It is intolerable to us that an erroneous thought should exist anywhere in the world, however secret and powerless it may be.
––O’Brien to Winston in Room 101, 1984.
Whether those who take part know it or not, this process of brainwashing by repetition of manifest absurdities is a sinister and deadly weapon. In the end, it renders the majority, who are marked down to be the victims of violence or revolution or tyrranny, incapable of self-defence by depriving them of their wits and convincing them that what they thought was right is wrong.
From 1984's The Theory and Practice of Oligarchical Collectivism.