One of the great challenges of our age, in which the tools of our productivity are also the tools of our leisure, is to figure out how to make more useful those moments of procrastination when we're idling in front of our computer screens.

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.

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.

To attain the rank of grand master of memory, you must be able to perform three seemingly superhuman feats. You have to memorize 1,000 digits in under an hour, the precise order of 10 shuffled decks of playing cards in the same amount of time, and one shuffled deck in less than two minutes. There are 36 grand masters of memory in the world.

Memory training is not just for the sake of performing party tricks; it's about nurturing something profoundly and essentially human.

During the Middle Ages they understood that words accompanied by imagery are much more memorable. By making the margins of a book colorful and beautiful, illuminations help make the text unforgettable. It's unfortunate that we've lost the art of illumination.

Our culture is an edifice built of externalized memories.