The Kahlil Gibran of the Me! generation called his last hero Jonathan, but now he's in full, self-y swing with a narrator named Richard who sells $3 rides on his biplane and learns to become "one messiah in a world of others." Richard starts all this learning in an Illinois cornfield the day that Donald Shimoda, the crowd-shy "Mechanic Messiah," lands his plane nearby and says: "There are somethings you do not know." And Donald's not kidding. Richard doesn't know how to fly a plane without gas, how to walk on water, how to work the off-on switch for celestial music, how to conjure up "thought-forms," or how to heal the crippled. Most of all, he doesn't know that everything's an illusion, and he's a slow learner. ("Oh, God, Richard. . . I thought you had reached this major knowing. . . .") But Richard does finally get it, thanks to Donald's show-and-tell and thanks to a magic book of illuminated verses, verses like "The/original sin is to/ limit the Is. Don't" or "You are led/ through your lifetime/ by the inner learning creature" or "A farewell is necessary before/ you can meet/ again." Bach's marketing instincts may be on-target again, mixing Rod McKuen and Christ with ESP and est, and providing, as a preface, Donald Shimoda's messiah life in a hand-written, biblically-phrased gospel. But Jonathan wasn't quite as, well, weird as Donald and Richard are, and the middle-road readers who cozily identified with a perfectionist seagull might decide to leave the walking on water to. . . a more specialized audience.