The pop minstrels of the first years of the last decade were outraged idealists venting their passion in livid terms while educating a generation about social injustices, moral atrocities and emotional ambiguities. They determined the key in which the epic opera of the '60s' vast conflagration was played. Now, two years into the '70s, a new crop of musical essayists and commentators has emerged and if they set the tone for this decade as their predecessors did for theirs, it will be a very strange and very different 10 years. Among these new minstrels, the Dylans and Paxtons of the '70s, are Loudon Wainwright, John Prine, David Ackles, Randy Newman and now Martin Mull. Their sensibilities are more soft-spoken, less strident and grandiose, and imbued with a very humane humor that flows from a gently resigned cynicism. The prediliction for allegorical anger has been replaced by...