Legend has it that St. Patrick, patron saint of Ireland, used the shamrock (or three-leaf clover) to explain the concept of the Holy Trinity (Father, Son and Holy Ghost) in the fourth century A.D. while converting the Irish to Christianity. But the story of St. Patrick and the shamrock, as we know it, is just that: There’s no mention of the shamrock in the saint’s writings, and the first written reference to the idea of St. Patrick using the plant to explain the Trinity is in the early 18th century, more than a thousand years after his supposed lessons.
One of the first symbols of luck that comes to mind is the shamrock — no, the four-leaf clover — wait, what's the difference? Unlike other good luck charms, the four-leaf clover got its rep for a pretty straightforward reason. Four-leaf clovers are really hard to find, and that rarity is why we consider them lucky. They're actually the product of a genetic mutation in the regular white clover plant, but that hasn't stopped humankind from assigning meaning to their unique shape.