井底之蛙，源于《庄子·外篇·秋水》中的一则寓言故事，成语“井底之蛙”和“坐井观天”均出自这则寓言，被用来比喻和讽刺比喻眼光狭隘且自以为是的人。
The frog at the bottom of the well is derived from a fable in “Zhuangzi · Waipian·Qiu Shui”. The idioms “frog at the bottom of the well” and “seeing the sky at the well” are both derived from this fable and are used to metaphor and satirize the narrow-eyed and self-righteous people.
《庄子·秋水》一开始讲述了河伯和北海的对话，秋天黄河涨水，河面陡然变宽，宽到连对岸的牛羊都无法看清。河伯洋洋自得，以为自己很了不起，但当其来到入海口看到大海之时，才知道自己何等渺小。北海说道：“井蛙不可以语于海者，拘于虚也”。
本篇其后又讲述了井蛙的完整故事，说得是一只青蛙住在一个埳阱[1] 之中，某一天遇到了一只来自东海的巨鳖。青蛙对鳖说：“你看我多快乐啊，出去可以在井边跳来跳去，回来了可以在井里的洞中休息，在水中可以只把头和嘴巴露出来，还可以把脚踩在软软的泥里。那些虾米、螃蟹、蝌蚪哪个能比得上我？我就是这一井之主，多么地快乐！你干嘛不常到井里来看看呢？”那只巨鳖于是想进到井里，可井却小得连脚都放不进去。鳖对青蛙说：“你见过大海吗？其阔何止千里？其深何止千仞？大禹治水之时十年中有九年洪水，也没有使大海水量增加，商汤之时八年中有七年旱灾，海水也没有减少多少。大海如此不受洪水大旱的影响，这才是住在东海的大快乐呢。”井里的青蛙听了，惊呆了，方才知道自己所居之地是何等的微不足道。
“Zhuangzi·Autumn Water” begins with a conversation between He Bo and Beihai. In autumn, the Yellow River is full of water, and the river suddenly widens, so wide that the cows and sheep on the opposite bank cannot be seen clearly. He Bo was so self-satisfied that he thought he was great, but when he came to the estuary and saw the sea, he knew how small he was. Beihai said: “Well frogs are not allowed to talk to the sea, they are stuck in the imaginary.”
This article later tells the complete story of the well frog. It is said that a frog lives in a trap[1] and one day encounters a giant soft-shelled turtle from the East China Sea. The frog said to the turtle: “You see how happy I am. Go out and jump around the well. When you come back, you can rest in the hole in the well. In the water, you can just expose your head and mouth, and you can also step on your feet. In the soft mud. Which of those shrimps, crabs, and tadpoles can compare to me? I am the owner of this well, so happy! Why don’t you come to the well often to see?” So the giant turtle I want to get into the well, but the well is so small that I can’t even put my feet in it. The turtle said to the frog: “Have you seen the sea? Its width is more than a thousand miles? Its depth is more than a thousand miles? There were nine years of floods in the ten years of Yu Da Yu’s control of water, and it did not increase the amount of sea water. There have been seven years of drought, and the sea has not decreased much. The sea is so unaffected by floods and droughts, this is the great joy of living in the East China Sea.” The frog in the well heard it and was shocked, only to know where he was living. How insignificant the earth is.