Mabon is the Wiccan and Pagan Sabbat of the autumn equinox (around 21-23 September), the second of the three harvest festivals, when day and night again stand equal before the dark half of the year takes hold. It is kept as a kind of pagan thanksgiving, giving thanks for the fruits of the "second harvest", the ripened orchard fruit, the vine and the later crops; its themes are balance (of light and dark, held in equilibrium at the equinox), gratitude, and the letting-go that autumn brings. Practitioners share a feast of the season's abundance, with grapes and wine, apples, gourds and grain as symbols, and reflect on what they release as the year turns toward rest.
Of all the Sabbats, Mabon has the most transparently modern name. There is no ancient autumn-equinox festival of this name; the name was supplied in 1974 by Aidan Kelly, who took it from Mabon ap Modron ("Son of the Mother"), a figure of Welsh mythology, in order to give the equinox a Celtic-sounding name to match Yule and Beltane, and it spread through the pagan movement. The autumn equinox as a harvest-home celebration draws on genuine and widespread European traditions of thanksgiving for the ingathering, but the name Mabon, and its attachment to the Welsh myth, is a deliberate twentieth-century coinage, an honest instance of a living tradition consciously making its own calendar.