Is everyone aware of the [i]true[/i] porpoise of this day? Saint Patrick's Day or the Feast of Saint Patrick is a cultural and religious holiday celebrated annually on 17 March, the death date of the most commonly-recognized patron saint of Ireland, Saint Patrick. Saint Patrick's Day was made an official Christian feast day in the early seventeenth century and is observed by the Catholic Church, the Anglican Communion the Eastern Orthodox Church and Lutheran Church. The day commemorates Saint Patrick and the arrival of Christianity in Ireland, as well as celebrates the heritage and culture of the Irish in general. Celebrations generally involve public parades and festivals, and the wearing of green attire or shamrocks. According to tradition, Patrick returned to Ireland to convert the pagan Irish to Christianity. The Declaration says that he spent many years evangelizing in the northern half of Ireland and converted "thousands". Tradition holds that he died on 17 March and was buried at Downpatrick. Over the following centuries, many legends grew up around Patrick and he became Ireland's foremost saint. St Patrick is said to have used the shamrock, a three-leaved plant, to explain the Holy Trinity to the pagan Irish. This story first appears in writing in 1726, though it may be older. In pagan Ireland, three was a significant number and the Irish had many triple deities. The triple spiral symbol appears at many ancient megalithic sites in Ireland.