The Chants of the Proprium Missæ versus “Alius Cantus Aptus”

What arrangement of the Mass chants emerges before the eyes of an unbiased reader of the Liturgical Constitution promulgated by the Second Vatican Council? If we disregard what happened after the Synod, and concentrate our attention upon the text of Sacrosanctum Concilium, this is the picture we get:
The Mass is celebrated in most cases in Latin (Art. 36), although some parts (lections, bidding prayer: Art. 54) sometimes (when and where it seems useful) can be said in the vernacular (Art. 36/2). The faithful are able to chant the responses, the acclamations, and the Ordinary in Latin (Art. 54, cf. Kyriale Simplex). Gregorian chant has pride of place in liturgical singing (Art. 116). The chants of the Proper are sung by a choir or schola (Art. 114), in larger churches from the Graduale Romanum, and in smaller ones from the Graduale Simplex (Art. 117); but the congregation, too, may join in the Chant (Art. 114), singing psalms and antiphons (Art. 30). Chant is complemented by sacred polyphony taken from the heritage of sacred music, or from a repertory of new compositions. These take their texts chiefly from the Holy Scriptures or the liturgical books (Art. 121), correspond at all points with the spirit of the liturgy (Art. 116), and are characterized by the hallmarks of true ecclesiastical thinking (Art. 121) and true art (Art. 112). Careful instruction must prepare the laity to take their part in liturgical singing, and so each part is sung by the very person concerned (Art. 28, 114), and yet in the way required by the nature of the given part (Art. 112). Congregational religious hymns are also accepted during various devotions, as well as in liturgical celebrations “in keeping with rubrical norms and requirements.” However, in consequence of all these stipulations the meaning of ‘congregational hymnody’ has been changed: people sing not only vernacular hymns but also many parts that are integral components of the liturgy. Hence it seems right to distinguish the cantus populi (the chanting of the people) from cantus popularis (popular religious songs). The first of these is plainly the task of present and future; it is the great task of the liturgical renewal in the field of congregational chant.

(László Dobszay – The Bugnini Liturgy and the Reform of the Reform, p. 85)