Heaven distributes the Five Phases (Wu Xing) to cultivate all living things; humans receive the Five Constants (Wu Chang) to form the Five Zang Organs. The meridians and fu acupoints are connected, yin and yang communicate with each other, their principles are profound and subtle, and their changes are inexhaustible.

The *Book of Changes* (*Yi Jing*) states: "If it were not the most profound principle under heaven, who could achieve this?" Observing physicians of today, they do not ponder and seek the purport of the classic texts to expand their knowledge; instead, they merely inherit family techniques, adhering strictly to old methods throughout. When examining patients and inquiring about illnesses, they focus only on being eloquent. After a brief conversation, they immediately prescribe decoctions. They palpate the cun position but neglect the chi position, hold the wrist but ignore the foot, and do not cross-reference the Renying (ST 9) and Duyang (ST 42) pulses. They do not count fifty breaths during pulse diagnosis, have no idea how to predict life expectancy through short-term prognosis, show no understanding of the nine pulse positions (Jiu Hou), and fail to inspect the Ming Tang (glabella area) and Que Ting (forehead). This is akin to looking at the sky through a tube. To distinguish between death and life through diagnosis is indeed difficult. These are deep warnings for physicians; how can patients not carefully evaluate them and take precautions?

Since ancient times, physicians have often been jealous and harmful to one another. Bian Que was harmed by Li Xi, the Imperial Physician of Qin, which is a case in point. When one physician prescribes a formula, they should not prevent other physicians from compounding it. If someone privately adds toxic substances, it may worsen the illness and lead to debilitation. Such cases are not rare; one must be particularly cautious. It is better to refuse the medication and rely on natural vitality than to let ignorant physicians, driven by jealousy, harm human lives, which is deeply sorrowful.

The root causes of various diseases include wind-stroke (Zhong Feng), cold damage (Shang Han), alternating chills and fever with warm malaria (Wen Nue), sudden evil (Zhong E) and cholera (Huo Luan), abdominal edema (Da Fu Shui Zhong), dysentery (Chang Pi Xia Li), obstruction of urination and defecation, rushing qi ascending (Ben Tun Shang Qi), coughing and vomiting, jaundice and wasting-thirst (Xiao Ke), retained fluid and food stagnation (Liu Yin Pi Shi), hard accumulations and masses (Jian Ji Zheng Jia), fright evil and epilepsy (Jing Xie Dian Xian), ghost attachment (Gui Zhu), throat obstruction and toothache (Hou Bi Chi Tong), deafness and blindness (Er Long Mu Mang), metal wounds and fractures (Jin Chuang Zhe), carbuncles, sores, and malignant ulcers (Yong Zhong E Chuang), hemorrhoids, tumors, and goiters (Zhi Liu Ying), five labors and seven injuries in men (Nan Zi Wu Lao Qi Shang), deficiency and emaciation (Xu Fa Lei Shou), leukorrhea and metrorrhagia in women (Nv Zi Dai Xia Beng Zhong), blood obstruction and genital erosion (Xue Bi Yin Shi), and injuries from insects, snakes, and gu poison. These are general indications; the specific variations and branches must be investigated according to their origins. There are also cold-heat exhaustion, overeating, sexual excess, fright and fear, worry and anger, postpartum lactation issues, miscarriage, and retained blood stasis. Additionally, there is the greed for taking the Five Minerals (Wu Shi) powder to seek sexual pleasure. These are the roots of disease, giving rise to various branch symptoms. One must know the root and the branches. Merely telling the doctor about the illness, whether male or female, young or old, half of which may be attributed to the disease source, allows for medication. Men are the gathering place of all yang energies and are often dry. Yang energy moves freely; excessive force and emission lead to exhaustion. Diseases of injury are numerous. Compared to women, they are ten times easier to treat. Women above the age of fourteen have menstruation. On the days of menstruation, if affected by wind, cold, dampness, heat, or seasonal pathogens, these must be reported. Otherwise, incorrect treatment may trigger complications and increase debility. Prescribers should inquire about these conditions.

Medication should always suit the local environment. In Jiangnan and Lingbiao regions, where the climate is hot and damp, people have thin and fragile skin with open pores, requiring light and simple medications. In Guanzhong and Hebei, where the land is rigid and dry, people have tough skin and closed pores, requiring heavier or more complex medications.

Among the young and vigorous, those who do not avoid wind and dampness, violate taboos, and suddenly exhaust their essence, even if they contract minor illnesses, should not be lightly treated with purgative medicines. If the purgative effect is too strong, it will deplete the essence, causing bedridden debilitation lasting months or even a year. For chronic diseases suitable for purgative decoctions, one need not finish the entire dose; stop when bowel movement is sufficient. If the disease source remains, prepare another dose later. If the patient has enough strength to finish the dose, this rule does not apply.

For diseases requiring purgative decoctions to remove the source, pill and powder preparations should be taken intermittently afterward to assist recovery.

After a patient recovers from a purgative decoction, one must be cautious and not immediately administer tonic decoctions. If tonics are given, the disease may return, and subsequent purging would cause further harm. If the patient has just recovered and strength is not fully restored, one should observe and wait. If medication is needed, use mild harmonizing drugs. For those who suffer from frequent illnesses but can walk and have not lost strength, wishing to take tonics, if there are pills or powders suitable for their cold or heat condition, they should first take a purgative decoction to clear phlegm and solid accumulation in the chest and abdomen, and only then take tonics. For extreme deficiency and exhaustion requiring tonics, three doses are sufficient. For treating wind diseases with wind-dispelling decoctions, improvement is not seen in three to five doses. Conditions like stagnant wind and hollow emptiness may require ten or more doses, sometimes taking over a hundred days to heal. Thus it is said: Excess is treated by purging; deficiency is treated by tonifying.

Within the two realms (Heaven and Earth), among yin and yang, humans are the most precious. Humans receive the harmonious qi of heaven and earth; laws, rites, and music all originate from humans. At conception, essence forms first; when essence is complete, brain and marrow are generated. The head is round, modeling Heaven; the feet are square, modeling Earth; eyes correspond to the sun and moon; the five zang organs correspond to the five planets; the six fu organs correspond to the six musical pitches, with the heart as the central pole. The large intestine is one zhang and two chi long, corresponding to twelve double-hours; the small intestine is two zhang and four chi long, corresponding to twenty-four solar terms; the body has three hundred and sixty-five collaterals, corresponding to the days of a year; humans have nine orifices, corresponding to the Nine Provinces; Heaven has cold and heat, humans have deficiency and excess; Heaven has punishment and virtue, humans have love and hate; Heaven has yin and yang, humans have male and female; the moon has waxing and waning, humans have tall and short. Therefore, improper consumption of the five grains, conflicting cold, heat, salty, and bitter flavors, attacking each other within the body, leads to disease. Diagnosis by physicians is inherently difficult; adding inquiry to discern the depth of the disease is called skillful medicine. Zhang Zhongjing said: "When preparing decoctions, compounding medicines, or using acupuncture and moxibustion, one must think carefully, must understand the twelve meridians, differentiate the three hundred and sixty acupoints and the circulation of ying and wei qi, know the location of the disease, and master the appropriate treatment methods." Ancient superior physicians observed complexion; color, pulse, and form must not contradict each other. Black overcoming red indicates death; red overcoming green indicates survival. Intermediate physicians listened to sounds; sounds conform to the five tones. Hearing water sounds like fire causes irritability and panic; hearing metal sounds like wood implies fear and punishment. Spleen belongs to earth, nourishing all things and assisting the four directions. When healthy, it is unseen; when dead, it returns to it. Excess leads to inability to move the limbs; deficiency leads to obstruction of the nine orifices, closure of the six senses, resembling drunkenness. The four seasons rotate in a cycle. Inferior physicians diagnose by pulse, knowing the origin of the disease, its flow and movement, the reversals and順逆 of the four seasons, mutual harm and generation, and comprehending the subtleties of the zang and fu organs; this is truly wonderful.