Zhou Yuanjue had once told Ning Muqing.
The human body's instincts are both a restraint and a form of protection.
They protect us from being harmed by the chaotic magnetic fields of the outside world, from being injured by imperceptible changes within our bodies, and from dying by exceeding the limits our bodies can withstand.
But this protection also implies the existence of limits. A Saint Awakening, however, must use their will to overcome these instincts and explore the powers that the body's instincts deem "dangerous," thereby breaking through the body's limits.
After realizing this, Zhou Yuanjue had experimented. He found he could suppress his body's instincts to unleash power beyond his normal limits, but his body's tissues would suffer varying degrees of damage afterward from being unable to withstand such power.
