Adams experienced a musical epiphany after reading John Cage's book "Silence" (1973), which he claimed "dropped into psyche like a time bomb". Cage posed fundamental questions about what music was, and regarded all types of sounds as viable sources of music. This perspective offered to Adams a liberating alternative to the rule-based techniques of serialism. At this point, Adams began to experiment with electronic music, and his experiences are reflected in the writing of "Phrygian Gates" (1977–78), in which the constant shifting between modules in Lydian mode and Phrygian mode refers to activating electronic gates rather than architectural ones. Adams explained that working with synthesizers caused a "diatonic conversion", a reversion to the belief that tonality was a force of nature.