A maiden pure unto the nether powers, Chosen by lot, of lineage Aepytid, Ye shall devote in sacrifice by night. But if ye fail thereof, take ye a maid E’en from a man of other race as victim, An he shall give her willingly to slay.
And the story goes on to tell how in the end Aristodemus devoted his own daughter, and she became the accepted victim.
Here Pausanias, it will be noticed, does not give any reason for the sacrifice being required. But three points in his narrative are highly suggestive. The story of the sacrifice follows immediately upon the mention of the building of new fortifications--and the foundation of what was to be practically a new city was eminently a question on which to consult the Delphic oracle; the powers to whom sacrifice is ordered are designated merely as νέρτεροι δαίμονες, the nearest equivalent in ancient Greek to _genii_; and the time of the sacrifice is to be night, when, according to modern belief, _genii_ are most active. If then modern superstition can ever teach us anything about ancient religion, it supplies the clue here. The maiden was to be sacrificed to the _genii_ of Mount Ithome to ensure the stability of the new fortifications.
Now if my interpretation of this story is right and the practice of human sacrifice to _genii_ was known in ancient Greece, the transition from the worship of _genii_ in the form of snakes or dragons to the worship of tutelary heroes or gods in human likeness is readily explained on the analogy of a similar transition in modern belief. What was originally the victim was mistaken for the genius. The same confusion of thought, by which, in one version of ‘the Bridge of Arta,’ the _genius_ in person demands a human victim and yet afterwards the victim speaks of herself as becoming the _genius_ of the bridge, can be detected even in the oracle given to the Messenians. ‘If ye fail to find a maid of the blood of the Aepytidae,’ it said, ‘ye may take the daughter of a man of other lineage, provided that he give her willingly for sacrifice.’ Why the condition? Why ‘willingly’ only? Because, I think, even the Delphic oracle halted between two opinions--between the conception of the maiden as a victim to appease angry _genii_ and the belief that the dead girl herself would become the guardian-_daemon_ of the stronghold.