This is the reincarnation story Yu Menglong shared with Yu Xiang, a new companion of “Yu En Speaks”:

During the Western Han dynasty, you were once a woodcutter.

In ancient times, every trade and craft could be a form of spiritual cultivation. Woodcutting, too, was a practice for cultivating one’s character: by learning to identify trees and selectively fell them, one helped maintain the ecological balance of the mountains and forests. Through the trials encountered while cutting wood, one refined one’s inner nature, with the ultimate aim of attaining immortality.

Under the guidance of your woodcutting master—whom we will simply call Master—you learned how to communicate with plants, distinguish native from introduced species, and understand from the messages conveyed by plants the cycle of formation, abiding, decay, and dissolution within a forest ecosystem.

At the time, you were calm, reserved, plain-spoken, and not inclined to reveal joy or anger. Whatever Master assigned, you simply did it, without complaint or preference. Unlike the other disciples, you never picked and chose among tasks, and Master held the highest hopes for you.

Master once said that the method you were cultivating was a Daoist practice. Once one achieved fruition, one would become an immortal artisan in Heaven: simply envision the appearance of a structure in one’s heart, point with a whisk, and it would come into being.

Master especially admired you because you always acted without speaking, and when you did speak, you never argued. You diligently completed every task he entrusted to you.

One day, Master privately made an agreement with you: the two of you would attain completion together. Rarely speaking, you said, “This disciple is willing to follow Master, but if Master leaves, what will become of my fellow brothers?”

“The woodcutting method I teach belongs to a Daoist path,” Master replied. “Cultivation is something each person gains for themselves. Those who do not attain it will enter another path and continue cultivating.”

You accepted this. Everyone’s innate capacity was different. Some disciples were not unwilling to work hard; they simply could not find the right way, no matter how hard they tried.

One day, Master taught everyone to make boats from large felled logs.

One disciple asked why they needed to make boats. Another questioned what use a boat could have in a forest. Another only wanted to make the wooden objects he personally preferred. Still another picked up his tools and began casually chiseling at a log.

Only you said nothing. You carefully used a branch as a pen, drew a design in the sand, and then began constructing the boat you imagined according to that design.

Because you had lived in the forest since childhood, you had never seen the ocean or a boat. You did not know what one was—but Master had told you to make it, so you did.

Before long, the disciples finished their pieces: bowls, cups, and shapeless wooden objects. Only your boat had been made according to Master’s instruction.

Master was very pleased. He clapped his hands, and all of the creations rose into the air.

Soon, some fell to the ground. Others could not remain aloft for long and also dropped. Only the boat you had made floated steadily in midair, quietly waiting.

Master waved his hand, and the boat descended. He took your hand and boarded it with you. In an instant, the boat rose into the sky, flying higher and higher. You felt no fear, and indeed no particular thought at all.

Suddenly, a familiar woman’s voice cried out in anguish. You were unmoved, but Master, seated behind you, could not help looking down.

It was his only daughter, Ju’er, crying and chasing after the boat without giving up.

Without a word, Master fell heavily from the boat.

You and Master boarding the boat signified that you had both attained completion. The boat had gained divine power and could ferry you to the heavenly realm to become immortals.

But Master looked down because he could not let go of his attachment to his daughter. In the eyes of the higher realm, he had failed the final test.

The gods had arranged this trial to help the two of you relinquish your last attachments: Master’s paternal love for Ju’er, and your own love for her.

You and Ju’er had been betrothed since childhood. You were childhood sweethearts and loved each other deeply. But after Ju’er grew up, she fell in love with a remarkably handsome junior disciple. You were left in profound pain and loneliness, yet out of respect for her wishes, you never brought up marriage to Master.

Only when you were flying heavenward in the boat did Ju’er understand that her true heart belonged to you. But it was too late. All she could do was weep and run after you.

When the boat arrived at the Heavenly Palace, you discovered that Master had vanished from the seat behind you. Looking down through the clouds, you saw that he had fallen because he still clung to his attachment to his only daughter.

