A little girl was dying of a disease from which her 8-year-old brother had recovered sometime before. The doctor said to the boy, "Only a transfusion of your blood will save the life of your sister. Are you ready to give her your blood?" The eyes of the boy widened in fear. He hesitated for a while, then finally said, "Okay I'll do it." An hour after the transfusion was completed the boy asked hesitantly, "Say, doctor, when do I die?" It was only then that the doctor understood the momentary fear that had seized the child -- he had thought that in giving his blood he was giving his life for his sister.