In truth, An Jing had realized that the reason he was able to awaken an ability similar to "Self in the Mirror" after receiving the revelation of the Haotian Mirror was entirely because he had already mastered the art of "Self-Observation."
The "Son of Heaven Art," derived from the Houtu Art, is precisely a form of introspective meditation used to examine one’s own inner self.
Its very essence is a "mirror" used to observe oneself!
Chapter 719