Though rivers flow green each year in his honor, most people know little about the patron saint of Ireland who sought freedom for Irish Catholics under British rule. An eloquent author who left two books-the Confessio and the Epistola-he railed against the British mistreatment of Irish Christians.
The fourth-century priest is credited with having brought Christianity to Ireland, though other credits, such as driving out the snakes, seem less genuine. It's true the St. Patrick ministered to many of the princes and warlords in Ireland to bring them into the fold of Christianity, baptizing them at "holy wells" all over the country. But the aspect of his reptilian charm is likely more symbolic of his fight against the nature-based religions present in Ireland at the time.
In his own words, he was a "most humble-minded man, pouring forth a continuous paean of thanks to his Maker for having chosen him as the instrument whereby multitudes who had worshipped idols and unclean things had become the people of God."
The snake has often been used in religious practices the world over and certainly was likely present at the time that St. Patrick visited Ireland. In fact, St. Patrick was the first Christian to stumble on to the Druidic rites at Tara, so it's likely that his snake association was born there. Snakes, however, have probably never existed on the island as it was cut off from the mainland at the time of the ice age. The symbolic nature of "driving out the snakes" was probably more a crushing of the religious iconic nature of druid practice.
The celebration of St. Patrick's Day has moved from a simple celebration of his exploits as a Catholic priest and to more of an "all things Irish" party. Rarely including a Christian display of any kind, one is more likely to see images of cheerful leprechauns, green beer and drunken celebrations.
It is quite unclear whether he died at Glastonbury or at Saul, Downpatrick, Ireland, but Downpatrick is considered to be the burial and March 17, 460 A.D as the date of death. The Chapel of St. Patrick still exists as part of Glastonbury Abbey. His jawbone was believed to be preserved in a silver shrine and was often requested in times of need by the local citizens.
The largest observance of the holiday takes place in Ireland. A blessing of hope is given for missionaries all over the world on St. Patrick's Day in accordance with a traditional mass.