How did a man about whom we know so little about definitively become the subject of one of the biggest single day celebrations in the world?  The very fact that we have so little information about Saint Patrick's true life is probably the biggest reason that his life has become legendary.  Just like the old fisherman's tale of the one that got away, with each telling, the fish gets bigger and bigger, and thus so does Patrick's feats.
    Much of the belief that Patrick single-handedly converted the entire country of Ireland comes from the first "biographers" of the saint.  Two of the earliest, the previously mentioned Muirchu and another by the name of Tirechan, both wrote books about Patrick's travels and trials.  Their works were written primarily to validate claims that the church in Armagh was pre-eminant over all others in Ireland, and to do so, focused on building up Patrick into an epic hero.  These works come 150 years after Patrick's work in Ireland, and much of the information Muirchu and Tirechan used were based on tradition and oral histories (the fisherman's tale).  Muirchu lists many miracles performed by Patrick, and gives the day of his death as March 17, when he was about 120 years old.  And thus, we have the beginnings of turning a simple, humble Christian missonary into a long-lived epic hero with the powers of a wizard straight out of a Dungeons and Dragons adventure.  This is who we celebrate every 17th day in March.  We know some of the details of the man now, but what of the Saint?
    We have already said that one of Patrick's first miracles came shortly after his escape from captivity, and that it is legend that holds him as the lone Christian savior of the Irish people.  One of his other feats comes with the defeat of the High King Loegaire and his druids at Tara.  Patrick and his companions decided to celebrate Easter at Tara because this was the site of the Pagan feast.  Pagan custom stated that no fire should be lit that night, until a fire appeared at the palace of Tara.  In a field at the foot of the hill on which Loegaire reigned, Patrick lit the paschal fire.  The heathen saw the flames and Leogaire set out to kill Patrick and extinguish his fire.  Thus ensues a battle between the druids and Patrick, each testing the other's power.  Patrick cursed one druid in the name of God, and he was risen up, then dropped back down, hitting his head on a rock, killing him.  As the king was about to attack for this outrage, Patrick called on God, and an earthquake wreaked havoc on the pagans.  The king fled, and Patrick followed, changing himself and his companions into deer.  The next day, on Easter, Patrick and his companions entered the closed doors of the king's compound during the pagan feast.  He was invited to eat and drink with them, and one of the druids attempted to poison Patrick's wine, but the saint prayed over the goblet and the liquid froze, allowing Patrick to tip the goblet and let the poison drip out.  Next, the druid called on a snowfall to cover the plain below, but once he did, could not remove it.  Patrick blessed the plain, and the snow vanished.  Then came the final test, where one of Patrick's followers, a boy named Benigus, would be placed in one half of a hut, made of dry wood, wearing the robes of the druid, while the druid was placed in the other half, made of green wood, wearing Patrick's chasuble.  Fire was set to the hut, and shortly thereafter, Benigus came out unharmed, but the druid's robes were burned up.  Nothing remained of the druid except for the chasuble.  Loegaire was angered, but upon being threatened with instant death, chose to believe in Patrick's God.
    Another of Patrick's miracles is the transformation of the King Coroticus into a fox.  Being in such an outrage over the kidnapping of several of Patrick's converts in Ireland, the saint prayed to the Lord to remove Coroticus from "this world and the next," and shortly thereafter, in full view of many of his followers, Coroticus transformed into a fox, which ran off into a nearby wood, never to be seen again.
    Of course, when asked, most people refer to Patrick's driving the snakes and serpents out of Ireland as one of his feats (and the only one they know of).  It is a work named Tripartite Life, which came another 200 years after Muirchu and Tirechan, and was written in Irish that gave us this legend.  Patrick made a pilgrimage to a mountain in County Mayo called Cruachan Aigil, where he stayed for 40 days and 40 nights, and was tormented by demons who had taken on the form of blackbirds.  Patrick sang psalms at the demons and rung his bell, in hopes of defeating them.  At one point, Patrick threw the bell so hard at the demons that it broke, and they departed.  Oral tradition has the snakes of Ireland being banished at the same time, and that is why there is not one snake to be found naturally on the whole of the island.  It was also during his stay that Patrick demanded of the Lord (a demand which was granted) that come Judgment Day, he be the one to judge all Irishmen.  Today that mountain is known as Croaghpatrick, or the Reek to the locals, and annual pilgrimages to the top are still made today.
So here we have it, a simple man dedicated to his faith and his people, who has (thanks to some good PR, early church politics, and dark depths of Time) has been transformed into a medieval version of the superhero, whose methods of teaching and learning have forever brought into popular use such simple things as a green clover.
   But from whence come the traditions of "wearing the green" and "drowing the shamrock"?  Again, oral tradition has Patrick using the three-leaved plant as a means of teaching the Holy Trinity, but actual use of the shamrock as a Saint Patrick's day tradition does not begin until the 17th Century.  It also became common for those in military service to be given an extra ration of grog on Saint Patrick's day, and it has been tradition to overindulge in the "spirits" of the holiday, often dropping a clover into one's glass, and thereby "drowning the shamrock."  The superstition of luck and the Irish date back much further, probably to pagan times and beliefs, where possessing a shamrock was thought to ward off the spells of witches, and protected travellers from faeries and banshees.
    These symbols and beliefs which had become so ingrained into Irish heritage were natural choices of the people to adopt as their identity of a nation, during their fight for independence from England.  It is only the color of green that has been officially adopted.  As we said in Sochet Patricius, to this day, the shamrock is only an unofficial symbol of the people of Ireland, and the only official recognition is its use as the symbol for Ireland's major airline -- Aer Lingus.