One summer evening during a violent thunderstorm a mother was tucking her small boy into bed. She was about to turn off the light when he asked with a tremor in his voice, "Mommy, will you sleep with me tonight?" The Mother smiled and gave him a reassuring hug. "I can't, dear," she said. "I have to sleep with Daddy." A long silence was broken at last by his shaky little voice: "The big sissy."