„Hazel frowned. “Why that one?””You don’t see the ghost?” Frank asked.”Ghost?” Nico asked.Okay… if Frank was seeing a ghost that the Underworld kids couldn’t see, something was definitely wrong.“

— Rick Riordan
„Please!’That word didn’t make sense to Nico. The Underworld had no mercy. It only had justice.‘You’re already dead,’ Nico said. ‘You’re a ghost with no tongue, no memory. You won’t be sharing any secrets.“
— Rick Riordan
„Nico di Angelo has warned them: the House of Hades would stir their worst memories, make them see things and hear things from the past Their ghosts would become restless.“
— Rick Riordan
„Of all ghosts the ghosts of our old loves are the worst.“
— Arthur Conan Doyle
„Are you a ghost?“
— Rick Riordan
„I remember you said this war was a story of Lightwoods and Herondales and Fairchilds, and it is, and Blackthorns and Carstairs as well, and it's amazing to see them. But when I do, it's as if I see the past that stretches out behind them. I watch Jace Herondale play, and I see the ghosts that rise up in the music. Don't you?“
— Cassandra Clare
„we need ghost stories because we, in fact, are the ghosts.“
— Stephen King