A Black Mass is a ritual characterized by the inversion of the Traditional Latin Mass celebrated by the Roman Catholic Church.
The reality of any such celebrations in medieval times is unclear, with the main sources being claims that witches practiced them, found in manuals for witch-hunters such as the Malleus Maleficarum (1486) and the Compendium Maleficarum (1608).
Modern revivals began with H. T. F. Rhodes' book, The Satanic Mass published in London in 1954, and there are now a range of modern versions of the Black Mass performed by various groups.
The Catholic Church regards the Mass as its most important sacrament, going back to apostolic times. In general its various liturgies followed the outline of Liturgy of the Word, Offertory, Liturgy of the Eucharist, and Benediction, which developed into what is known as the Mass. However, as early Christianity became more established and its influence began to spread, the early Church Fathers began to describe a few heretical groups practicing their own versions of Masses. Some of these rituals were of a bizarre sexual nature. The fourth-century AD heresiologist Epiphanius of Salamis, for instance, claims that a libertine Gnostic sect known as the Borborites engaged in a version of the Eucharist in which they would smear their hands with semen and menstrual blood and consume them as the blood and body of Christ respectively. He also alleges that, whenever one of the women in their church was experiencing her monthly period, they would take her menstrual blood and everyone in the church would eat it as part of a sacred ritual.
Within the Church, the rite of the Mass was not completely fixed, and there were places at the end of the Offertory for the Secret prayers, when the priest could insert private prayers for various personal needs. These practices became especially prevalent in France (see Pre-Tridentine Mass). As these types of personal prayers within the Mass spread, the institution of the Low Mass became quite common, where priests would hire their services out to perform various Masses for the needs of their clients (Votive Masses) -- such as blessing crops or cattle, achieving success in some enterprise, obtaining love, or even cursing enemies (one way this latter was done was by inserting the enemy's name in a Mass for the dead, accompanied by burying an image of the enemy). In the 12th and 13th centuries there was a great surplus of clerics and monks who might be inclined to perform these Masses, as younger sons were often sent off to religious universities, and after their studies, needed to find a livelihood. Also within the Church, the Mass was sometimes reworked to create light-hearted parodies of it for certain Church festivities. Some of these became accepted practices at times, such as a festive parody of the Mass called "The Feast of Asses", in which Balaam's ass (from the Old Testament) would begin talking and saying parts of the Mass. A similar parody was the Feast of Fools.
Another result of the surplus of (sometimes disillusioned) clerical students was the appearance of the Latin writings of the Goliards and wandering clerics (clerici vagantes). There began to appear more cynical and heretical parodies of the Mass, also written in ecclesiastical Latin, known as "drinkers' masses" and "gamblers' Masses," which lamented the situation of drunk, gambling monks, and instead of calling to "Deus" (God), called to "Bacchus" (the God of Wine) and "Decius" (the god of dice, which were used in gambling). Some of the earliest of these Latin parody works are found in the medieval Latin collection of poetry, Carmina Burana, written around 1230. At the time these wandering clerics were spreading their Latin writings and parodies of the Mass, the Cathars, who also spread their teachings through wandering clerics, were also active. Due to the proximity in time and location of the Golliards, the Cathars, and the witches, all of whom were seen as threatening the authority of the Roman Catholic Church and the Papal Authority in Rome, some historians have postulated that these wandering clerics may have at times offered their services for performing heretical, or "black" Masses on various occasions.
A further source of late Medieval and Early Modern involvement with parodies and alterations of the Mass, were the writings of the European witch-hunt, which saw witches as being agents of the Devil, who were described as inverting the Christian Mass and employing the stolen Host for diabolical ends. Witch-hunter's manuals such as the Malleus Maleficarum (1487) and the Compendium Maleficarum (1608) allude to these supposed practices. The first complete depiction of a blasphemy of the Mass in connection with the witches' sabbath, was given in Florimond de Raemond's 1597 French work, The Antichrist (written as a Catholic response to the Protestant claim that the Pope was the Antichrist). He uses the following description of a witches' meeting as a sign that Satanic practices are prevalent in the world, and a sign that the Antichrist's power is on the rise:
An Italian man took her [Jeanne Bosdeau] to a field on Saint John's Eve. The man made a large ring with a rod of holly, muttering a few words which he read from a black book. Thereupon appeared a large, horned goat, all black, accompanied by two women, as well as a man dressed as a priest. The goat asked the Italian who this girl was, and having replied that he had brought her to be his, the goat made him make the sign of the cross with his left hand. Then he commanded all of them to come and greet him, which they did, kissing his rear. The goat had a lighted black candle between his two horns, from which the others lit their own candles. The goat took the woman aside, laid her in the woods, and carnally knew her, to which she took an extreme displeasure, suffered much pain, and felt his seed as cold as ice. Every Wednesday and Friday of each month the general meeting was held, where she went numerous times, with more than sixty other persons, all of whom carried a black candle, lighted from the candle that the goat had between his horns. After that they all began to dance in circles, their backs turned to one another. The person who was performing the service was clothed in a black robe without a cross. He raised a round slice of turnip, dyed black, instead of the Host, and cried at the Elevation: Master, help us. Water was put in the chalice instead of wine, and to make Holy Water, the goat urinated into a hole on the ground, and the person who was performing the service asperged the attendants with a black asperges (sprinkling of water). In this group they performed the practices of witchcraft, and every one gave a story of what they had done. They were to poison, to bewitch, to bind, to cure illnesses with charms, to make waste the fruits of the earth, and other such maladies.
