A Christmas Carol is bursting at the seams with all sorts of supernatural transformations, and readers are constantly invited to feast their eyes on the way an object, a person, or even a whole scene melts into another, often totally without commentary from the characters who are living it. All this is fitting for a work which is in itself a story of two transformations—a young lonely boy's gradual evolution into an embittered old man, and the Herculean efforts necessary to reconnect that old man back to the emotionally available person he once used to be.
Because we see that Scrooge was a sensitive and loving boy when he was a child, this is not a true transformation story so much as a story of a man reclaiming qualities he has already had all along.
Okay, okay. More than any memory, it is the horrifyingly chaotic and unpredictably shifting supernatural assault that bugs Scrooge.