论曰∶人生四十以下，多有放恣，四十以上，即顿觉气力一时衰退，衰退既至，众病蜂
起，久而不治，遂至不救。所以彭祖曰∶以人疗人，真得其真。故年至四十，须识房中之术。
夫房中术者，其道甚近，而人莫能行。其法一夕御十人，闭固而已，此房中之术毕矣。兼之
药饵，四时勿绝，则气力百倍，而智能日新。然此方之作也，非欲务于淫佚，苟求快意，务
存节欲，以广养生，此房中之微旨也。是以人年四十以下，即服房中之药者，皆所以速祸，
故年未满四十者，不可与论房中之事，欲心未止，兼饵补药，倍力行房，不过半年，精髓枯
竭，唯向死近。少年极须慎之。四十以上，常固精养气不耗，可以不老。又饵云母，足以愈
疾延年，勿服泄药，常饵补药大佳。凡御女之道，不欲令气未感动，阳气微弱即以交合，必
须先徐徐调和，使神和意感良久，乃可令得阴气推之，须臾自强，所谓弱而内迎，坚急出之，
进退欲令疏迟，情动而止，不可高自投掷，颠倒五脏，伤绝精脉，致生百病。但数交而慎密
者，诸病患皆愈。能百接而不施泻者，长年矣。凡人精少则病，精尽则死，不可不思，不可
不慎。数交而一泻，精气随长，不能使人虚也。若不数交，交而即泻，则不得益，泻之精气
自然生长，但迟微，不如数交接不泻之速也。凡人习交合之时，常以鼻多纳气，口微吐气，
自然益矣。交会毕蒸热，是得气也，以菖蒲末三分、白粱粉敷摩令燥，既使强盛，又湿疮
不生也。凡欲施泻者，当闭口张目，闭气，握固两手，左右上下缩鼻取气，又缩下部及吸腹，
小偃脊膂，急以左手中两指抑屏翳穴，长吐气并琢齿千遍，则精上补脑，使人长生。若精妄
出，则损神也。《仙经》曰∶令人长生不老。先与女戏，饮玉浆。玉浆口中津也。使男女感
动，以左手握持，思存丹田中有赤气，内黄外白，变为日月，徘徊丹田中，俱入泥垣，两半
合成一因，闭气深纳勿出但入，上下徐徐咽气，情动欲出，急退之，此非上士有智者不能行
也。其丹田在脐下三寸。泥垣者在头中对，两目直入内思，作日月想，合径三寸许，两半放
形则一，为日月相 者也。虽出入仍思念所作者勿废，佳也。又曰∶男女俱仙之道，深纳勿
动，精思脐中赤色大如鸡子形，乃徐徐出入，情动乃退，一日一夕可数十为定，令人益寿。
男女各息意共存思之，可猛念之。御女之法能一月再泄，一岁二十四泄，皆得二百岁，有颜
色，无疾病，若加以药，则可长生也。人年二十者，四日一泄，三十者八日一泄，四十者十
六日一泄，五十者二十日一泄，六十者闭精勿泄，若体力犹壮者，一月一泄。凡人气力自有
强盛过人者，亦不可抑忍，久而不泄，致生痈疽。若年过六十，而有数旬不得交合，意中平
平者，自可闭固也。昔贞观初有一野老，年七十余，诣余曰∶数日来阳气益盛，自思气血已
衰，何有此盛，未知垂老有此，为善恶耶？余答之曰∶是大不祥，子独不闻膏火乎，夫膏火
之将竭也，必先暗而后明，明止则灭，今足下年迈桑榆，久当闭精息欲，兹忽春情猛发，岂
非反常耶。窃谓足下忧之，子其勉欤，后四旬发病而死，此其不慎之效也。如斯之辈非一，
且疏一人，以勖将来耳。所以善摄生者，凡觉阳事辄盛，必谨而抑之，不可纵心竭意以自贼
也。若一度制得，则一度火灭，一度增油。若不能制，纵情施泻，即是膏火将灭，更去其油，
可
晚而自保，犹得延年益寿。若年少壮而能行道者，神仙速矣。或曰年未六十，当闭精守一为
可尔否，曰∶不然，男不可无女，女不可无男。无女则意动，意动则神劳，神劳则损寿。若
念真正无可思者，则大佳长生也。然而万无一有，强抑郁闭之，难持易失，使人漏精尿浊，
以致鬼交之病，损一而当百也，其服食药物，见本卷服篇中。御女之法，交会者当避丙丁日
，及弦望晦朔，大风大雨大雾大寒大暑雷电霹雳，天地晦冥，日月薄蚀，虹霓地动，若御女
则损人神不吉，损男百倍，令女得病，有子必癫痴顽愚，喑哑聋聩，挛跛盲眇，多病短寿，
不孝不仁。又避日月星辰，火光之下，神庙佛寺之中，井灶圊厕之侧，冢墓尸柩之旁，皆所
不可。夫交合如法，则有福德，大智善人降托胎中，仍令性行调顺，所作和合，家道日隆
，祥瑞竞集，若不如法，则有薄福愚痴恶人来托胎中，仍令父母性行凶险，所作不成，家道
日否，殃咎屡至，虽生成长，家国灭亡。夫祸福之应，有如影响，此乃必然之理，可不再思
之。若欲得子者，但待妇人月经后一日、三日、五日，择其王相日，生气时夜半后乃施泄，
有子皆男，必寿而贤明高爵也；以月经绝后二日、四日、六日施泄，有子必女；过六日后勿
得施泄，既不得子，亦不成人。黄帝杂禁忌法曰∶人有所怒，血气未定，因以交合，令发痈
疽。又不可忍小便交合，使人淋茎中痛，面失血色。及远行疲乏来入房，五劳虚损，少子。
且妇人月事未绝而与交合，令人成病，得白驳也。水银、鹿脂不可近阴，令阴痿缩。
