If you were a medieval scholar reading a book, you knew that there was a reasonable likelihood you'd never see that particular text again, and so a high premium was placed on remembering what you read. You couldn't just pull a book off the shelf to consult it for a quote or an idea.

It is forgetting, not remembering, that is the essence of what makes us human. To make sense of the world, we must filter it. "To think," Borges writes, "is to forget.

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.

Many memory techniques involve creating unforgettable imagery, in your minds eye. Thats an act of imagination. Creating really weird imagery really quickly was the most fun part of my training to compete in the U.S. Memory Competition.

The best memorizers in the world - who almost all hail from Europe - can memorize a pack of cards in less than a minute. A few have begun to approach the 30-second mark, considered the 'four-minute mile of memory.'

If you want to make information stick, it's best to learn it, go away from it for a while, come back to it later, leave it behind again, and once again return to it - to engage with it deeply across time. Our memories naturally degrade, but each time you return to a memory, you reactivate its neural network and help to lock it in.

The fact that books today are mostly a string of words makes it easier to forget the text. With the impact of the iPad and the future of the book being up for re-imagination, I wonder whether we'll rediscover the importance of making texts richer visually.