Authors:

Blood!...Blood!... That's a good thing! A ghost who bleeds is less dangerous!

Gaston Leroux (2016). “The Phantom of the Opera & The Mystery of the Yellow Room (Mystery Classics): The Ultimate Gothic Romance Mystery and One of the First Locked-Room Crime Mysteries”, p.105, e-artnow
Blood!...Blood!... That's a good thing! A ghost who bleeds is less dangerous!