The oracles of Apollo at Delphi were the most respected priestesses in Ancient Greece. The oracles delivered the messages of the "gods," providing advice for rulers, citizens, and philosophers regardless of how big or small their issue. Before answering questions of visitors, the oracles would enter a trance by inhaling some holy smoke from a tripod vase. However, it turns out that the fumes the oracles inhaled consisted of a combination of carbon dioxide and methane, effectively drugging the oracles.
So how where the oracles able to give highly regarded advice that all their visitors followed? High on their holy concoction, the oracles in ecstatic gibberish that their visitors did not understand. In order to convey the "gods'" message, male priests would translate the oracle's cryptic message. But these male priests were no normal priests, they were networking spies who had eyes and ears all over the world. Their extensive network allowed them to provide advice that worked the best with the world's climate, as the priests could interpret the oracle's gibberish however they wanted.
Thus, these famous and well-respected oracles were not delivering the orders of the gods, but advice from mankind to mankind.