In the Byzantine Rite the week preceding Easter, I during which we spiritually relive the mysteries of our redemption, is called Passion Week. It is also referred to as the Great Week, on account of the "great and indescribable benefits that have befallen us during this week (St. John Chrysostom). Consequently, each individual day of Passion Week is also designated as Great (St. Athanasius). Hence Holy Thursday liturgically is referred to as Great Thursday, in commemoration of the institution of the Holy Eucharist.

Although the celebration of the Holy and Great Thursday is very ancient, it did not originally form part of the liturgical celebration of the Paschal Mysteries (the crucifixion, burial and glorious resurrection of Christ). At the beginning, Holy Thursday was rather a day of preparation for the Easter Vigil, the primitive Sacred Triduum, which started on the eve of the Holy and Great Friday, and ended at the dawn of Easter Sunday. Thus, originally, Holy Thursday was assigned to the reconciliation of penitents in order that they be able to participate in the paschal festivities with the rest of the faithful.

The catechumens, also, who were to be baptized on the Vigil of Easter, were examined on Holy Thursday. They had to recite from memory the Symbol of Faith before the presiding bishop.

It was only natural that a special commemoration of the institution of the Holy Eucharist should be made on the day when this great event took place. Thus the custom to celebrate the Holy Liturgy in the evening of Holy Thursday originated, with all probability in Jerusalem, at the end of the fourth century. It was at this commemmorative Divine Liturgy that the faithful were expected to receive Holy Communion in fulfillment of their Easter duty (cf. Egeria, Diary of Pilgrimage, 35).

The celebration of the Divine Liturgy on the evening of Holy Thursday encountered some difficulties, especially on account of the Eucharistic fast, prohibiting any food, or even a drink of water, to be taken before Holy Communion. Thus, in the seventh century they began to celebrate the Holy Liturgy in the morning hours to make it possible for the people to receive Holy Communion while fasting. This practice was approved by the Council of Trullo, in 692 A.D.

On Great Thursday we celebrate the Liturgy of St. Basil the Great (cf. Byzantine Leaflet Series, n. 20), preceded by solemn Vespers (cf. Byzantine Leaflet Series, n. 29). The Liturgy of St. Basil the Great was chosen, since the Anaphora, the priestly prayer preceding and following the Consecration, describes the institution of the Holy Eucharist with much more detail than that of St. John Chrysostom. The Divine Liturgy is preceded by Vespers to indicate that the Liturgy is celebrated in commemoration of the institution of the Holy Eucharist at the Mystical (Last) Supper, which was celebrated by Jesus with His Apostles after the evening sacrifice at the temple. Thus the evening character of the Divine Liturgy of Great Thursday is observed at least liturgically.

The morning celebration of the Holy Liturgy on Great Thursday was prompted by another practical reason, the anticipation of the All-night Vigil in order to attract larger crowds. With time, the All-night Vigil (Passion Services) of Great Friday became less and less attended. By moving the celebration of the Divine Liturgy to the morning hours, they were able to begin the Great Friday Vigil early in the evening and complete it before midnight. And the people responded.

Since the Great Thursday Liturgy is celebrated in commemoration of the institution of the Holy Eucharist, which can be performed only on a properly consecrated altar, it was logical that the consecration of the Antimensia (Greek antimension—in stead of the altar) by the bishop would also take place at the Liturgy of Great Thursday.

The Antimension (equivalent to a portable altar in the Latin Rite) is a square piece of linen or, recently, of silk, on which is depicted the deposition of Christ’s body from the cross, with the four Evangelists in the corners. A small pocket, containing the relics of a Martyr, is then sewn to the reverse side of the cloth, which is then consecrated by the bishop and authenticated by his signature.

In the first centuries the Holy Liturgy was usually celebrated on altars built over the tombs of Martyrs who gave living witness to the Gospel of Christ by sacrificing their own life. This practice was suggested by the Scriptures, describing the heavenly altar: "I saw under the altar the spirits of those who had been martyred because of the witness they bore to the Word of God" (Rev. 6:9).

