What effect does the ghost of Christmas past have on Scrooge?
Initially, Scrooge feels a strong desire to see the ghost put on its extinguisher cap. He "begged him to be covered." Something about the light is painful or, at least, uncomfortable for Scrooge and he "had a special desire to see the Spirit in his cap." Next, Scrooge wants to know why the spirit has come, interrupting his sleep, in the first place, and he scoffs when the Ghost says that concern for Scrooge's welfare is what brought him.
Almost immediately, when the spirit removes Scrooge from the present and takes him into the past, Scrooge becomes aware of smells that bring back all kinds of memories. The Ghost sees that the old man's "'lip is trembling'" and he asks about a tear on Scrooge's cheek. Then, when Scrooge is reminded of the fact that he spent his holidays alone, neglected by friends and family, "he sobbed."
When Scrooge sees the shadows of his lonely childhood, he "wept to see his poor forgotten self as he used to be." His weeping continues until he is reminded of the books he used to read and the characters with which he used to populate his imaginative world. Later, he cries again over his poor childhood and remembers the "'boy singing a Christmas Carol at [his] door last night'" and he now feels that he "'should like to have given him something.'" It is clear that, even at this early stage, Scrooge's goodness is being rekindled by the Ghost of Christmas Past. He still has a long way to go before he will be totally reclaimed, but his regret about how he treated the young boy at his door, as well as his copious and sincere tears, shows that he's begun to change already.
The first of the three spirits to visit Ebenezer Scrooge in Charles Dickens' A Christmas Carol is the Ghost of Christmas Past, who looks like a young person and an old man at the same time. The spirit takes Scrooge to several scenes of past Christmases, and several of those points affect Scrooge's view of himself and make him want to change his actions or attitudes. When he sees himself as a child at boarding school, left alone over the Christmas vacation, he wishes he had been kinder to the Christmas caroler who had come to his shop the previous evening. When he sees his sister, Fan, coming to pick him up another year to bring him home, it is implied that he may wish he treated his nephew, Fan's son, better when he invited him to Christmas dinner. The biggest effect on Scrooge in Stave Two is when he observes Fezziwig's festive employee Christmas celebration. The contrast between himself and his generous former employer is so stark that Scrooge wishes he "could say a word or two to my clerk just now," showing that he is having a change of heart about the way he treats Bob Cratchit. But when the spirit brings him to the scene of Belle breaking their engagement, and when it shows him Belle's happy life married to another man, Scrooge protests and finally responds with anger, trying to snuff the spirit out with his large cap. This shows that the changes that are taking place in Scrooge, although important, are not sufficient to help him truly "keep Christmas in his heart."