Among Protestant and secular historians alike, there is a tendency to assert that the practice of Eucharistic Adoration is of high medieval origin. The Fourth Lateran Council of 1215 is often targeted as the moment when belief in Transubstantiation was "invented", with all the Eucharistic devotions following afterward. While Lateran IV certainly defined Transubstantiation, we should not view this moment as a kind of external irruption of a concept foreign to Christianity. Rather, Eucharistic Adoration and all related devotions are grounded in principles that go right back to the Scriptures and the apostolic Church. In this article, we will examine the history of Eucharistic Adoration prior to the year 1264, which is the year the Feast of Corpus Christi was instituted by Pope Urban IV. Far from being some sort of wild medieval novelty, it is a classic example of the Catholic idea of development of doctrine.
First, let us define our terms. By "Eucharistic Adoration", we mean the reservation of the Blessed Sacrament for veneration outside of the Mass. Implied in this is the corollary idea that Christ is truly present in the Blessed Sacrament and that His presence endures after Mass has concluded.
The presence of Jesus Christ in the Eucharist is very plainly taught in the New Testament. In the sixth chapter of the Gospel of St. John, Christ made it manifestly evident that He intended for His followers to consume His flesh and blood (see "Flesh" and "Eating" in John 6). The skepticism of Christ's followers, when He preached the reality of His flesh and blood as food and drink, was recorded by St. John (John 6:66-68).
St. Paul rebuked the Corinthians for making their gatherings occasions of discord when they should have been celebrations of unity. He reminded them that the Eucharist they received at their gathering was no ordinary food; it is actually the Body and Blood of Jesus Christ, according to "the tradition which I handed on to you that came to me from the Lord Himself." He further warned that those who were not discerning in how they received the Body of Christ would be guilty of a serious sin (1 Cor. 11:23-26). Paul's teaching in 1 Cor. 11 is important because it establishes that the teaching of Jesus in John 6 was interpreted by the early Church to refer to Christ's presence in the Eucharist.
St. Ignatius of Antioch, writing on his way to martyrdom in 107 AD, admonished Christians of Smyrna to abstain from fellowship with those who denied that the Eucharist was truly the Body of Christ, the same flesh which suffered for our sins:
"Take note of those who hold heterodox opinions on the grace of Jesus Christ which has come to us, and see how contrary their opinions are to the mind of God… They abstain from the Eucharist and from prayer, because they do not confess that the Eucharist is the Flesh of our Savior Jesus Christ, Flesh which suffered for our sins and which the Father, in his goodness, raised up again. They who deny the gift of God are perishing in their disputes" (Letter to the Smyrnaeans, Ch 6).
We could bring forth other quotes from the Fathers on the Real Presence of Jesus in the Eucharist, but we are not attempting to establish this point, as much as set it up as the foundation for the later practice of Eucharistic Adoration. St. Paul and St. Ignatius taught not only that Christ was present in the Eucharist, but that the reception of the Eucharist was a sign of one's unity with the Church. There is a connection here between the two ideas of the Eucharist as the Body of Christ and the Church as the Body of Christ. The way one professes their unity with the Church, the communal Body of Christ, is by reception of the Eucharist, the sacramental Body of Christ.
The reception of the Eucharist was not only a means of grace but a sign of communion with the Church. This presented a conundrum for the early hermits, who had to figure out a way to receive Holy Communion without breaking their solitude. Some undoubtedly had attendants who brought them Holy Communion regularly, but many did not. Thus arose the practice of hermits reserving the Eucharist in their cells and self-communicate on Sundays, since they most likely did not leave their cells to attend weekly Mass (see "How did the hermits keep the Sunday obligation?").
