There is a legend that when St. Patrick came to Ireland to convert the pagans to Christianity he used the common shamrock to explain the Trinity.
The shamrock has three parts, but it is only one plant. Likewise, God is Father, Son, and Holy Spirit, but only one God. Nice story. Did it happen? Well, we don't know. That's the way it is with legends. But it could have, and here's why:
The Irish had a love for numbers and their order and balance. Three was one of the numbers that they thought had special significance, but there were others, like five. There are five provinces of Ireland, there are five fingers on each hand and five toes on each foot, and so on. But the number three was used in little wise sayings called triads. I love to read those. Here are a few:
Three best to have in plenty:
sunshine, wisdom, and generosity.
Three good things to have:
a clean shirt, a clean conscience, and a guinea in the pocket.
Three things that never rust:
a sword, a spade, and a thought.
Three truths:
sunrise, sunset, and death.
Three best friends and three worst enemies:
fire, wind, and rain.
So, it's not out of the question that St. Patrick (or perhaps someone else) used the shamrock to explain the One True God.
