Consider how different the people's music of the ordinary, which tends more toward a syllabic structure, is from the highly specialized music of the propers for Mass, which can incredibly elaborate. Listen first to Gloria XV, which mostly has one note per syllable:
Now look at Jubilate Deo Universa Terra, an offertory that appears twice in the new calendar (2nd Sunday after Epiphany and on the 5th Sunday in Easter). The antiphon is great of course but the verses become melismatic beyond anything one can imagine. In the version below, it is sung by a soloist - a practice which Hiley says was traditional. The longest melisma appears in verse two. It features vast melodic invention on one vowel - unthinkable for any congregation to attempt but so beautiful to hear as method of liturgical contemplation. The passage to which I refer, in the graphic below, occurs starting at about 5 minutes into the video.
