Joseph Glanvill (1885). “Scepsis Scientifica: Or, Confest Ignorance, the Way to Science ; in an Essay of the Vanity of Dogmatizing and Confident Opinion”
Note in the appendix of "Grundlagen der Arithmetik" (Vol. 2), after Frege had received a letter of Bertrand Russell in which Russell had explained his discovery of, what is now known as, Russell's paradox, 1903.