St. Patrick - Did He Banish Snakes from Ireland?

Legend has it that St. Patrick rid Ireland of snakes.  He's often pictured with snakes, for that reason.  But here's something to think about.  Snakes exist everywhere in the world except for the island countries of Ireland, Iceland, Greenland, New Zealand and Antarctica.  Assessing the no-snake evidence, scientists have concluded that cold-blooded snakes cannot survive in such places.

So ... where did the snake-banishing legend originate?  Most scholars think it has to do with paganism, which St. Patrick did help to destroy in Ireland.  For more on that analysis, see this article from the Smithsonian.