The Testimony of St. Justin on Carrying the Sacrament to "Those who are Absent"
At first we may suspect we are seeing a true departure from apostolic practice with the eremitic reservation of the sacrament. This is no innovation, however, as the development of the practice flows very naturally from apostolic custom. We already know from the Apology of St. Justin Martyr that it was common for the Eucharist to be carried from Mass to be given to the home-bound. St. Justin says in Chapter 65 of the Apology:
"And when the president has given thanks, and all the people have expressed their assent, those who are called by us deacons give to each of those present to partake of the bread and wine mixed with water over which the thanksgiving was pronounced, and to those who are absent they carry away a portion."
Three inferences follow from this passage. First, we should note that St. Justin clearly believes in the Real Presence, as in the succeeding chapter of the same work he says:
"And this food is called among us Eucharistia [the Eucharist], of which no one is allowed to partake but the man who believes that the things which we teach are true, and who has been washed with the washing that is for the remission of sins, and unto regeneration, and who is so living as Christ has enjoined.
For not as common bread and common drink do we receive these; but in like manner as Jesus Christ our Savior, having been made flesh by the Word of God, had both flesh and blood for our salvation, so likewise have we been taught that the food which is blessed by the prayer of His word, and from which our blood and flesh by transmutation are nourished, is the flesh and blood of that Jesus who was made flesh."
"The food which is blessed by the prayer of His word...is the flesh and blood of that Jesus who was made flesh." The Eucharist is not the Body of Christ in a symbolic manner, but is truly His flesh and blood.
Second, by St. Justin's time (c. 155 AD), it was already common to take the Eucharist from worship to the administer it to the home-bound. It notes that portions of the Eucharist were taken to be served "to those who were absent." This was common throughout the patristic era; over a century later, the martyr St. Tarcisius was killed while bringing the Eucharist to imprisoned Christians. The transportation of the Eucharist was common.
Third, this practice demonstrates the Church's belied that the presence of Christ in the Eucharist endures beyond the ritual of the Mass itself. At the time of the Reformation, Luther - as well as Cranmer - taught that whatever presence Christ maintained in the Eucharist extended only to the duration of the Eucharistic liturgy itself. Hence they condemned any sort of Eucharistic piety that made the Blessed Sacrament itself outside of Mass an object of veneration (see "The Propriety of Eucharistic Devotions"). Apostolic practice, on the other hand, attests to the opposite - the early Church clearly understood Christ's presence in the Blessed Sacrament to endure beyond the conclusion of Mass; indeed, there is nothing in the Fathers to suggest anything other than that the early Church believed the presence of Christ in the consecrated host was perpetual. If Christ was not still present in the consecrated host, what was the purpose of carrying it away to the home-bound? For what reason did St. Tarcisius suffer martyrdom if he did not believe he was carrying the real flesh of Christ in his bosom?
Reservation and Adoration by the Monks
Understanding this makes it easy to see how the monastic practice of reserving the Eucharist developed from existing custom. Apostolic practice had already encouraged the Eucharist to be taken to those who were absent. The context implies this referred to the sick or home-bound, but there is no reason to doubt that, as monasticism spread, this principle was extended to those who were absent because of their consecration to God. Because of the great isolation in which many of the hermits lived, it stands to reason that the Eucharist was not brought to them regularly, but on some kind of schedule - perhaps monthly or in accordance with the liturgical cycle. The hermits would thus maintain their isolation and reserve the sacrament for self-communication.
However, knowing that they also believed that Christ was present in the sacred host, it is difficult to imagine that the reserved host did not easily become an object of veneration. The monk, consecrated to Christ, dwelling alone in his cell with the consecrated host, in which he knew Christ was truly present - this must have had a profound effect on the spiritual life of the hermit. It is safe to say that the first Eucharistic Adoration as we know it probably occurred in these eremitic cells in the 3rd century, but it should also be stressed that this grew out of existing beliefs about the Eucharist that are grounded in the New Testament.
