The pine breeze enters the thatched hut, the wind chimes answer the stream's murmur.

Midday is the most leisurely time at Wansong Academy.

After breakfast, there was a rest period of more than an hour. Some students went back to their dormitories to rest, some went to the library to read, some chatted, and some played.

Wang Shu and Gu Jun, these two disciples of Meng Wenlang, had a unique custom. They often received private lectures from Meng Wenlang at noon. The lectures usually did not take place inside the academy, but rather at "Songzha" on the back mountain.

That day, the two had breakfast together at the Fine Dining Kitchen and then headed towards the back mountain.

Passing through the back gate of the school, there is a field, and beyond that, a winding mountain path. The path is made of uneven bluestone, with fine moss growing in the cracks, making it soft to walk on.

On both sides were dense pine forests, the pine trees of countless years old, many as thick as a person's embrace, their branches and leaves blocking out the sky. The pine needles had fallen and covered the ground, piling up thickly, making a rustling sound when stepped on.

Wang Shu walked ahead, his steps slow and his back ramrod straight. Gu Jun followed behind him, his steps unhurried and his expression serene, occasionally pausing to look up at the dense pine branches overhead.

After walking for a while, the view suddenly opened up before us.

We've arrived at "Songzha".

Meng Wenlang built a thatched hut in the back mountains and named it "Songzha".

Although it's called a thatched cottage, it's actually small and elegant. The roof is covered with several thick layers of thatched grass, golden in color, with neatly trimmed edges. Several strings of wind chimes hang under the eaves, made of bamboo strips, which tinkle and chime when the wind blows, with a clear and melodious sound, like mountain springs tapping on stones.

A fence surrounded the front of the house, made of split pine wood, with each log stuck into the ground. The bark of the pine was still peeled off, making it rough and unrefined. Several unknown vines climbed the fence, adorned with tiny white flowers that emitted a faint, delicate fragrance only when you got close.

The wooden door of the thatched cottage was ajar. On the stone steps in front of the door lay a few pine needles, and a pinkish-white petal, its edges already curled, drifted in from who-knows-where.

Wang Shu stepped forward and gently knocked on the door frame: "Sir, your disciples Wang Shu and Gu Jun request an audience."

A gentle voice came from inside the door: "Come in."

The two pushed open the door and entered.

Meng Wenlang sat leisurely on a bamboo mat by the window. In front of him was a low table with a book open on it. Beside him was a rough earthenware teacup, the tea still steaming.

Outside the window, a mountain stream flows directly ahead. The water cascades down from a higher point, leaping and tumbling among the rocks, splashing up tiny, delicate droplets. The sound is soft, a gentle murmur. Several clumps of orchids grow along the stream's edge, their long, glossy green leaves glistening with moisture, appearing vibrant and fresh.

Meng Wenlang lifted his gaze from the book, paused on the two faces, and smiled slightly, saying, "Sit."

Wang Shu and Gu Jun knelt down on the bamboo mat opposite Meng Wenlang.

Wang Shu began, "Sir, I would like to report on Jia Zhai's debate yesterday."

Meng Wenlang looked at him and nodded slightly.

Wang Shu then recounted the entire debate from the previous day.

From Sun Yuangui's theory of "root and branch," to Gu Jun's theory of "two sides of one body," to Yu Yanzhi's theory of "sequence and sequence," then Zhu Jiuling stood up to refute Yu Yanzhi, describing self-cultivation and practical application as "you are in me, and I am in you," then Jia Boyang used Yan Hui as an example to refute Zhu Jiuling, and finally Liang Shanbo dismantled Jia Boyang's theory, proposing "substance and function are inseparable, and the manifest and the subtle are not two."

Wang Shu explained in great detail. He had an excellent memory; he remembered everything who said what, how they cited classical texts, and how they debated each other.

When he finished speaking, the thatched hut suddenly fell silent.

Outside the window, the stream murmurs and the wind rustles through the pines. The wind chimes are tinkled by the breeze, making a clear and crisp sound.

Meng Wenlang remained silent for a long time, then suddenly murmured, "Substance and function are inseparable; the manifest and the subtle are not two!"

His voice was very soft. After he finished reading, he fell silent again.

Wang Shu and Gu Jun exchanged a glance, but neither of them spoke.

Meng Wenlang pondered those eight words over and over in his mind.

He considered himself well-versed in Confucian classics, Lao-Zhuang metaphysics, and the Prajnaparamita school of thought. Yet, these eight characters, strung together with such seamless logic, were something he had never encountered in any other text. Han dynasty Confucian scholars did not speak in this way; Zheng Xuan and Ma Rong, in their interpretations of the classics, only spoke of "substance" and "function," never combining them so tightly. Nor was it a common phrase in Wei-Jin metaphysics; Wang Bi, He Yan, and Guo Xiang had never used such language.

Yet, these eight characters are so fitting and insightful in explaining the relationship between self-cultivation and practical application, like mortise and tenon joints fitting together perfectly.

He suddenly recalled the day he tested Liang Shanbo. Liang Shanbo interpreted the word "learning" as a trinity of seeking knowledge, cultivating oneself, and putting it into practice. He used planting trees as a metaphor, saying that seeking knowledge is watering, cultivating oneself is pruning, and putting it into practice is blossoming and bearing fruit. At that time, he felt that this young man had extraordinary insight and was not comparable to ordinary students.

In hindsight, he underestimated it!

Seeing that Meng Wenlang remained silent for a long time, Gu Jun couldn't help but speak up, "Sir, I still have some doubts about the concept of 'the unity of substance and function, the non-duality of the manifest and the subtle.' I would appreciate your guidance."

Wang Shu also said, "I haven't fully grasped it either."

