The Ghost of Christmas Past is the first of the three ghosts that visit Scrooge (excluding Marley's ghost). He shows him memories of his past, including him spending Christmas alone at school, his time as an apprentice of Fezziwig, and his fiancée Belle wishing to break their engagement. He is described as looking both like a child and an old man at the same time, wearing a tunic of the purest white (potentially symbolising the innocence of childhood) and a crown emitting a bright jet of light. He marks the beginning of Scrooge's redemption.
Quotes said by or that describe the Ghost of Christmas Past that you may find useful:
"would you so soon put out, with worldly hands, the light I give?"
"it wore a tunic of the purest white"