The hermits not only reserved the Eucharist in their cells, but carried it on their persons when they traveled. It was already common for bishops to send particles of the Eucharist (called fermentum) to neighboring bishops, which could then be consumed as a sign of unity between the local churches. There is evidence of the popes themselves doing this in the 2nd century, and bishops sometimes sent the fermentum to their priests. As the eremitic life became more communal - and as monks turned into missionaries - it was common for monks to carry the Eucharist on a voyage, to bring a particle from one monastery to another, and to be ready for Holy Communion on the Lord's Day. The host could be carried in a case called a chrismal which was worn on a strap across the breast like a bandoleer; it was also kept in a little leather pouch called a perula that was worn about the neck. Irish and British manuscripts mention this practice frequently, along with many tales of the sacrament serving as a deterrent against would-be robbers. The Vita of St. Comgall (d. 601) says that on one occasion he was attacked by pagans while working in a field. When the heathen saw the chrismal about his breast, however, they drew back for fear of divine judgment, for they surmised that Comgall was carrying his God.
Thus, the origin of reservation and adoration of the Eucharist is bound up with growth of monasticism. There is evidence that by the time of the Council of Nicaea (325) the Eucharist was already being reserved in the churches of monasteries and convents. The first definitive reference we have of this is in the life of St. Basil (d. 379). Basil is said to have divided the Eucharist into three parts at Mass: one part he consumed, the second he gave to his monks, the third he placed into a golden dove suspended above the altar.
It took a bit longer for the custom to come to the west, but once communal monasticism began to replace eremitic monasticism, it was natural that the Blessed Sacrament which was once reserved in individual cells was now reserved in a special location accessible to the entire monastic community. Church history furnishes us with many different names for this place of reservation: It is variously referred to as the pastoforium, secretarium, diakonikon, and the prothesis, among others. The names varied regionally, but it appears they all refer to a special room just off the sanctuary but separated from the main church where Mass was offered. The Eucharist was held in reserve in this room. The presence of the Eucharist in early monasteries was a source of spiritual consolation to these monks, who treated it with great reverence.
In the High Middle Ages
By the Carolingian period the place of reservation had moved to the main church itself, quite close to the altar; it is probably during this period that we see the emergence of Eucharistic tabernacles, as we now know them. An Anglo-Saxon poem from the year 802 tells of a pyx containing the Blessed Sacrament that was reserved on the high altar of the abbey church at Lindisfarne, England. The reservation of the Eucharist in religious houses was universal by the year 1000, though it is uncertain to what degree this extended to diocesan parish churches at the time. We know of the ubiquity of the practice in religious houses from several extant regulations that deal with protecting the sacred host. One such regulation speaks of protecting the sacrament "from profanation by mice and impious men." These high medieval regulations share much in common - the receptacle (tabernacle) is to be raised high enough to be out of easy reach of profaning hands, and the vessel is to be kept under lock and key. Two such Eucharistic tabernacles dating from the year 1087, one of gold and one of silver, used to be kept in Monte Cassino but were destroyed in the bombing of the Second World War.
By the year 1000 reservation of the Blessed Sacrament in religious houses and probably cathedrals and major basilicas was universal. The Eucharistic presence was adored and paid homage to in the private worship of the monasteries. The heresy of Berengar, an archdeacon of Angers, would lead to a kind of renaissance in Eucharistic devotion. It is beyond the scope of this article to examine the heresy of Berengar at length, but we recommend our article "Berengar and His Importance" for the theological background of this controversy. It is sufficient to note that Berengar had denied the physical presence of Christ in the sacrament as the Church had always understood it.
Pope St. Gregory VII compelled Berengar to sign a retraction which entered history as the Church's first Magisterial statement authoritatively defining the Catholic faith concerning Christ's presence in the sacrament. Gregory formulated the statement as an oath, which read:
"I believe in my heart and openly profess that the bread and wine that are placed on the altar are, through the mystery of the sacred prayer and the words of the Redeemer, substantially changed into the true and proper and lifegiving flesh and blood of Jesus Christ our Lord, and that after the consecration they are the true body of Christ—which was born of the Virgin and which hung on the Cross as an offering for the salvation of the world—and the true blood of Christ—which flowed from His side—and not just as a sign and by reason of the power of the sacrament, but in the very truth and reality of their substance and in what is proper to their nature."
