The most obvious thing that the ghosts all represent is choices. Throughout his travels in the spirit world, Scrooge is confronted with choices he has made and the consequences of those choices. Some choices, such as the ones in the past, Scrooge has tried to forget. Choices in the present and future are just as important, but Scrooge has given little thought to them.
Specifically, the Ghost of Christmas Past represents events that shaped Scrooge’s life. He shows Scrooge himself as a boy, as an apprentice, and as a young man. The person he has become is shaped through this progression of sad, happy, and sad again. Scrooge comes to realize that his choices in the past made him who he is.
“Spirit!” said Scrooge, “show me no more! Conduct me home. Why do you delight to torture me?” (Stave 2, p. 26)
Thus, Scrooge goes from being just a mean old miser to a man who is tortured by his past, and perhaps does not even realize it. Scrooge has shut himself up away from everything, even his emotions. When Scrooge says, “I don't wish to see it,” he is vocalizing how he does not want to face his past.
In the present, Scrooge is shown people enjoying themselves. Scrooge never enjoys himself, and he realizes that Christmas Present symbolizes happiness and joy found in togetherness. All of the people are poor, yet “content to be so” and happy to have each other. Scrooge is stunned to see that his clerk has a crippled son.
“Spirit,” said Scrooge, with an interest he had never felt before, “tell me if Tiny Tim will live.” (Stave 3, p. 34)
Scrooge has never felt affection or interest in anyone, but Tiny Tim’s gentle, pious manner has influenced him. The spirit reminds him that Tiny Tim is a member of the “surplus population” and Scrooge regrets not having taken interest in the poor before.
The Present also represents what Scrooge can have. He cannot change the past, but he can become a part of the present. The Present is basically the future, because it is about to happen but has not happened yet. Scrooge can relive the positive events, such as Fred’s party, with instant gratification the very next day. He is thrilled when he learns this.
The true future is very bleak for Scrooge, as the Ghost of Christmas Yet to Come shows him that he will die alone and his deathbed will be looted by less than savory characters. Scrooge is in complete denial until he realizes that the dead man whose life he is seeing is himself.
“Men's courses will foreshadow certain ends, to which, if persevered in, they must lead,” said Scrooge. “But if the courses be departed from, the ends will change…” (Stave 4, p. 50)
Scrooge has clearly decided to reform. He wants to live the life he saw in Christmas Present. This is what Dickens means when he says:
“I will honour Christmas in my heart, and try to keep it all the year. I will live in the Past, the Present, and the Future.” (Stave 4, p. 51)
Scrooge does better than his word, and becomes a second father to Tiny Tim and a good friend to the Cratchits. He also becomes a good Uncle. Scrooge realizes, seeing the present as he did, that he has a ready-made family. All he has to do is open his heart to them.
The ghost of Christmas past represents memory. By taking Scrooge through the different stages in his life, the ghost of Christmas past is showing Scrooge that he was once able to love and that he once cared about others. But as he ages, Scrooge is shown how much less compassion he has for people, as well how much more greedy he becomes due to his lust for money.
The ghost of Christmas yet to come represents death. It is Scrooge's fear of death that finally seals his fate and makes him change his ways. More literally, the ghost of Christmas yet to come represents the difference between heaven and hell, showing Scrooge how awful his life will be if he continues living the way he is, compared to how his life used to be when he had more compassion for the human spirit.