What was the sky?
In ancient times, it was the boundless vault overhead. People believed some fearsome consciousness within it governed everything in the human world. They blurred the line between heaven and humanity, giving rise to the Heavenly Dao, Heavenly Fate, the Heavenly Emperor, heavenly gods, and other personified powers.
As modern technology advanced, humanity came to understand that the boundless vault overhead was the atmosphere and the vastness of space. But when the sky split open above Mount Tai, people discovered that beyond the atmosphere and outer space, the sky seemed to encompass time and space as well.
Within a rift of unfathomable length and breadth, a world stretching countless millions of miles came into view. Its sun and moon shone without night, and its mountains and rivers floated in the air.
"Is that... the celestial realm?"
"It must be the Return to the Ruins. There's no doubt about it. It's exactly as described in Liezi: Questions of Tang."
"Liezi: Questions of Tang says: East of the Bohai Sea, countless millions of miles away, lies a bottomless valley called the Return to the Ruins. Within it stand five mountains: Daiyu, Yuanqiao, Fanghu, Yingzhou, and Penglai. Each mountain rises and spans thirty thousand miles, with a level summit nine thousand miles across. Separated by seventy thousand miles, they stand as neighbors. Their terraces and towers are made of gold and jade, their birds and beasts are pure white, and groves of pearl-bearing trees grow upon them. Their flowers and fruit are delicious; whoever eats them neither ages nor dies. Their inhabitants are immortals and sages, and countless among them fly back and forth from morning till night."
At the sight of the scene revealed within the rift, an expert in the conference room who knew ancient Daoist teachings inside