Miskatonic University PressWilliam Butler Yeats, 1919: "The best lack all conviction, while the worst / Are full of passionate intensity" ("The Second Coming").
Bertrand Russell, 1933: "The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt." ("The Triumph of Stupidity" in Mortals and Others: Bertrand Russell's American Essays, 1931-1935, Routledge, 1998.)