Clapton’s legacy as a guitar hero was secured as early as 1966, but it was his '70s output that confirmed his place in the hall of rock 'n' roll’s greatest figures. True to its title, Timepieces encapsulates the period from 1970 to 1978, when Clapton was—to put it very simply—in the zone. Having already proved his mettle as a guitarist, Clapton used these years to hone his songwriting and study various forms of rhythm and group interplay. The results were magnificent. Who could have predicted that the man once defined by “Sunshine of Your Love” would within a few years inhabit the wiry reggae of “I Shot the Sheriff” and in turn use that rhythm to revitalize a Bob Dylan standard (“Knockin’ on Heaven's Door”)? “Layla,” of course, marked a pinnacle of guitar bacchanalia, but the most defining element of this collection is J.J. Cale's influence. Clapton hired Cale’s compatriots (Carl Radle, Dick Sims, Jim Oldaker), covered his songs (“After Midnight,” “Cocaine”), and did everything he could to promote Cale’s distinctive blueprint into one of the most beloved and recognizable songforms in all of rock.