"In the sense used by Marx and Engels, the concept of ideology was intended to mean forms of which prevent people from realising that their thinking about the world is determined by some conditions which do not depend on them and which are not themselves ingredients of consciousness. In ideological thinking, people imagine that the logic of thinking itself rules their consciousness and they are organically incapable of being aware of the social situations and of the interests which mould their mental work."
January 1, 1970
https://en.wikiquote.org/wiki/Ideology