To the scientific mind of a modern European living in the atmosphere of a highly secularised society, nothing can appear more curious and incomprehensible than the almost universal belief in ubiquitous supernatural forces which is revealed in ancient literature. Such a belief is not, however, a symbol of savagery or barbarism; it is merely a symptom of the absence of scientific knowledge. The general principle that men in all ages attribute to occult forces every effect of which the cause is unknown or mysterious, is clearly expressed by Lucretius[13]: quippe ita formido mortales continet omnes quod multa in terris fieri caeloque tuentur quorum operum causas nulla ratione videre possunt ac fieri divino numine rentur. It was natural then, in an age of unscientific mentality, that plagues and pestilences, and diseases of all kinds, lunacy and sterility, the failure of harvests, misfortune in peace or war, adverse winds, volcanoes, inherited characteristics, the activities of genius, emotion and desire, birth, growth, death and decay—almost everything that crosses the threshold of human consciousness—should be ascribed to the ubiquitous and perpetual operation of supernatural agents. The literature of ancient Greece and Rome is permeated with such beliefs. We will quote just one characteristic passage from the _Eumenides_ of Aeschylus. When the avenging Erinnyes of the slain Clytaemnestra threaten to hurl the shafts of their wrath upon the Attic land because it has harboured Orestes, whom they regard as the murderer of his kin, Athene, who has caused a murder-court to declare him free from guilt, apparently on a plea of justifiable homicide, commands the Erinnyes to be appeased, and says: ‘Hurl you not the weight of your wrath upon Attica; be not indignant, nor cause barrenness by sending down the blighting drops that come from Spirits, the cruel bitter destroyers of our seed.[14] ... Fling not upon earth the fruit of thy wild curse, causing all things not to prosper.[15] ... Sow not within my boundaries those spurs to bloodshed that ruin young men’s hearts, maddened by a frenzy not born of wine[16] ... but (send) blessings from earth and from the waters of the deep, and from the sky wind-breezes that blow with kindly sunshine over earth: (send) fruit of the soil and of things that live, flowing with untiring vigour to my citizens, and of man’s seed a safe deliverance at the birth.’[17] The Erinnyes, in consenting to be appeased, reply: ‘With kindly prophecy we pray for you here, that the radiant sunlight may bring forth with speed from earth the blessings of your life[18] ... never—such is my boon—may the trees feel the hurtful wind or the scorching fire that robs them of their buds ... or blight creep over them eternally that blasts their fruitfulness: and may Pan bring to full growth the prosperous flocks that will bear from wombs a twofold fruit, and in due season may the produce