During the Eastern Han Dynasty, there was a scholar named Huang Xian who came from humble beginnings but, through diligent study, became exceptionally learned and noble in character, earning great respect from his neighbors.
At fourteen, Huang Xian was staying at an inn in Shenyang when the renowned scholar Xun Shu happened to meet him there. Struck by the boy's bright demeanor, Xun Shu invited him to his room for a chat. After just a few exchanges, Xun Shu recognized Huang Xian's extraordinary talent. They talked until sunset, when Xun Shu reluctantly saw him out, saying, "I never expected you would be my teacher!"
The next day, Xun Shu visited his friend Yuan Lang, a merit officer in Runan Commandery, and asked upon meeting, "Does your commandery have a Yanzi (Confucius's student Yan Yuan, young but exceptionally talented)? Do you know him?"
“You must be referring to Huang Xian, right?”
Later, the renowned scholar Guo Tai from Taiyuan traveled to Runan. He first visited Yuan Lang, but after a brief conversation, he took his leave. Then he went to see Huang Xian and ended up staying at his home for several days. Guo Tai remarked to others, "Yuan Fenggao (referring to Yuan Lang) is like a clear spring—you can see straight to the bottom at a glance. But Huang Shudu (referring to Huang Xian) is like a vast lake of a thousand acres—deep and unfathomable."
In the same village as Huang Xian lived a man named Dai Liang, who was also renowned for his talents but possessed an arrogant nature, believing no one in the world could match him.
But when the arrogant Dai Liang met Huang Xian, his pride instantly deflated—he stood respectfully, dared not act casually, and after parting, he stood dazed for a long time, lost in thought.
As the scholar-officials praised him, Huang Xian's fame grew ever greater
Later, people used the idiom "at a loss" to describe being in a daze, as if something were missing from their hearts.
Source: *Book of the Later Han*, "Biography of Huang Xian"
Meaning of the Idiom: Later, the Chinese idiom "惘然若失" came to describe being in a daze, as if something were missing from their hearts.