During the Eastern Jin Dynasty, there was an old fisherman in Wuling. One day, he took his boat out to go fishing. As the boat floated downstream, the fisherman lost his way. Suddenly, a beautiful forest of peach trees with flowers in full bloom caught his eyes. He carried on sailing to the end of the forest where he found a mountain with a small cave at its foot. After the fisherman walked through the cave, a new world opened up before him. The people seemed happy and gentle, and lived peaceful lives with no arguments or disputes. The old rested quietly while the young played happily. Unlike the world outside the cave, there was no conflict or turbulence. When they saw the fisherman, the people asked him not to tell others what he had seen there.
But when he got home the fisherman told the other villagers about his experiences. They did not really believe him but followed him back to the cave out of curiosity. But he never found the place again.
The idiom is used to describe a haven of peace, or utopia.
shì wài táo yuán
bù chĭ xià wèn
Not feel ashamed to seek advice from one's subordinates; learn from those beneath oneb