24Andersen, Jørgen. The Witch on the Wall: Medieval Erotic Sculpture in the British Isles. Copenhagen: Rosenkilde and Bagger, 1977. 47+.
The author balances his purely architectural explanation with this statement: "Certainly there is more to the image than the mere display of pudenda; something darkly colouring that medieval carver's conception. There is some foundation here for involving mythology in the study of sheelas and in their whole application to churches." (p. 111)
A journal article in 1840 suggests that "some [sheela-na-gigs] had been originally used as grave-stones, and probably intended to act as charms to avert the evil eye, or its influence, from the place." (Clibborn, E., Esq. "On an Ancient Stone Image Presented to the Academy by Charles Halpin, M.D." Proceedings of the Royal Irish Academy 2 (1840-1844): 566.)
Anne Ross wrote, "I would like to suggest that, in their earliest iconographic form they do in fact portray the territorial or war-goddess in her hag-like aspect, with all the strongly sexual characteristics which accompany this guise in the tales; and that they are not 'pornographic' or 'erotic' monuments but have both a fertility and an evil-averting significance. [note: It is a well known and widespread belief that to expose the genitalia of either sex acts as a powerful apotropaic gesture]. This would serve to explain why they are frequently to be found in association with Christian churches. Such figures could hardly have been built into religious buildings of the post-pagan period unless it was to canalise the evil-averting powers they were believed to possess. If they were found on the site of the church their powers could then be used for the benefit of Christians, once they had been purified as it were by Christian rites; and any latent paganism in the area would find a double satisfaction both in the continuing homage offered to this once-powerful deity and in her inclusion in the wider Christian pantheon as a still-vital protectress of the ground over which she was once sovereign." (Ross, Anne. "The Divine Hag of the Pagan Celts." in The Witch Figure, Venetia Newall, ed. London and Boston: Routledge & Kegan Paul, 1978. 148-49.)