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 in Daddy's room."Along silence was broken at last by his shaky little voice: "The big sissy."