Pious legend credits Patrick with banishing snakes from the island, though post-glacial Ireland never actually had snakes;[37] one suggestion is that snakes referred to the serpent symbolism of the Druids of that time and place, as shown for instance on coins minted in Gaul (see Carnutes), or that it could have referred to beliefs such as Pelagianism, symbolized as “serpents”. Legend also credits Patrick with teaching the Irish about the concept of the Trinity by showing people the shamrock, a 3-leaved clover, using it to highlight the Christian belief of 'three divine persons in the one God' (as opposed to the Arian belief that was popular in Patrick's time). Whether or not these legends are true, the very fact that there are so many legends about Patrick shows how important his ministry was to Ireland. Some Irish legends involve the Oilliphéist, the Caoránach, and the Copóg Phádraig. During his evangelising journey back to Ireland from his parent's home at Birdoswald, he is understood to have carried with him an ash wood walking stick or staff. He thrust this stick into the ground wherever he was evangelising and at the place now known as Aspatria (ash of Patrick) the message of the good news took so long to get through to the people there that the stick had taken root by the time he was ready to move on. The 12th century work Acallam na Senórach tells of Patrick being met by two ancient warriors, Caílte mac Rónáin and Oisín, during his evangelical travels. The two were once members of Fionn mac Cumhaill's warrior band the Fianna, and somehow survived to Patrick's time. They traveled with the saint and told him their stories.