E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
To carry away the meal from the grave. The Greeks and Persians used to make feasts at certain seasons (when the dead were supposed to return to their graves), and leave the fragments of their banquets on the tombs (Eleemosynam sepulcri patris).
With one foot in the grave. At the very verge of death. The expression was used by Julian, who said he would learn something even if he had one foot in the grave. The parallel Greek phrase is, With one foot in the ferryboat, meaning Charons.