The selections on Willie Nelson’s four-disc career retrospective support everything we suspected: With few exceptions, the material he recorded in Nashville in the 1960s was undistinguished, assembly-line work. It was only when he broke away from country conventions and headed south to Austin, Texas, with the ’70s “Outlaw” movement that Nelson found his stride with a string of great songs such as “I’d Have to Be Crazy,” “Blue Eyes Crying in the Rain,” “Good Hearted Woman” and others. During his peak years he stripped country down to its basics while allowing the music to be entirely contemporary. Some of his ’80s career decisions were dubious (a duet with Julio Iglesias?), but he bounced back a decade later in collaborations with Don Was and Daniel Lanois.