Answer: Our irrational fear or panic is what causes these mass hysteria episodes to repeat, since we cannot understand some things. Once we understand what everything is about, our fear dissapears, but, of course, until that happens, we will either react by panicking or running away in fear. For example, no one is scared of a common disease, since we know everything about it; but many would be scared if they heard an unidentified noise at 3AM.
