顺应食物的精粗），穿着舒适（随顺衣服的美恶），喜爱风俗习惯（去除倾慕之心），高低地位互不羡慕，百姓因此被称为质朴（无所求，这就是所谓的内心满足）。因此嗜欲不能扰乱他的视线，淫邪不能迷惑他的心，无论愚笨、聪明、贤能或不肖，都不被外物所惊扰（不被外物夺走心神），所以符合大道，因此能活到百岁而动作不衰败，是因为他们的德行完备而没有危险（不放纵情感欲望，不涉足危险境地）。黄帝说：“人老了却没有子女，是精力耗尽了呢？还是天命如此呢？”岐伯说：“女子七岁时肾气旺盛，牙齿更换头发生长；（老阳之数极于九，少阳之数极于七，女子属于少阴之气，所以用少阳的偶数对应它，说明阴阳之气和谐，才能生成形体。）十四岁天癸至，任脉通畅，太冲脉盛旺，月经按时来潮，所以能生育；（癸指壬癸北方水，是天干名。肾气全盛，冲任二脉流通，天真之气下降，应时而下，所以叫天癸，冲脉为血海，任脉主胞胎，月经调匀，所以能生育。）二十一岁时肾气平均，智齿长出且身体长到极限；（智齿，是最后长出的牙齿，牙齿是骨头的余气。）二十八岁时筋骨坚实，头发长到极限，身体壮盛；三十五岁时阳明脉开始衰退，面部开始憔悴，头发开始脱落；（阳明经脉的气血荣润于面部，所以它衰退时，面部憔悴头发脱落。）四十二岁时三阳脉在头部开始衰退，面部全部憔悴，头发开始变白；（三阳经脉，都上行到头，所以三阳衰退则面部全部憔悴，头发开始变白，之所以衰退，是因为随着月数泄脱的缘故。）四十九岁时任脉虚弱，太冲脉衰少，天癸枯竭，月经断绝（经血绝止，这就叫地道不通），所以形体坏败而不能生育。（气血不能荣养自身形体，何况还能生育他人呢？）男子八岁时肾气充实，头发生长牙齿更换；（老阴之数极于十，少阴之数次于八，男子属于少阳之气，所以用少阴的数配合它。）十六岁时肾气旺盛，天癸至，精气满溢而排泄，阴阳调和，所以能生育；（男女有阴阳体质的不同，天癸作为精血的形态也有差异，阴静如海满而去血，阳动应血而泄精，二者通和，所以能生育。《易经》说男女交合精气，万物生化，说的就是这个道理。）二十四岁时肾气平均，筋骨强劲有力，所以智齿长出且身体长到极限；三十二岁时筋骨隆盛，肌肉丰满壮实；四十岁时肾气衰退，头发脱落牙齿枯槁；（精气无所滋养，所以导致头发脱落牙齿枯萎。）四十八岁时阳气在上部衰竭，面部憔悴，两鬓斑白；（阳气，指阳明之气。）五十六岁时肝气衰退，筋脉不能灵活运动，天癸枯竭，精气减少，肾气衰败，形体极度疲惫；六十四岁时牙齿头发脱落。（落也。）肾主水，接受五脏六腑的精气而储藏它，所以五脏精气旺盛才能向肾输送；（五脏各有精气，随使用而灌注于肾，这乃是肾作为汇聚关司之所，并非只有肾这一脏独有精气，所以说五脏旺盛才能泻注给肾。）现在五脏都衰败，筋骨松弛懈怠，天癸已尽，所以两鬓变白，身体沉重，行走不稳，而不能生育。黄帝说：“有的人年纪已经老了却有子女，为什么呢？”岐伯说：“这是因为天赋寿命超过常人，气脉经常通畅，而且肾气有余。这种人虽然有子女，但男子不超过六十四岁，女子不超过四十九岁，天地间的精气都已经竭尽了。（虽然年老而生子，子女的寿命也不能超过天癸存在的年限。）黄帝说：“得道的人，都能活到百岁，还能生育吗？”岐伯说：“得道的人，能抗拒衰老而保全容颜，身体年龄虽高，仍能生育。”
Since physicians understand the cultivation of virtue, they must also cherish their own spirit and essence. The difficulty in medicine lies precisely here. If one's spirit is confused and depleted, observation and discernment cannot be precise, and the selection of prescriptions and herbs cannot be appropriate. Although there may be a heart willing to help others, circumstances will prevent achieving this goal. As for illnesses that do not respond to herbal decoctions or acupuncture, it is because the patients do not know the methods of preserving health. The ancients said: "It is better to prevent illness well before falling sick than to take good medicine after becoming ill." The preceding section records the *Tianzhen Lun* (Discourse on Primal Truth), which represents the origin of preservation; the middle section records *Rudan* (Dietary Lightness) and *Yin Huo Lun* (Discourse on Yin Fire), indicating that preservation essentially involves regulating diet and sexual activity; the latter section further elaborates on expelling evil and revering righteousness, which is the method of adhering to the path of nurturing.
