Miss (Lat. missa, from mittere, to dismiss), in the Roman Catholic church, the form of celebrating the Lord's supper. When first introduced, the term denoted the dismissal of the catechumens and penitents, who were permitted to be present at the introductory, but not at the sacramental service, before the beginning of which they were called upon to leave the church. The two parts of the service were then distinguished as missa cate-chumenorum and missa fidelium. The oldest writing in which we find the term missa is a letter of St. Ambrose, and very soon after his time it passed into general use. According to the definition of Roman Catholic theologians, the mass is the true sacrifice of the new law - an offering instituted by Christ, in which, by the consecration and consumption of his body and blood under the form of bread and wine, Christ himself is mystically slain and offered as a victim to God the Father in recognition of his sovereign dominion. The Catholic church believes that by the words of consecration, pronounced by the priest over the bread and the wine, these elements are changed into the body and blood of Christ. The sacrifice of the mass is not considered to be substantially different from the sacrifice offered by Christ on the cross, but a repetition of it, Christ offering himself again through the hands of the priest.

Through it the merits of Christ are believed to be available to men. It is called a propitiatory sacrifice, as Christ is believed to be really present as a victim, asking pardon for sinners as he did on the cross. The Roman Catholic church therefore sometimes offers masses specially for the dead, whom she mentions indeed in every mass. As she believes that Christians who leave this world without having sufficiently expiated their sins are obliged to suffer a temporary penaltvin the other, she prays God, through Jesus Christ, for the remission of this penalty. The mass is called a eucharistic sacrifice, because it is believed that by offering Christ the church expresses gratitude to Cod in the best possible manner; and an impetratory sacrifice, because she hopes that God, touched by this offering, will grant new mercies. - In the first centuries bishops when celebrating mass were attended by other bishops or by priests, who offered, consecrated, and communicated with them. This was termed concelebrare and consacrificare. This custom prevailed in both the Greek and Latin churches • and in the latter it is still usual for priests on the day of their ordination to celebrate with the ordaining bishop.

In the Lyonnese rite, which has very recently been abolished, a , number of priests thus officiated with the bishop at solemn pontifical mass. It was also a | rule in the early church, when bishops visited each other, that they should unite in celebrating as a sign of their being of the same communion. - In a liturgical point of view, the mass is divided into five parts: 1, the preparatory part, formerly called the mass of the catechumens; 2, the offering, which extends from the offertory to the canon; 3, the canon, including the consecration; 4, the breaking of the host and the communion; 5, the thanksgiving or post-communion. In these parts the liturgies of all the eastern or western churches, except in the Protestant communions, substantially agree (see Liturgy), as well as in prescribing the breaking of the bread, in conformity with the words of the Scriptures, which say that Christ broke the bread. In the beginning, as Justin Martyr testifies in his second apology, the Lord's supper was only celebrated on the Lord's day; but, according to Pellicia, the western Christians began in the 2d century to celebrate it on Fridays and Wednesdays as well, and in the East during the 4th century it became customary to celebrate on Saturdays. St. Augustine says that a great diversity existed about this in his time; it was then the rule to offer the sacrifice daily in the churches of Africa, Spain, and Constantinople, and this rule was made universal in the 6th century.

At this epoch the Latin church allowed bishops and priests, wherever there existed insufficiency of church room, to celebrate twice on certain great festivals, as on the feast of the Circumcision, Jan. 1. In some places this was done thrice and even four times. On Holy Thursday, every priest was allowed to celebrate thrice, and twice daily during the whole of Easter week. In the 8th century at Rome the privilege of triple celebration was also attached to June 29, the feast of St. Peter and St. Paul. At present the privilege of saying three masses on the same day is restricted in the Roman Catholic church to Christmas. In Spain the privilege is enjoyed by priests on All Souls' day, Nov. 2. In missionary countries, where there is a scarcity of clergymen, each priest is permitted, by a special indult from Rome, to say mass twice on Sundays and holidays of obligation. In modern times it has been often proposed in the church to celebrate the mass more rarely, and only when a large attendance of the people is to be expected. But the council of Trent confirmed the practice of saying private masses, and recommended a daily celebration. The presence of one who recites the responses is required at private mass.

The liturgy of the mass still indicates that in former times all the people'who were present communed with the priests. This usage gradually ceased, and the priest was often left to commune alone. Still, in populous parishes in most Roman Catholic countries, communion is distributed at most private masses, and the utility of frequent communion is sedulously inculcated. - With respect to the language used in the celebration of mass, the western churches use the Latin, and the Roman missal. (See Liturgy, and Missal.) The eastern churches in union with that of Rome use the ancient idioms of their respective peoples, and are not allowed to celebrate in Latin. The wishes sometimes expressed by larger or smaller bodies of the Catholic church to translate the liturgy of the mass into the modern languages, and to let the responses at the mass be recited or sung by the entire congregation, have never been favored by the highest ecclesiastical authorities, though in some cases it has been permitted as a privilege, as .for instance to the duke Eugene of Wurtemberg, who in 1786 received from Pius VI. permission to introduce the German mass into his court chapel. - There are different kinds of masses.

A high or solemn mass is celebrated with the assistance of a deacon and subdeacon, and is sung by choristers; but the principal mass on Sundays and festivals, in wmich part of the service is sung by the priest without deacon or subdeacon, is usually called in this country high mass. A low mass is one of which no part is sung, and at which the priest has no assistant but his clerk. The ordinary duration of a low mass is half an hour. The mass of the presanctified (missa prcesancti-ficatorum) is the name given to the service celebrated in the Latin church on Good Friday, and in the orthodox Greek church on nearly all the week days in Lent. It consists in the consumption by the priest of the bread consecrated on a previous day; and is, properly speaking, not a mass at all, the consecration being an essential part of the sacrifice. At all masses the priest wears vestments which indicate by their color the ecclesiastical season of the year or the stated festival which is celebrated. Thus red is used for the feast of martyrs, white for those of virgins, purple for the penitential seasons of Lent, Advent, and vigils.

At the masses for the dead black vestments are used, some psalms and ceremonies omitted, and the people are dismissed without the benediction. - Masses may be said for any special purpose (votive masses), as for the recovery of health, for the avoiding of danger, for obtaining a special favor, etc. In the middle ages some practices crept in which the church condemned, as the celebration of the mass without the assistance of a clerk, the combination of several masses in one in order to get a greater payment, etc. The "Congregation of Rites," instituted by Sixtus V. in 1587, watches over the purity of the ritual. The Greek church and the other eastern churches hold, in the main, the same views with regard to the mass as the Roman Catholic church. The difference is mostly limited to ceremonies. - Every member of the Catholic church is bound, under pain of mortal sin, by one of the "precepts of the church," unless prevented by sickness or other grave impediment, to attend mass every Sunday and on certain holidays called days of obligation.