The author's understandable admiration for and fascination with former heavyweight boxing champion Muhammad Ali underlies a barely sustainable portrait of ``Ali as mystic . . . as a vessel into which enlightenment pours, and from which it flows.'' Still, this is an often profound, intimate visit with the charismatic Ali. Now a contributing editor at Sport magazine, Miller first met his childhood idol in 1975, when he pitted his martial arts skills against the champ's boxing prowess: Miller actually hit him several times, but a single Ali jab almost broke his neck, and the exhibition was quickly halted. Still a student, Miller sold the story of that bout to Sports Illustrated. Years later, having become friends with the retired Ali, Miller would turn other encounters with the now-stricken fighter into an acclaimed magazine piece, ``The Zen of Muhammad Ali,'' the basis of this book. The portrait he paints of Ali is a tender, enchanting one: Seemingly enfeebled by Parkinson's syndrome, Ali nevertheless takes 10-mile walks, playfully spars with friends, family, and strangers, and delights in childish pranks, such as locking Miller in the bathroom. There's a lovely scene when Miller helps the champ with his tie; and an understated one when Ali confesses that he did not throw his Olympic gold medal into the Ohio River: ``Just lost it, that's all.'' Miller writes of the adoration paid Ali (though little is said of those who vilified the brash young boxer); of his extraordinary generosity; and of his loving, gentle way with children. There's much here that's truly endearing, but at times Miller seems on the verge of pinning some kind of New Age godhood on the man. He backs off, thankfully, and tidily sums up the mystique of Ali: He ``can't imagine anyone whose time on this planet--including through his illness, maybe especially through his illness--has been more life-affirming.''