As
director of aural skills courses, I soon became
aware of the importance of the harmonic dimension to the study of tonal
music. The tonal system is, in fact, defined specifically and primarily
by the harmonic dimension, but it is this very aspect has always
proved to be the most disheartening for students because it is the most
difficult to
circumscribe. The constraints imposed by this type of formation, which
is rooted in reading and listening, made it necessary for me to maintain
a
constant preoccupation with the relationship between what we hear and
what we see. With this in mind, I had to search beyond (or beneath!)
the procedures of musical analysis such as, for example,
Schenkerian or
semiological systems. We know very well
  that, it is only at the end of a long and
  meticulous re-writing process that we can attain the Schenkerian objective, and in the same way, the  semiological perspective demands, when analysing a text,   a process of microscopic
  dismantling that is incompatible with our goal of maintaining a strong
  reference to the auditive data.
Thus,
  the challenge for me was this: to find or create tools that can help
  students who are faced with the complexities of harmonic listening
  (tonal harmony in this case). Was there a way to extract the basic principles of an harmonic practice common to composers from Bach
  to Wagner
  by identifying their preferred habits and thus constants that could be
  defined with
  enough precision that they could serve as the foundation for both an
  aural and visual formation in this language? Such a perspective, however,
  led me to exclude
  all historical contexts or circumstances, as well as all stylistic
  considerations concerning each and every one of these tonal works which
  contribute to a single, immense corpus. 
