To this end, most groups use certain images as signs of membership. These shared symbols of identity help to create the psychological, social and psychic connections so necessary for effective group action. Provided that these images are used as positive signs of inclusion, rather than as negative signs of exclusion, they can only be of benefit to us. Twenty years back, a ceremonial tabbard was made with a tree in full leaf on the front and the Sigil on the back with its wreath and stavewood matching. I always thought it would be nice to have more vestments that followed this pattern, changing the leaf colors or tree species for each season.
Nobody knows for sure.
He claimed that it was a symbol of Druidism in general and the Earth Mother in particular. Some think he may have gotten the design from a hasty glance at a picture in Piggott's book The Druids, which showed the foundations of an old Roman-Celtic temple. Others think he may have gotten it from some Mesopagan Druid organization to which he may have belonged. Regardless of its historical origins, I think that it is a quintessentially female symbol and is thus psychologically powerful. As a magical sign, I've used the Druid Sigil for over thirty years as both a blessing symbol and as a banishing sign.