At the beginning of the third stave, how does Scrooge know he should open the door and enter the other room?

Early in the third stave, while Scrooge is waiting for the arrival of the next ghost, he sees a bright light shining. It look as though this light is coming from the "adjoining room" so Scrooge gets up and walks over to the door. As he put his hand on the lock, he hears a strange voice and call his name and tell him to enter the room. Scrooge obeys and this leads to his...

Early in the third stave, while Scrooge is waiting for the arrival of the next ghost, he sees a bright light shining. It look as though this light is coming from the "adjoining room" so Scrooge gets up and walks over to the door. As he put his hand on the lock, he hears a strange voice and call his name and tell him to enter the room. Scrooge obeys and this leads to his meeting with the Ghost of Christmas Present. 

Given Scrooge's nature, it seems odd that he would obey the ghost's request and open the door. This is, perhaps, evidence that Scrooge's character is starting to change and that he is beginning to work with people, instead of fighting against them. It also suggests, then, that he is committed to this process of change and has become a willing participant in his own reformation.