What exactly is an oracle? Or, more specifically, what was an oracle in an ancient Greek context? The communication of divine knowledge from god to mortal, also known as divination, played a major role in ancient Greek religion. Divination took many forms, from the study of sacrificial entrails to the interpretation of the flight of birds. But perhaps the most important form of divination was the practice of consultation of a god through an intermediary. This intermediary was known as an oracle.