To hold the same views at forty as we held at twenty is to have been stupefied for a score of years, and take rank, not as a prophet, but as an unteachable brat, well birched and none the wiser. It is as if a ship captain should sail to India from the Port of London; and having brought a chart of the Thames on deck at his first setting out, should obstinately use no other for the whole voyage.

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).