It sounds simple but let's hear a good description of how it actually works. Believe me, I've being there, seen it and done it. The following e-mail is from Eddy of Brunei:
It was autumn, and the Red Indians on the remote reservation asked their NEW CHIEF if the winter was going to be cold or mild. Since he was a Red Indian chief in a modern society, he couldn't tell what the weather was going to be. Nevertheless, to be on the safe side, he told his tribe that the winter was indeed going to be cold and that the members of the village should collect wood to be prepared.
But, also being a practical leader, after several days he got an idea. He went to the phone booth, called the National Weather Service and asked, "Is the coming winter going to be cold?"
"It looks like this winter is going to be quite cold, indeed," the meteorologist at the weather service responded.
So the Chief went back to his people and told them to collect even more firewood.
A week later, he called the National Weather Service again. "Is it going to be a very cold winter?"
"Yes," the man replied at the National Weather Service again replied. "It's definitely going to be a very cold winter."
The Chief again went back to his people and ordered them to collect every scrap of wood they could find.
Two weeks alter, he called the National Weather Service again. "Are you absolutely sure that the winter is going to be very cold?"
"Absolutely," the man replied. "It's going to be one of the coldest winters ever."
"How can you be so sure?" the Chief asked.
The weatherman replied, "The Red Indians are collecting wood like crazy."
THIS IS HOW THE STOCK MARKET WORKS!