The path of the history is clear: during the first centuries of Christianity there was no “church music,” but only liturgy performed in singing. In the course of time, two byways were opened: the first is artistic church music (starting as early as the 7th—8th century), the second is the folk hymn which appears in the 10th— 11th century). At first the use of both was limited and they remained in close proximity to the liturgy. As their autonomous life developed, they moved away from the liturgy: art music toward compositions inspired by religious sentiments, the vernacular folk hymn toward popular genres. Although the church musicians of today have some control over the folk hymn through the hymnals, in fact they left the church music of weekdays and normal Sundays to its own fate. They failed to protest resolutely as a group against the corruption of liturgical music, and to search for the path of a real renewal in the spirit of the liturgy. They regarded the rescue of ecclesiastical art music as their main task and found satisfaction in the artistic production of solemn Masses and concerts.
Thus church music has been broken into two, reflecting the disruption of the Church herself into a low and high Church. The high-church music is in this case the sphere of Gregorian and polyphonic Masses. The low-church music is the multitude of Masses celebrated with popular cantiunculae ditties, and amateur pop music compositions. Somewhere between the two we find a “traditional” low-church music: congregational hymns lead by organ mixed with rather poor Ordinary compositions. Adding up the percentages: high-church music is in one or two percent of the Masses and churches, low-church music in all the other ninety-eight percent.
Laszlo Dobszay, The Bugnini-Liturgy and the Reform of the Reform (2003)