St. Patrick was kidnapped as a young man and was sold into slavery in Ireland, spending six years in captivity before escaping and returning home. In a dream he was commanded to return to Ireland to spread Christianity, which he did apparently right away. Although he did not actually drive all the snakes out of Ireland in a literal sense, he did drive out slavery, centuries before it was outlawed in continental Europe. Thus it's ironic that many Irish have forsaken their Christianity, only to still celebrate the life of a Catholic saint. Without St. Patrick Ireland would have been just another backwater island, mired in the Dark Ages, rather than a beacon of enlightenment and civilization.
So for all those folks who will be drowning their metaphysical sorrows tonight in green beer and poorly poured Guiness, here is a section of St. Patrick's Breastplate:
Christ to shield me today
Against poison, against burning,
Against drowning, against wounding,
So that there may come to me abundance of reward.
Christ with me, Christ before me, Christ behind me,
Christ in me, Christ beneath me, Christ above me,
Christ on my right, Christ on my left,
Christ when I lie down, Christ when I sit down, Christ when I arise,
Christ in the heart of every man who thinks of me,
Christ in the mouth of everyone who speaks of me,
Christ in every eye that sees me,
Christ in every ear that hears me.