Going Home by William Saroyan

　　This is a sad story. The protagonist comes back to his home town, to his home, to the kitchen window after a long absence, but he could not knock at the door even though he desperaely wants to see his mother, his brother and his sister. His old memory-- an ugly and bitter memory--prevents him from entering his house. He leaves the house "weeping becaue there was nothing he could do, not one confounded thing."
  This is a moving story. The writer reveals the protagonist's feelings so well that I found myself identified with him. 
   I want to know why he had gone out of the house and had been away from it for a long time. Have I missed the part which describes the reason? Someone out there, help me.