"The Human Emperor found the entrance here back then."
"With the Dingjun Sword as the guide and the Human Emperor Token as the key, a door can be opened."
He took a step forward.
The invisible boundary trembled faintly as he approached, like a stone tossed into a calm surface of water.
Su Ming could feel that there was something on the other side of the boundary.
He did not keep walking.
He merely stood before the boundary, held the Dingjun Sword horizontally in front of him, and sensed the extremely subtle ripples across its surface.
After a long while, he withdrew the sword and took a step back.
Luo Yiyi looked at him. "How is it?"
"The boundary is alive."
"It's breathing. Every time it breathes, it opens a tiny crack."
"Those cracks are too small, so small that even light can't pass through them, but if we can find the instant when its breath is weakest..."
"Perhaps we can open a door large enough."
Luo Yiyi was silent for a moment. "How long will it take to find that instant?"
"I don't know." Su Ming put away the Dingjun Sword and turned to look at her.
"But at least we know now that the coordinates the Human Emperor left behind are correct. The boundary exists. The door can also be opened. What's left is only a matter of time."
They stood before that invisible boundary and watched in silence for a long time.
Then Su Ming turned and flew back in the direction they had come from.
Luo Yiyi followed behind him. Two streaks of light drew out long, slender bands in the darkness, like the last threads of smoke left in the wind by two candles about to go out.
The return trip was nearly half as