Westphal, in Germany, was probably the first to place the study of sexual inversion upon a sound scientific basis. Since the earliest ages it has been a favorite theme of poets and romancers. Balzac, whose treatment of love-themes shows considerable psychological knowledge, touches upon it in his "La Fille aux Yeux d'Or;" and Gautier in his wonderful romance, "Mademoiselle de Maupin," makes his heroine a sexual invert, as he makes her in "Claramonde" a vampire. Ariosto pointed out the homosexual practice of women ; and in Diderot's novel, " La Religieuse," first published anonymously, and thought to have been written by a nun, a story of sexual lasciviousness and torture, fairly representative of the monastic life of the times, is founded on sexual inversion. Breckenridge Ellis touches upon it in the loves of Rosamunda and Anna. Zola treats of it in his " Nana" with the most frank realism; and Adolphe Belot, in "Mademoiselle Giraud, Ma Femme," tells of a man whose bride denied him sexual intercourse on account of her love liaison with a young lady friend. Swinburne hints at it in his first "Poems and Ballads;" Verlaine, in "Parallèlement;" Lamartine, in "Regina;" and Bourget, Daudet, Mendes, Whitman, and Maupassant, are modern writers in whose works homosexuality is, if at all, only thinly veiled.