The essays in this collection celebrate the work of the late John Clough, a revolutionary musical thinker and a pioneer in enquiry into the nature of diatonic systems. Clough, who held the Slee Chair of Music Theory at University at Buffalo (SUNY) for many years, brought to music theory new perspectives in four roughly chronological phases.

The first phase of Clough's work, in the late 1970s, focused on the definition of diatonic sets and an enquiry into interval cycles and sequences; he became interested in extending Allen Forte's atonal methodology to the diatonic system. Milton Babbitt and Carlton Gamer, among others, had noticed intriguing structural properties of the diatonic system when considered as a subset of the equal-tempered chromatic scale. Clough conjectured that, just as arithmetic modulo 12 serves to formalize chromatic pitch-class space, arithmetic modulo 7 would be the appropriate tool for heptatonic systems. This conjecture was not as obvious as it seems now. The elements in the 12-tone chromatic scale have an obvious logarithmic equality of step sizes. Clough realized that a more abstract but no less powerful equivalence rules the diatonic system, in which steps of different sizes are perceived as identical. That is, steps or seconds define an equivalence class in the set of diatonic intervals, as do thirds, fourths, and so on. Using this methodology, Clough established the mod-7 diatonic sets, and defined diatonic set classes under transpositional equivalence only, rather than through the standard T/I invariance of atonal theory. The insight behind this choice led to important and powerful results in his later work.

Clough's earliest work in scale theory grew out of his interest in interval cycles in the mod-12 and mod-7 universes. These interval cycles provided a framework for a hierarchical non-Schenkerian tonal theory. His work on interval cycles also intersected with a lifelong fascination with diatonic sequences. Clough's essay in this collection contains more comprehensive thoughts on the topic—returning to his starting point with the benefit of a lifetime of study.

The second period of Clough's work undertook a deeper study of the nature of diatonic systems. In the mid-1980s, Clough worked with mathematician Gerald Myerson and published seminal works that reveal three unexpectedly interrelated properties of the diatonic scale.