When the Church first left the catacombs (following the edict of Milan in 313 introducing religious freedom), it began to organise itself into parishes and bishoprics. Liturgical and musical needs came to the fore and soon, under the impetus of the most powerful monasteries, religious rites and a repertory of songs developed. The bishops founded schools, or scholæ, where children were taught singing and the seven liberal arts (including music, taken in its theoretical aspects, and mathematics). The young pupils of these establishments, the predecessors of our choir schools, provided the choral part of the religious services, alongside the cantors.
Paris had an episcopal school from the 4th century, one of whose first pupils was Saint Marcel, the ninth bishop of Paris, born in 350. Marcel taught in his turn and so the school continued from bishop to bishop. It developed significantly under the reign of Childebert 1st who, at the instigation of the influential bishop at the time, Saint Germain (ca. 496-576), completely rebuilt the first cathedral, dedicated to Saint Etienne. The magnificence of the liturgy had to be equal to the new edifice, to which a second church, Sainte Marie, was added.Witnesses describe the sumptuousness of the hymns sung from matins onwards in the brand new nave, under the aegis of the dynamic Germain. Shortly afterwards, masters began to be brought from the schola de Rome, a venerable institution made prestigious by Saint Grégoire, who was pope from 590 to 604.
On the death of Charlemagne in 814, despite the boost the emperor had given to education, many episcopal schools collapsed. However, the school in Paris continued to shine with an international brilliance. Several institutions were set up in England based on the same model.
The cathedral also developed a solid reputation thanks to Pierre Abélard (1079-1142), the tragic lover of the beautiful Héloïse. A particularly brilliant and rebellious spirit, who battled against Saint Bernard and the greatest theologians of his time, he wrote very popular love songs (now lost)and 133 hymns for the liturgy (only 2 of which have been passed down to us with their music) and 6 planctus - laments written as if in the words of biblical figures.
In 1108, the canon Guillaume de Champeaux left the cathedral riddled with quarrels and intrigues; five years later, on the left bank of the Seine, he founded a monastery of regular canons, the Abbey of Saint Victor. A school was immediately created there, which taught the ideas of Saint Augustin. Many clerics at Notre-Dame, including high dignitaries, liked to retreat there now and then and also offered subsidies that were gratefully received by the abbey. Saint Victor enjoyed a significant musical influence, which reached its height at the end of the 12th century thanks to another defector from Notre-Dame, the precentor (cantor) Adam, known as Adam of Saint Victor (ca. 1110-1192). Although he gave the income from his prebend to the abbey, Adam kept his post at the Cathedral. Until his death and the most recent biographical works indicate that he composed the majority of his poems and music, such as the Laudes crucis sequence, for the cathedral, rather than for the rival monastery.