is sometimes specified with a term for "boat fare" (in Greek naulon, ναῦλον, Latin naulum); "fee for ferrying" (porthmeion, πορθμήϊον or πορθμεῖον); or "waterway toll" (Latin portorium). The word naulon (ναῦλον) is defined by the Christian-era lexicographer Hesychius of Alexandria as the coin put into the mouth of the dead; one of the meanings of danakē (δανάκη) is given as "the obol for the dead". The Suda defines danakē as a coin traditionally buried with the dead for paying the ferryman to cross the river Acheron, and explicates the definition of porthmēïon (πορθμήϊον) as a ferryman's fee with a quotation from the poet Callimachus, who notes the custom of carrying the porthmēïon in the "parched mouths of the dead." Charon's obol as viaticum In Latin, Charon's obol is sometimes called a viaticum, which in everyday usage means "provision for a journey" (from via, "way, road, journey"), encompassing food, money and other supplies. The same word can refer to the living allowance granted to those stripped of their property and condemned to exile, and by metaphorical extension to preparing for death at the end of life's journey. Cicero, in his philosophical dialogue On Old Age (44 BC), has the interlocutor Cato the Elder combine two metaphors — nearing the end of a journey, and ripening fruit — in speaking of the approach to death: Drawing on this metaphorical sense of "provision for the journey into death," ecclesiastical Latin borrowed the term viaticum for the form of Eucharist that is placed in the mouth of a person who is dying as provision for the soul's passage to eternal life. The earliest literary evidence of this Christian usage for viaticum appears in Paulinus’s account of the death of Saint Ambrose in 397 AD. The 7th-century Synodus Hibernensis offers an etymological explanation: "This word ‘viaticum’ is the name of communion, that is to say, ‘the guardianship of the way,’ for it guards the soul until it shall stand before the judgment-seat of Christ." Thomas Aquinas explained the term as "a prefiguration of the fruit of God, which will be in the Promised Land. And because of this it is called the viaticum, since it provides us with the way of getting there"; the idea of Christians as "travelers in search of salvation" finds early expression in the Confessions of St. Augustine. An equivalent word in Greek is ephodion (ἐφόδιον); like viaticum, the word is