The beginnings of the magical-religious conception of disease would go back to before the development of writing (prehistory). During ancient times the world was conceived as a place where the supernatural was essential for mankind's survival, therefore, explanations of all phenomena, including disease, were based on supernatural causes. With the development of Greek civilization began the establishment of a rational approach to the nature of the world, which gradually included medicine. But the origin of the rational and naturalist perspective of medicine is due in part to the influence of ancient Egyptian civilization. Various terms were used to refer to healing agents at the pre-Hippocratic period of ancient Greece: iatromantis, pholarcos, ouliads, and asclepiads. Later, in the ancient Greek civilization, healing through prophecy was gradually replaced, though not entirely displaced, by a new medicine, based on a rational theoretical framework about health and disease: techne iatrike.