The Religion of the Ancient Celts
Pliny speaks of the nudity of the women engaged in the cult.
Nudity is an essential part of all primitive agricultural rites,
and painting the body is also a widespread ritual act. Dressing
with leaves or green stuff, as among the Namnite women, and often
with the intention of personating the spirit of vegetation, is also
customary. By unveiling the body, and especially the sexual organs,
women more effectually represented the goddess of fertility, and
more effectually as her representatives, or through their own
powers, magically conveyed fertility to the fields. Nakedness thus
became a powerful magico-religious symbol, and it is found as part
of the ritual for producing rain.