I found the short film below to be very moving as director, William Hoffman
attempts to share his vision of the answer to that question:
Radiolab provides the music.
Music by Parachutes: "Where Were You?"
Presented by WNYC Radiolab.
From the "ABOUT" section of the Radiolab site:
"Radiolab believes your ears are a portal to another world. Where sound illuminates ideas, and the boundaries blur between science, philosophy, and human experience. Big questions are investigated, tinkered with, and encouraged to grow. Bring your curiosity, and we'll feed it with possibility."