The Legend
Legends abound regarding Patrick. Two of the most enduring: He purportedly drove the snakes off the island (likely a metaphor for driving out Druidism, which was symbolized by snakes). And stories tell of how he used the green three-leafed clover, a shamrock, to teach the Trinity. Traces of these legends remain in Irish (and Irish-American) culture.
Legend has it that Patrick created the design of the Celtic cross on a day when he was preaching close to a pagan standing stone. Potential converts considered such stones sacred because they already carried carvings of a circle, a symbol of the sun or moon gods. As the legend says, Patrick drew a cross through the circle and then blessed the stone. In thus creating the first Irish Celtic Cross, he displayed his willingness to adapt heathen practices and symbols to Christian beliefs as a way of easing the transition from pagan to Christian.