论曰：人生四十岁以前，大多行为放纵不羁；到了四十岁以上，就会突然感到气力在一瞬间衰退。衰退一旦到来，各种疾病便会蜂拥而起，如果长期不治疗，最终会导致无法挽救的后果。所以彭祖说：“以人治人（指通过房中术调节人体精气），才能真正获得生命的真谛。”因此，人到了四十岁，必须懂得房中之术。
所谓房中术，其道并不深奥难行，但人们往往不能实行。其方法在于一夜之间与十位女性交合，关键在于固守精气不外泄罢了，这就是房中术的精髓。如果再配合服用药物，四季不间断，就能使气力增加百倍，智慧日益更新。然而制定这个方术的目的，并不是为了追求淫乱逸乐、苟且求得一时快感，而是旨在节制欲望，以扩充养生之道，这是房中术的精微旨意。因此，四十岁以下的人如果服用房中补益的药物，都是在加速灾祸的到来。所以年龄未满四十岁的人，不可以与他谈论房中之事，因为他们的欲心尚未止息，如果再加上服用补药，加倍努力行房，不超过半年，精髓就会枯竭，离死亡就不远了。年轻人对此必须极其谨慎。四十岁以上的人，如果能经常固摄精气、保养元气而不耗散，就可以保持不老。另外服用云母，足以治愈疾病、延长寿命，但不要服用泻药，经常服用补药是非常好的。
大凡与女子交合的道理，不希望在自己气机未动、阳气微弱的时候就进行交合，必须先慢慢调和，使精神和谐、情意感应很久之后，才可以让阴气推动自己，片刻之后自然强健有力。这叫做“弱而内迎，坚急出之”（在自身尚弱时接纳对方，在坚硬时快速抽出）。进退要力求缓慢从容，情动即止，不可盲目投掷，以免颠倒五脏，损伤精脉，导致产生百病。只要多次交合而谨慎严密，各种病患都能痊愈。能够一百次交合而不射精的人，可以长寿。大凡人精液少就会生病，精液耗尽就会死亡，不可不思考，不可不谨慎。多次交合而只射精一次，精气会随着生长，不会使人虚弱。如果不多次交合，一交合就射精，那就得不到益处，虽然射出的精气自然会生长，但缓慢微弱，不如多次交接而不射精的速度快。大凡习惯于交合的时候，常用鼻子多吸入清气，嘴巴微微呼出浊气，自然有益。交合结束后身体蒸热，这是得气的表现，用三分菖蒲末和白粱粉敷摩身体使其干燥，既能使身体强盛，又不会生湿疮。
凡是想要射精的人，应当闭口张目，屏住呼吸，两手握固，左右上下收缩鼻部吸气，同时收缩下部及腹部，背部微微后仰，急忙用左手中指和食指按压屏翳穴，长长地吐气并研磨牙齿一千遍，那么精气就会上行补脑，使人长生。如果精气妄自流出，就会损伤神气。《仙经》说：能让人长生不老。先与女子嬉戏，饮用玉浆。玉浆就是口中的津液。使男女感动，用左手握住阴茎，意念存想丹田中有赤色之气，内黄外白，变为日月，在丹田中徘徊，一起进入泥垣宫，两半合成一个整体，屏住呼吸深深纳入不要出来只进不出，上下慢慢吞咽气息，情动想要射出时，急忙退出来，这不是上等的智者不能实行的。其丹田位于脐下三寸。泥垣宫在头部正中，两目直入内部思虑，想象日月，直径约三寸，两半放开形状则合一，如同日月相合的样子。虽然进出仍然思念所修持的方法不要废弃，这样很好。又说：男女共同成仙的方法，深深纳入不要移动，精心思虑脐中红色大如鸡蛋的形状，然后慢慢出入，情动才后退，一天一夜可以作为几十次的定数，能让人益寿。男女各自平息心意共同思虑，可以猛烈念诵。御女之法如果能一个月两次泄精，一年二十四次泄精，都能活到二百岁，面色红润，没有疾病，如果加上服药，就可以长生了。人二十岁的，四天一次泄精；三十岁的，八天一次泄精；四十岁的，十六天一次泄精；五十岁的，二十天一次泄精；六十岁的，封闭精气不要泄精，如果体力还强壮的，一个月一次泄精。大凡人的气力自有超过常人的，也不可抑制忍耐，长时间不泄精，会导致生痈疽。如果年过六十，而有几十天不得交合，心中平平常常的，自然可以固摄精气。
过去贞观初年有一位乡下老人，七十多岁，来见我说道：“这几天阳气越发旺盛，我自己思考气血已经衰弱，怎么会有这种旺盛？不知道垂老之年有此现象，是吉是凶？”我回答他说：“这是非常不吉祥的，您难道没听说过膏火吗？膏火将要耗尽的时候，必定先变暗然后变亮，光亮停止后就熄灭了。现在您年纪大了，长久以来应当闭精息欲，忽然春情猛发，岂不是反常吗？我私下为您担忧，您要努力克制啊！”后来过了四十天发病而死，这就是不谨慎的后果。像这样的人不止一个，暂且记录这一人，以勉励后来者。所以善于养生的人，凡是觉得阳事勃起旺盛，必须谨慎抑制它，不可放纵心意竭尽精力来残害自己。如果一次能控制住，就是一次火灭，一次添油。如果不能控制，纵情施泻，就像是膏火将灭，又去掉它的油，晚上还能自我保全，还可以延年益寿。如果年少壮健而能行道的人，成神仙就快了。有人说：年龄不到六十岁，应当闭精守一这样可以吗？回答说：不对，男人不可没有女人，女人不可没有男人。没有女人则心意动摇，心意动摇则神劳损，神劳损则减寿。如果念头真正无可思恋的，那最好，可以长生。然而万中无一，强行压抑封闭，难以坚持容易失去，使人漏精尿浊，以致发生鬼交之病，损害一处相当于损害百处。至于服食药物，见本卷服饵篇中。
