Published
Officium Defunctorum (Oficio de Difuntos)

The ordinary prayer for the dead echoed the other, solemn and particular prayer performed upon the death of the faithful.
This practice was already established in the fourth century during the interval between death and burial. During the day, and even more so at night, the dead were watched over while psalms were sung and recited. Saint Augustine describes such a vigil on the occasion of the death of his mother, Saint Monica.
These psalms, in whole or in part and interspersed with suitable spiritual readings, essentially formed the core of the vigil for the dead.
The practice of reciting the entire Psalter during the vigil remained in the Church for a long time. In Rome it continued at least until the sixth century in Benedictine monasteries; in Fulda, Germany, until the eighth century; in St Gallen in Switzerland and in monasteries in England and France until the eleventh century; and in Lombard monasteries until the twelfth century. Outside the monastic sphere in Rome, no trace of it appears in any liturgical book before the ninth century.
This complex euchological formula formed the oldest core of the Commendatio animae (Commendation of the Soul). After being recited beside the bed of the dying person, it also served as a prayer of intercession around the coffin. The Commendatio is prescribed in the earliest rituals for the funeral vigil praesente cadavere, for the third, seventh and thirtieth days after death and on the anniversary, as well as a general liturgical formula of suffrage for the dead. This is why the Commendatio animae often appears in sacramentaries and medieval Books of Hours.
It remained in widespread use because, when it emerged around the middle of the eighth century, the Office of the Dead proper had not yet entered general liturgical practice. After the Carolingian period, the Office was initially associated with the Commendatio, then gradually overtook it and finally replaced it, causing it to disappear almost entirely as a mortuary office.
The liturgical historian Callewaert demonstrated that the Office of the Dead was not of monastic origin and was not composed in the eighth century, as had been believed. The examination of its constituent parts suggests that it predates even Gregory the Great: the number and ordering of the psalms are distinctly Roman, without Gallican or monastic traces and without the additions made after Gregory—introductory prayers, invitatory, hymns, chapter and the final doxology of the psalms. It can therefore be inferred that the Office was modelled on the Sacred Triduum and represents a pre-Gregorian stage of the liturgy. Callewaert’s conjectures were confirmed by the Ordo of John, archcantor of St Peter’s, which around 680 attests to a fairly widespread liturgical practice. Amalarius also implicitly acknowledges its Roman origin, noting that it appeared in the earliest antiphonaries brought from Rome to Gaul in the eighth century. Callewaert showed that the Office of the Dead was created not for the vigil over the body, but for the third, seventh and thirtieth days as an addition to the daily office.
One of the essential characteristics of the Office of the Dead is that, unlike other offices, the Church does not pray in the name of everyone. Instead, taking the place of the souls in Purgatory, it groans and implores in the person of the deceased.
Litaniæ Sanctorum (Litany of the Saints) and Officium Defunctorum (Office of the Dead) belong to the “common fund” of Gregorian chant, which is anonymous by definition because it was transmitted orally, refined collectively and never signed.
Entierro de un niño (1784) por Juan Ruiz Jiménez
On 20 February 1784, the burial of a child (a “párvulo”) took place in the Church of the Sagrario. The cathedral’s music chapel was invited, and twenty parts attended together with the choirboys; in general, each musician held one part, although some received half a part. Bartolomé Polo was the steward of the music chapel. The chapel assembled by order of Canon Pedro del Campo, its protector. They agreed that, in accordance with “immemorial practice, the wind players at the funerals of children and in processions shall play in alternation with the chapel, one verse and then another, for such is the established practice, and should they fail to do so they shall forfeit their fee.” They played in the procession that carried the deceased from the family home to the church where the burial took place.
ABSOLUTIO / ABSOLUCIÓN: Responsorium: Libera me, Domine.