A fisherman happened to come upon（偶然见到） a place called Peach-Blossom Spring. Squeezing（压榨，推挤） through a cave, he found a village, the residents of which were descendants（后代，晚辈） of refugees from the Qin Dynasty. It was a paradise isolated（鼓励，绝缘） from the outside world, without exploitation or oppression, and everybody living and working in peace and contentment（满足，满意） . The fisherman left the villagers and went home. But he could never find the place again.This idiom is derived from the above story, and is used to mean an isolated, ideal world.