Happy Walpurgisnacht!

[Dave Monroe]

Walpurgisnacht

293; German: St. Walpurgia Night. The night before May 1, originally
dedicated to St. Walpurgia, the 8th century English nun who founded
religious houses in Germany. It is associated in German folklore with
the witches' Sabbat on the Brocken, where the witches and sorcerers
perform their black rites and reaffirm their subservience to the demon
Master.

http://www.thomaspynchon.com/gravitys-rainbow/alpha/w.html