Music from the Earliest Notations to the Sixteenth Century

Compare the tenors. They all cut up the “In seculum” melisma into three-note ordines. The first, called
In seculum longum (“In seculum by longs”) casts the tune in perfect longs throughout, as in the spondaic
“fifth mode.” The second, called In seculum viellatoris (“The fiddle-player’s In seculum”), uses trochaic
(“first mode”) LBL patterns as fixed by the mensural ligatures. And the third, called In seculum breve (“In
seculum by breves”) reverses the patterns of the second piece into iambic (“second mode”) BLB patterns,