In his book Written in Blood, Robert Coleman tells the story of a little boy whose sister needed a blood transfusion. The doctor had explained that she had the same disease the boy had recovered from two years earlier. Her only chance for recovery was a transfusion from someone who had previously conquered the disease. Since the two children had the same rare blood type, the boy was the ideal donor.

"Would you give your blood to Mary?" the doctor asked.

Johnny hesitated. His lower lip started to tremble. Then he smiled and said, "Sure, for my sister."

Soon the two children were wheeled into the hospital room--Mary, pale and thin; Johnny, robust and healthy. Neither spoke, but when they met, Johnny grinned. As the nurse inserted the needle into his arm, Johnny's smile faded. He watched the blood flow through the tube.

With the ordeal almost over, his voice slightly shaky, broke the silence. "Doctor, when do I die?" Only then did the doctor realize why Johnny had hesitated, why his lip had trembled when he'd agreed to donate his blood. He'd thought giving his blood to his sister meant giving up his life. In that brief moment, he'd made his great decision.

Johnny, fortunately, didn't have to die to save his sister. Each of us however, has a condition more serious than Mary's, and it required Jesus to give not just his blood, but his life.