Who is Dan Millman from Sacred Journey of the Peaceful Warrior and what is their importance?

Dan Millman is the author and first-person narrator of this novel, Dan Millman is an ex-gymnast, who marries in 1967 during his senior year at the University of California Berkeley, has one daughter, Barbara, and teaches briefly at Stanford before taking a position at Oberlin College. Earlier, as he describes in his book, Way of the Peaceful Warrior, Dan endures a five-year "ass-kicking" from a gas station mechanic/guru, Socrates, who expands Dan's awareness and sends him out to assimilate his teachings.