I met with amnesiacs and savants, educators and scientists, to try to understand what memory is, why it works, why it sometimes doesn't, and what its potential might be.

Back when I lived in Brooklyn, I'd sometimes take the Q train all the way out to Coney Island and back, and work on my laptop. There's something about pushy New Yorkers looking over your shoulder that really makes you produce sentences.

We've outsourced our memories to digital devices, and the result is that we no longer trust our memories. We see every small forgotten thing as evidence that they're failing us.

How much are we willing to lose from our already short lives by losing ourselves in our Blackberries, our iPhones, by not paying attention to the human being across from us who is talking with us, by being so lazy that we're not willing to process deeply?

Our lives are structured by our memories of events. Event X happened just before the big Paris vacation. I was doing Y in the first summer after I learned to drive. Z happened the weekend after I landed my first job. We remember events by positioning them in time relative to other events.

Evolution has programmed our brains to find two things particularly interesting, and therefore memorable: jokes and sex - and especially, it seems, jokes about sex.

Just as we accumulate memories of facts by integrating them into a network, we accumulate life experiences by integrating them into a web of other chronological memories. The denser the web, the denser the experience of time.