During the Jin Dynasty, Liu Dan, the governor of Jinling, was so incorruptible that his family lived in poverty. After his death, his wife Ren and their son Liu Tan had to move to Jingkou, where they dwelled in a humble thatched hut.
As a young boy, Liu Tan balanced his studies with weaving straw sandals to help his mother make ends meet. Despite their poverty, he was fiercely proud and refused all gifts from wealthy families.
When Liu Tan was young, he was highly regarded by the scholar-official class for his extensive knowledge and upright character. People compared him to the contemporary learned and talented scholars Yuan Yang and Fan Wang. Liu Tan was very pleased upon hearing this, but his mother, Lady Ren, said:
“Though others may praise you highly, you must know yourself and not accept excessive flattery.”
From then on, Liu Tan focused even more on his scholarly cultivation, and his reputation grew louder each day. Emperor Ming of Jin admired Liu Tan's character and learning so much that he married his daughter, Princess Luling, to him.
After his marriage, Liu Tan remained true to his own character, refusing to associate with high-ranking officials and the unlearned. A master of debate, his arguments were always sharp and well-reasoned, earning him the respect of Sima Yu, the younger brother of Emperor Mingdi (later known as Emperor Jianwen of the Jin Dynasty), who honored him as a distinguished guest.
Once, the renowned scholar Sun Sheng wrote a treatise titled "On the Subtlety of the Image of Change," which was profoundly abstruse. Sun Sheng boasted that no one could refute this essay. Sima Yu doubted this and sent the quick-witted and eloquent Yin Hao to challenge it, but indeed, he could not refute it. Still unconvinced, Sima Yu said, "If Liu Tan came, he would surely be able to refute him."
When Liu Tan was invited to the gathering, Sun Sheng, who had long admired him, engaged in debate. Liu Tan's arguments were sharp, his analysis incisive, and every point struck home. Soon, Sun Sheng had nothing left to say, and the guests marveled at Liu Tan's profound knowledge.
From then on, Liu Tan's fame grew, but so did his arrogance—he would only associate with those of the highest moral character and deepest learning.
Liu Tan, a devoted follower of Daoist philosophy, championed a life of quiet simplicity. When he served as the governor of Danyang, his office was so serene that not a single sound of chaos could be heard. His home, far from resembling a typical official's mansion, felt more like a hermit's retreat—never visited by disorderly people, truly "no miscellaneous guests at the door." Liu Tan passed away in office at the young age of 36. Later, the idiom "no miscellaneous guests at the door" came to describe someone who is extremely selective in choosing friends.
Source: *Book of Jin*, "Biography of Liu Tan"
Meaning of the Idiom: Later, the Chinese idiom "门无杂宾" came to describe how someone is extremely selective in choosing friends.