Spectropia : Or Surprising Spectral Illusions Showing Ghosts Everywhere and of Any Colour

This book explores the ghosts that it claims are everywhere, so long as you know how to look. Originally published in 1864, this book was marketed as a science-based guide to seeing ghosts, ghouls, spirits, skeletons, and witches, with graveyard lurking optional. The way it works is by simply staring at the sixteen color plates inside this book for twenty seconds, and you’ll see colorful spooky specters IRL! This fun book for the believers or the skeptical to experience a little bit of the paranormal.