Kissing could have begun as a way of sniffing out who's who. From a whiff to a kiss was just a short trip across the face.

Once upon a time, this idea of having a trained, disciplined, cultivated memory was not nearly so alien as it would seem to us to be today.

Sequencing - the careful striptease by which you reveal information to the reader - matters in an article, but it is absolutely essential to a book.

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.

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.

The more we remember, the better we are at processing the world. And the better we are at processing the world, the more we can remember about it.

Over the last few millennia we've invented a series of technologies - from the alphabet to the scroll to the codex, the printing press, photography, the computer, the smartphone - that have made it progressively easier and easier for us to externalize our memories, for us to essentially outsource this fundamental human capacity.