consonances, they had always been described by theorists as an interval normally avoided. Here,
bizarrely, they seem to be the prevalent interval. But the duo carries a “canon” or rubric that says, “If you
desire a three-part piece, take the top notes and start with them, but down a fourth.” When this is done,
fifths are added to the framing octaves, and thirds are added to the sixths, so that the prevailing
parallelism becomes exactly like the one in Beata viscera: an exhaustive parallelism of imperfect
consonances amounting to a parallelism of triads, voiced for maximum smoothness with the “hard” and
“hollow” perfect fifth avoided. In Example 11-20 c, the beginning of the Communion is “realized”
according to the given recipe; but any singer who can read the top part can deduce the unnotated middle
voice from it by transposition, without any need for a special notation. Those handicapped by perfect
pitch can substitute a different clef in their mind’s eye (using what fifteenth-century musicians called
“sights”), but most can make the transposition “by ear.” Try it yourself with two companions: sing through
Ex. 11-20b following the model indicated in Ex. 11-20c. When you do this,
EX. 11-20A Guillaume Du Fay, Vos qui secuti estis me (Communion from Missa Sancti Jacobi), original chantEX. 11-20B Guillaume Du Fay, Vos qui secuti estis me (Communion from Missa Sancti Jacobi), as notated (chant notes denoted by
‘+’)