On May 1, 1776, Adam Weishaupt founded the Order of Illuminati in the German state of Bavaria, where the majority Witch hunts in Europe took place. The Bavarians called May 1st Hexennacht (Witches' Night). Witches celebrate this day because of the Sun's relationship with the beginning of Summer. As the Earth rotates on its axis (rotation), producing days and nights, it also moves around the Sun (translation) in an elliptical orbit (elongated circle). This “journey” requires approximately 365 and 1/4 days to complete.

The Earth's axis of rotation is tilted in relation to its orbital plane, causing seasons to exist. When the Earth's axis points towards the Sun in a given hemisphere, we have Summer. When the Earth's axis points in the opposite direction, it is winter in that hemisphere. Since the inclination of the planet's axis is 23.5 degrees, the pole is never directly facing the Sun, but, on the Summer solstice, it comes as close to this as possible and, on the winter solstice, that's when it stays further away. Halfway between these two extremes, that is, in Spring and Autumn, the Earth's axis of rotation is 90 degrees in relation to the Sun. This means that, on this date (equinox), days and nights are approximately the same length: around 12 hours each.

Also called Saint Walpurga's Night in Germany. Walpurga is a Christian Saint, and the niece of Saint Boniface (the same Saint that cut down Donars Oak in modern day Germany). So why is a Christian Saint associated with Witches? Because Walpurga's folklore ties into a ton of Germanic pagan motifs. Walpurga was nun from a cloister called Heidenheimer Kloster (Heathen Home Cloister) believed to be built on top of a heathen temple, so named for a nearby holy spring, Heidenbrunnen (Heathen Well). Plus we see tons of holy springs connected to the Germanic Goddesses throughout Germany. (Nerthus, Holda/Holle, etc.). Walpurga's association with sheaves of grain was adapted from pagan agrarian goddesses.