Truth is a matter of the imagination
In Ursula Le Guin's The Left Hand of Darkness, Genly Ai is sent by humans as an ambassador, a messenger, to the planet Gethen to persuade the people to join what's essentially this universe's 'Federation'. Half of the book is him relating what happened.
In a scenario where we might expect someone to say "this is the truth, the whole truth, and nothing but the truth" Genly says it's a story, that
I'll make my report as if I told a story, for I was taught as a child on my homeworld that truth is a matter of the imagination
Thus, the theme. The book is very much about the tension between Genly's culture and the new one he finds himself in and struggles to adapt to. This new world has subtle cultural and social rules he can't handle plus gender norms he really can't handle.
My wife loves Traitors, the TV show, which we have just had the fourth season of. I like how completely convinced people are... when they are completely wrong. Getting hung up on nonsense details, remembering conversations wrong, wild interpretations of completely normal behaviour. Accusing each other of lying, when it's just remembering things differently. But very few people are acknowledging how fallible we are, our senses are, our brains are.
This is also because a definition of 'truth' as being to do with 'reality' is the same problem. Our reality is definitely a matter of the imagination. I've got a passing interest in phenomenology and such. As well as in a neuroscience way - a good book is Anil Seth's Being You: A New Science of Consciousness.
So I try to remember. All of this is a matter of the imagination.