From Madsen Pirie's 101 Great Philosophers:
"Thales (c 624-547 BC), from the Ionian city of Miletus in Asia Minor, is hailed as the first philosopher ...
"Thales was asked why, if he was so clever, was he not rich? His response was to predict from astronomical observations that the next olive harvest would be a bumper one, and to buy futures on olive presses. He leased them out at higher rates when the bumper harvest materialized, simply to show that he could make money if he wished."