Imagine it’s your 100th birthday. You’ve just spent all day celebrating with a big party, and now you’re resting quietly in your bedroom. Friends and family linger, taking care of after-party clean up.

Against the backdrop of household sounds—the clatter of silverware on china, the tinkle your great-grandchildren’s laughter, the chatter of guests—you reflect on the last century. Suddenly, you’re drawn from your reverie by the sound of your name. As you strain to listen in, you realize your friends are talking about you...