The Soul of the Earth
Traditional Celtic teaching informs us that the earth was not viewed by the Celts as simply dead matter but as a living, breathing thing. Furthermore, the material of which it was composed was inextricably bound to the spirits of those who dwelt on it. Material was therefore filled with spirit and that spirit revealed itself through material. Later commentators would refer to this belief as anima loci . The creation of sanctity was little more than an acknowledgement of the reflection of that spirit.

People directing prayers to sacred mountains, trees or rivers were often required to wash their faces, put on clean clothes and fast for a day, out of respect for the spirit who dwelt there. Similarly when passing great stones, it was customary to raise one's cap or make some other sign of obeisance towards it. So common was the practice that Thomas Pennent remarked that there was hardly any large stone in Scotland that the country people did not salute or leave some kind of offering for. These small acts of worship gradually inculcated a healthy and generalised respect for the environment into those who dwelt on the land.

Places of the Gods
It was well known that many spirits lived in high and often inaccessible places, placing them within the context of air or the sky and weather gods. It also made them remote and aloof from their worshippers on the ground and any devotional ritual at their 'home' had to be carried out after a long journey or pilgrimage (something that the early Christian church was later to copy). Throughout the Celtic world, inscriptions and dedications to aerial spirits and sky gods are to be found scattered throughout mountainous regions.

Croaghpatrick in Co Mayo - the most holy mountain in Ireland - was formerly Cruachan Aighle (or Aickle), the seat of an important spirit to which men frequently prayed and made pilgrimage. This later became a Christian site with a pilgrimage up its slopes in honour of the saint, following in the tradition of the pagans before them. According to Julian of Furness, it was from this mountain that Patrick expelled the serpents and crawling creatures from Ireland, surely symbolic of the rooting out of paganism and pagan shrines on the mountain.