It’s that mad time of the year again when the beer turns green, the music goes diddly-diddly, and you’re liable to find a drunk Irishman sleeping it off in the doorway of your local pub (true story). Yes, St Patrick’s Day is today, and if you want to know why, Patrick might enlighten. It’s a look at the priest who brought Christianity to Ireland, and who is said to have used the shamrock to explain the doctrine of the Trinity. The documentary explains how Patrick forged an unprecedented synthesis between Christianity and Celtic tradition, and that his influence extended to the western world as a whole through his Irish monasteries’ role in preserving literary traditions. Liam Neeson narrates and Gabriel Byrne is the voice of Patrick, while author Frank McCourt provides commentary on how a foreign evangelical would have interacted with the Irish. Philip Freeman, author of St Patrick of Ireland: A Biography, also features.