A heavenly official congratulated you on becoming an immortal, but you refused. To fulfill your promise to ascend with Master, you asked the official to send you back to the human world to cultivate anew.

This troubled the official. You had already attained an immortal body. Returning to the mortal world would mean creating karma for that immortal body.

Since taking life creates karma, the only way to relinquish your immortal body would be to end your own life. But doing so would create an unimaginably great karmic burden. Upon returning to the mortal realm, you would no longer be able to be born human.

And without a human birth, you could not cultivate. You would have to repay karma for a very, very long time before having another chance to be human.

The official’s expression grew grave. Just as you did not know what to do, thunder suddenly sounded. A rift opened in the sky, pouring out golden light so bright that no one could keep their eyes open. A higher deity descended.

The deity was entirely enveloped in golden light. Neither you nor the heavenly official could see the deity’s form clearly.

“Wu Gang, heed my command!”

The deity did not open his mouth, yet everyone heard the voice clearly.

Hearing your own name, you immediately knelt.

The deity said, “You are one I have chosen, and a citizen of the heavenly realm under my authority. Because of your righteousness and your determination to honor your promise, I have decided to send you to the Moon Palace. When your master attains completion, you shall return together to the immortal realm.”

Though you had acted to honor a promise, in Heaven, clinging to a promise was still an attachment—and attachment created karma.

Thus, you were sent to the Moon Palace to cut down an osmanthus tree for five hundred years. The tree was enormous. With every stroke of your axe, its wound immediately healed, so your work was endlessly repeated.

Yet for the sake of your promise, you harbored no resentment. You silently continued cutting the tree.

After one hundred years, Lady Chang’e came with palace maidens from the Guanghan Palace and stood beneath the osmanthus tree.

Seeing you endlessly cutting the tree, she felt sorrow for you and thought your suffering undeserved. She urged you to stop, ascend on your own, and no longer suffer for the sake of a promise.

You replied that cutting the osmanthus tree was not merely waiting for someone. Through the hardship of the task, you were also tempering your will, releasing attachment, and elevating your character.

Moved by your words, Lady Chang’e no longer tried to persuade you. She returned to the Guanghan Palace.

After two hundred years, a toad hopped to the base of the tree. It claimed to be your Master, saying that after two hundred years of cultivation, it had finally reached the Moon Palace. It asked you to put down your axe and take it to Heaven.

You ignored it and continued cutting the tree.

The toad said sadly, “Disciple, do you no longer remember your Master? I went to great lengths to reach the Moon Palace to find you, yet you treat me this way!”

Still, you ignored it and continued your work.

Suddenly, the toad leapt into the air and transformed into a pure white jade rabbit. Pretending to be angry, it said, “Wu Gang, how can you be so heartless? What of your promise? If I truly were your Master, would you not have missed your chance?”

“The great deity told me to cut osmanthus wood for five hundred years. That means five hundred years. The deity will not alter the decree for anyone, and neither will I.”

You spoke without expression as you continued cutting. The jade rabbit saw that you had passed the test and happily hopped away.

Five hundred years later, you were still cutting the tree that would never fall when your body suddenly became light and rose into the air, drifting farther and farther away from the Moon Palace. You knew the time had come.

When you returned to the Heavenly Palace, your Master embraced you with tears in his eyes. The heavenly official looked at you with admiration and relief.

“Now all is well. Master and disciple can finally become immortals together!”

“Ancient accounts say that there is a cassia tree and a toad in the moon. Thus, an extraordinary text records: ‘The moon’s cassia tree stands five hundred zhang tall. Beneath it, a man continuously chops at it, yet every wound closes at once. The man’s surname is Wu and his given name is Gang; he was from Xihe. Having erred in his pursuit of immortality, he was banished and ordered to fell the tree.’”
— Duan Chengshi, Youyang Miscellany, Vol. 1, “Tian Zhi” (Tang dynasty)

The Master for whom you waited five hundred years was one of Xiao Yu’s secondary primordial spirits.