An eight-year old boy had a younger sister who was dying of leukemia. His parents explained to him that she needed a blood transfusion and that his blood was probably compatible. They asked if they could test his blood. "Sure," he said. The results showed that his blood would be a good match. Then they asked if he would give his sister a pint of his blood, that it could be her only chance at living. He said he would have to think about it overnight.
The next day he went to his parents and said he was willing to donate his blood to his sister. So they took him to the hospital where he was put on a gurney beside his sister. Both of them were hooked up to IVs. A nurse withdrew a pint of blood from the boy, which was then put into the girl's IV. The boy lay on his gurney in silence while the blood dripped into his sister. The doctor came over to see how he was doing. The boy opened his eyes and asked, "How soon until I start to die?"