The ancient Oracle said that I was the wisest of all the Greeks. It is because I alone, of all the Greeks, know that I know nothing.
oraclequotes
They sometimes behave like the Delphic oracle that told King Croesus that if he crossed the Halys River he would destroy a large kingdom. It was only after he had been completely defeated in battle after the crossing that he discovered that the kingdom meant by the oracle was his own.