...weil er sonst blind verfährt und, nachdem er mannigfaltig umher geirrt hat, doch wieder zu der Unwissenheit zurückkehren muß, von der er ausgegangen war.
Otherwise he proceeds blindly, and after manifold wanderings must come back to the same ignorance from which he started.
Immanuel Kant, Critique of Pure Reason, Norman Kemp Smith translation, p. 123 (A88/B121) [St. Martin's Press, New York, 1929, 1965]
But in stating prudential rules for our government in society, I must not omit the important one of never entering into dispute or argument with another. I never saw an instance of one of two disputants convincing the other by argument. I have seen many, on their getting warm, becoming rude, and shooting one another. Conviction is the effect of our own dispassionate reasoning, either in solitude, or weighing within ourselves, dispassionately, what we hear from others, standing uncommitted in argument ourselves.
Never wrestle with pigs.
You both get dirty and the pig likes it.
George Bernard Shaw, provenance unknown.