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.

Invented languages have often been created in tandem with entire invented universes, and most conlangers come to their craft by way of fantasy and science fiction.

With our blogs and tweets, digital cameras, and unlimited-gigabyte e-mail archives, participation in the online culture now means creating a trail of always present, ever searchable, unforgetting external memories that only grows as one ages.

Once I'd reached the point where I could squirrel away more than 30 digits a minute in memory palaces, I still only sporadically used the techniques to memorize the phone numbers of people I actually wanted to call. I found it was just too simple to punch them into my cell phone.

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.

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.

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.