《灵枢·天年篇》帝曰∶人之始生，何气筑为基？何立而为 ？何失而死？何得而生？岐伯曰∶以母为基，
以父为 ，失神者死，得神者生也。帝曰∶何者为神？岐伯曰∶血气已和，营卫已通，五脏已成，神气舍心，
魂魄毕具，乃成为人。
此言人之始生，由父母之气血以成形体。而母则乳哺，故为基；父则抚卫，故为 。得以气血调和，而神
气舍心，以生成之。如其气血未和，不能生长，则神气渐丧而死，所以父母为之基 也。
帝曰∶人之寿夭各不同，或夭寿，或卒死，或病久，愿闻其道。岐伯曰∶五脏坚固，血脉和调，肌肉解
利，皮肤致密，营卫之行，不失其常，呼吸微徐，气以度行，六腑化谷，津液布扬，各如其常，故能长久。帝
曰∶人之寿百岁而死，何以知之？岐伯曰∶使道隧以长，基墙高以方，通调营卫，三部三里起，骨高肉满，
百岁乃得终。
此言人赖气血以资生。气血调和，肉坚肤密，脏腑生化，营卫流行，自然无病，而可延年。然禀质有浓薄，
其无病者，得尽天寿；而长短本于天赋，非学道不能永寿也。如其禀浓，则外貌亦浓而可验。使道者，鼻下水
沟也，亦名唇中。隧者，沟深也。基墙者，面与耳也。三部者，上额、中颧、鼻下口颐也。起者，隆盛，即
骨高肉满也，如此，故其天寿可至百岁也。
In the "Tian Nian" (Natural Lifespan) chapter of *Ling Shu* (Spiritual Pivot), the Yellow Emperor asked: When human life first begins, what constitutes the foundation? What serves as the support? What loss leads to death? What gain leads to life? Qibo replied: The mother's Qi and Blood constitute the foundation, while the father's Qi and Blood serve as the support. One dies when Shen (Spirit) is lost, and one lives when Shen is acquired.
The Yellow Emperor asked: What is Shen (Spirit)? Qibo said: When Qi and Blood are harmonized, Ying (Nutritive) Wei (Defensive) Qi are unobstructed, the Five Zang Organs are formed, Shen resides in the Heart, and Hun (Ethereal Soul) and Po (Corporeal Soul) are fully present, then a human being is formed.
This passage explains that the initial formation of human life relies on the parents' Qi and Blood to shape the physical body. The mother provides nourishment through lactation, thus serving as the foundation; the father provides care and protection, thus serving as the support. If Qi and Blood are harmonized and Shen resides in the Heart, life is generated. Conversely, if Qi and Blood are not harmonized and growth cannot occur, Shen will gradually dissipate leading to death. This is why the parents serve as the foundation and support.
The Yellow Emperor further asked: People have different lifespans; some die young, some live long, some die suddenly, and some suffer from chronic illness. I wish to hear the principles behind this. Qibo replied: If the Five Zang Organs are solid, blood vessels are harmonious, muscles and joints are supple, skin is dense, the circulation of Ying and Wei Qi follows its normal pattern, respiration is gentle and slow, Qi moves according to regular measures, the Six Fu Organs transform food and grain, and Body Fluids are distributed throughout the body, with all functions maintaining their normal state, then longevity can be achieved.
The Yellow Emperor asked: How can one know that a person will live to a hundred years before passing away? Qibo replied: If the Ren Zhong groove (Shi Dao, located below the nose and above the upper lip) is deep and long, the facial bones and ears are high and square, Ying and Wei Qi are well-regulated, the three regions (San Bu) and the San Li areas are prominent, bones are high, and flesh is full, then one may reach the natural lifespan of a hundred years.
This section discusses how humans rely on Qi and Blood for sustenance. When Qi and Blood are harmonized, muscles are firm, skin is dense, Zang-Fu transformation and transportation function normally, and Ying-Wei circulation is smooth, disease is naturally absent, allowing for extended life. However, innate endowment varies in thickness or thinness. Those without illness may enjoy their full natural lifespan; yet, the length of life is determined by heaven-endowed constitution, and one cannot achieve immortality without cultivating the Dao. If one has a robust endowment, external features will also reflect this robustness, making it verifiable. "Shi Dao" refers to the philtrum (Ren Zhong acupoint), also known as Chun Zhong. "Sui" means deep trench. "Ji Qiang" refers to the face and ears. "San Bu" refers to the upper forehead, middle cheekbones (Zigong), and the area from below the nose to the chin/mouth. "Qi" means prominence or swelling, corresponding to high bones and full flesh. With such characteristics, one's natural lifespan can indeed reach one hundred years.