The Merchant of Oltarno

A wine maker walks in to Cosimo's shop in Florence, and offers him a taste of wine made from a grape called Sangiovese, the "blood of Zeus". The liquid has the ability to turn in to whichever Tuscan wine Cosimo labels it as: Chianti, Brunello, Vino Nobile, table wine, anything. Cosimo realizes this will make him incredibly rich. The stranger offers to supply Cosimo with this magic wine endlessly, for free, with one condition: that Cosimo never drinks it ever again. Cosimo agrees to the terms, and becomes the world's wealthiest, most famous wine merchant. And one day, he decided to take a sip. Just a sip.