1 - Gödel, Escher, Bach: An Eternal Golden Braid also known as GEB, 1979 by Douglas Hofstadter

I was a young student and my teacher who would be my best friend, was always carrying and reading this book. Some day he emigrated and left me the book as a treasure. It introduced me to things that I consider central: Zen, Art, Mathemagic, paradoxes and the joys of thinking.
Link: GEB