御女之法，交合时要避开丙丁日，以及弦望晦朔（农历每月初七、初八、十五、十六、三十、初一），大风大雨大雾大寒大暑雷电霹雳，天地昏暗，日月亏蚀，虹霓地动等情况，如果在此时御女则损伤人的神气，不吉利，损伤男子百倍，使女子得病，有孩子必定癫痴顽愚，哑聋盲跛，多病短寿，不孝不仁。还要避开日月星辰之下，火光之下，神庙佛寺之中，井灶厕所旁边，坟墓尸柩旁边，都是不可取的。如果交合合乎法度，就有福德，大智善人会降托胎中，仍会让性情行为调顺，所作所为和谐，家道日益兴隆，祥瑞竞相聚集；如果不合法度，则有薄福愚痴恶人来托胎中，仍会让父母性情行为凶险，所作之事不成，家道日益衰败，殃咎屡次到来，即使生成长大，家国也会灭亡。祸福的应验，就像影子跟随形体一样，这是必然的道理，可以不再次深思吗？如果想要得子，只需等待妇人月经后一日、三日、五日，选择其王相日，生气时夜半后进行施泄，有儿子必定长寿贤明高爵；如果在月经绝后二日、四日、六日施泄，有女儿；超过六日后不要施泄，既不得子，也不成人。黄帝杂禁忌法说：人生气时，血气未定，因以交合，令发痈疽。又不可忍小便时交合，使人淋茎中痛，面色失血色。以及远行疲乏后入房，导致五劳虚损，少子。而且妇人在月事未结束时就与交合，令人成病，得白驳病（白癜风）。水银、鹿脂不可接触阴部，令阴痿缩。
Commentary states: Before the age of forty, people often indulge in unrestrained behavior; upon reaching forty, one may suddenly feel a rapid decline in physical strength. Once this decline sets in, various diseases will arise like swarms of bees. If left untreated for a long time, it leads to an incurable state. Therefore, Peng Zu said, "Healing man with man [through sexual regulation] truly captures the essence of life." Thus, at the age of forty, one must understand the art of bedchamber (Fangzhong).
The art of bedchamber is not far-fetched, yet few can practice it. Its method involves intercourse with ten women in one night, focusing solely on retaining and securing the essence (Bi Gu). This constitutes the entirety of the bedchamber art. Combined with medicinal intake without interruption throughout the four seasons, one's strength will increase a hundredfold, and intelligence will renew daily. However, the purpose of formulating this method is not to pursue licentiousness or seek fleeting pleasure, but to conserve desire and expand the path of health preservation. This is the subtle purport of the bedchamber art. Therefore, those under forty who take bedchamber tonics are hastening disaster. Hence, one under forty should not be discussed regarding bedchamber matters, as their desire remains