The BPS asks some leading psychologists to share, in 150 words, one nagging thing they still don't understand about themselves. Melissa McEwan quotes this one: "There's plenty I don't understand about myself, but nothing nags. Paradoxically, the deeper I got into neuropsychology the less interested I became in the details of my own inner workings. I'm not sure why. It certainly is not because I arrived at any great insight or understanding. I still experience the almost visceral sense of puzzlement over matters of brain, mind and selfhood that first drew me to the field. What happened, I think, was a shift - let's imagine a neural switch somewhere in the frontolimbic circuitry - from one preoccupying question, What am I? to another, What should I do? It left me less inclined to bother about self-understanding than to consider the value of things, moral and aesthetic. How best to live? But here's a nagging thought: might those two preoccupying questions turn out to be one and the same, like the evening star and the morning star?"