Yellow Emperor said: "I have heard that people in ancient times lived beyond a hundred years without decline in movement, whereas now people decline in movement by half their life span. Is this due to differences in times, or did people lose the way?" Qibo replied: "People in ancient times who understood the Dao followed Yin and Yang (One Yin and One Yang is called Dao). They aligned with Yin and Yang (Yin and Yang are the beginning and end of all things, the root of life and death; opposing them brings disaster, following them prevents severe diseases). They harmonized with techniques and numbers (Technique refers to the manifestation of Yin and Yang; number refers to the rhythm and limits of Yin and Yang. Harmonizing technique and number means following Yin and Yang. This implies regulated diet and daily routine, adapting to seasons and contentment without indulgence). Their diet was moderate, their daily routine regular, and they did not overexert themselves (The body requires slight exertion so that Qi and Blood do not stagnate; excessive exertion harms the body). Thus, their form and spirit remained united, allowing them to complete their natural lifespan and pass away after a hundred years. People today are different. They treat wine as water, make reckless labor a habit, engage in intercourse while drunk, exhaust their Jing (Essence) through desires, and dissipate their Zhen (True Qi) through depletion. They do not know how to maintain fullness, nor do they control their Shen (Spirit) in time (Not cherishing the body is like holding a full vessel, fearing it might spill; failing to control the Shen constantly is like driving six horses with rotten reins). They pursue only the satisfaction of their hearts, going against the joy of life, lacking regulation in daily routines (Intercourse is part of daily internal affairs). Therefore, by half their life span, their form and spirit decline. The sages of old taught the people to avoid empty evils and thieving winds at the proper times, to remain tranquil and void, allowing True Qi to follow, and keeping Spirit within, so that disease would have no place to arise. Thus, their wills were leisurely with few desires, their hearts peaceful without fear, their bodies labored but not exhausted, and their Qi and Blood flowed smoothly in accordance. Each followed their wishes and achieved their hopes (Without greed, desires are fulfilled; with contentment, hopes are realized; without seeking the extraordinary, nothing is difficult to obtain). They found delight in their food (accepting coarse or fine), comfort in their clothing (accepting beautiful or plain), and happiness in their customs (abandoning envy). They did not envy high or low positions, and the people were thus called simple (Having no demands, this is called mental contentment). Therefore, lustful desires could not disturb their eyes, and perverse thoughts could not confuse their minds. Whether foolish or wise, virtuous or unworthy, they were not frightened by external objects (Not being frightened means not being taken away by external things). Thus, they conformed to the Dao. This is why they could live beyond a hundred years without decline in movement: because their virtue was complete and they avoided danger (Not indulging emotions or desires, avoiding dangerous situations).
