In the Inner Canon of Yellow Emperor (黄帝内经), human development is classified into 4 stages: Wise Person (贤人), Saintly Person(圣人), Outmost Person(至人), and Real Person(真人).

A wise person follows the laws of sky, earth, sun, moon, star, follows the law of yin-yang four seasons, lives in accordance with the methods and ways prescribed in the ancient period. Their age extended, but still limited. Typical spiritual practitioners falls into this category.

A saintly person positions himself in harmony with sky and earth and their laws, allows appropriate desire within the secular world, has no anger, does not depart form the world, but does not follow it blindly either, externally does not fatigue his form, internally does not have mind problem, strives at simple happiness, of self sufficiency, body stays health, spirit stays condensed, age reaches one hundred. Confucius (孔子) is an example of this type of person.

An outmost person aligns with Dao with pure virtue, harmonizes with Yin-yang, regulates with four seasons, departs from the world and the secular, accumulates essence to full the spirit, travels between sky and earth, sees and hears from afar. Life strengthened and extended. Chuangzi (庄子) is an example of this type of person.

A real person supports sky and earth, masters yin-yang, breathes essence and chi, abides one spirit independently, integrates body as one, lives long like sky and earth, without end, as the Dao. Laozi (老子) is an example of this type of person.