FIG. 5-4 The conductus Congaudeant catholici as it appears in the Codex Calixtinus (fol. 214, the bottom half of the page).
What may in fact be the earliest surviving three-part polyphonic composition is a Christmas
conductus, Verbum patris humanatur (“The word of the Father is made man”). It is found as a two-part
discant setting in one of the Aquitanian manuscripts, and in three parts (of which one, the tenor of course,
is common to both settings) in a small French manuscript of the late twelfth century now kept in the library
of Cambridge University. The notation is still noncommittal with respect to rhythm. The transcription in
Ex. 5-10 is “isosyllabic,” resulting in an implicit duple meter based on the accentual scansion of the text.
The longer values on the exclamatory O’s and elsewhere are conjectural; they arise out of the same
implicit (or perhaps it would be more honest to say “presumed”) musical pulse.
The basic “harmony of three voices” emerges here as octave (or unison) plus fifth. The octave-filled-
by-fifth sonority includes every perfect consonance (or symphonia, to recall the old organum
terminology). In places where imperfect consonances had been common before (especially the
“precadential” position), we are now apt to find triads, or else a combination of fourth or fifth plus a
seventh over the lowest voice that is justified by its characteristic approach to the concluding consonance
by contrary motion—a harmonically amplified occursus.
EX. 5-9 Congaudeant catholici transcribed as two separate two-part pieces, but aligned