A brief history of Gregorian chant from King David to the present

In reality, Gregorian chant it is anything but plain, except in the sense that its beautiful melodies are meant to be sung unaccompanied and unharmonized, as befits the ancient monastic culture out of which they sprang.  What we call "Gregorian chant" is one of the richest and most subtle art forms in Western music — indeed, in the music of any culture.

The tradition of chanting Scripture, a practice known as cantillation, began at least 1,000 years before the birth of Christ.  Various Old Testament books, especially the Psalms and the Chronicles, testify to the central function of music in temple worship.  Some Gregorian melodies still in use are remarkably close to Hebrew synagogue melodies, most notably the "Tonus Peregrinus" used for Psalm 113, In exitu Israel; the ancient Gospel tone; and the Preface tone.

Since the Psalter of David was composed for the very purpose of divine worship and was seen as the messianic book par excellence, we find Peter, Paul, and the Apostolic Fathers citing it heavily in their preaching.  The first Christians spontaneously chose the Psalter for their "prayer book."  The Christian liturgy as a whole, then, sprang from the combination of Psalter and Sacrifice.  The psalter is the "verbal incense" of our prayers and praises, the homage of our intellects.  The bloody sacrifice, the death and destruction of an animal, is the total surrender of our being to God.  In the Mass these two are wondrously combined into the rational sacrifice consisting of the perfect offering of Jesus Christ on the altar, who unites our prayers and praises to His and makes them worthy of the Ever-Blessed Trinity.

Chant developed prodigiously in the first Christian millennium.  By the time we reach Pope St. Gregory the Great, who reigned from 590–604, a body of chant already existed for the Sacrifice of the Mass and the daily round of prayer (Divine Office).  Even as he gave final form to the Roman Canon, which is the defining trait of the Latin rite, St. Gregory organized this musical repertoire, as a result of which the chant ever afterwards has been honored with his name: "Gregorian."

Over time, not just the psalms and their antiphons were cantillated, but also the Scripture readings, orations, intercessions, litanies, instructions (e.g., "Flectamus genua"), and, in general, anything meant to be proclaimed out loud.  The core of the Gregorian chant repertoire dates to before the year 800; the bulk of it was completed by the year 1200.

Since chant was the music, custom-made, that had grown up with the Church's liturgy, wherever the latter traveled, the former traveled with it.  No one dreamed of separating the texts of the liturgy from their music; they were like a body-soul composite, or a happily married couple.  Or one could compare the chant to the vestments worn by a liturgical minister.  Once this ceremonial apparel had developed, no one in his right mind would get rid of the chasuble, stole, alb, amice, and maniple.  These are the garments that the ministers of the king are privileged to wear! So too, the chants are the garments worn by the liturgical texts.

The Council of Trent (1545–1563) reaffirmed the place of chant in the liturgy and discouraged the use of excessively complex polyphonic music, especially when it was based on secular tunes.

No one dreamed of separating the texts of the liturgy from their music; they were like a body-soul composite, or a happily married couple.

Nevertheless, over time the old chant melodies became abbreviated or corrupted, as they were forced to conform to a regular beat like the metered music of the day.  By the beginning of the 19th century, chant was in a state of serious disrepair and neglect.

Restoration of such an immense treasure of the Church — and such an integral part of her solemn liturgy! — was bound to come sooner or later.  It came through the combined efforts of a monk and a pope.  Dom Prosper Guéranger (1805–1875) founded Solesmes Abbey in 1833 and built it up into a powerhouse of monastic observance, including the fully chanted Divine Office and Mass.  The monks of Solesmes pored over ancient manuscripts in their work to restore the chant's distinctive melodies and rhythms.

Soon after his accession in 1903, Pope St. Pius X met in Rome with monks of Solesmes and placed on their shoulders the task of publishing all of the liturgical books of chant, with corrected melodies and rhythms.  The monks complied, and Pius X gave their work his stamp of approval.  From this papal directive was born a long string of influential publications from (or licensed by) Solesmes, most of which are still in use today, most notably the Liber Usualis, the Graduale Romanum, and the Antiphonale Monasticum.

From Solesmes and Pius X to the Vatican II's Constitution on the Sacred Liturgy Sacrosanctum Concilium is a straight and logical line.  Here is what Vatican II had to say on the subject:

Liturgical worship is given a more noble form when the divine offices are celebrated solemnly in song . . . The treasure of sacred music is to be preserved and fostered with great care.  Choirs must be diligently promoted . . . The Church acknowledges Gregorian chant as specially suited to the Roman liturgy, with the result that, other things being equal, it ought to be given the foremost place in liturgical services. But other kinds of sacred music, especially polyphony, are by no means excluded from liturgical celebrations, so long as they accord with the spirit of the liturgical action.

The original Liturgical Movement out of which these stirring words came was devoted to restoring and recovering the richest and most beautiful traditions of Catholic prayer.  Unfortunately, an explosive combination of false antiquarianism and novelty-mongering modernism threw a gigantic wrench into the works, leaving a war zone of competing visions in which we are still entrenched — and in which chant has suffered near extinction.  The good news is that the tide is beginning to turn here and there.  Chant will never die because it is perfect liturgical music.