unchecked. Coupled with tonic herbs and excessive exertion, within half a year, the essence and marrow will be exhausted, bringing them close to death. Youth must be extremely cautious. Those over forty who constantly secure essence and nourish Qi without depletion can avoid aging. Additionally, consuming Yumu (Cloud Mother/Mica) can cure diseases and prolong life. One should avoid purgative drugs and frequently take tonics, which is highly beneficial.
In general, the principle of intercourse dictates that one should not engage when Qi is unaroused and Yang Qi is weak. One must first harmonize slowly, allowing spirit and intent to resonate for a long time, before Yin Qi can drive the process, leading to natural vigor. This is described as "welcoming inwardly while weak, withdrawing firmly and quickly." Movements should be slow and deliberate; stop when emotion stirs. Do not throw oneself recklessly, lest the Zang-Fu organs be inverted, Jing Mai (essence vessels) damaged, and myriad diseases born. Frequent, cautious intercourse can cure various ailments. One who can have intercourse a hundred times without ejaculation can achieve longevity. Generally, scant essence causes illness; exhausted essence leads to death. This requires deep reflection and caution. Frequent intercourse with infrequent ejaculation allows essence to regenerate, preventing deficiency. Infrequent intercourse with immediate ejaculation yields no benefit; although regenerated essence grows naturally, it does so slowly and weakly, inferior to the speed of regeneration seen in frequent non-ejaculatory intercourse. During intercourse, inhale deeply through the nose and exhale slightly through the mouth, which is naturally beneficial. Post-intercourse steaming heat indicates obtaining Qi. Apply three parts Changpu (Rhizoma Acori Tatarinowii) powder mixed with Bai Liang Fen (White Millet Flour) to the body until dry; this strengthens the body and prevents damp sores.
