Divination with the bodies of human victims is attested by Tacitus, who says that "the Druids consult the gods in the palpitating entrails of men," and by Strabo, who describes the striking down of the victim by the sword and the predicting of the future from his convulsive movements.750 To this we shall return.
Human sacrifice in Gaul was put down by the Romans, who were amazed at its extent, Suetonius summing up the whole religion in a phrase—druidarum religionem diræ immanitatis.751 By the year 40 A.D. it had ceased, though victims were offered symbolically, the Druids pretending to strike them and drawing a little blood from them.752 Only the pressure of a higher civilisation forced the so-called philosophic Druids to abandon their revolting customs. Among the Celts of Britain human sacrifice still prevailed in 77 A.D.753 Dio Cassius describes the refinements of cruelty practised on female victims (prisoners of war) in honour of the goddess Andrasta—their breasts cut off and placed over their mouths, and a stake driven through their bodies, which were then hung in the sacred grove.754 Tacitus speaks of the altars in Mona (Anglesey) laved with human blood. As to the Irish Celts, patriotic writers have refused to believe them guilty of such practices,755 but there is no a priori reason which need set them apart from other races on the same level of civilisation in this custom. The Irish texts no doubt exaggerate the number of the victims, but they certainly attest the existence of the practice. From the Dindsenchas, which describes many archaic usages, we learn that "the firstlings of every issue and the chief scions of every clan" were offered to Cromm Cruaich—a sacrifice of the first-born,—and that at one festival the prostrations of the worshippers were so violent that three-fourths of them perished, not improbably an exaggerated memory of orgiastic rites.756 Dr. Joyce thinks that these notices are as incredible as the mythic tales in the Dindsenchas. Yet the tales were doubtless quite credible to the pagan Irish, and the ritual notices are certainly founded on fact. Dr. Joyce admits the existence of foundation sacrifices in Ireland, and it is difficult to understand why human victims may not have been offered on other occasions also.
The purpose of the sacrifice, namely, fertility, is indicated in the poetical version of the cult of Cromm—
"Milk and corn
They would ask from him speedily,
In return for one-third of their healthy issue."757
The Nemedian sacrifice to the Fomorians is said to have been two-thirds of their children and of the year's supply of corn and milk758—an obvious misunderstanding, the victims really being offered to obtain corn and milk. The numbers are exaggerated,759 but there can be no doubt as to the nature of the sacrifice—the offering of an agricultural folk to the divinities who helped or retarded growth. Possibly part of the flesh of the victims, at one time identified with the god, was buried in the fields or mixed with the seed-corn, in order to promote fertility. The blood was sprinkled on the image of the god. Such practices were as obnoxious to Christian missionaries as they had been to the Roman Government, and we learn that S. Patrick preached against "the slaying of yoke oxen and milch cows and the burning of the first-born progeny" at the Fair of Taillte.760 As has been seen, the Irish version of the Perseus and Andromeda story, in which the victim is offered not to a dragon, but to the Fomorians, may have received this form from actual ritual in which human victims were sacrificed to the Fomorians.761 In a Japanese version of the same story the maiden is offered to the sea-gods. Another tale suggests the offering of human victims to remove blight. In this case the land suffers from blight because the adulteress Becuma, married to the king of Erin, has pretended to be a virgin. The Druids announced that the remedy was to slay the son of an undefiled couple and sprinkle the doorposts and the land with his blood. Such a youth was found, but at his mother's request a two-bellied cow, in which two birds were found, was offered in his stead.762 In another instance in the Dindsenchas, hostages, including the son of a captive prince, are offered to remove plagues—an equivalent to the custom of the Gauls.763
Human sacrifices were also offered when the foundation of a new building was laid. Such sacrifices are universal, and are offered to propitiate the Earth spirits or to provide a ghostly guardian for the building. A Celtic legend attaches such a sacrifice to the founding of the monastery at Iona. S. Oran agrees to adopt S. Columba's advice "to go under the clay of this island to hallow it," and as a reward he goes straight to heaven.764 The legend is a semi-Christian form of the memory of an old pagan custom, and it is attached to Oran probably because he was the first to be buried in the island. In another version, nothing is said of the sacrifice. The two saints are disputing about the other world, and Oran agrees to go for three days into the grave to settle the point at issue. At the end of that time the grave is opened, and the triumphant Oran announces that heaven and hell are not such as they are alleged to be. Shocked at his latitudinarian sentiments, Columba ordered earth to be piled over him, lest he cause a scandal to the faith, and Oran was accordingly buried alive.765 In a Welsh instance, Vortigern's castle cannot be built, for the stones disappear as soon as they are laid. Wise men, probably Druids, order the sacrifice of a child born without a father, and the sprinkling of the site with his blood.766 "Groaning hostages" were placed under a fort in Ireland, and the foundation of the palace of Emain Macha was also laid with a human victim.