The Ghost of Christmas Past informs Scrooge, upon first making its appearance, that it has come to deal with Scrooge's "welfare...your reclamation". It then takes Scrooge on a tour of Christmas scenes from his past.
At each stop, Scrooge is unable to remain merely an observer of the events that occurred years ago. He is delighted to see and hear the greetings the children and adults of his hometown are exchanging, explains some of his favorite childhood stories with great animation and enthusiasm, and fully identifies with his former self during the Fezziwigs' Christmas Eve dance.
His heart and soul were in the scene, and with his former self. He corroborated everything, remembered everything, enjoyed everything, and underwent the strangest agitation.
All these appearances are for the same purposes - to give Scrooge a reminder of the ways in which he has conducted himself and his relationships to others in years past, and to give him an opportunity to reconsider those patterns in the future. "I told you these were shadows of the things that have been," said the Ghost. "That they are what they are, do not blame me!"