The name Saint Patrick conjures specific images in the minds of most. For some it’s the story of him driving the snakes out of Ireland (not impressive if taken literally as their haven’t been snakes in Ireland at least since the last Ice Age). For others its Shamrocks, beer and parties. Thanks to a handful of books like The Dresden Files a few might even associate him with cursing Irish kings to transform into wolves (ironically where the story of the shamrock is a 12th century invention that one is part of the legends of Saint Patrick). The story of Saint Patrick’s Purgatory is one that many people are unaware of despite its significance as a pilgrimage site in the middle ages.
The story goes that Saint Patrick was becoming frustrated in his efforts to convert the pagans of Ireland and he sought aid from God. Jesus Christ appeared to Patrick and showed him a cave on Lough Derg. While in the cave Saint Patrick experienced visions of Hell and he was able to bring other Christians who’s faith was wavering their so that their faith could be strengthened by a vision of the reality of the next world and the torments awaiting those consigned to Hell. Additional stories continue well into the Middle Ages of knights and others coming to the site to meditate and receiving similar visions.
One of the most detailed is the story of Sir Owain. Sir Owain was a particularly sinful knight who came to the site seeking redemption. After being warned multiple times of the dangers he was left in the cave for 24 hours and experienced a journey on which he sees souls being tormented by demons and is subject to punishments for his earthly sins. With each new punishment he calls out in the name of Jesus Christ and the punishment ceases and he is permitted to carry on till in time he returns to the land of the living where he repents of his sins.
While the cave itself, described in first hand accounts from the middle ages as just large enough to kneel in, was sealed in 1632 the monastery built on the site remains a major site of pilgrimage in Ireland. The site is open to individuals interested in visiting for a spiritual and religious experience (although its not welcoming to casual tourists) allowing for full three day pilgrimages, considered one of the hardest in the modern world, as well as shorter day long periods of contemplation.
Summary of the story of Sir Owain: http://d.lib.rochester.edu/teams/text/foster-three-purgatory-poems-sir-owain-introduction
Catholic Encyclopedia article: http://www.newadvent.org/cathen/12580a.htm
Web Site for Lough Derg: http://www.loughderg.org/