In time immemorial, when the first cavemen had just learnt how to make fire and invented the wheel, Grak Cave was besieged by unusually clever inhabitants. One clear moonlit night, when the stars were shining brightly and the mammoths were snoring peacefully, the cave elder decided that they urgently needed to come up with something new to make life even more... interesting.

The Elder thought for a long time and finally called his most intelligent assistant, named Brook.

- Brook," said the Elder, "we do a lot of hunting and fishing and painting on the cave walls. But I think something is missing. We need to reinvigorate our community.

Brook, scratching the back of his head, suddenly brightened up and replied:

- Maybe we should start trading on the stock exchange.

$PDG