Bear in mind that this was composed in 1939, well before the Second Vatican Ecumenical Council and some rubrics may have been modified...Other changes will be noted accordingly. Nevertheless, some may find the history fascinating.
Questions answered in this chapter:
How did the practice of entombing the relics of saints in altars originate? What was the decree of the Second Council of Nicaea? How is the practice of placing relics in altars suggested by the text in the Apocalypse? By St. Augustine? St. Ambrose?==========================
What kind of relics are placed in altars? What is the Congregation of Sacred Rites? Why is it unnecessary to know the names of the saints whose relics are placed in the altars? What classes of saints are so honored today? What are direct and indirect relics? What feast is- celebrated in many dioceses on November 5?
In what solemn rite is the altar identified with Christ? Of what three parts does the ceremony consist? What other ceremony does it resemble?
What does the word "tabernaculum" mean? What does it suggest? How is the tabernacle constructed? How was the Blessed Sacrament reserved during the first three centuries? What was the "arca"?
What were some methods of reservation in use during the early ages of the Church? What was the eucharistic dove? Where are such doves in use today? What was the eucharistic tower. When and how was the tower replaced?
When and for what reasons was the reredos introduced? Why did Pope Paul order that the relics be brought to the churches? What custom developed in some parts of Europe? Why were reredoses built?
What movement is bringing about a new development in the sacred arts? How is good taste in ornamentation being achieved? What are the requirements of the rubrics in regard to the altar? What purpose do cloth hangings serve?
The practice of entombing relics of the saints in altars and later in altar stones, is traceable to the custom of celebrating Mass over the graves of the martyrs. So firmly was the "cult of relics" established that in the year 787 the Second Council of Nicaea decreed that all consecrated churches should possess some relics. The law was so strict that a bishop who consecrated a church without them could be deposed.
TESTIMONY OF THE SAINTS: The altar quite naturally became the ideal repository for these relics because of the martyrs' resemblance to the Lamb of God. St. John the Evangelist, describing his vision of the heavenly Jerusalem, relates in the Apocalypse: " . . . I saw under the altar the souls of them that were slain for the word of God, and for the testimony which they held" (VI, 9). Their fellowship in the sufferings of Christ prompted St. Augustine to say: "Rightly do the souls of the just rest beneath the altar since on it the body of the Lord is immolated." The word "altar" in these two quotations refers to Christ as the altar of heaven under which the souls of the martyrs live as their bodies rest under our altars. When St. Ambrose discovered the bodies of the Martyrs Gervase and Protase in the year 386, he placed them under an altar with the explanation: " . . . the martyrs are entitled to this resting place."
AUTHENTICATION OF RELICS: The relics which are placed in the sepulchres of altars and altar stones must be authenticated ones. The Congregation of Sacred Rites [Ed.Note: Pre Vatican II, currently it is the Congregation for the Causes of Saints], a body composed of cardinals and other officials charged with the direction of the liturgy, decides upon the authenticity of such relics. When relics bear the official stamp of approval of this body, it does not matter whether or not the name of the saint is known. It became customary, however, to include in the sepulchre of the altar the relics of one martyr, to which may be added those of confessors and virgins or, when possible, a relic of the saint in whose honor the altar is dedicated. The rubric does not state that the relics must be direct, that is, parts of the bodies of saints. Liturgical writers, however, insist that the relics so honored must be direct. (Indirect relics are obtained from objects connected with the lives of saints). On November 5 [Old Calendar] the Church celebrates, in many dioceses, the feast of the Holy Relics preserved in the churches of the respective dioceses.
CONSECRATION OF THE ALTAR: The altar is identified with Christ in the beautiful and solemn rite of consecration which is performed by a bishop. This rite consists of three distinct phases: (1) The blessing of the altar with Gregorian water; (2) the entombment of the relics; and (3) the anointing with holy oils.
The entombment of the relics of the saints is one of the most profound and touching parts of the ceremony and closely resembles the formula of the ritual used in the burial of the bodies of the martyrs. On the day previous to the consecration of the altar, the relics are taken to the church in a special reliquary. Three grains of incense are enclosed with them and at least two candles are kept burning all night before them. "On the day of the consecration the relics are carried in solemn procession with cross, lights and incense, first around the church and then into the church. At the same time responses and antiphons are sung; the Church calling out to the Saints: 'Arise from your abodes, ye Saints of God; proceed to the place of your destination; sanctify all the places through which you pass, bless the people and preserve us sinful men in peace!' Amid clouds of incense, amid prayer and singing, they are placed in the receptacle anointed with chrism, and the opening is closed." 
