The introit (Latin: introitus, "entrance") is part of the opening of the celebration of the Mass. Specifically, it refers to that part of the Tridentine Mass, though the term is used in other orders of the Mass to label the antiphon that is spoken or sung at the beginning of the celebration. It is one of the "propers" of the Mass, that is, a part that changes over the liturgical year. Latin is the language originally spoken in the region around Rome called Latium. ... Then-Cardinal Joseph Ratzinger (now Pope Benedict XVI) presiding at the 2005 Easter Vigil Mass in place of the dying Pope John Paul II. Mass is the term used of the celebration of the Eucharist in the Latin rites of the Roman Catholic Church. ... A pre-Vatican II altar with reredosThe altar is preceded by three steps, as was most common for a churchs main altar, though some main altars, such as that in Saint Peters in the Vatican, had (and have) much more than three. ... This article is about the musical term. ...

Most introits are taken from Psalms, though there exist those from Proverbs or Wisdom. Generally they follow the same structure: two to four lines of scripture related to the "theme" of the feastday or celebration. Most often the choice of scripture passage has something in common with the liturgical readings that will be featured later in that Mass. Psalms (Tehilim תהילים, in Hebrew) is a book of the Hebrew Bible or Tanakh, and of the Old Testament of the Christian Bible. ... The Book of Proverbs is a book of the Tanakh/Old Testament. ... Wisdom is one of the books of the Bible that is not a translation of a Hebrew original. ...

The introit can be either sung or spoken, depending on the formality of the Mass as well as the preferences of the priest and his congregation. Not all Masses have introits; traditionally the service of Holy Saturday in the Roman Catholic rite does not. Roman Catholic priest LCDR Allen R. Kuss (USN) aboard USS Enterprise A priest or priestess is a holy man or woman who takes an officiating role in worship of any religion, with the distinguishing characteristic of offering sacrifices. ... Holy Saturday is the day before Easter in the Christian calendar. ... The Roman Catholic Church, most often spoken of simply as the Catholic Church, is the largest Christian church, with over one billion members. ...

The practice evolved from the singing of a psalm as the priest and ministers approached the altar, sung verses having been part of the celebration of the Mass since earliest times. The Liber Pontificalis claims that the introit originated by the request of Celestine I, but it was in the reign of Gregory I that the familiar form emerged, and Gregory is credited with "composing" many introits himself. Saint Celestine I was pope from 422 to 432. ... Saint Gregory I, or Gregory the Great (called the Dialogist in Eastern Orthodoxy) (circa 540 - March 12, 604) was pope of the Catholic Church from September 3, 590 until his death. ...

In many cases the introit also serves another purpose: it gives a name to a particular Mass, based on the first word or phrase of the introit. Since the introit for a Mass is different for each day of the Liturgical Calendar (sometimes multiple Masses even exist for a single day, such as Christmas), and unique Masses exist for special functions, it provides a key for determining which order of the Mass is to be performed. This is why a funeral Mass is called a Requiem and the second Mass of the Feast of the Sacred Heart is called the Exordium, for example. Even though Latin is no longer used widely in the celebration of the Mass, the traditional names remain for purposes of organization of the calendar. The liturgical year, also known as the Christian year, consists of the cycle of liturgical seasons in some Christian churches which determines when Feasts, Memorials, Commemorations, and Solemnities are to be observed and which portions of Scripture are to be read. ... Christmas (literally, the Mass of Christ) is a holiday in the Christian calendar, usually observed on December 25, which celebrates the birth of Jesus. ... The Feast of the Sacred Heart (or properly, the Solemnity of the Sacred Heart) is a holy day in the liturgical calendar of the Roman Catholic Church. ... Latin is the language originally spoken in the region around Rome called Latium. ...

An interesting side effect of this is that unnamed feast days acquire the names of their respective Masses. As an unusual example, the first Sunday after Easter Sunday, though having no official liturgical name, is colloquially labelled "Quasimodo Sunday" as the first phrase of the introit is "Quasi modo geniti infantes...". Sunday is considered either the first or the seventh day of the week, between Saturday and Monday, and the second day of the weekend in some cultures. ... Easter (also called Pascha) is generally accounted the most important holiday of the Christian year, observed March or April each year to celebrate the Resurrection of Jesus from the dead (after his death by crucifixion; see Good Friday), which Christians believe happened at about this time of year, almost two... Quasimodo is a handsome man, deformed on the outside, but handsome on the inside, he is made to ring bells for his master claude frollo who is the real monster, quasimodo may look like a freak of nature, but it is the inside that counts, he is a handsome young...