The custom of burying the dead with a small coin fixed between the teeth was also explained as provision for the passage-money that would have to be paid to Charon.
Rohde grounds Charon’s mythological function in actual Greek funerary ritual, demonstrating that the ferryman’s toll was materially enacted through burial practice, giving psychological and religious weight to the threshold crossing.
, Psyche: The Cult of Souls and the Belief in Immortality among the Greeks, 1894thesis