Which preposition to use with firmus

by Occurrences 1%

"This," he said, "did a former bishop of the Church of Tagaste, Firmus by name, and even more firm in will.

for Occurrences 1%

The reform Palestrina undertook, or was entrusted with, was the ending of the old scandal brought upon the Church by the elaborate lengths to which contrapuntal composers had gone in using popular melodies, and often even street songs of an obscene nature, as a foundation melody or cantus firmus for their vocal gymnastics.

Which preposition to use with  firmus