My wife and I were surprised some years ago when my younger daughter, Jessica, was born with blue eyes. We both have brown. I remembered enough from high school biology to deduce that both of us had inherited a recessive blue-eye gene from our parents; in my case, it was my Dad’s. He adored both my daughters, but took special pride in Jessie’s blue eyes; I could see, when he studied her sweet features, that he found there a very tangible form of immortality. “Where did you get those blue eyes?” he’d say. “Pop-pop,” Jessie always replied. They went through this routine dozens of times over the years, but every time he heard her answer, he’d beam as if he’d won the Lottery.

One day last week, Jessie, now 12, sat at the breakfast table, all lit up by the morning sun, while I told her that her Pop-pop was dying. His body had taken him as far as it could, I said, and there was nothing more he could do. But he’d lived a rich, full life: He’d won two Bronze Stars fighting the Nazis, carved out a career he relished, raised a family, traveled widely, and loved deeply. He made everyone he met laugh; when he was admitted to the emergency room in great pain, I found him teasing the nurses and telling them jokes. On this day, I’d have to go to the hospital and tell the doctors to turn off the life-support equipment and set the unforgettable Byron Falk free, as he instructed in his living will. Jessie listened quietly, nodding, trying to understand. In those blue eyes, shining with tears, I saw the unbreakable chain of generations: Life. -William Falk