To the naked eye, nothing had changed. The starry sky was still the same—deep and dark—but only by drawing near could one touch that boundary.
The boundary stretched into the unknown distance. Riding Xu Wuji, Lu Yin set out from the stone gate in one direction and discovered that no matter how far he went, the boundary still existed.
Jialan Zhi Luo also sent word from the other side. The place she touched had the same boundary.
After some time, they regrouped at the stone gate.
"The boundary is just like the stone gate. It can't be broken," Jialan Zhi Luo said.
Lu Yin's expression darkened. "This isn't the limit of a parallel space-time universe. The many parallel space-times within the universe vary in size, but regardless of their size, their limits aren't physical. One can tear open the void and reach other parallel space-times. But this limit is different. It's like—"
"A wall." Jiang Feng finished. He hadn't investigated the surroundings; he had to guard the stone gate and prevent Tian Ci from emerging.
"What did Uncle Jiang think of?" Lu Yin asked.
Jiang Feng exhaled. "When Butterfly accepted Heaven's Grace on behalf of the heavens and invited me to join the Four Directional Guardians, she mentioned the Guardians' responsibilities. I asked her then: What is the difference between one universe and another? How can one tell whether something belongs to the Outer Universe?"
Heaven's Grace had replied with four words: "Different auras."
"If there were no barrier, the auras wouldn't be different. There must be a barrier between universes, and it must be extremely tight, just like a wall—the wall of a universe."
Jialan Zhi Luo looked at the stone gate. "This is where Tian Ci is located. The Four Directional Guardians means they guard four directions separately.