E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Marquis of Est, married Parisina, who fell in love with Hugo, a natural son of Azo. The marquis ordered Hugo to be beheaded; but no one knows what the fate of Parisina was. Azo, at any rate, married again, and had a family. This Azo was in reality Niccolo of Ferrara. (Byron: Parisina.)