Before you pin a copy of the quotation up on the wall, you ought to know that it's a hoax. Although a man named Petronius did exist; he was a satirist in the Roman empire at the time of Nero. A lot of his writings have survived, but the quotation isn't one of them. It was invented back in the 1940s or 50s. The precise origin is obscure, but it's certain that the quotation didn't exist prior to the second World War.
Doesn't stop it being relevant though!