THE TABERNACLE: The name tabernacle comes from "tabernaculum," a Latin word meaning "tent." It is suggestive of the tent of the Israelites which served as their sanctuary during their wandering in the desert before the erection of Solomon's Temple. The tabernacle is a box or chest made of solid marble, wood, stone, or metal, closed on all sides and permanently fixed to the altar. The interior should be lined with silk. A corporal is placed on the floor for the sacred vessels to rest upon.
During the first three centuries the Blessed Sacrament was not, as a rule, reserved in the churches, but the faithful, because of persecutions, were permitted to take It to their homes for the purpose of communicating themselves when in danger of death. The sacred Species was kept in a small silver box lined with cedar, called an "arca," a Latin word meaning "ark." As conditions became more favorable for the practice of the Christian religion, this custom was abandoned. During the fourth century the Holy Eucharist was reserved in the churches, but only for the sick.
DEVELOPMENT OF THE TABERNACLE: When the practice of reserving the Blessed Sacrament became more general, the method adopted varied according to time and place. The vessel in which the Host reposed was sometimes kept in a niche in the wall or in a pillar; in a recess under the altar or in a portable turret-shaped cabinet which was kept in the sacristy or in an adjoining room called the "bridal chamber."
The cabinet was carried to the altar at the beginning of each Mass. Later on it was customary to reserve the Blessed Sacrament in a pyx which was placed in a receptacle of gold or silver fashioned in the form of a dove. The dove, which was covered with a richly embroidered silk veil ("dove-cot"), was suspended above the altar from the roof of the ciborium or canopy. By special permission eucharistic doves are still in use in two churches in France, one in Amiens and another in Valoires. [Ed. Note: I'm unclear whether this sti;; applies.]
The ciborium, which was supported by four columns, was later replaced by the eucharistic tower. This tower was octagon-shaped, made of wood or stone, and erected on the Gospel side of the altar. It was sometimes surmounted by a staff designed like a bishop's crozier, from which the dove was suspended.
In Rome it was customary to enclose the dove or a casket containing the sacred Species in the tower itself. These towers were used as receptacles for the Blessed Sacrament until the end of the sixteenth century when they were permanently replaced by our present form of tabernacle built in the middle of the altar and inseparable from it.
THE REREDOS: The earliest types of altars did not have the superstructure at the back which is such a familiar ornamental feature today. About the tenth century, a panel, later called a reredos, was introduced. Curiously enough, the reredos, too, grew out of the "cult of relics" and the plundering of the Roman shrines and catacombs by the Goths and Lombards. In 761 Pope Paul I ordered that the bodies of the martyrs should be transferred to the "crypts of the churches" in order to give them safety and protection. In some parts of Europe, however, costly shrines and caskets containing the bodies of the saints were stacked behind the altars; some of them even rested on the altars. Later on this haphazard arrangement of relics was hidden by the erection of panels or reredoses built back of the altar and in front of the reliquaries. Although admitting of much decoration, these reredoses remained comparatively simple until the fifteenth and sixteenth centuries when they became great structures, sometimes reaching to the roof of the church. The altar often appeared to be merely a part of the reredos. They were usually made of wood and were elaborately carved and painted. Frequently they were covered with gold leaf and precious stones. Sometimes they contained niches for statues of the saints.
NEW STANDARDS: With the spread of the Liturgical Apostolate in the United States, architects, craftsmen, artists, and the clergy are turning their attention to the development of more worthy standards in the arts which are employed in the ornamentation of the altar. Simplicity and good taste are achieved by designs which are reduced to the fundamental liturgical requirements and by the omission of all unessential details.
A stone slab supported by stone columns, a tabernacle enclosed in an all-seasonal canopy or veil of colored silk, six tall candle sticks and a large crucifix (which may be suspended from above), fulfill all the requirements of the rubrics. Cloth hangings are often used to bring these simple outlines into relief, an arrangement which admits of unlimited possibilities in light and color harmonies.
(1) Glhr, Tbe Holy Sacrifice of the Mass. Page 243.
Adapted from Altar and Sanctuary, An Exposition of the Externals of the Mass
by Angela A. Glendenin (© 1939)
Published by the Catholic Action Committee
The Catholic Action Series of Discussion Club Textbooks