Music: Return of a Supergroup

A potent but short-lived rock phenomenon was the supergroup—an amalgam formed by the talented malcontents of other bands. While they lasted, groups like Cream and Blind Faith—both starring Guitarist Eric Clapton and Drummer Ginger Baker—played enormous arenas and made megabucks, and sometimes megamusic. Their performances were fueled by dueling egos. Musical infighting built up the excitement they generated, but it also made breakups inevitable. Now, with half a decade gone, perhaps the mightiest U.S. supergroup of all is back together: Crosby, Stills, Nash & Young, whose pungent lyrics and soft-edged counterpoint to acid rock made them a primal force in popular...