If Chen Jie cannot answer this question, or his understanding of Dao does not reach that level, he could likely suffer and be trapped within his sea of consciousness, with his demise occurring within the Flood Dragon Cave.
And don't forget, outside there is the Siamese State Preceptor, and the Flood Dragon is returning; if Chen Jie wakes up a bit late, he might die here.
Chen Jie was completely dazed, his eyes focused on the world before him.
Looking at Ah Dai's eyes cast through time and space, Chen Jie found himself engulfed in confusion in that moment, Dao!
He didn't understand the Dao at all, yet if he couldn't answer Ah Dai's question, he wouldn't be able to break free from the illusion realm before him, so he must explain what exactly Dao is.
Upon this realization, Chen Jie had to save himself.
What is Dao?
Chen Jie's mind was racing quickly, and immediately he began speaking: "The Dao that can be told is not the eternal Dao."
