Confucius had many disciples, one of whom was Zixia, a solitary figure who kept mostly to himself and only occasionally socialized with his fellow student Zeng Shen.
When Zixia's son died one year, he was so grief-stricken that he wept day and night, nearly crying himself blind.
One day, Zeng Shen visited him at home. Zixia wept bitterly and said, "Heavens! I have done nothing wrong, why have you punished me so harshly by taking my son's life?"
Zeng Shen, unconvinced, said, "Brother Zixia, you shouldn't blame heaven. I think you should blame yourself—you're not without fault; your mistakes are great!" Zixia exclaimed in surprise, "Please tell me what mistakes I've made?"
"Alright, I'll tell you. When your father died, I didn't see you grieve much; now that your son has died, you're heartbroken to this extent. Comparing the two, isn't your mistake obvious?"
Zixia, as if waking from a dream, reflected, "I have lived apart from others for so long that I heard no friends' advice, leading to such mistakes. From now on, I will correct them!"
From then on, Zixia indeed accepted his grief and adapted to the change, making an effort to blend in with his classmates and no longer isolating himself from the group.
Later, the idiom "Living Apart from the Herd" came to describe leaving friends behind to live in solitude.
Source: *The Book of Rites*, Chapter "Tan Gong"
Meaning of the Idiom: Later, the Chinese idiom "离群索居" came to describe leaving friends behind to live in solitude.