This sequence text, which first appeared at the end of a fifteenth-century notated missal used in Paris, is a plea to St. Sebastian. Although the saint is not mentioned by name, it is one of several similar texts set to music that appear in manuscripts containing votive masses for him. It is a personal, direct appeal for the saint to intervene and protect his supplicants from one of the most devastating illnesses to affect Western Europe in the Middle Ages: the bubonic plague. The medieval laity believed that such settings served as vehicles to carry their words directly to these protective figures, and through them to God.

Plague epidemics affected everyone, forcing men and women of all walks of life to come face to face with their mortality. The disease first appeared in Western Europe in 1347, recurring every ten to fifteen years until well into the eighteenth century, and had a profound effect on the populace. For instance, before 1433, the city of Paris had a population of approximately two hundred fifty thousand people, but between 1433 and 1444, a mere decade, the plague took the lives of over forty-eight thousand Parisians. This is a rather large figure for a late-medieval urban population. One can imagine a certain helplessness that people felt when confronted with this disease, causing them to routinely seek divine intervention from patron saints thought to have special protective powers.

St. Sebastian was viewed as one of the most powerful protectors from the plague in northern France from the fourteenth through the sixteenth centuries, but he was not alone. He was one of a group of saints called the fourteen holy helpers, who were commonly invoked for protection against sickness and death in the region. St. Barbara, St. Nicholas of Myra, and St. Catherine of Alexandria were all thought to protect one against an untimely death, as was the Virgin Mary