I propose that to understand the significance of the Carol is to integrate the psychological and spiritual messages. To begin with, Scrooge's memory is dead. The legacy of the Ghost of Christmas Past is the heart-felt transformation of memory. That Scrooge attempted to repress his recollection of the past, especially the feelings of his past, is revealed by his reception of the first spectre. The coming of this first ghost is accompanied by theophany, a light, emanating from the head of the ghost, that Scrooge wants to repress.
Scrooge prefers darkness to the light.
Scrooge begs that the light of memory be taken away. The Ghost chides him. With memory uncapped, Scrooge is taken back to his youth where his pain, loneliness, and joy are recounted. Through early friendships, celebrations, and a jilted love affair, Scrooge meets his inner child, who becomes an emblem of every child. The Ghost of Christmas Past reminds him of his own misery as a rejected little boy placed in a boarding home by a father who was as callous as Ebenezer had become.