A big lie (German: große Lüge) is a propaganda technique. The expression was coined by Adolf Hitler, when he dictated his 1925 book Mein Kampf, about the use of a lie so "colossal" that no one would believe that someone "could have the impudence to distort the truth so infamously." Hitler falsely claimed the technique was used by Jews to blame Germany's loss in World War I on German general Erich Ludendorff, who was a prominent nationalist and antisemitic political leader in the Weimar Republic.
The source of the Big Lie technique is this passage, taken from Chapter 10 of James Murphy's translation of Mein Kampf:
But it remained for the Jews, with their unqualified capacity for falsehood, and their fighting comrades, the Marxists, to impute responsibility for the downfall precisely to the man who alone had shown a superhuman will and energy in his effort to prevent the catastrophe which he had foreseen and to save the nation from that hour of complete overthrow and shame. By placing responsibility for the loss of the world war on the shoulders of Ludendorff they took away the weapon of moral right from the only adversary dangerous enough to be likely to succeed in bringing the betrayers of the Fatherland to Justice.
All this was inspired by the principle—which is quite true within itself—that in the big lie there is always a certain force of credibility; because the broad masses of a nation are always more easily corrupted in the deeper strata of their emotional nature than consciously or voluntarily; and thus in the primitive simplicity of their minds they more readily fall victims to the big lie than the small lie, since they themselves often tell small lies in little matters but would be ashamed to resort to large-scale falsehoods.
Thus, according to Hitler, the "Big Lie" was a propaganda technique typically used by "the Jews".
The principle is sometimes translated and abbreviated as the pithy saying: "Make the lie big, make it simple, keep saying it, and eventually they will believe it."
Later, Joseph Goebbels put forth a slightly different theory which has come to be more commonly associated with the expression "big lie". Goebbels wrote the following paragraph in an article dated 12 January 1941, 16 years after Hitler's first use of the phrase. The article, titled Aus Churchills Lügenfabrik (English: "From Churchill's Lie Factory") was published in Die Zeit ohne Beispiel.