Armand, Duc de Guiche: &quot;Armand, through his mother, the Duchesse de Gramont, née Rothschild, was like Proust, half Jewish, even though he bore one of the most exalted titles in France.   He married the daughter of the Comte and Comtesse Greffulhe...one of the models for The Duchesse de Guermantes.&quot; (http://theesotericcuriosa.blogspot.com/search?q=Armand,+Duc+de+Guiche)