Not Mass XVII. Still, an attractive text.
The various Gregorian settings of the Mass Ordinary parts have, in recent years (since the 19th century), been compiled into particular numbered and named Masses. Further, they are assigned particular occasions when they are most suitable.
For instance, Mass I, Lux et Origo, is for the Easter Season; Mass IV, Cunctipotens Genitor Deus, for Feasts of Apostles; Mass VIII, De Angelis, for Feasts (2nd class) generally; Mass IX, Cum Jubilo, for Feast of Our Lady; Mass XI, Orbis Factor, for Sundays per annum (After Epiphany or Pentecost -- Ordinary Time); and Mass XVII, Adventus et Quadragesimae, for Advent and Lent, as the name implies. Mass XVIII has adaptations for both Masses of the Dead or weekday Masses during Advent or Lent.
As we have entered the first week of Lent, it seems an good time, then, to present the parts of Mass XVII, which are appropriate for the season. This Mass, of course, lacks the Gloria that is missing from the Sunday Masses of Lent, or Advent for that matter, for which this setting is designated.
The Kyrie XVII, from the 14th century:
The Sanctus XVII, from the 11th century:
The Agnus Dei XVII, from the 13th century:
This blogger has the priviledge of singing this Mass on a regular occasion at the Holy Masses offered at his school.