When the Spirit of Christmas Past appears before him, Scrooge desires "to see the Spirit in his cap"; that is, to cover the light of knowledge from memories that it spreads through the room.
"What!" exclaimed the Ghost, "would you so soon put out, with worldly hands, the light I give? Is it not enough that you are one of those whose passions made this cap, and force me through whole trains of years to wear it low upon my brow?"
However, he is unable to do this because the Spirit of the Past is too strong with its long muscular arms. Memory's light persists. When Scrooge disclaims any intention of "bonneting" the Spirit at any time in his life, the Spirit refutes this claim by saying that it has come for Scrooge's "reclamation." It orders Scrooge to stand up and walk with him. When the Spirit moves toward the window, Scrooge pleads with it that the weather and the hour are not appropriate for travel, but the Spirit tells Scrooge to lay his hand upon its heart. As Scrooge does so, they are swept away to the time when he was a boy. Memories begin to flood Scrooge's mind and he "reclaims" the memory of his young self as a lonely boy. This recall of his own misery reminds him that a boy was singing a Christmas Carol at his door and he ignored him. Now, however, he sheds a tear, wipes his eyes and tells the Spirit, "I should like to have given him something; that's all."
Thus, the knowledge provided by memory of one's own loneliness and misery extends its light into the heart of Scrooge and he realizes that he should have relieved another boy's same misery with a kindness to him.