The difficulty of literature is not to write, but to write what you mean; not to affect your reader, but to affect him precisely as you wish.

Robert Louis Stevenson (1850–1894) Scottish essayist, novelist, poet

Essay (1879-05), “The Truth of Intercourse,” Cornhill Magazine, Vol. 39
    (Source)

Collected in Virginibus Puerisque and Other Papers, ch. 1, part 4 (1881)