This is a key phrase.
So thoroughly and consciously did the Communists "take over" the media, the schools, some unions, etc. that people coming up after the 50s often have absolutely no idea that they have been raised on a steady diet of Communist precepts. Their "ideas" are Communist ideas. These people in the "nomenklatura*" of our institutions are for the most part, Lenin's "useful idiots." However, some are true believers. Perhaps Obama, is possibly in the "Useful Idiot" category ... Classic example Debbie Wasserman Schultz. True believers? Valerie Jarrett, Axelrod, Hillary?
For example, prior to Roosevelt, many college instructors and professors were very conservative! What the Communists did, and brilliantly, was go "mainstream." To do this, they united themselves, the Socialists, and the Progressives in the Democrat Party.
*"nomenklatura" is the Soviet term for those top spots in an organization chart that form the actual structure of the entity. Who reports to whom? Who hires whom? Take those positions, and the whole organization works for the Communists, even though the actual workers may not realize it.
It is how they work it...
Every time I consider the recent history of the US, that simple realization scares.