Another of their functions σφάγια share with the ordinary animal-sacrifices, the ἱερεῖα. Like the ἱερεῖα they could be used for purposes of divination. Used as they were for purification in any great emergency, mere economy may have suggested that they should be further utilized for oracular purposes. The greater solemnity of σφάγια would lend to the omens taken from them a specially portentous virtue[166]. It is amusing to find that even Porphyry[167], averse though he is to human sacrifice, still seems to feel a dim possibility that for mantic purposes human entrails may have special virtue. ‘But it will be urged,’ he says, as though stating a possible and reasonable argument, ‘that the future may be more clearly divined from the vitals of a man.’ Precise authors who know about ritual always distinguish between the omens taken from ordinary animal sacrifice and those from σφάγια. Thus Xenophon[168] in the _Anabasis_ says, ‘The sacrifices (ἱερεῖα) are propitious to us, the omens favourable, the σφάγια most propitious.’ The practice of using σφάγια for omens before a battle would seem to have been uniform. When women, says Eteocles[169], are wailing and making a commotion, it is the part of men ‘To slay the victims, take therefrom the omens Before the gods, at the onset of the foe.’ It is probably to this oracular function of σφάγια that we owe the very frequent use of the middle σφαγιάζεσθαι, as in the parallel case of θύειν, the sacrifice by fire. For θύειν and θύεσθαι the distinction is familiar, and expressly stated by Ammonius[170]: ‘of those who simply sacrifice (active) the victims the word θύουσι is used, of those who take omens from the entrails θύονται.’ The active is of the nature of thanksgiving, the middle partakes of prayer and impulsion. In the case of σφάγια the active is very rarely in use, and naturally, for the sacrifice of σφάγια has in it no element of thanksgiving[171]. The ritual then of σφάγια and of ἐναγισμοί, of slaughter and of purification, is based on the fear of ghosts, of ghosts and their action on men alive, whether as evil winds, or for dread portents, or for vengeance on the broken oath, or, first and foremost, for the guilt of shed blood. Its essence is of ἀποτροπή, _aversion_. Nowhere perhaps is this instinct of aversion so clearly seen, seen in a form where the instinct has not yet chilled and crystallized into definite ritual, as in the account of the murder of Absyrtos by Jason and Medea as given by Apollonius Rhodius[172]. The murder was by a treacherous ambuscade set for Absyrtos at the threshold of the temple of Artemis; Jason smites him like a bull for sacrifice, while Medea stands by.