The so-called fear is a strong and depressed emotional state that individuals or groups deeply feel in real or imagined dangers. Its manifestations are high tension, inner fear, inability to concentrate, blank mind, inability to correctly judge or control one's behavior, and impulsiveness.

It is only 10,000 years before and after human beings entered civilized society. Homo sapiens had existed for hundreds of thousands of years before this. Most of the time, human beings have to face unknown forests and grasslands, worrying about whether there will be wild animals, diseases and dangers in places where their eyesight is poor, and whether there will be a pair of eyes staring at them, but they are unaware of it. Although human beings are already at the top of the food chain, individual people are still very fragile. Mysterious stories, a kind of rules, take advantage of this fear instinct of human beings.