Prayer, in the Christian tradition, is an exercise almost by definition riddled with contradiction. The tension goes back to the Gospels; it is, likewise, at the root of many contemporary debates over the purpose of the liturgy and the role of individual experience in developing a relationship with God. For medieval Christians, as for the Fathers on whom they relied, prayer was something that everyone, even the unlettered knowing only the words of the Our Father (Pater Noster) or the Hail Mary (Ave Maria), was expected to be able to achieve. At the same time, it was also considered an art or discipline requiring long experience and great skill that even specialists (e.g., monks and nuns) could not realize without grace. Irreconcilable as these two extremes of practice and experience might seem today, for early and medieval Christians, at least, this much was clear: to be a Christian meant to be one who prayed. Yet, then as now, many struggled to explain not only how one should pray but also, and even more urgently, why.

Throughout the Middle Ages, prayer, at its most basic level, was defined as an act of speech and, therefore, of reason; as Cassiodorus (d. ca. 585) put it, “prayer (oratio) is spoken reason (oris ratio).” Yet, in its purest form, prayer would seem to go beyond reason, as the Augustinian canon Hugh of Saint Victor (d. 1141) explained: “pure prayer (pura oratio) is when out of an abundance of devotion the mind is so inflamed that, about to make a request to God, it is so transformed before the magnitude of his love it even forgets its petition.” Formally speaking, the most perfect prayer was (and, arguably, is) without contest that which the Lord Jesus Christ taught to the apostles (Mt 6:9–13; Lk 11:2–4); according to Augustine of Hippo (d. 430), “if you go over all the words of holy prayers, you will find nothing which cannot be comprised and summed up in the petitions of the Lord’s Prayer.” Nevertheless, not only the Old Testament Psalms, but also the various hymns, chants, and other similar pieces “made by the Holy Spirit” for “the worship of the church,” that is, the Mass, the Hours of the Divine Office, and other formal rites of the liturgy, were reckoned as integral to the practice of prayer.