‘The black bolt from below comes from the slain Of kin who cry for vengeance, and from them Madness and empty terror in the night Comes haunting, troubling.’ It is ‘the slain of kin’ who cries for vengeance. As Pausanias[564] says of the same house, ‘the pollution of Pelops and the avenging ghost of Myrtilos dogged their steps.’ ‘Fate,’ says Polybius[565], ‘placed by his (Philip’s) side Erinyes and Poinae and Pointers-to-Vengeance (προστροπαίους).’ Here clearly all the words are synonymous. Apollo threatens the slayer of his mother with ‘Yet other onsets of Erinys sent Of kindred blood the dire accomplishment, Visible visions that he needs must mark, Aye, though he twitch his eyebrows in the dark[566].’ To cause these ‘onsets,’ these προσβολαί, or, as they are sometimes called, ἔφοδοι, was, Hippocrates[567] tells us, one of the regular functions of dead men. Behind the notion of these accesses of fright, these nocturnal apparitions caused by ghosts, there is in the mind of Aeschylus the still more primitive notion that the shed blood not only ‘brings these apparitions to effect,’ but is itself a source of physical infection. Here we seem to get down to a stratum of thought perhaps even more primitive than that of the bacillus-like Keres. The Chorus in the _Choephori_ sings[568]: ‘Earth that feeds him hath drunk of the gore, Blood calling for vengeance flows never more, But stiffens, and pierces its way Through the murderer, breeding diseases that none may allay.’ The blood poisons the earth, and thereby poisons the murderer fed by earth. As Dr Verrall (_ad loc._) points out, it is the old doctrine of the sentence of Cain, ‘And now art thou cursed from the earth, which hath opened her mouth to receive thy brother’s blood from thy hand; when thou tillest the ground, it shall not henceforth yield unto thee her strength.’ In the crudest and most practical form, this notion of the physical infection of the earth comes out in the story of Alcmaeon. Pausanias[569] tells us that when Alcmaeon had slain his mother Eriphyle, he came to Psophis in Arcadia, but there his disease nowise abated. He then went to Delphi, and the Pythia taught him that the only land where the avenger of Eriphyle could not dog him was the newest land which the sea had laid bare subsequently to the pollution of his mother’s blood, and he found out the deposit of the river Acheloüs and dwelt there. There, by the new and unpolluted land he might be nourished and live. Apollodorus[570] misses the point: he brings Alcmaeon to Thesprotia and purifies him, but by the _waters_ of Acheloüs. The case of Alcmaeon does not stand alone. It has a curious parallel in the fate that befell Bellerophon, a fate that, I think, has not hitherto been rightly understood.