井底之蛙 — “A person with a very limited outlook or narrow perspective”

Once upon a time, there lived a frog in an abandoned well. One day, the frog met a large sea turtle that had come from the ocean.

The frog proudly boasted to the sea turtle, “Look how happy I am living here! Sometimes when I'm in a good mood, I jump around the well curb; when I'm tired, I return to the well and sleep in a brick hole. Or I just leave my head and mouth out, soaking my whole body quietly in the water. Sometimes I even take a comfortable stroll in the soft mud. No shrimp or tadpole can compare to me! Moreover, I am the master of this well, enjoying complete freedom here. Why don't you come often to visit and enjoy my well?”

The sea turtle was intrigued by the frog's words and actually wanted to go in and see. But before its left foot was fully in, its right foot got caught. It quickly retreated two steps and told the frog about the ocean: “Have you ever seen the sea? The ocean's vastness is more than a thousand miles; its depth is more than a thousand zhang. In ancient times, even when there were floods nine out of ten years, the ocean's water didn't rise much; later, during seven out of eight years of drought, the ocean's water didn't noticeably shallow. This shows that the ocean is unaffected by droughts or floods. Living in such a vast ocean is true happiness!”

The well frog listened to the sea turtle's words, utterly astonished, and had nothing more to say.