"Lord, I feel the ocean swaying me/ Washing away all my pain," Jimi Hendrix sings at the start of this magnificent discovery. The title track of a new album of previously unreleased Hendrix studio recordings, "Valleys of Neptune" was important to the guitarist, a heavy-rock hymn to rebirth that he worked on at multiple sessions starting in February 1969, yet never finished, at least to his satisfaction, before his death. But this version is perfection, cut on May 15th, 1970, with drummer Mitch Mitchell of the Jimi Hendrix Experience and bassist Billy Cox. (Hendrix used a lead vocal and percussion from an earlier date.) It opens with a gorgeous swirl of guitar atop Mitchell's dancing cymbals, and Hendrix's animated rhythm work is like a second counterpoint vocal, while his instrumental bridge is a dramatic upward surge of liquid treble and slicing sword-blade chords. Hendrix died four months later. He sounds here like he was never more alive.