Undying hope is co-ruler of the human bosom with infallible credulity. A man finds he has been wrong at every preceding stage of his career, only to deduce the astonishing conclusion that he is at last entirely right.

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

Essay (1878-03), “Crabbed Age and Youth,” Cornhill Magazine, Vol. 37
    (Source)

Collected in Virginibus Puerisque and Other Papers, ch. 2 (1881)