In the places where there were no tombs of Martyrs the local bishop usually enshrined a piece of a Martyr’s relics in the altar at the time of the consecration of a newly erected church. Finally in 787 A.D., the Second Council of Nicea legislated: "If any church has been consecrated without the relics of the Martyrs, we decree that the holy relics be deposited therein with the customary prayers" (Can. 7).

As a result of the above decree the use of the consecrated antimension became widespread in the Byzantine Church, although originally it was meant to be used on the altars which were not consecrated by the bishop. Beginning with the 17th century the on every altar, whether it has been consecrated by the bishop or not.

The ritual of the consecration of antimensia is almost the same as that of the altar. As a matter of fact, in the prayers of consecration, the antimension is referred to as "the holy altar" since it contains the holy relics and, after being consecrated by the bishop, the Holy Liturgy can be celebrated upon it. For the consecration of the antimensia, just as for the consecration of the altar, the bishop uses holy chrism (myron).

The holy chrism (myron) is used by the bishop in the consecration of the churches, altars and antimensia. It is also used by the priests in the administration of Holy Confirmation, which in the Byzantine Rite is appropriately called Chrismation—in Old Slavonic Myropomazanije.

The first instructions about the ingredients and preparation of the chrism, referred to as sacred anointing oil, were given by God Himself to Moses (Ex. 30:22-30). To the present day the chrism is basically composed of a mixture of olive oil and balm, to which various fragrant spices and roots are added in powdered form. After adding some white wine to it, the entire mixture is then carefully boiled until all the ingredients are smoothly blended together. During the boiling of the mixture certain prayers are said.

This perfumed ointment is then solemnly consecrated by the bishop during the Divine Liturgy on Great Thursday. The vessel with the properly prepared ointment is placed on the altar during the Great Entrance and is consecrated by the bishop after the Anaphora by a "holy invocation." The oldest prayer for the consecration of chrism, entitled the Holy Invocation, comes to us from the fourth century (cf. The Apostolic Constitutions, VII, 44). The oldest ritual of the consecration of chrism can be found in the Euchologion from the eighth century, generally known as the Barberini Code.

Originally, the consecration of chrism took place during the Easter Vigil on Great Saturday, just before the solemn baptism of the catechumens. At the end of the sixth century the consecration of chrism was moved to the Great Thursday Liturgy in order to alleviate the crowded services of the Easter Vigil.

Holy Chrism was always considered by the Church Fathers as a very sacred thing, imbued with the presence of the Holy Spirit, as explained by St. Cyril of Jerusalem (d. 386) to the newly baptized: "After the invocation (of the bishop) this holy ointment is no more a simple or common ointment, but is Christ’s gift of grace and by His advent is able to impart the Holy Spirit" (cf. his Catechetical Lectures, XXI, 3).

After Easter, the Holy Chrism is distributed by the bishop to all parishes under his jurisdiction, and the priests then use it in the administration of the Mystery of Chrismation.

At the Mystical Supper Our Lord washed the feet of his disciples, giving them a practical lesson of the humble service to which they were called, saying: "What I just did was to give you an example: as I have done, so also you must do" (Jn. 13:15). In the early Church the washing of the feet as an act of Christian charity became a common practice (I Tim. 5:10).

In the following centuries the custom of washing the feet outlived its practical use and was abandoned by the Christian communities. Nevertheless it survived as a liturgical ceremony and was performed by the bishop, or by the superior of a monastery, at the end of the Divine Liturgy on Great Thursday.

During this symbolic ritual the bishop, representing Our Lord Jesus Christ, re-enacts the entire event as described by the Evangelist (Jn. 13:3-17) and washes the feet of twelve clerics or altar boys, symbolizing his readiness to serve the people in humility. The symbolic meaning of the entire ceremony is beautifully described in the concluding prayer, recited by the bishop:

TROPARION OF GREAT THURSDAY
(Tone 8)

Receive me this day, 0 Son of God, as a partaker of Your Mystical Supper, for I will not reveal the mystery to Your enemies, nor will I give a kiss as did Judas, but rather as a (good) thief I confess to You by exclaiming: "Remember me, O Lord, when You come into Your kingdom!"