1.The term tonalily has been used in a variety of ways in twentieth-century music theory.
To clarify our usage of this term, we will define tonality as a system in which pitches
are organized hierarchically around a tonal center, or tonic. The tonal system prevalent
in what we know as the common-practice period is usually known as major-minor, or
functional tonality. In functional tonality, chords have a harmonic or tonal function,
which we can define as the relationship of a chord with the other chords in the key,
and especially its relationship with the tonic. We usually label the specific functions of
chords with Roman numerals. The basic harmonic functions are tonic, dominant, and
predominant, although chords can also have a prolongational function (most often by
providing an extension of another chord by means of passing or neighbor linear mo-
tion). In the music of some late-Romantic or post-Romantic composers such as Rich-
ard Wagner, Hugo Wolf, Anton Bruckner, Gustav Mahler, Richard Strauss, Alexander
Skryabin, and others, we find a variety of harmonic and linear procedures that have the
effect of weakening functional tonality. These procedures may produce a suspension
of tonality or may create a sense of tonal ambiguity, even to the point that at times the
sense of tonaljty is completely lost.