Legend credits St. Patrick with teaching the Irish about the doctrine of the Holy Trinity by showing people the shamrock, a three-leafed plant, using it to illustrate the Christian teaching of three persons in one God. For this reason, shamrocks are a central symbol for St Patricks Day.
St. Patrick was a Romano-British Christian missionary and bishop in Ireland. Known as the "Apostle of Ireland". St. Patrick was born ca. 390 in roman-occupied Britain. When he was about 16, he was captured from his home and taken as a slave to Ireland, where he lived for six years before escaping and returning to his family. Patrick recounts that he had a vision a few years after returning home: I saw a man coming, as it were from Ireland. His name was Victoricus, and he carried many letters, and he gave me one of them. I read the heading: "The Voice of the Irish". As I began the letter, I imagined in that moment that I heard the voice of those very people who were near the wood of Foclut, which is beside the western seaand they cried out, as with one voice: "We appeal to you, holy servant boy, to come and walk among us."