From Doubles: Studies in Literary History by Karl Miller, which is very interesting in the context of our own time:

During the 1880’s and 1890’s duality underwent a revival which carried the subject, together with its predicated psychic state, into the century that followed. During these years, which are sometimes mistaken for the inaugural years of the subject, a hunger for pseudonyms, masks, new identities, new conceptions of human nature, declared itself. Men became women. Women became men. Gender and country were put in doubt: the single life was found to harbor two sexes and two nations…James’s tale of 1894, “The Death of the Lion”, describes an age in which there seemed to be three sexes, and age tormented by genders and pronouns and pen-names, by the identity of authors, by the “he” and the “she” and the “who” of it all. Proteus stole down the back streets of the Late Victorian Babylon, and his portrait came to life. Anglo-America, and well beyond, rang to the cry of Robert Louis Stevenson’s Dr. Jekyll: “This, too, was myself.”