Top 3 greatest books ever on the art of self-discovery?

I’m looking for the top 3 greatest books of all time on the theme of self-discovery…books that genuinely change how you understand yourself, your purpose, identity, mindset, or way of living. Not just generic self-help books, but works that everyone/most of them consider timeless and transformative. They can be philosophy, psychology, spirituality, or any genre [...]