The origins of the Black Mass are shrouded in the mists of history, but very likely date from the
12th century or later.
Satan, as a
demiurge, was comparatively late on the scene in
Christian mythology -- his initial duty was as God's
DA, whose job it was to report the
evil deeds of humanity. Also, the Mass was not made fixed until at least the
tenth century.
The first "variant" Mass we know of was originally conceived in the spirit, not of scorn, but of pious celebration -- The Feast of the Ass. This celebration was traditionally held on or around January 1st (which was not then the beginning of the civil year), and was nominally a celebration of the donkey that carried Mary to Bethlehem and to Egypt. In monasteries, it was celebrated with some of the rituals of Boxing Day today: the novices got the run of the monastery, which was given over to drinking, feasting, and various kinds of fun.
The day would begin at nine in the morning, when most of the monks would have had a full three or four hours of extra sleep. After a rousing prayer service (sung to the contemporary equivalent of the "Thong Song" and "Because I Got High") the monks would eat -- either dinner (which was repeated three times) or supper (with dinner at noon and breakfast food at night). The lectionary would be a nonsensical story, composed for the day, a comical fable, a story by a pagan author, or outright pornography, read with feeling and drama -- as you might imagine, applause and comments were warmly encouraged! The rest of the day would be taken up with similar reversals, parodies, or other pranks, under the direction of a pro-tem Abbot, who would decree as many nonsensical regulations as he could devise. Monks might be told to walk backwards, with sandals on their heads, to wear habits inside out or not at all, to speak without stopping, only in rhyme, or to sing when they should speak, and speak when they should sing, and quite naturally, to goof off, and to eat and drink their fill of the abbey's cellars and larder.
The highlight of the day was the Mass, celebrated near the end of the day's festivities, an event planned for with all the deviousness of overworked geeky young men in any era. Shoes might be burned in the censer, with the crucifix upside down. The whole text might be said backwards, with brandy in the chalice and a Host of cake, or other sweetmeats, and responses to the Collects might be well-nigh unprintable. Finally, with a last toast, the novices would go back to their dormitory, to rise again (with muzzy heads) at five the next morning.
It was a charming ritual, the memory of which helped leaven the days when nothing seemed to be going right. Eventually, abuses crept in, and the whole matter simply forgotten, if not for a growing problem.
Witches. And heretics. (Same difference, legally.) Folk rumor had it that they had Masses, priests, and even popes of their own. And they did...well, terrible things. Instead of elevating the Host, they whispered, they put it in a woman's...oh, the shame! Or they pissed on it, trampled it...They spat on crosses, they did. They had a pregnant whore dressed in a wimple and veils, who'd have sex, right out in the open! And for the most festive occasions...there'd be...babies.
Women, who'd conceived at previous orgies, would abort for the ceremony, and the fetus liquified in the chalice, or a baby would be snatched, and killed and eaten as a Host. Yes..yes...it's all true, I swear!
This last was taken, ironically enough, from an account of the early Christians given by Minicus Felix, a pagan Roman writer, whose lurid recountings of Christian ritual became transferred, first to the mystical Gnostics and then, to the apostates we know as the historical witches. Further rumor had it that a Black Mass could work miracles, especially if the object were something ... un-Christian, like seduction, wealth or revenge.
In this way, we come to the fable of La Voisin, hairdresser to Mme. de Maintenon, mistress to Louis XIV of France. Seems like Louis was getting bored with Madame, who feared losing him to a younger and more lively replacement. Confiding in La Voisin, all sorts of strategems were tried...new hairstyles, exotic sexual techniques...none made a whit of difference. Maybe you could arrange...no, I don't want to even think it...um...
--A Black Mass, Madame?
--Why, yes...
An unfrocked priest was found, for a little money. An inconveniently pregnant peasant girl was found for even less. A ceremony was hastily arranged, at Midnight on the grounds of Versailles, using the priest's memory of an Ass Feast in semanary. The year was 1664. Madame, and her courtiers assembled.
The girl aborted, right on cue, and Madame gagged down the fetal tissue in a foreshadowing of cell therapy. It was a rousing success. Madame moved with supreme self-confidence once more, and with that, managed to have quite the night with the King...
By request, La Voisin was called upon to repeat the performance often in the next four years, and the whole psychodrama became a sophisticated entertainment for a certain set, who thrilled at the thought of being present for a real Black Mass. La Voisin, however, was found, tried, and beheaded in 1668.
Since then, any number of people and/or groups have claimed themselves to be "Satanists" and celebrated similar rituals, including the famous Anton Szandor La Vey, in 1967. Many have also claimed that Black Masses have occured in their childhood as part of Satanic Ritual Abuse, but no hard evidence of this happening has ever turned up.