Meng Wenlang snapped out of his daze, looked at his two disciples, and his gaze became more serious.

He picked up his teacup, took a sip to moisten his throat, and then slowly said, "Do you know where the terms 'substance' and 'function' originate?"

Wang Shu replied, "Yesterday, Liang Shanbo quoted the 'Appended Remarks' of the Book of Changes, saying, 'That which is above form is called the Way, and that which is below form is called the instrument.' The Way and the instrument seem to be the relationship between substance and function."

Meng Wenlang nodded: "That's right. The metaphysical principle is the 'essence'; the physical principle is the 'function'. The principle is the foundation, and the function is the application. The two are inseparable."

He paused, then continued, "However, Liang Shanbo's saying, 'Substance and function are inseparable, the manifest and the subtle are not separate,' goes a step further than the statement in the Appended Remarks. 'Substance and function are inseparable' means that substance and function depend on each other; without substance there is no function, and without function there is no substance. 'The manifest and the subtle are not separate' means that the hidden substance and the manifest function appear to be two different things, but in fact they are one."

He looked at Gu Jun: "When you read Zhuangzi, do you remember the chapter 'The Dao is in excrement and urine'?"

Gu Jun nodded: "I remember. Dongguo Zi asked Zhuangzi, 'Where is the Dao?' Zhuangzi first said, 'It is everywhere,' then he said, 'In ants,' then he said, 'In weeds,' then he said, 'In tiles,' and finally he said, 'In excrement.' Dongguo Zi dared not ask any more questions."

Meng Wenlang smiled slightly: "This is the principle of 'the unity of essence and function.' The Dao is the 'essence,' while ants, weeds, tiles, and excrement are all 'functions.' The Dao is not something suspended high in the void; it is hidden in the most ordinary and humble things. Apart from these ordinary things, where can you find the Dao?"

He stretched out his right hand and pointed to the mountain stream outside the window: "Look at that stream. Water has its own nature, and that nature is its 'body'. What is the nature of water? It is moistness, it flows downwards, it moves, it takes shape wherever it meets a square or a round shape."

But if you ask me, where is the nature of water? I can only point to this stream and tell you—this is the nature of water. Apart from this stream, apart from rivers, lakes, and seas, apart from rain, dew, frost, and snow, the nature of water cannot be found. Essence is in function, and function is in essence. This is the 'interdependence of essence and function'.

Gu Jun seemed to be deep in thought, his brows furrowed slightly, as if he were pondering these words.

Meng Wenlang then pointed to his heart: "Look at the human heart. Benevolence, righteousness, propriety, and wisdom are the 'essence' of the heart. But how can you see these benevolence, righteousness, propriety, and wisdom?"

You can only see it in people's words and deeds. Seeing one's father, one naturally knows filial piety; this is the "application" of benevolence. Seeing one's elder brother, one naturally knows brotherly love; this is the "application" of righteousness. Apart from these concrete words and deeds, benevolence, righteousness, propriety, and wisdom are just empty words. The essence is revealed in its application, and the application is rooted in the essence. This is the "unity of the manifest and the subtle."

Upon hearing this, Wang Shu said, "What you mean is that Liang Shanbo said self-cultivation is the 'essence' and application is the 'function,' meaning that the 'essence' of self-cultivation inherently contains the possibility of application; and the 'function' of application is the manifestation of self-cultivation."

Meng Wenlang nodded: "Exactly."

He picked up his teacup, noticing the tea had gone cold, but he didn't mind. He took another sip and continued, "Since the Wei and Jin dynasties, metaphysics has flourished. He Yan and Wang Bi annotated the *Laozi* and the *Zhouyi*, advocating 'taking nothingness as the foundation.' 'Nothingness' is the essence, and 'existence' is the function. All things arise from nothingness and return to nothingness."

This statement, while ingenious, easily leads to a misunderstanding, suggesting that "essence" is lofty and mysterious, while "function" is base and coarse; that cultivating the Tao means abandoning "function" and returning to "essence."

He exclaimed, "That's a misinterpretation. Liang Shanbo's 'the unity of substance and function' precisely corrects this deviation. He said that self-cultivation and practical application are inseparable, just as burning and light are inseparable. This metaphor is truly brilliant!"

At this point, Meng Wenlang looked out the window and fell silent again.

More thoughts were churning in his mind.

The eight characters "substance and function are one, manifestation and subtlety are not two" also have a corresponding meaning in the Buddhist Prajna teachings.

At the beginning of the Eastern Jin Dynasty, the study of Prajna flourished, and eminent monks used Laozi and Zhuangzi's metaphysics to interpret Buddhist scriptures, which was called "Geyi".

Zhi Daolin, in his lectures on Zhuangzi's "Free and Easy Wandering," established the theory of "wandering in the profound through form," arguing that "form is not form itself; though form, it is empty." Doesn't this "form is not form itself" mean that phenomena are not isolated and exist independently, but arise from the essence? How similar this is to the principle of "the unity of essence and function."

But Liang Shanbo was clearly not a Buddhist.

Where did he, a teenager, get such knowledge?

Meng Wenlang suddenly remembered that during the test that day, Liang Shanbo had mentioned that he only had a few dozen old books at home. Could a few dozen old books cultivate such knowledge? Could it be that his father, Liang Yuanqing, taught him? Even if it was Liang Yuanqing who taught him, it still proved that this boy was truly gifted!

Thinking of this, a thought suddenly arose in Meng Wenlang's mind:

"Liang Shanbo is truly a prodigy. Although he comes from a poor family with no wealth, making it difficult for him to rise above others, his talent and knowledge, his composure during the test that day, and the kindness his grandfather showed me in my upbringing—such a person is worthy of being my disciple!"

Thinking of this, he tapped his fingers lightly twice on the bamboo mat.