I've been researching for a novel I'm writing, and I came across this entry in a history timeline:

1114 AD -   Two peasants at Soissons are accused of holding meetings outside of the Church. A deep vat of water is blessed. One of the peasants, Clement, is tied up and tossed into the tank, and he floats, leading to the conclusion that the "holy water" has rejected him and that he is therefore guilty. After this, the other peasant confesses. Two others are imprisoned with the two. Local people excited and passionate about heresy break into the jail and burn the four to death. 

Does that sound familiar to anyone?

Wot floats?

A Duck!