St. Patrick is credited with taking Christianity to Ireland around A.D. 432. To sell his message, Irish legend says he chose the shamrock as a symbol of the Christian church. Its three leaves were meant to represent the Holy Trinity: God, Son and the Holy Spirit, joined together by a common stalk. Apparently, the shamrock campaign worked: by the time of St. Patrick's death on March 17, 461, he had created a number of churches, schools and monasteries dedicated to the faith.