Beyond a Chant: “Tui sunt caeli” and its Tropes
A notable example in which music and text combine to form an organic entity unifying chant and trope is provided by the tropes for the offertory "Tui sunt caeli" from the third Mass on Christmas Day. The main set of tropes to be considered in this study, "Qui es sine principio," is taken from the Aquitanian repertory. The opening of the first trope element is syntactically and musically related to the opening of the first antiphon phrase, and the end of the same antiphon phrase is syntactically and musically related to the end of the second trope element. A textual connection between the troped antiphon and the first offertory verse also supports the substitution theory. While the meaning of the last phrase of the untroped antiphon is complete and clear—"Righteousness and judgment are the preparation of our throne"—the meaning of the substitute text is ambiguous.