Say you're an average medieval Euro-Joe and you want to have sex with your wife. But first, you need to know, IS IT SINFUL? Digging through all those manuscripts of canon law can take forever (plus, as average medieval Euro-Joe, you can't read, anyway). Luckily, James A. Brundage has prepared a handy flow chart for sexual decision making the summarizes the medieval Christian church's take on when sex was OK (Think: In the dark, Mondays, Tuesdays and Thursdays only), and when you were totally going to go to hell.
Unfortunately, I'm not cool enough to figure out how to gank a picture from a Google Books page, so you'll have to follow this link to see the flow chart in all its glory.
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.