Despite bearing the name of a late 6th century Pope, Gregorian chant has nothing to do with him - the earliest manuscripts of Gregorian chant date from the 13th century. Before this there were a multiplicity of chant styles, including a distinctly Roman style which ironically was exported to the Carolingian kingdoms of the 8th century, ultimately transformed into what we now know as Gregorian chant, and then transported back to Italy in the 13th century to supplant the Roman rite (and indeed to supplant the other styles elsewhere).
In the early 20th century, manuscripts from the 11th-12th centuries were rediscovered in the Vatican library containing such 'Old Roman' liturgy. These presented problems in understanding how they would have been performed, being effectively unsingable if 19th/20th century ideas about Gregorian chant were applied.
Marcel Pérès has sought an essentially Greek character to the chant, with the help of Orthodox chant specialist Lycourgos Angelopoulos (who sings as precentor on this disc). That this should be so should really not come as a surprise, knowing the close connection between Rome and Constantinople in the 7th-8th centuries when the Old Roman chant originally took shape. Part of Italy including Rome was part of the Byzantine Empire at this time. Between 644 and 772, fourteen of the twenty Popes were Greek speakers from the east, of whom three (Leo II, Sergius I and Gregory III) were musically skilled and exerted an influence on the Roman liturgy. In the early 7th century during the Persian invasion many Greek and Syrian monks fled to Italy to reestablish monasteries there as far north as Rome. Between 726 and 775 during the Iconoclast controversy, nearly fifty thousand more monks from the East left for Italy.
As if the historical connections were not enough, the Old Roman chant manuscripts themselves show Byzantine influence, with Alleluias sung in Greek. Here on this disc are three such Alleluias sung on Vespers for Easter Monday, Masses for Good Friday & 2nd Sunday after Easter, and Vespers for Easter Day & Mass for Easter Monday. The Latin chants all belong to the Mass for Easter Day.
The result of Pérès' research to try to rediscover the form of the Old Roman chant as it might have sounded in the 7th and 8th centuries is not only indescribably beautiful but utterly convincing, and demonstrative of the cultural and spiritual unity between Rome and Constantinople at the time.
The booklet has notes by Pérès (French with English & German translations), plus full Latin/transliterated Greek sung texts, with French translation only.