In the Byzantine liturgical system, each week is assigned to one of the eight modes or tones. Modes 1-4 in Byzantine music, are each a unique scale, while modes 5-8 are a derivation of such, being called Plagal modes. Most often the modes are called 1st-4th mode, and then Plagal First mode, Plagal Second mode, Grave Mode, and Plagal Fourth mode.
1. Diatonic: contains 1st mode, Plagal 1st, 4th, and Plagal 4th.
2. Chromatic: contains 2nd and Plagal 2nd mode.
3. Enharmonic: contains 3rd and Grave Mode.
According to the Byzantine musicologist Savas I. Savas, each mode has its own character:
1. Diatonic Modes
* 1st mode is distinguished by its axiomatic, magnificent, happy and earthly character
* Plagal 1st mode is distinguished by its merciful, stimulating and dancing-like character
* 4th mode is distinguished by its festive, dance-like, and joyous character
* Plagal 4th mode: the humble style, the appeasing, the sufferings distinguish this mode
2. Chromatic Modes
* 2nd mode is distinguished by its moving, languid, and graceful character
* Plagal 2nd mode is distinguished by its funeral-like character and in general its sorrowful tone
3. Enharmonic Modes
* 3rd mode is distinguished by its arrogance, bravery, and mature air
* Grave mode is distinguished by its manly character and by its strength of melody
Savas I. Savas grouped the modes into their families. As you can see each of the modes that are related in family, have similar qualities to them.
Each mode can be sung in different styles: sticheraric, heirmologic, etc, changing the tempo of a piece, not through literal rhythm per se, but through a whole change in cadence formula, the amount of notes per syllable, and so on. Often a mode might change from say diatonic to hard chromatic for a certain section.
It should be noted that Russian ecclesiastical chant is not divided like Byzantine chant nor does it have the same character, though they also use eight modes (numbered straight one through eight).
The role of a chanter in the Byzantine style is not to impose on the chant any personal meaning or emotion, but to realize in song the meaning and the feeling that are there in the text and the music.
Russian chant however, influenced by the Western Renaissance style of music, is very much about bringing out the physical emotions. As Metropolitan Eugene of Kiev has said:
"They have often disregarded the sanctity of the place and subject of their compositions, so that, generally speaking, it is not the music which is adapted to the sacred words, but instead the words are merely added to the music and often in a contrived manner. Apparently, they wanted more to impress their audience with concert-like euphony than to touch the hearts with pious melody, and often during such compositions the church resembles more an Italian opera than the house of worthy prayer to the Almighty."
Some may consider such criticism harsh, but it is offered here to emphasize the difference in character between Russian ecclesiastical music and Byzantine ecclesiastical music.