The human body is referred to as a "house" in immortal formulas. The ears, eyes, mouth, and nose are the windows and doors of the house; the hands, feet, limbs, and joints are the beams and rafters; the hair and skin are the walls and fences. Terms such as *Qishu* (Qi Pivot), *Xueshi* (Blood Chamber), *Yishe* (Residence of Intent), *Canglin Xuanfu* (Mysterious Mansion of Granary), *Niwan Yougong* (Dark Palace of Niwan, referring to the upper Dantian/brain), *Zifang Yuque* (Jade Palace of Zifang, referring to the heart/chest), *Shi'er Chonglou* (Twelve-Story Tower, referring to the trachea), *Benmen* (Gate of Rejection, referring to the cardia of the stomach), *Feimen* (Flying Gate, referring to the lips), and *Xuanpin* (Mysterious Female, referring to the root of life) constitute numerous gates, yet there is one who governs them. Just as a house may be shaken by violent storms and rain, eroded by insects and ants, or damaged by thieves; if left unchecked and unguarded, day after day and month after month, it will tilt and collapse, becoming uninhabitable. The body is like a house, and the Heart (*Xin*) is the master residing within. If the master can consistently exert control, then the windows, beams, and walls will remain intact and solid, thereby allowing one to attain "Longevity of Di Yuan" (longevity derived from cultivating earthly Qi).

Laozi said: The maximum lifespan of humans is limited to one hundred years. Those who practice moderation and care can live up to a thousand years, much like the difference between a small wick and a large wick in an oil lamp. While others speak loudly, I speak softly; while others are troubled by many affairs, I keep my mind simple; while others are fearful and irritable, I do not anger. By not letting worldly affairs burden the mind, remaining calm and non-action-oriented (*Wuwei*), the Spirit (*Shen*) and Qi naturally become abundant, serving as medicine for immortality.

Zhuangzi said: One who respects life does not let wealth and honor harm the body through excessive indulgence, nor does one let poverty and low status burden the form through the pursuit of profit. Currently, those in high positions and noble ranks in the world severely violate this principle. The Inscription of Sun Simiao states: Excessive anger injures Qi unevenly; excessive thinking greatly damages Shen. When Shen is exhausted, the Heart is easily dominated; when Qi is weak, diseases entangle. Do not allow joy or sorrow to reach extremes; ensure dietary balance. Guard repeatedly against night intoxication; first, abstain from morning drunkenness. At night, sleep with alertness akin to ringing drums; in the morning, rinse with jade saliva (swallowing oral fluids). Even if evil influences attack, Essence (*Jing*) and Qi protect the whole body. To avoid all illnesses, always moderate the consumption of the Five Pungents (*Wuxin*). To calm the Spirit, seek joy and happiness; to preserve Qi, maintain harmony and purity. Do not discuss longevity or shortness of life as fate; cultivation lies within human effort. If one follows this principle, one can ascend to truth even on flat ground.

Books state: Those who have not heard the Dao release their hearts to rebellion, going against the joys of life, chasing wisdom and cleverness with their Spirit, chasing gains and losses with worry and fear, chasing etiquette with labor and hardship, and chasing wealth and profit with their bodies. If these four desires are not abandoned, the Heart becomes diseased.

Tao Hongjing said: Among all things, humans are the most spiritual and precious, yet a hundred years of time are but a temporary lodging. Unless one focuses on remembrance and cultivation, one inevitably suffers from illness and hardship as a burden to the body.