The 15th volume of 's Bootleg Series focuses on the recordings he made in Nashville in the waning years of the 1960s. There are outtakes from and , along with a pair of cuts from the sessions, but the fulcrum of the three-disc set is 's sessions with in February 1969. Some of this is due to pure scarcity. There weren't an extensive number of outtakes from the sessions, plus didn't play with his arrangements in the studio; the seven alternate takes from these sessions prove this point. Then, wound up not paying the fee for a storage facility, so a number of sessions were lost. The outtakes that did survive are lively and friendly, accentuating the good humor that flows through the finished product, but they're so amiable, they're bound to be overshadowed by the disc and a half of running through their respective songbooks while supported by , who was 's guitarist at the time. The sessions happened as was in the middle of recording , and it was possible that it was intended as the genesis of a duet album that never materialized. While "Girl from the North County" wound up kicking off , the rest of the recordings remained in the vaults, bootlegged heavily over the years before appearing in this official, complete form. The additional context of -- not just the alternate takes of disc one, but a joyous epilogue of a handful of tracks cut with bluegrass banjoist in early 1970 -- lends some gravity to the amiable, occasionally wobbly / sessions. The looseness can be ascribed to two mutual admirers attempting to find common ground. The pair knew they shared a bond -- patterned his "Understand Your Man" after 's "Don't Think Twice, It's All Right," a connection made apparent when producer had them sing the songs simultaneously, each sticking to their own lyrics -- but finding a groove takes time, and much of the appeal of lies in how the duo finally fall into step together. They start to move in the same direction by playing oldies from , , and himself, throwing in a few folk standards and originals -- including "Wanted Man," which wrote for -- along the way. If the results aren't epochal, they're nevertheless illuminating, revealing how these two American icons shared the same musical vocabulary. ~ Stephen Thomas Erlewine