• I recall once saying that when I had given the same lecture several times I couldn't help feeling that they really ought to know it by now.

    John Edensor Littlewood: I recall once saying that when I had given the same lecture several times I couldn't help feeling that they really ought to know it by now.
    John Edensor Littlewood, Béla Bollobás (1986). “Littlewood's Miscellany”, p.135, Cambridge University Press