How did the shamrock become the symbol of Ireland?

The shamrock is a symbol of Ireland, but it is not the national symbol. The official national symbol of Ireland is the harp, which can be seen on Irish coins and documents. Tradition says that St. Patrick, in attempting to explain the meaning of the Holy Trinity, picked up a shamrock leaf to illustrate his point of three parts to one whole object. The three leaves of the shamrock represent the Father (God), Son (Jesus Christ), and the Holy Spirit. It has become a popular symbol over the centuries and now often symbolizes pride in one's Irish heritage.