The Yellow Emperor asked: "When people grow old and have no children, is it because their strength has been exhausted, or is it the decree of Heaven?" Qibo answered: "At age seven, a girl's Kidney Qi becomes abundant, her teeth change, and hair grows. (The number of Old Yang peaks at nine, and Young Yang at seven. Girls belong to Young Yin Qi, so they correspond to the even number of Young Yang, illustrating that harmonious Yin and Yang Qi generates the physical form.) At fourteen, Tian Gui (Heavenly Water/Reproductive Essence) arrives, the Ren Mai (Conception Vessel) becomes unobstructed, and the Chong Mai (Penetrating Vessel) becomes vigorous. Menstruation occurs regularly, enabling conception. (Gui refers to Ren and Gui, the Northern Waters, and Heavenly Stems. When Kidney Qi is fully abundant, Chong and Ren vessels flow freely, and Primal Qi descends timely, hence called Tian Gui. Chong is the Sea of Blood, Ren governs the uterus; regular menstruation enables conception.) At twenty-one, Kidney Qi is balanced, wisdom teeth erupt, and growth reaches its limit. (Wisdom teeth are the last to emerge; teeth are the surplus of bone.) At twenty-eight, sinews and bones are firm, hair reaches its maximum length, and the body is robust. At thirty-five, the Yangming Meridian begins to decline, the face starts to wither, and hair begins to fall. (Yangming meridians nourish the face; their decline causes facial withering and hair loss.) At forty-two, the three Yang meridians decline above, the face completely withers, and hair turns white. (The three Yang meridians ascend to the head; their decline causes facial withering and whitening hair, due to monthly depletion.) At forty-nine, the Ren Mai is deficient, the Chong Mai declines, Tian Gui is exhausted, and the earthly pathway (menstruation) is blocked. (Menstrual blood ceases, which is called the blocking of the earthly pathway.) Thus, the form deteriorates and conception is impossible. (Qi and Blood no longer nourish the self, let alone generate offspring.)
At age eight, a boy's Kidney Qi becomes solid, hair grows, and teeth change. (The number of Old Yin peaks at ten, and Young Yin follows at eight. Boys belong to Young Yang Qi, so they correspond to the number of Young Yin.) At sixteen, Kidney Qi is abundant, Tian Gui arrives, Jing (Essence) overflows and is discharged, Yin and Yang harmonize, enabling conception. (Males and females differ in Yin-Yang constitution, and Tian Gui differs in form as semen and blood. Yin is still, like a full sea releasing blood; Yang is active, responding to blood by discharging semen. Their harmony enables conception. The *I Ching* says male and female combine essence to generate all things, which is what this refers to.) At twenty-four, Kidney Qi is balanced, sinews and bones are strong, wisdom teeth erupt, and growth reaches its limit. At thirty-two, sinews and bones are robust, muscles are full and strong. At forty, Kidney Qi declines, hair falls, and teeth become dry. (Lack of Jing nourishment causes hair loss and tooth decay.) At forty-eight, Yang Qi衰竭 (depletes) above, the face withers, and temples turn gray. (Yang Qi refers to Yangming Qi.) At fifty-six, Liver Qi declines, sinews cannot move, Tian Gui is exhausted, Jing is scarce, Kidney Qi fails, and the form reaches extremity. At sixty-four, teeth and hair fall out. (Falling out.) The Kidney governs Water and receives the essence of the Five Zang and Six Fu organs to store it. Thus, only when the Five Zang are abundant can it discharge. (Each Zang organ has its essence, which pours into the Kidney as needed. The Kidney is the hub and gatekeeper; it does not possess essence exclusively. Hence, 'when Five Zang are abundant, they discharge to the Kidney.') Now, when all Five Zang decline, sinews and bones become lax, Tian Gui is exhausted, temples turn white, the body feels heavy, gait is unsteady, and conception is impossible.
The Yellow Emperor asked: "Some people are old yet have children. Why?" Qibo answered: "This is due to exceeding normal longevity, constant patency of Qi and vessels, and surplus Kidney Qi. Although such people may have children, men do not exceed the limit of 8x8 (64 years), and women do not exceed the limit of 7x7 (49 years), at which point the essence and Qi of Heaven and Earth are exhausted. (Even if an old person has a child, the child's lifespan cannot exceed the duration of Tian Gui.) The Yellow Emperor asked: "Can those who have mastered the Dao, living past a hundred, still have children?" Qibo answered: "Those who master the Dao can resist aging and preserve their appearance. Although their chronological age is advanced, they can still reproduce."