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.