Who is The Narrator from Zen and the Art of Motorcycle Maintenance and what is their importance?

The Narrator is a middle-aged man who has led an unusual life. He is brilliant, has studied Eastern and Western philosophy and spirituality, and is grounded in scientific thinking and technological understanding, too. He has served in the armed forces, been a university professor, and writes technical documents for a living. He is preoccupied with thinking, and that trait reveals something unresolved in his personality.