According to William Smith's Dictionary of Greek and Roman Antiquities, the Meditrinalia was a festival connected with the cultivation of vineyards that took place on October 11. On that day the people of Latium began to taste their new wine and to offer libations to the gods. (Jupiter was associated with this festival.) In drinking the new wine, it was customary to pronounce the words: "vetus novum vinum bibo, novo veteri morbo medeor." I'm no Latinist, but I think that the gist of the quote is that drinking new wine cures an old man of his ills.