Hans Baldung ‘Grien’, Witches’ Sabbath woodcut (1510).
This German woodcut produced in the time of the witch hunts depicts witches tending their brew. Smoke and fumes flow from the pot as one witch lifts the cover. A fifth witch rides a goat backward in the sky.
See https://www.britishmuseum.org/blog/prints-darkness.
The Witches’ Sabbath
From Wikipedia, the free encyclopedia:
“There is no agreement among authors concerning the dates on which the Sabbats were to be celebrated. Some hypothosized they would take place during the night of the Sunday before the time the Christian mass was celebrated, some authors disagreed telling that Satan was less powerful on holy days.
Some commonly mentioned dates were February 1 (to some February 2), May 1 (Great Sabbat, Walpurgis Night), August 1 (Lammas), November 1 (Halloween, commencing on October 30’s eve), Easter, and Christmas. Other less frequently mentioned dates were Good Friday, January 1 (day of Jesus’ Crucifixion), June 23 (St. John‘s Day), December 21 (St. Thomas), and Corpus Christi. and others.”
From <http://en.wikipedia.org/wiki/Witches%27_Sabbath>.