Saint Patrick, Patron Saint of Ireland

Patrick was a British lad who was kidnapped by Irish raiders; he lived as a slave until his escape. He went into ministry, and later had "visions" of God telling him to save the people of Ireland from their current state of "heathenism" (read Pagan here).

Although this was occurring around the world, it was St. Patrick's ability to do it without bloodshed that was truly amazing. It is said that St. Patrick was able to accomplish this by using the shamrock, a sacred symbol in Celtic society, as a way to teach The Holy Trinity.

The shamrock was recognized by Celts as a mystical plant. The three leaves represented the Supreme Goddess, who has the ability to take three forms; The maiden, the mother, and the crone. St. Patrick conveyed the message of the Father, Son, and Holy Spirit.

Contrary to popular belief, the shamrock is not the symbol for Ireland, but rather a harp is.

In 1790 (something) a rebellion was led in Ireland between Catholics and Protestants. Catholics in green and Protestants in orange. It is said that all battles between the to factions resulted in a "sea of orange and green. This is why the flag of Ireland is tricolor, the white is to represent peace between the two.

Wearing of green and the whole pinching thing is American culture.