HE was a key figure in ripping down the iron curtain and ending the cold war, which brought the 20th century to a close with America as the only superpower. Yet Ronald Reagan’s horizons have shrunk to his bedside as Alzheimer’s disease ravages his mind. Michael Reagan, his elder son, believes that death would be a merciful release for the former American president. “It’s time for him to go. It’s very sad,” he said in an interview. “I’m going to hate the day Dad dies. You think you are ready for it, but you never are. But I sometimes pray...