Many years ago, when I worked as a volunteer at a hospital, I got to know a little girl named Liz who was suffering from a rare and serious disease. Her only chance of recovery appeared to be a blood transfusion from her 5-year-old brother, who had miraculously survived the same disease and had developed the antibodies needed to combat the illness. The doctor explained the situation to her little brother, and asked the little boy if he would be willing to give his blood to his sister. I saw him hesitate for only a moment before taking a deep breath and saying, "Yes, I'll do it if it will save her." As the transfusion progressed, he lay in bed next to his sister and smiled, as we all did, seeing the color returning to her cheeks. Then his face grew pale and his smile faded. He looked up at the doctor and asked with a trembling voice, "Will I start to die right away?" Being young, the little boy had misunderstood the doctor; he thought he was going to have to give his sister all of his blood in order to save her.