Answer: Scrooge is presented to us as a bitter old man who never thinks of anyone else but him. After that was stablished to the reader, the spirits come and they three show his past, present & future. Dickens writes about the famous sentence you have probably heard before: "You get what you give". The extract above makes Scrooge question his own senses — something he had never done before for think so highly of himself — and punishes the character by making he realize that nothing he’ve done so far in his life mattered and won’t matter. The most precious thing he could’ve done was to be nice to the people he knows, and be loved and love.
Explanation: In the third paragraph it says how Scrooge was in shock, scared and questioned his senses, which must be really weird for a guy with such high ego.