Are you the sum total of your experiences – or a sum total of your memories? The fact that the two are so wildly different isn’t only because, over time, memories fade. It is also because we may not fully experience what we see in front of us at the time.

In my book, Wilful Blindness, I was intrigued by the common human experience in which we ignore crucial information, people or events that stare us in the face. Albert Speer, Hitler’s favourite architect and, later on, the man responsible for supplying the army with manpower, weapons and material, famously could not remember what he had known of Hitler’s final solution. He wasn’t sure whether he’d been at the Wannsee conference or, if he had, how long he had stayed. And this was not because he believed himself innocent – he pleaded guilty at Nuremberg – but because, even under intense and sustained interrogation by Gitta Sereny, he simply could not remember.

Many people believed Speer lied. But Sereny considered Speer’s experience. He did know, she thought – but only enough to ensure that he looked away. After all, she explained, you have to know it’s bad to make the choice to look in the other direction.