Chants for the Mass

 The gradual contains the sung portions of the mass, particularly the chants for feasts, Sundays, and the common of saints. In each mass several chants were "proper" to the occasion (introit, gradal, sequence, alleluia replaced by a Tract in penitential seasons, offertory, and communion). The ordinary chants were those sung at every mass (Kyrie, Gloria, Credo, Sanctus, Agnus Dei, and Ite Missa Est). While the melodies of the ordinary chants varied, their texts did not, except through the addition of tropes (poetic interpolations). graduals from the high and late Middle Ages may incorporate material that earlier was contained in separate books or sections: the kyriale (containing choir chants of the Ordinary of the Mass), the cantatorium (a book for soloists, containing the gradual and Alleluia, the solo chants of the Proper), the earlier type of gradual (containing choral chants of the Proper), the sequentiary or proser (containing sequences, also called proses) and the troper (containing troped versions of various chants).

X936.C28, f. 214: A missal from mid-15th century Germany, with the non-notated Alleluia verses for the hierarchy of saints listed in order (apostles, many martyrs, one martyr, one confessor, virgins). Plimpton MS 040A, recto:
A gradual from 15th century Italy.
Plimpton MS 040C, f. 2v:
A gradual from 13th century Italy.
Med/Ren Frag. 28, f. 2:
A gradual from 12th century Germany.
Barnard College, MS 3: A gradual from 16th century Portugal
Barnard MS3f. 7v:Introit for the feast of the Dedication of a Church. [5856] Barnard MS3f. 40v:Different melodies for the Kyrie. Barnard MS3f. 49:The end of a troped Gloria and the beginning of another.
Barnard MS3f . 22v:Prose (another name for the sequence) for continents (chaste spouses). Barnard MS3f. 42v:Kyries for feasts of the Virgin Mary, preceded by a trope.  
A sequentiary from late 12th / early 13th century Spain, possibly Burgos:
HSA12Leaf with musical notation. HSA13Leaf with musical notation.