Following an unsatisfying three-year stint at Mercury Records, Chuck Berry returned home to Chess in 1969, just like Phil Chess predicted. Heading home didn’t necessarily mean retreating, as the four-disc Have Mercy: His Complete Chess Recordings 1969-1974 illustrates. During his time at Mercury, Chuck followed the kids wherever they went, aligning himself with the psychedelic ‘60s in a way none of his peers did. This shift is immediately apparent on “Tulane,” the very first song he cut upon his return to Chess. An ode to a couple of kids who dealt dope underneath the counter of a novelty shop, “Tulane” puts Chuck on the side of the counterculture, and over the next five years, he never strayed back to the other side of the fence, often singing about getting stoned, dabbling with a wah-wah pedal, rhapsodizing about rock festivals, cheerfully telling smutty jokes. All these elements, along with his propensity for playing with pickup bands -- he cut 1971’s San Francisco Dues with amiable garage rockers the Woolies outside of Lansing, MI, and roped Elephant's Memory into the studio to knock out much of 1973’s Bio -- defined the last act of Chuck’s career. But the big difference between the five years documented here and what came afterward is that Berry was still active as a writer and record-maker during the first years of the ‘70s, conscious of his legacy but not encumbered by it, still attempting to graft new fads onto his three-chord boogie while spending more and more time playing the blues and ballads of his youth. Have Mercy chronicles all of this and more, putting his final Chess recordings into CD circulation for the first time, and adding 22 unreleased cuts to the mix. If there are no major revelations among this unheard material there are at least minor ones in the form of a studio version of “My Ding-A-Ling,” which is lighter in touch and marginally more charming than the live hit, and the preponderance of loose, instrumental blues jams culminating in an extended studio version of “Turn on the Houselights,” the song he used to play toward the end of concerts. All these blues -- and there are many with vocals, too, including a very good take on Elmore James’ “Dust My Broom” and a ripping live version of Big Joe Turner’s “Roll ‘Em Pete” -- find Berry coasting somewhat, preferring to rework standards instead of write new ones, which is a sentiment that also applies to how “My Ding-A-Ling” re-jiggers Dave Bartholomew’s song, but Chuck always did turn blues tropes into something of his own, so what’s new is how infrequently Berry was writing during this final stretch. The originals may not have flowed freely, but he did pen a handful of classics: “Tulane,” its slow sequel “Have Mercy Judge,” the dreamy spoken poem “My Dream,” and the cracking autobiography “Bio” all belong in his canon. But the thing about Have Mercy is that it proves that an artist as great as Chuck Berry has pleasures that lay outside the canon, that his sly touch invigorates classics from “Jambalaya” to “Swanee River Rock”; that it’s good to hear him just lay back and riff, that there’s a delight in hearing him affect an absurd Mexican accent on “South of a Border.” Sure, these are pleasures only for the committed, but in light of the lack of new recordings following this -- just 1979’s Rock It, which did produce the minor classic “Oh What a Thrill” -- it’s easier to cherish this music for the minor, yet lasting, pleasures it provides.