Mabon Sabbat occurs at Autumn Equinox, when the Sun enters the sign of Libra, usually around September 20 - 23.
At Mabon, day and night are in equal balance for a moment in time. We are poised upon the threshold of the waning Sun. From now on the days will grow shorter and the nights longer. We are harvesting our crops; we are reaping what we have sown, both physically and psychically.
Mabon is a good time to reflect upon, and appreciate the previous year. Because of the theme of balance, ideas of Karma, justice and tying up loose ends are appropriate.
In the Wheel of the Year, the God journeys to the Underworld and the Goddess grows older, She misses the God and follows him to the Underworld. As she withdraws her power the land begins to turn cold and wither.