It’s fun stumbling upon psychological concepts in unexpected places. I remember first learning about the Johari Window (an obscure framework for thinking about the limits of self-knowledge) in the Robert Galbraith novel The Cuckoo’s Calling (2013). It happened again the other day. I was enjoying the action thriller Nobody’s Hero (2024) by M W Craven – my middle-aged version of brain rot – when the hero Ben Koenig invoked the ‘Peter Principle’ – the idea that people tend to get promoted to the point of maximum incompetence.

Koenig is already a curious character for anyone interested in psychology. He has Urbach-Wiethe disease, which has calcified his right amygdala – apparently rendering him incapable of feeling fear (a handy attribute for an action hero). By dint of his training with various special forces, he’s also a repository of fun psychological wisdom, such as the Peter Principle, which he draws on to explain why the assassins have chosen to murder a bunch of mid-ranking infrastructure experts, rather than their superiors.

I checked it out, and the Peter Principle is a genuine concept that originated with a bestselling, semi-satirical book of the same name in 1969, co-written by two Canadians, the educationalist Laurence J Peter and the playwright Raymond Hull. There’s a simple logic to their idea – you keep performing well, you keep getting promoted, until you reach a managerial role at which you struggle and so you don’t get promoted again. Various studies have confirmed there’s a truth to the logic, at least in the context of sales, the military and academia.

I’m going to add the Peter Principle to my mental dictionary of psychological concepts – and use it as a reminder not to rest on my laurels. We can’t assume that the skills and knowledge that served us well in the past will be enough for whatever challenges we face in the future.

Often, forgetfulness is a mere inconvenience: that name, date or task that simply slipped through the cracks. But, sometimes, it’s downright unsettling to forget something. A friend asked me the other day: ‘Remember that hilarious dinner we had there a few years ago?’ And when for the life of me I couldn’t, I felt as if a slice of my existence had been cast into oblivion.

The ancient Greeks harbored a similar, if more pronounced, terror of forgetting. Plato associates forgetting with ‘non-being’, nothingness. Homer’s heroes do heroic things in order to achieve kleos (fame), and thereby defeat the destruction that comes with being forgotten. (As one of the Seven Wise Men said: ‘You will obtain memory through deed.’) Perhaps as a kind of buttress against the fear of forgetting, they anointed Mnemosyne, memory, the mother of the nine muses.

But I enjoyed learning the other day that this negative view of forgetting wasn’t shared by all ancient peoples. Daoism positively celebrates forgetting, indeed raises it to the status of an art. Zhuangzi, a founder of the tradition, urges people to master this art in order to gain a glimpse of Dao (the way), the eternal substratum of our passing world. As the philosopher Xia Chen writes, Zhuangzi’s idea is that the more of the world we’re able to forget – be it morality, history, the arts – the more we’re able to discover our true self, shaving off all that’s inessential to get down to the pith that we ultimately are.

Now, I don’t know if that will be of help when I inevitably confront the next lost memory, but it’s good to remember, if possible, that there’s a certain, subtle benefit in forgetting. ‘Only by forgetting,’ wrote the German philosopher Hans-Georg Gadamer, ‘does the mind have the possibility of total renewal.’