The Litany of the Saints is the oldest and most solemn litany in the Catholic Church. Its roots reach back to the early centuries — fragments of the form appear in seventh-century Western liturgical books, and Pope Gregory the Great instituted the great litanic processions of Rome in 590, asking the faithful to call upon the saints by name in supplication during plague. The litany became part of the Easter Vigil baptismal liturgy at least by the eighth century. Its current Roman-rite text was formally fixed by Pope Pius V in 1568 and revised in the post-Vatican II liturgical reform (1969). The structure unfolds in five major movements: (1) Kyrie eleison invocations and Trinitarian petitions; (2) the great roll-call of saints by name — Blessed Virgin Mary first, then archangels (Michael, Gabriel, Raphael), patriarchs and prophets (Abraham, Moses, Elijah, John the Baptist), apostles and evangelists (Peter, Paul, Andrew, John, James, etc.), martyrs (Stephen, Lawrence, Polycarp, Ignatius of Antioch, Cyprian, Sebastian, Agatha, Agnes), confessor-bishops and doctors (Athanasius, Basil, Gregory, Augustine, Jerome, Ambrose), founders and virgins (Anthony of the Desert, Benedict, Francis, Dominic, Catherine of Siena, Teresa of Ávila); (3) petitions of deliverance ('From all evil, deliver us, O Lord'); (4) petitions of supplication ('That You would govern and preserve Your holy Church, we beseech You, hear us'); (5) closing Agnus Dei and collect. The litany is one of the principal prayers of the Catholic liturgy and is used at: the Easter Vigil (during the Liturgy of Baptism), Holy Saturday baptisms, priestly and episcopal ordinations (the candidates lie prostrate while the gathered church sings the litany over them), the Rite of Christian Initiation of Adults (RCIA) at the Rite of Election, the dedication of a church, the consecration of altars, and the conferral of religious vows. It is also customary in many parishes on the Solemnity of All Saints (November 1), at funerals of priests and religious, in moments of grave public need (war, pandemic, natural disaster), and as the closing prayer of pilgrimage processions. The litany names many saints; the local diocese or community is also free to add the patron saints of the local church.