On Christmas morning, I met an old acquaintance who had come down from London with his family to spend the holidays with his parents. With the help of a caretaker, he was in the process of moving his father from a wheelchair into his car.   “We’re taking mom and dad to my place for Christmas lunch,” he said after we exchanged greetings. “My sister and her family, from Sydney, are here too.”   “That’s wonderful,” I said. “I can’t imagine how happy they must be.” I wished him a