SUPERNATURAL ENTITY
The Ghost of Christmas Past is described as a supernatural entity with fluctuating physical form and the ability to transport Scrooge through time and space.
GHOST OF CHRISTMAS PAST
instant at another time was dark, so the figure itself fluctuated in its distinctness; being now a thing with one arm, now with one leg, now with twenty legs, now a pair of legs without a head, now a head without a body: of which dissolving parts no outline would be visible in the dense gloom wherein they melted away. And, in the very wonder of this, it would be itself again; distinct and clear as ever. ... As the words were spoken, they passed through the wall, and stood upon an open country road, with fields on either hand.