The old man looked agitated today. Had he figured out some of his toys were missing? Well, there was nothing to be done about that now. Hugo needed the toys.
-- Narrator (Narrator Part 1, Chapter 1 paragraph 1)

Importance: Early in the novel, Hugo's sole purpose in life is made apparent: he is determined to make the automaton in his possession work again. To do this, he needs parts to fix the automaton, and he gains many potential parts from the toys he steals from the old man's toy shop. But eventually, the old man notices that toys are going missing, and Hugo is about to be caught.

Ghosts…” the old man muttered to himself. “I knew they would find me here eventually.
-- Georges (Part 1, Chapter 1 paragraph 26)

Importance: The old man, later revealed as Georges Melies, is horrified that his past has caught up to him. He sees his past as something like ghosts which haunt him, and the ghosts have been brought about...