John Coltrane’s recording of Giant Steps in 1959 epitomized his three-year period ofharmonic explorations, most notably with symmetrical intervallic cycles. 3 Hiscomposition “Countdown,” which is based on Miles Davis’s “Tune Up,” illustrates theuse of so-called “Coltrane” substitutions. Characterized by fast harmonic rhythm, thissubstitution projects a major-third cycle in which each local major 7th chord is tonicizedwith the corresponding dominant 7th. In the context of the Dmin7–G7–CMaj7progression shown in Figure 13.10, the first member of the major-third cycle, ≤VImaj7,is accessed through its dominant 7th that follows the structural predominant, ii 7. Thenext member of the major-third cycle, IIImaj7, is also preceded by its dominant, V 7/III,before the progression completes its trajectory with the structural dominant 7th resolvingto the tonic.