Omen

An omen (also called portent or presage) is a phenomenon that is believed to foretell the future, often signifying the advent of change. People in the ancient times believed that omens lie with a divine message from their gods.

These omens include natural phenomena, for example an eclipse, freak births of animals and humans and behavior of the sacrificial lamb on its way to the slaughter. They had specialists, the diviners, to interpret these omens. They would also use an artificial method, for example, a clay model of a sheep liver, to communicate with their gods in times of crisis. They would expect a binary answer, either yes or no answer, favorable or unfavorable. They did these to predict what would happen in the future and to take action to avoid disaster.