In the 15th century, the Catholic church banned followers from consuming butter during Lent because they believed that dairy fueled lust, but there was an asterisk to their rule. The church allowed people to pay a fee so they could consume butter even while they were forbidden, which had surprisingly huge implications for history.

The Roman Catholic church was run by men who consumed mostly olive oil as their fat of choice, so restricting themselves from butter wasn't a huge deal. However, French Catholics preferred to pay over abstaining from butter, and the church raised so much money that it built the Rouen Cathedral from these butter taxes.

Surprisingly, this butter ban would end up contributing to Martin Luther’s mounting frustration with the church, and the writing of his famous 95 Theses. Breaking away from the church was an easy sell for northern countries who survived on meat and dairy, so the butter ban led to the Protestant Reformation and ensured its success.