In an article in The Christian Century, history professor Steve Ware asks the question, "When Is Easter this year?" For those of you who didn't learn this in confirmation class, the date of Easter corresponds to the first Sunday after the first full moon after the vernal equinox. Seriously.

In his article, Ware explains how this came to be. Here's the short version of the story: In 325 A.D., Constantine, emperor of the Holy Roman Empire, convened the Council of Nicea. Among the business before the council was to establish a…