This work examines the genetic processes that shaped two of the great literary masterpieces of modernity: Flaubert's "L'Education Sentimentale" and Proust's "A la Recherche de Temps Perdu". A detailed investigation of Flaubert's notebooks and scenarios from 1864 and 1869 and Proust's "Cahiers" from 1908 to 1911 reveals the almost diametrically opposed ways in which the two novels evolved in their early stages.