No doubt about it, Conrad Letendre is the greatest music theoretician of all time.

  In a field where, before him, one knew nothing of rhythm and only a few scattered falsehoods of harmony, Letendre had the insight and the courage to create order in the deplorable and unforgivable jumble which existed and unfortunately still survives.

  All harmonic thought was oriented toward its horizontal aspect (what is sequential in time) rather than toward its vertical aspect (which exists and is perceived at the same time). The capricious and enigmatic scale was placed as a base for the structure of chords. Each of its degrees (a) served as root on which could be piled a series of thirds and (b) thus disposed an incomprehensible mixture of major and minor chords (one major, two minor, two major, one last minor before the poor diminished chord with which one knew not what to do). This was for the major mode, more was still to come. The minor mode (the only one known was the parallel chromatic mode and not the symmetrical diatonic mode), with its " natural ", " melodic", and "harmonic" scales, only made an already deplorable situation still worse. In this faulty structure, one could find neither (a) indications of progression, b) definitions of chordal or non-chordal tones, nor (c) possibility of inversion.

  Letendre had the initial insight to separate the wheat from the chaff in the works of preceding authors, specifically the priority of tetrads over triads and progressions by fifths (with François-Auguste Gevaert) and the possibility of inverting chords, melodies, and even complete modes (with Hugo Riemann). He now had " sixth chords " at his disposal which corresponded to the " seventh chords " and which furnished the Dominant chords for the two missing modes, the diatonic minor mode and the chromatic major mode. This would have been enough to crown him a " master-theoretician " but he was to add still more daring and fruitful elements.

  In the field of harmony, he proposed the concept of " ambiguity " with which a chord (the same four notes) could have a different function with respect to the chord which precedes it and to the chord which follows it. This allowed him to elucidate the first theory of harmony which was perfectly logical and coherent, WITHOUT ANY EXCEPTIONS.

  In the field of rhythm, he had to start from scratch. From the Gregorian concept of "arsis" and "thesis", he established rhythmical structure AT ALL LEVELS which he clearly explained in the Musique et Musiciens periodical, from 1952 to 1954.

  Fifty years after his work and twenty five after his death, there is no appreciable propagation of his insights. A great shame for Québec. An immense loss for humanity.

Michel Perrault, April 2004