The “big lie” is an expression coined by Adolf Hitler to describe his propaganda technique of telling a lie so colossal that no one would believe someone “could have the impudence to distort the truth so infamously.”
He first described this concept in Mein Kampf (German for “My Struggle”), the autobiographical manifesto outlining his plans for ruling Germany.
Hitler proposed that the big lie is credible because the broad masses are less likely to fall for a small lie. This is due to the fact that they themselves often tell small lies in little matters but would be ashamed to resort to large-scale falsehoods.
It would never come into their minds to fabricate colossal untruths, so they would not believe others had either. In other words, Hitler understood that the masses saw the world through rose-colored glasses tinted by their own basic honesty and their assumption of that same trait in others.