from Roman Gloucester

Behind the Horse Goddess is a goddess of the land and of blessing and libation. The sacred drink is offered from the Cup of Rosmerta and the liquor is the Cup Bearer’s confirmation of guardianship, of hospitality and belonging. To drink of the cup is to make a pact and binds the tribe to a common purpose, affirming being in the mythic domain as well as in the world of praxis.

Mererid, as the Guardian of the Well, is also the Cup Bearer – ‘Machteith’ as the poem in the Black Book of Carmarthen has it – and so the waters of the otherworld well are also the liquor in the cup of libation.