Translated into English for the first time, Foundations of Modern Harmony, by composer and music theorist Karel Janec̆ek, addresses the analysis and composition of music not based on the tonal harmony that was common language until the early 20th century. Discussing this newer music requires a vocabulary in which all combinations of notes, or chords, can be named. Janec̆ek developed his theory of modern harmony over many years. In this book, he classifies chords according to their intervallic structure, their possible arrangements, and then based on their consonance and dissonance. His focus on what we hear leads to a discussion of “imaginary” pitches, those that are still heard after they are no longer sounding. Dealing with such issues as harmonizing a melody, resolving dissonant chords, and the formation and extinction of a sense of the tonic, Janeček’s work is an exciting complement to the theories of Schoenberg and Hindemith. His discussion of harmonic motion leads to the consideration of harmonic function, of establishing the tonic, of modulation, of atonal composition, and of static and kinetic conceptions of harmony. First published in 1965, Janeček’s concerns are of continuing importance to music theorists and composers.