The most dominant metaphors in A Christmas Carol are the three spirits who visit Scrooge.
The Ghost of Christmas Past is a personification of memory. In order for Scrooge to grow as a human being, he must remember his past and learn both positive and negative lessons from it. The light that shines from this Ghost's head symbolizes the "illumination" which can come from reflecting on one's past, and the cap which the Ghost wears symbolizes the ability each person has to extinguish the light of memory, if he or she chooses to do (as Scrooge attempts to do at the end of Stave Two).
The Ghost of Christmas Present is a personification of generosity. All the details of this figure's appearance-its large, exposed breast; its cornucopia-like torch; the abundance of food on which it rests in Scrooge's rooms-lead readers to conclude that this Ghost symbolizes generosity, which for Dickens is at the heart not only of Christmas but also of a truly human life. A sprinkling of seasoning from the Ghost's torch enhances the flavor of meals and of relationships at Christmas. The Ghost stands for generosity not only of material goods, but also and especially of spirit; it alone, for example, protects the "children" Ignorance and Want, and warns Scrooge-and readers-that they must do so as well.
The Ghost of Christmas Yet to Come is a personification of the relentless march of time towards both a fixed and an unfixed end. Resembling nothing so much as traditional depictions of the Grim Reaper, this Ghost may be seen as symbolizing death, the common lot of all human beings; see Fred's comment on Stave One, that all people are "fellow-passengers to the grave." When Scrooge asks to erase the writing on his own headstone, however, he is not asking for immortality; rather, he is asking that his life before his inevitable death be of a different quality than it would be otherwise. Therefore, the Ghost's austerity and imposing manner symbolize the unstoppable passage of time. The Ghost does not engage in conversation or reflection; it simply leads Scrooge from scene to scene, pointing always forward with its outstretched hand. Its stern presence warns readers that-as the saying goes-time waits for no one; should you wish to change your life, do so today. The fact that your life will end is fixed; the meaning that your life will have had is up to you.
Music is another important metaphorical motif in the work-appropriate for a book whose title is A Christmas Carol! Music can be seen as symbolizing the joy of Christmas and of life itself, which we have the power to either reject or accept. Scrooge chases away a caroler at his door (whose song is a plea for God's blessing upon Scrooge); in contrast, other characters celebrate the season with music-from Fred and his family to the men in the solitary lighthouse-and so receive joy.