Walter Burkert (1931-2015),
Greek Religion, tr. John Raffan (Cambridge: Harvard University Press, 1985; rpt. 2001), p. 81, with note on p. 379:
After Aeschylus it was imagined how Apollo himself had purified
Orestes at Delphi with a pig sacrifice. Vase paintings give an idea of the
procedure, similar to that used for the purification of the Proitides: the piglet is
held over the head of the person to be purified and the blood must flow directly
onto the head and hands.60
60 Esp. the bell-krater Louvre K. 710, Harrison (1) 228, JHS 89 (1969) Pl.2.1.
The purification of the Proitides: krater from Canicattini AK 13 (1970)
Pl.30.2. That the purification in Delphi does not rest on local cult practice, but
only on Aesch. Eum. 282 f. is emphasized by R.R. Dyer, JHS 89 (1969) 38–56.
Louvre K. 710, from Dyer, Plate II, fig. 1:
Another view of the krater:
