“…all Gregorian chants have a special unmistakable character, which provides their particular attraction and fascination. The reason for this is to be sought in the principles, common to all these compositions, on which the text is set to music. The relationship between words and music is such that the melody is entirely determined by the text, down to the last detail, resulting in a “word melody” in the fullest sense.
The texts are either treated “syllabically,” i.e. with one note per syllable, or “melismatically,” with a single syllable being set to several notes. A “melisma,” that is to say the rich adornment of a syllable or a high note, creates a special emphasis within the melody, and important syllables or words are highlighted in this way.”
From sleeve notes for Gregorian chant performances by the Schola Cantorum of Amsterdam Students. I’m a big fan of GC without knowing anything much about it at all, mostly I think because plainchant is the only vocal music I can stand to have on while working or trying to do anything requiring focused thought. Whale Child and his older brother don’t exactly clamour for it, but they do carry on quite happily with whatever they are doing while it’s on (which is quite an endorsement, believe me) and I imagine when they’re older they’ll unthinkingly hunt down GC by various Schola Cantorum manifestations, the way my siblings and I have all somehow managed to acquire over the years parental music foibles such as The Pearl Fishers and The World of Miriam Makeba and Poems, Prayers & Promises (you heard me, all three times. I don’t actually think I really like any of them, but at this point that’s like saying I hate my nails or I hate my butt. No doubt you do, but hey, they’re yours — get over it.)
Anyhow, that whole melismatic thing is very attractive. This Wiki article goes into more detail:
“.. some melismatic chants have syllables that are sung to a long series of notes, ranging from five or six notes per syllable to over sixty..”
How’s that for a poetic device to highlight important words or syllables? Sixty notes per syllable! Chalk one up for music.