In ancient Greece, the Buphonia (Greek: Βουφόνια "ox-slayings") denoted a sacrificial ceremony performed at Athens as part of the Dipolieia, a religious festival held on the 14th of the midsummer month Skirophorion— in June or July— at the Acropolis. In the Buphonia a working ox was sacrificed to Zeus Polieus, Zeus protector of the city, in accordance with a very ancient custom. A group of oxen was driven forward to the altar at the highest point of the Acropolis. On the altar a sacrifice of grain had been spread by members of the family of the Kentriadae, on whom this duty devolved hereditarily. When one of the oxen began to eat, thus selecting itself for sacrifice, one of the family of the Thaulonidae advanced with an axe, slew the ox, then immediately threw aside the axe and fled the scene of his guilt-laden crime.
The Athenians of the age of Aristophanes regarded the sombre ritual as archaic; its founding myth attributed its inception to Cecrops, the chthonic king of remotest legend (Aristophanes) or to archaic Erechtheus (Pausanias 1.28.10). The Dipolieia survived at least to the time of the Roman Empire.
Details of the rite can be reconstructed in detail, thanks to a passage in Porphyry that has been traced to a source in Theophrastus The offering of grain was a reminder of the time "when people shrank from eating oxen," as Plato related in The Laws (782c), "and offered no animals in sacrifice, but rather, cakes and the fruits of the earth soaked in honey, and other such pure sacrifices."
Although the slaughter of a laboring ox was forbidden, it was excused in these exceptional circumstances; nonetheless it was regarded as a murder. The axe, therefore, as being polluted by murder, was immediately afterward carried before the court of the Prytaneum, which tried the inanimate object for murder, and, after the water-bearers who lustrated the axe, the sharpeners who sharpened it, the axe-bearer who carried it, each denied in turn responsibility for the deed, the guilty axe or knife was there charged with having caused the death of the ox, for which the axe was acquitted (Pausanias) or the sacrificial knife was thrown into the sea (Porphyry). Apparently this is an early instance analogous to deodand. In the enactment of this comedy of innocence, and the joint feasting of all who participated save the slayer himself, individual consciences were assuaged and the polis was reaffirmed.