E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Hugues, the founder of the French monarchy, was surnamed Capetus (clothed with a capot or monks hood), because he always wore a clerieal costume as abbot of St. Martin de Tours. This was considered the family name of the kings of France; hence, Louis XVI. was arraigned before the National Convention under the name of Louis Capet.