That world begins where the lawful wife finishes; it finishes where the venal wife begins. It is divided from the world of honest women by the public scandal it provokes; it is divided from the world of courtesans by money.
Ce monde commence où l'épouse légale finit, et il finit où l'épouse vénale commence, il est séparé des honnêtes femmes par le scandale, des courtisanes par l'argent.
Original text (French)
Source, in full
Preface to Le Demi-Monde (1855), in Théatre complet de Al. Dumas fils (Paris: Michel Lévy Frères, 1868-98) vol. 2, p. 10; translation from Albert D. Vandam Undercurrents of the Second Empire (London: William Heinemann, 1897) p. 247.