Say you’re a Godly fellow of pure heart and intention in the seventh century, and you’ve met a lady, and the two of you would like to have some sex. There are so many rules, though. Where does one begin?
Penitentials were handbooks carried by some priests in the Middle Ages that delineated various sins for private confession and their penances. They were full of strict limitations as to what constituted pious behavior. They went on and on. To digest it all, James A Brundage, a scholar of the Crusades, aggregated the complex rules about sex into this excellent flowchart.