From NPR, this is Hidden Brain, I'm Shankar Vedantam.

Vivek Murthy was seven years old when his mom woke him up one night, long after he'd gone to sleep.

She rushed him and his sister into their car.

I remember piling back into the back seat and my sister was sleepy sitting next to me.

Vivek's parents, who were immigrants from India, ran a medical practice in Miami.

His dad was a physician.

As they reached through the night in the car,

my parents told me that their patient, Gordon, had just died after a long struggle with a sadic cancer.

And we were driving to a trailer park in Miami where Gordon lived,

because my parents were worried that his widow Ruth would be grieving alone.

And to this day, I will never forget, like the image of my mother in her traditional sorry,

standing on the steps of that trailer illuminated by the moonlight,

and embracing Gordon's wife Ruth as they both cried and cried.

And in that moment, you know, it struck me that their lives were so different,

Ruth's and my mother's.

But in that moment, they were family, like not the kind of family that's chosen for you,

but the kind that you choose for yourself.

Vivek is now a physician himself.

He has experienced what it's like to be at the bedside of sick patients,

to comfort the families of the dying.

One lesson that has stayed with him is something he learned that night when he was seven.

In the final moments, when only the most meaningful strands of life remain,

...