It was a cold winter evening. Mr. Frank was lying on his bed. He was about fifty-five years old. Anyone could guess his age by looking at his physical weakness. He was retired doctor. Mrs. Frank was sitting on a couch in front of the bed and she was reading a digest. She was about fifty years old. She was a housewife. They were the only ones in the big house.
             Mr. Frank looked at the door by chance and said to his wife if she heard some one knocking at the door but she refuses it. Mr. Frank kept insisting that some one is at the door. At first she did not agree but after his strong claim she went to the door and no one was at the door. She thought it was just his imagination and that she would talk about it with her family doctor.
             Next day Dr. John came to the house. He was a young doctor. He used to come for Mr. Frank's daily check up. And while he was doing it Mrs. Frank told about his about Mr. Frank's false imagination about some one knocking at the door. Then Doctor asked him about the reason for these thoughts. Frank told him that about twenty years ago he came back home late from his practice. Those days he was very busy in his practice. That night he was very tired so he went to sleep right away. Then after about half an hour his servant told him that an old has come on the door want to take Frank to see his son who was very sick. But Frank refused to go and told his servant not to bother him again. The servant did that and forced the old man out of the house. The old man kept knocking at the door but Frank went sleep again. Next morning when he woke he felt bad that he did could not help the old man.
             Dr. John told frank that even the old man left that night but still Frank's conscious makes him feel like that some one is knocking at the door. And he also told him that he is the grandson of that old man whose son died that night due to his illness. Frank felt very ashamed at this. Dr. John told
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