Once upon a time, on the outskirts of Lisbon, villagers threw their doors open to the street whenever they heard the clopping of donkeys laden with baskets of sardines. Every household claimed its share of Portugal’s ocean bounty. But one day in early 1773, the Marquis of Pombal, a statesman who ruled the country much as the prime minister does today, learned that yet another load of sardines had been smuggled across the border into Spain. No more, he declared.