Along with the Virgin Mary, Conrad is one of the patron saints of Konstanz. He was also a former bishop of the Konstanz diocese so this Proper was undoubtedly part of Isaac’s commission, created especially for the cathedral.
This introit begins with the bass voice in ¢2 with the other voices notated in ¢. It makes for an interesting transcription puzzle and indicates that the chant resides in the bass voice. In similar fashion, the verse bass voice is notated in ¡ with the others in ¢ until the last seven notes of the bass voice join the rest of the voices in ¢. The chant is similar to that in the modern Gradual Romanum, but the Graduale Pataviense version is closer to that used here.
Sacerdotes tui Domine induant justiciam et sancti tui exsultent propter David servum tuum, non avertas faciem Christi tui. Memento Domine David. Et omnis mansuetudinis ejus.
Domine probasti me et cognouisti me.
May your priests, Lord, put on righteousness and holiness in imitation of David your servant. Do not turn the face of your Christ away. Lord, remember David and all his troubles.
The Lord has proved me and known me.