Of all these varieties of human sacrifice, those offered for fertility, probably at Beltane or Midsummer, were the most important. Their propitiatory nature is of later origin, and their real intention was to strengthen the divinity by whom the processes of growth were directed. Still earlier, one victim represented the divinity, slain that his life might be revived in vigour. The earth was sprinkled with his blood and fed with his flesh in order to fertilise it, and possibly the worshippers partook sacramentally of the flesh. Propitiatory holocausts of human victims had taken the place of the slain representative of a god, but their value in promoting fertility was not forgotten. The sacramental aspect of the rite is perhaps to be found in Pliny's words regarding "the slaying of a human being as a most religious act and eating the flesh as a wholesome remedy" among the Britons.768 This may merely refer to "medicinal cannibalism," such as still survives in Italy, but the passage rather suggests sacramental cannibalism, the eating of part of a divine victim, such as existed in Mexico and elsewhere. Other acts of cannibalism are referred to by classical writers. Diodorus says the Irish ate their enemies, and Pausanias describes the eating the flesh and drinking the blood of children among the Galatian Celts. Drinking out of a skull the blood of slain (sacrificial) enemies is mentioned by Ammianus and Livy, and Solinus describes the Irish custom of bathing the face in the blood of the slain and drinking it.769 In some of these cases the intention may simply have been to obtain the dead enemy's strength, but where a sacrificial victim was concerned, the intention probably went further than this. The blood of dead relatives was also drunk in order to obtain their virtues, or to be brought into closer rapport with them.770 This is analogous to the custom of blood brotherhood, which also existed among the Celts and continued as a survival in the Western Isles until a late date.771
One group of Celtic human sacrifices was thus connected with primitive agricultural ritual, but the warlike energies of the Celts extended the practice. Victims were easily obtained, and offered to the gods of war. Yet even these sacrifices preserved some trace of the older rite, in which the victim represented a divinity or spirit.
Head-hunting, described in classical writings and in Irish texts, had also a sacrificial aspect. The heads of enemies were hung at the saddle-bow or fixed on spears, as the conquerors returned home with songs of victory.772 This gruesome picture often recurs in the texts. Thus, after the death of Cúchulainn, Conall Cernach returned to Emer with the heads of his slayers strung on a withy. He placed each on a stake and told Emer the name of the owner. A Celtic oppidum or a king's palace must have been as gruesome as a Dayak or Solomon Island village. Everywhere were stakes crowned with heads, and the walls of houses were adorned with them. Poseidonius tells how he sickened at such a sight, but gradually became more accustomed to it.773 A room in the palace was sometimes a store for such heads, or they were preserved in cedar-wood oil or in coffers. They were proudly shown to strangers as a record of conquest, but they could not be sold for their weight in gold.774 After a battle a pile of heads was made and the number of the slain was counted, and at annual festivals warriors produced the tongues of enemies as a record of their prowess.775
These customs had a religious aspect. In cutting off a head the Celt saluted the gods, and the head was offered to them or to ancestral spirits, and sometimes kept in grove or temple.776 The name given to the heads of the slain in Ireland, the "mast of Macha," shows that they were dedicated to her, just as skulls found under an altar had been devoted to the Celtic Mars.777 Probably, as among Dayaks, American Indians, and others, possession of a head was a guarantee that the ghost of its owner would be subservient to its Celtic possessor, either in this world or in the next, since they are sometimes found buried in graves along with the dead.778 Or, suspended in temples, they became an actual and symbolical offering of the life of their owners, if, as is probable, the life or soul was thought to be in the head. Hence, too, the custom of drinking from the skull of the slain had the intention of transferring his powers directly to the drinker.779 Milk drunk from the skull of Conall Cernach restored to enfeebled warriors their pristine strength,780 and a folk-survival in the Highlands—that of drinking from the skull of a suicide (here taking the place of the slain enemy) in order to restore health—shows the same idea at work. All these practices had thus one end, that of the transference of spirit force—to the gods, to the victor who suspended the head from his house, and to all who drank from the skull. Represented in bas-relief on houses or carved on dagger-handles, the head may still have been thought to possess talismanic properties, giving power to house or weapon. Possibly this cult of human heads may have given rise to the idea of a divine head like those figured on Gaulish images, or described, e.g., in the story of Bran. His head preserved the land from invasion, until Arthur disinterred it,781 the story being based on the belief that heads or bodies of great warriors still had a powerful influence.782 The representation of the head of a god, like his whole image, would be thought to possess the same preservative power.
A possible survival of the sacrifice of the aged may be found in a Breton custom of applying a heavy club to the head of old persons to lighten their death agonies, the clubs having been formerly used to kill them. They are kept in chapels, and are regarded with awe.783
Animal victims were also frequently offered. The Galatian Celts made a yearly sacrifice to their Artemis of a sheep, goat, or calf, purchased with money laid by for each animal caught in the chase. Their dogs were feasted and crowned with flowers.784 Further details of this ritual are unfortunately lacking. Animals captured in war were sacrificed to the war-gods by the Gauls, or to a river-god, as when the horses of the defeated host were thrown into the Rhine by the Gaulish conquerors of Mallius.785 We have seen that the white oxen sacrificed at the mistletoe ritual may once have been representatives of the vegetation-spirit, which also animated the oak and the mistletoe. Among the insular Celts animal sacrifices are scarcely mentioned in the texts, probably through suppression by later scribes, but the lives of Irish saints contain a few notices of the custom, e.g. that of S. Patrick, which describes the gathering of princes, chiefs, and Druids at Tara to sacrifice victims to idols.786 In Ireland the peasantry still kill a sheep or heifer for S. Martin on his festival, and ill-luck is thought to follow the non-observance of the rite.787 Similar sacrifices on saints' days in Scotland and Wales occurred in Christian times.788 An excellent instance is that of the sacrifice of bulls at Gairloch for the cure of lunatics on S. Maelrubha's day (August