What are the character traits in The Christmas Carol for the Christmas Past ghost?

The Ghost of Christmas Past is, by far, the most confusing of all the spirits that visit Scrooge on Christmas Eve.  Its appearance not only changes to contradict itself from one moment to the next, but also creates confusion even in a single moment.  It is described as both "like a child," but "no so like a child as like an old man."  Its long hair "was white as if with age"; and yet the face had "not a wrinkle on it."  Even though it looks like an old man, "the arms were very long and muscular."  Other traits build on these contradictions, as its tunic is decorated with summer flowers, yet "[i]t held a branch of fresh green holly in its hand." Dickens finishes the description by saying,

the strangest thing about it was, that from the crown of its head there sprung a bright clear jet of light, by which all this was visible; and which was doubtless the occasion of its using, in its duller moments, a great extinguisher for a cap, which it now held under its arm.

To further confuse the reader, Dickens says that the figure varies between light and dark, and "fluctuated in its distinctness," to the point that in one moment it looks like it only has one arm or one leg, and then twenty legs, or a headless body, or a head without a body.All of these shifting qualities could result in Dickens's reader losing track of the narrative as they struggle to visualize the character he has presented.   However, the ambiguities are reconciled because of what the spirit represents.  It is the Ghost of Christmas Past.  Everything that has occurred before the very moment that marks "the present" is part and parcel of the spirit.  Youth and old age are all contained within it.  Years upon years of spring, summer, fall, and winter are all manifested at once.  It is light and, at times, the absence of it.  The way in which Dickens represents the physical form, as the spirit manifests itself with single, multiple, or even no body parts, presents a very surprising perspective on the idea of time, which is later explored in science-fiction.  In this way the spirit almost becomes a vision of what one would see if not limited to seeing the world in three dimensions.  The idea of twenty legs, of a centipede-like creature, is actually something that Kurt Vonnegut explored with the way that the alien Tralfamadorians viewed humans in Slaughterhouse-Five, more than one hundred years after Dickens penned his timeless text.  In that text, the Tralfamadorians are not limited to seeing a person in a given moment in time.  Rather, they see the entire existence of the person stretching out from birth to death, and the creature looks very much like a person to them.  Here Dickens hints at a similar perspective, albeit very briefly.While the Ghost of Christmas Past is initially somewhat confusing, it actually stands as one of Dickens's richest symbols.