The iron curtain is a metaphor used for the non-physical boundary between the two parts of Europe that had two different sets of ideology. Churchill uses this term in order to describe the situation in which the iron curtain represents a separation line, and that nothing goes through it, nor the western ideas toward the east, nor the eastern toward the west. It is also used to describe a situation where the continent has been divided artificially by ideologues, who set an iron curtain for their people to not be exposed to what the other sides propagates.