Both persons simultaneously recounted words of profound meaning, and there's usually only one possibility.
They were quoting a famous saying!
Yet, what Air said didn't sound like a famous quote.
Although Shen Yue thought so, he still asked, "May I ask, the necessary condition you mentioned, is it a must-know principle for a Spiritual Master?"
Air's eyes flashed slightly, "Of course not. You..."
He was halfway through his sentence when he suddenly smiled and said, "Does it sound like a principle?"
Shen Yue shook his head, "Not really."
Ye Xuan'er suddenly had an intuition that there was a deeper meaning to the words exchanged between the two men, and both seemed to understand the nuances in each other's statements.
Without delving further into this topic, Air spoke in a gentle tone, "Within these necessary conditions, belief is the threshold, and also a barrier; those who surpass this hurdle are few and far between. The obstacle to belief is..."