This story was originally published on The Conversation. It appears here under a Creative Commons license. St. Patrick’s Day usually conjures images of partying, Catholicism, Irish nationalism and, perhaps most famously, the color green: green clothes, green shamrocks, green beer, and green rivers. So my students are often surprised when I tell them that St. Patrick’s Day was once a solemn feast day when you’d be far more likely to see the color blue. In fact, there’s even a color known as St. Patrick’s blue. ‘True Blue’ Historians don’t know…
