TAUROBOLIUM. - A ceremony originating in Asia Minor, where it was connected with the cult of the great female deity, and which, from Phrygia (whose evidence dates back only to the 2nd century AD), along with the cult of Cybele, spread to Rome and Italy in general, whence it passed into Gaul, Spain, and the Roman provinces of North Africa.
Almost nothing is known from Eastern sources about the development of the rite; the Greek term shows that the bull to be sacrificed had to be captured in the hunt, by hurling (δάλλω) a thrown weapon, according to an ancient custom widespread throughout the East. This hunt eventually became a circus game, a bullfight, performed independently of the religious sacrifice, which survived only without the hunt or the chase: such is the taurobolium as it appears in the age of the Antonines.
The most detailed accounts of the taurobolium come from late Roman sources: Prudentius (Peristeph., X, 1011-71), where the taurobolium of the high priest of Cybele is described in great detail. The priest descended into a pit, the upper opening of which was then covered by a poorly fitted platform pierced with holes. Above this, the priests led in procession, to the accompaniment of drums and cymbals (as shown by the iconography of ex-voto altars), a bull crowned with flowers and garlands, which was then slaughtered with a hooked spear (venabulum, a survival of the ancient hunting rite?), in such a way that the blood flowed through the platform into the pit, completely drenching the body and garments of the high priest, who even turned his face upward, placed his ears below, and protruded his lips and nostrils, so that his eyes were befouled by that gory flood. Nor did he spare his palate, but soaked his tongue until it was entirely steeped in the black blood (Prudentius, loc. cit., trans. Marchesi). After such a repugnant aspersion, the celebrant emerged from the pit and presented himself for the adoration of the assembled initiates. Even the testicles (vires) of the animal were of importance in the rite, being collected in the κέφνος, a cernus (cf. CIL, VI, 508; a kind of dish that also played a high role in the Eleusinian mysteries), consecrated to Demeter, and thus buried (vires excepti, transtulit, condidi: CIL, XIII, 1751); this ceremony, with every probability, was intended to replace the (older and more barbaric) self-castration of the initiate and the offering of his own genitals to the goddess.
From these accounts, it is clear that the taurobolium was essential as a pouring out and washing in blood, linked to the primitive concept that drinking and sprinkling oneself with the blood of the freshly slain beast meant transferring its strength into one’s own person; while the descent into the pit was like an access to the Underworld from which the initiate was drawn forth, precisely for the purpose of revivification through the blood, as in the Homeric episode of Odysseus summoning the soul of Tiresias (Odyssey, XI). Moreover, it must not be overlooked that the tauroboliatus, having to place himself beneath the bull to receive the blood, in a sense became the altar of the sacrifice himself.
Anyone could be initiated into the taurobolium, which, to confer true new life (cf. St. Augustine, De civ. Dei, VII, 24-26), had to be repeated, it seems, a second time after twenty years (CIL, 6, 502: Taurobolio criobolioque repetito [the criobolium was a similar ceremony performed, however, with a ram]). It was celebrated at any time of the year (and lasted several days) for one’s own benefit or for others (e.g., pro salute imperii, CIL, XIV, 40), and in Rome (celebrated in the Phrygianum, on the Vatican Hill) it assumed, perhaps from the time of Antoninus Pius, an official character as a state rite, sometimes under the authority of the quindecimviri sacris faciundis.
The apostate Emperor Julian attributed such efficacy to the bloody taurobolic rite that he subjected himself to it with the intention of effacing the washing he had once received in Christian baptism (cf. Gregory Nazianzen, Or., IV, 52; PG 35, 576).