Gregorian chant

The Music

The church modes

Ever since the 17th century, we've been classifying both classical and popular music according to their character: either major or minor. For Gregorian chant, things are a little more complicated. Or at least so it seems when you look at the scheme underneath for the first time. Actually, things are quite logical.

The church mode of a chant is actually determined by the position of the semi-tones in the specific scale. That scale is determined by the so-called finalis (last note of the chant, red on the scheme). Most of the chants have re, mi, fa or sol as finalis notes. A second element is the tenor, the reciting tone (also called dominant, blue on the scheme). The melody of a chant is determined by the tension between the two poles. That may sound somewhat theoretical, but the position of the semi-tones between finalis and tenor is of vital importance for the specific character of the different modes. Just try and pay attention to it when listening to Gregorian chant, and you'll soon recognise the modes yourself.

The modes are traditionally divided into four pairs, each of them consisting of an authentic mode and a plagal counterpart. These are the groups:

Name	Finalis	Church mode
Protus	RE	I and II
Deuterus	MI	III and IV
Tritus	FA	V and VI
Tetrardus	SOL	VII and VIII

But as we said earlier, this division is mainly a traditional one, imposed after the repertoire had taken its more or less final form. So, inevitably, not every chant can be classified into this fairly rigid system, and even the ones who match a certain profile are bound to have an 'exceptional' note here or there. That is mainly due to the fact that only two notes of the entire chant are taken into consideration : the finalis and the tenor. A RE-finalis with a psalm verse being recited on LA is by definition a Protus I, whereas a MI-finalis with a LA tenor is bound to be a Deuterus IV, regardless the melodic developments of the chant as a whole.
Most of the chants of the Divine Office have the nasty habit of not fitting into this 'octo-echos' (Greek for 'eight tones') system. Thus for instance the chants ending on MI but reciting on DO ! Therefore, scholars were obliged to make a few adjustments to their system. The Antiphonale Monasticum (containing the psalms and a number of short antiphons for monastical use) shows the following modes: