Researches suggest that there are creatures that do not know what light means at the bottom of the sea. They don't have either or ears;  they can only feel. There is no day or night for them.  There are no winters, no moon, and no stars. It is as if a child spent its life in darkness in bed, with nothing to see or hear. How different our own life is! Sight shows the ground beneath feet and the heavens above us- the sun, moon, and stars, shooting stars, lightning, and the sunset. It shows us day and night. We are able to hear voices, the sound of the sea, and music. We feel, we taste, we smell. How fortunate we are!  Judging from the passage, we can say that this story is mainly about----