Bona Dea means 'good goddess'. Bona Dea is not the name of a specific goddess, although Fauna is sometimes associated with the title 'Bona Dea'. The Bona Dea was an ancient Roman festival held at the start of May, or the kalends. The Bona Dea also had movable feast in December. During the May Bona Dea celebration a pregnant sow was sacrificed to Mother Earth and Ceres. The celebration was for women only, whether patrician, free or slave. This means not even male animals were allowed. Nor were myrtle branches. Women consumed wine at the festival, but since wine was officially taboo for women, it was called "milk." The worship of the Bona Dea was part of a mystery religion. Margaret Imber's Roman Civilization - Bona Dea page at Bates College [oabacus.bates.edu/~mimber/Rciv/bonadea.htm] provided this and more basic information. The festival of the Bona Dea that caused the greatest stir was the one in December 62 B.C.
Clodius Pulcher attended the women-only December feast of the Bona Dea which was held at the home of Caesar and hosted by his wife Pompeia, thought to have been having an affair with Clodius. The improbable version of events from Plutarch has a roughly 30-year-old Clodius showing up dressed in women's garb, described as diaphanous flute-girl garb, yet looking so much like a woman that he passed -- until he opened his mouth. By attending the Bona Dea festival, Clodius violated the rites of the Vestal Virgins. This was a sacrilege (or act of what was technically considered incest) that landed Clodius in court facing prosecution and Cicero. Although Clodius was acquitted and Caesar did not actually accuse his wife of adultery, Caesar divorced Pompeia because, he said, his wife must be above suspicion.
Plutarch describes this is in his Life of Caesar 9ff
One reference used that is no longer online is Roman Persecutions.
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