It is, or was at least, called "The Long March through the Institutions" and was a consciously and purposefully developed concept. It developed during the early 1950s in Europe, especially Germany and Italy, when marxist intellectuals realised the working class wanted nothing to do with communism, neither theortical or in practice (hardly surprising). The workers wanted fair pay, the weekends off, enough for a pension, and when they didn't work they wanted to be left alone - not Hectored on the class struggle or stuff like that. So the plan became, roughly, to further the careers of generally like-minded academics, with an eye to teachers and budding politicians and union members especially, so as to slowly - generationally - move the "Normal" more and more to the left. This included european academics in the humanities moving to the US and making contact with US radicals in the Civil Rights-movements and media/entertaintment industry. While that may cause despair initially, consider this, seeing as you are a Lit major: a story isn't over until the telling stops, and all the tools of the academic left are just that - tools. Anyone can learn to use them.