Douglas Hofstadter’s Gödel, Escher, Bach: An Eternal Golden Braid. I find it impossible to summarize, but this book was formative in my early 20s. I hesitate to recommend it because it’s equal parts insanity-inducing and mind-blowingly brilliant. You should probably not hate math to read it. I’ve read it three times and I probably understand half of it (at best). But I keep coming back to it because I learn something new each time and there’s some perfect magic that lives in Hofstadter’s mind.