This morning at five to eight I left our house to walk to exercise class and encountered a deep silence. The roads were empty. There were no buses or taxis rushing down our street, no construction workers hammering away on the new condominium project two doors down. Parque Leoncio Prado, which at this time ordinarily would be filled with city gardeners trimming hedges and maids walking their employers’ dogs, was just an empty grid of grass and concrete. You could hear cuculis (morning doves) cooing plaintively, a noise that echoed eerily off the poured-concrete streets. For a moment I was puzzled by the lack of cars and people, and then…