Between the 16th and the 19th centuries, many examples of interest in the Black Mass come from France.
Scholarly studies on the Black Mass relied almost completely on French and Latin sources (which also came from France):
He went on in the Satanic Rituals (1972) to present it as the most representatively satanic ritual in the book.
The usual assumption is that the Satanic ceremony or service is always called a Black Mass. A Black Mass is not the magical ceremony practiced by Satanists. The Satanist would only employ the use of a Black Mass as a form of psychodrama. Furthermore, a Black Mass does not necessarily imply that the performers of such are Satanists. A Black Mass is essentially a parody on the religious service of the Roman Catholic Church, but can be loosely applied to a satire on any religious ceremony.
In spite of the huge amount of French literature discussing the Black Mass (Messe Noire) at the end of the 19th century and early 20th century, no set of written instructions for performing one, from any purported group of Satanists, turned up in writing until the 1960s, and appeared not in France, but in the United States. As can be seen from these first Black Masses and Satanic Masses appearing in the U.S., the creators drew heavily from occult novelists such as Dennis Wheatley and Joris-Karl Huysmans, and from non-fiction occult writers popular in the 1960s, such as Grillot de Givry, author of the popular illustrated book Witchcraft, Magic and Alchemy, and H. T. F. Rhodes, who provided a title for the satanic ritual in his 1954 book The Satanic Mass. Herbert Sloane, the founder of an early Satanist group, the Ophite Cultus Satanas, speaks of Satanists performing the ritual of the "Satanic Mass" in a letter he wrote in 1968 (see the article on his group), and in 1968 and 1969 also appeared the first two recordings of Satanic rituals, both entitled the "Satanic Mass":
Soon after Coven created their Satanic Mass recording, the Church of Satan began creating their own Black Masses, two of which are available to the public. The first, created for the Church of Satan by Wayne West in 1970, was entitled "Missa Solemnis" (named after the Missa Solemnis version of the Latin Mass; originally published only in pamphlet form, later published in Michael Aquino's history of The Church of Satan), and the second, created by an unknown author, was entitled "Le Messe Noir" (published in Anton LaVey's 1972 book The Satanic Rituals).
All three of these newly created Black Masses (the one by Coven and the two by the Church of Satan) contain the Latin phrase "In nomine Dei nostri Satanas Luciferi Excelsi"  (In the name of our God, Satan Lucifer of the Most High), as well as the phrases "Rege Satanas" and "Ave Satanas" (which, incidentally, are also the only three Latin phrases which appeared in the Church of Satan's 1968 recording, "The Satanic Mass"). Additionally, all three modify other Latin parts of the Roman Catholic Missal to make them into Satanic versions. The Church of Satan's two Black Masses also use the French text of the Black Mass in Huysmans' Là-Bas to a great extent. (West only uses the English translation, LaVey publishes also the original French). Thus, the Black Mass found in The Satanic Rituals is a combination of English, French, and Latin. Further, in keeping with the traditional description of the Black Mass, all three also require a consecrated Host taken from a Catholic church, as a central part of the ceremony.
A writer using the pseudonym "Aubrey Melech" published, in 1986, a Black Mass entirely in Latin, entitled "Missa Niger". (This Black Mass is available on the Internet). Aubrey Melech's Black Mass contains almost exactly the same original Latin phrases as the Black Mass published by LaVey in The Satanic Rituals. The difference is that the amount of Latin has now more than doubled, so that the entire Black Mass is in Latin. Unlike Coven and Wayne West, LaVey and Melech don't give the source for the Latin material in their Black Mass, merely implying that they received it from someone else, without saying who.
The French sections that LaVey published were quotations from Huysmans's Là-bas. The Latin of Melech and LaVey is based on the Roman Catholic Latin Missal, reworded so as to give it a Satanic meaning (e.g. the Roman Mass starts "In nomine Patris, et Filii, et Spiritus Sancti, introibo ad altare Dei", while LaVey's version, printed in the Satanic Rituals, starts "In nomine magni dei nostri Satanas, introibo ad altare Domini Inferi"). There are a small amount of copyist and grammatical errors. For example, "dignum" from the Mass, is once incorrectly spelled "clignum", in the printed Satanic Rituals. Another example, also appearing once, is "laefificat" instead of "laetificat". One of the more obvious grammatical errors is "ego vos benedictio", "I bless you", which should have been "ego vos benedico". Another grammatical peculiarity is that, throughout his version of the Mass, LaVey does not decline the name Satanas, as is typically done in Latin if the endings are used, but uses only the one form of the word regardless of the case. Melech uses Satanus. "Satanas" as a name for Satan appears in some examples of Latin texts popularly associated with satanism and witchcraft, such as the middle age pact with the Devil supposedly written by Urbain Grandier. Both Black Masses end with the Latin expression "Ave, Satanas!" -- "Welcome, Satan!" (expressing the opposite sentiments of the similar statement made by Jesus to Satan in the Latin Vulgate Bible (Latin Vulgate, Matthew 4:10), "Vade, Satanas!" - "Go away, Satan!").