Six seven, the three Yang Meridians decline above, the face is withered, and hair begins to turn white. Seven seven, the Ren Meridian is deficient, the Thoroughfare Vessel weakens, heavenly water is exhausted, and earthly pathway is blocked, hence the body deteriorates and is childless. At eight, the boy’s kidney Qi is solid, hair grows, and teeth change.

At two eight, kidney Qi flourishes, heavenly water arrives, essence Qi overflows and spills, Yin and Yang harmonize, hence a child can be conceived. At three eight, kidney Qi is balanced, tendons and bones are strong and firm, hence adult teeth grow to full length. At four eight, tendons and bones are sturdy, muscles are full and strong.

At five eight, kidney Qi declines, hair falls out, teeth wither. At six eight, Yang Qi is exhausted above, the face is withered, temples and hair turn white. At seven eight, liver Qi weakens, tendons cannot move, heavenly water is exhausted, essence is diminished, kidney storage declines, and the body reaches its limit. At eight eight, teeth and hair fall out.

The kidneys store essence, essence transforms into Qi, when kidney essence is sufficient, kidney Qi is abundant, when kidney essence is deficient, kidney Qi declines.

The life process of growth and development, from birth to maturity, aging, and demise, can be divided into several stages: infancy, adolescence, adulthood, and old age, each phase of growth and development is dependent on the prosperity or decline of kidney essence and kidney Qi, reflecting in the changes of "teeth, bones, hair". After birth, as kidney essence and kidney Qi gradually fill up, in infancy, it is manifested as rapid growth of hair, increasingly dense, replacement of milk teeth, skeletal growth, and increased height;

In adolescence, kidney essence and kidney Qi peak, manifested in the growth of wisdom teeth, bone maturation, and reaching a certain body height;

In adulthood, kidney essence and Qi are at their peak, demonstrated by the strength of tendons and bones, black and shiny hair, solid body, and abundant energy;

In old age, as kidney essence and Qi gradually decline, it is manifested in a haggard complexion, hair loss, withered teeth, etc. In children, if kidney essence and Qi are insufficient, growth and development are stunted, showing five delays (late standing, late speech, late walking, late hair growth, late teething), and five weaknesses (soft head, soft neck, soft limbs, soft muscles, soft mouth); in adults, it leads to premature aging.

The development of the reproductive system, the maturation and maintenance of sexual function, and reproductive capability are equally dependent on the prosperity or decline of kidney essence and Qi.

After birth, as kidney essence and Qi continuously fill, heavenly water is subsequently produced.

Heavenly water, produced when kidney essence and Qi reach a certain level, is a subtle substance that promotes the development and maturation of human reproductive organs and maintains reproductive functions.

With the arrival of heavenly water, menstruation occurs in women, and essence Qi overflows in men, indicating that sexual organs are mature and reproductive capability is present.

Thereafter, the increasing fullness of kidney essence and Qi maintains the ever-growing reproductive functions.

After middle age, as kidney essence and Qi gradually decline, heavenly water also diminishes until exhaustion, reproductive functions gradually weaken, reproductive organs wither. Eventually, reproductive capability is lost, entering old age.

Clinically, to prevent and treat certain congenital diseases, developmental delays, low reproductive functions or some primary infertility, as well as eugenics, health preservation, anti-aging, many also focus on supplementing kidney essence and Qi.

Upon hearing this, Zhang Guangli took a breath, feeling deeply respectful.

Shocked!

Zhang Guangli’s face revealed an unprecedented shock!

Since starting to learn about traditional Chinese medicine from his father until now, it was the first time Zhang Guangli had seen someone explain knowledge about the kidneys in such detail.

At this moment, Zhang Guangli somewhat regretted that he should have taken notes.

These matters are worth studying for a lifetime.

Moreover, even a lifetime of study might not fully explore its profound mysteries.

The most crucial thing is, Zhang Guangli knew, these were just a very small part of it, the records and knowledge about kidneys in traditional Chinese medicine are far more than that.

Because, Lu Xuan’s "performance" was still ongoing.

The depth and breadth of traditional Chinese medicine go far beyond this.