This definition by Pope Gregory VII led to a proliferation of Eucharistic piety. Processions of the Blessed Sacrament were instituted, acts of Eucharistic adoration were encouraged and legislated. Private adoration of Christ in the tabernacle was encouraged as a devotion for both religious and lay persons. The cells of anchorites and anchoresses were fitted with windows looking into the Church so that those in seclusion could view the tabernacle (see, "Hermits and Anchorites of England"). An early ordinal of the Carmelites from the following century included the words "for devotion of those in the choir" when referring to the reservation of the Blessed Sacrament.
This all led to a great flowering of lay devotion as well, and the 12th century is the great century of the Church's lay saints. This all culminated in the year 1215 with the formal definition of Transubstantiation at the council of Lateran IV, convened under the great Innocent III. The Council defined Transubstantiation in this manner:
"There is indeed one universal church of the faithful, outside of which nobody at all is saved, in which Jesus Christ is both priest and sacrifice. His body and blood are truly contained in the sacrament of the altar under the forms of bread and wine, the bread and wine having been changed in substance, by God's power, into his body and blood, so that in order to achieve this mystery of unity we receive from God what he received from us" (Lateran IV, Cap. 1).
This is important because, as we noted at the outset, this is often taken as the origin of the doctrine of Christ's Real Presence in the Blessed Sacrament, with all subsequent Eucharistic devotions and the practice of Eucharistic Adoration coming afterward. But, as we have seen, the belief in Christ's presence in the Eucharist comes from the New Testament itself, that His presence continues after the liturgy is attested to in the 2nd century, and the first instances of Eucharistic adoration come from the hermits in the 3rd century - and by the 4th century St. Basil records the sacrament being reserved in a special vessel near the altar for devotional purposes. Clearly Eucharistic Adoration predates the Fourth Lateran Council.
Our essay promised to take us to the year 1264, which is the year Pope Urban IV instituted the Feast of Corpus Christi, a solemnity dedicated to honoring the mystery of our Lord's Body and Blood in the Blessed Sacrament. Corpus Christi is of especial importance because it highlights the Church's belief in the perpetual presence of our Lord in the Blessed Sacrament outside of the Mass. St. Thomas Aquinas was commissioned to compose the hymns for this feast, and from this commission we have the beautiful hymns O Salutaris Hostia, Tantum Ergo Sacramentum, and Panis Angelicus. Aquinas' hymns are a treasury of Eucharistic theology. Fr. John Hardon, S.J., says this of Aquinas' Eucharistic theology:
"Aquinas, like the Church, never separated the Eucharist as Sacrifice, Communion, and Presence. But, with the Church, he also realized that without the Real Presence there would be no real sacrifice nor real communion. Aquinas assumed that God became man so He might offer Himself on Calvary and continue to offer Himself in the Mass. He became man that He might give Himself to His disciples at the Last Supper and continue to give Himself to us in Holy Communion. He became man to live in flesh and blood in Palestine and continue to live now on earth as the same Jesus who died and rose from the dead and is seated at the right hand of His heavenly Father." 
Eucharistic Adoration does not originate in the Middle Ages, not with Corpus Christi nor with Lateran IV. It has a lengthy pedigree that takes us from the Middle Ages back through the Eucharistic controversies of the 11th century to the flowering of the monastic age and the desert fathers - right on down to the New Testament itself. Those who consider Eucharistic Adoration a strange aberration of the Middle Ages should consider that Eucharistic Adoration not only was practiced in the early Church, but that the principles upon which Eucharistic Adoration is based are all developed from apostolic teaching.
 This citation, as well as all other unattributed citations in this essay, are taken from The History of Eucharistic Adoration by Fr. John A. Hardon, S.J. (Marian Publishers: Oak Lawn, Ill, 1997), 1-6