When intending to ejaculate, keep the mouth closed, eyes open, hold the breath, clench hands into fists (Wo Gu), inhale by contracting the nose up and down, contract the lower abdomen and perineum, arch the back slightly, and press the Pingyi acupoint with the middle and index fingers of the left hand. Exhale slowly and grind teeth a thousand times. This directs essence upward to nourish the brain, promoting longevity. Wasteful loss of essence damages Shen (Spirit). The *Xian Jing* (Immortal Classic) states this enables immortality. Begin with foreplay and drink Yu Jiang (Jade Fluid/Saliva). Use the left hand to grasp the penis, visualize red Qi in the Dantian (Lower Elixir Field), yellow inside and white outside, transforming into sun and moon imagery, circulating in the Dantian, merging into Ni Yuan (Mud Pill Palace/Upper Dantian). Hold breath, penetrate deeply without withdrawal, swallow Qi slowly. When arousal peaks, withdraw immediately. This is difficult for all but the wise and virtuous. The Dantian is three cun below the umbilicus. Ni Yuan is in the center of the head; visualize the sun and moon between the eyes, diameter about three cun, merging halves into one. Maintain this visualization during entry and exit. Another method for mutual immortality involves deep penetration without movement, visualizing red Qi in the navel the size of a chicken egg, moving slowly, retreating upon arousal. Doing this dozens of times daily extends life. Both partners should focus intensely. Regulating ejaculation to twice a month (twenty-four times a year) allows living to two hundred years with good complexion and health; adding herbs ensures longevity. Men aged twenty should ejaculate every four days; thirty, every eight days; forty, every sixteen days; fifty, every twenty days; sixty, retain essence without ejaculation. If physically robust at sixty, once a month is acceptable. Even those with exceptional strength should not suppress ejaculation indefinitely, as retention can cause carbuncles and sores. For men over sixty who go weeks without intercourse and feel neutral, retention is appropriate.
In the early Zhenguan era, a villager over seventy visited me, saying his Yang energy was unusually strong despite his frailty, asking if this was auspicious. I replied, "This is highly inauspicious. Have you not heard of oil lamps? When oil runs out, the flame flickers bright then dies. You are old and should have ceased desire; sudden passion is abnormal. I worry for you; restrain yourself." He died forty days later from illness, proving the danger of imprudence. Such cases are common; I record this to warn future generations. Good preservers of life must restrain rising Yang Qi, not indulging to self-harm. Controlling ejaculation extinguishes fire and adds oil. Indulgence extinguishes fire and removes oil, though late protection may still extend life. Young practitioners of this Dao may become immortals quickly. Some ask if one under sixty should retain essence. I say no: men need women, and women need men. Without women, mind wanders, Shen labors, and lifespan shortens. Only if one has no desires can they truly live long. Forced suppression is dangerous, causing leakage, turbid urine, and "ghost intercourse" disease, doing more harm than good. See the Tonics chapter for herbal details.
Avoid intercourse on Bing-Ding days, lunar quarters (Shang Xiang, Full Moon), New Moon (Hui Shuo), and during extreme weather (wind, rain, fog, cold, heat, thunder, lightning), celestial darkness, eclipses, earthquakes, or rainbow phenomena. Violating these harms Shen, especially for men, sickens women, and produces children who are foolish, deaf, mute, blind, crippled, short-lived, unfilial, and unkind. Avoid locations under stars/moon, firelight, temples, wells, stoves, latrines, or near graves/corpses. Proper intercourse brings fortune, attracting wise souls to the fetus, ensuring harmonious temperament and family prosperity. Improper intercourse attracts wicked souls, causing parental aggression, failure, family decline, and calamities. Fortune and misfortune follow like shadows; this is inevitable. To conceive, wait one, three, or five days after menstruation ends, choosing auspicious days/times (after midnight). Sons will be long-lived and noble. Conceive on two, four, or six days post-menstruation for daughters. After six days, do not attempt conception, as it yields neither child nor viability. The *Huangdi Za Jin Ji Fa* warns: Intercourse during anger disrupts Qi/Blood, causing sores. Do not urinate before intercourse to avoid painful dysuria and pallor. Do not have sex when fatigued from travel, to prevent Five Wastes deficiency and infertility. Intercourse during menstruation causes disease and Bai Bo (vitiligo). Mercury and deer fat applied to the genitals cause impotence and retraction.