During the Spring and Autumn period, there was a man named Bian Qingzi who taught many students, one of whom was named Sun Xiu.
Sun Xiu was a mediocre man with an inflated sense of self-importance. One day, he visited his teacher Bian Qingzi and sighed deeply, "Alas! Why is my fate so cruel? When I farmed, my fields yielded no harvest; when I served at court, I met no wise ruler; when I was exiled to the countryside, local officials bullied me. I truly don't know what crime I've committed against heaven to suffer such misfortune?"
Bian Qingzi, after hearing Sun Xiu's complaints, scolded him, "You don't understand how a sage conducts himself, do you? They are so pure that they forget all worldly worries, turning a blind eye and a deaf ear to things they don't care about, with hearts as clear as if living beyond the mundane world. But you? You're just an ordinary person, obsessed with trivial matters, flaunting your desires and talents as blatantly as the sun and moon, walking through life with such obviousness—how could you ever match a sage's conduct? You're healthy, with all limbs and senses intact, married with children, enjoying family bliss—isn't that enough? Yet you waste time blaming heaven and others. I suggest you go home and stop exhausting your spirit."
Sun Xiu, deeply ashamed, quietly returned home.
Later, the idiom "as clear as day" came to describe a situation where the truth or essence of a matter is fully exposed.
Source: *Zhuangzi*, Chapter "Da Sheng"
Meaning of the Idiom: Later, the Chinese idiom "昭然若揭" came to describe how the truth or essence of a matter is fully exposed.