Stephen of Autun: Tractatus de Sacramento Altaris

This treatise on the sacrament of the altar is ascribed to Stephen of Bâgé, bishop of Autun (d. c. 1140). The prologue begins with the Wisdom of God ordering all things from end to end, the Son, who clothed himself in flesh and clothed us with immortality, and who, wishing to leave us all things necessary for salvation, ordained invisible sacraments in visible matter, since humans could not grasp spiritual gifts without something visible: baptism in water, marriage as the union of Christ and the Church, anointing with oil as divine mercy. The treatise then explains the clerical orders, from doorkeeper, lector, exorcist and acolyte to subdeacon, deacon and priest, showing how Christ himself fulfilled each office.

The later chapters expound the Mass, its prayers and actions, in allegorical terms; the middle passage distinguishes the peace of quiet meditation from the peace that passes all understanding, which Christ promised and gave to his disciples. The work belongs to the twelfth-century genre of liturgical commentary and was widely read, offering a compact explanation of the orders and the Mass for clergy.