What’s a piece of media (book, movie, song) that changed how you see the world?

Apart from my own books, I read this one around 40 years ago maybe longer. It’s a book on the psychology of our relationships.
I was reading this book between flights on an RAF base. I literally started to see Transactional Analysis come to life around me.
The relationship of Parent, Adult and Child . In the armed forces. Amazing. I’ve never looked at relationships the same way again.
The book changed my view on a lot of things.