Lyric discussion by mister care-too-much 

I think it's about being a different person around different people/in different situations, hence all her outfits. She feels like she has to blend in, e.g. being amused by the guys who are saying 'those same things', and hides her true personality, which, I'm assuming, is the one in the library laughing at medieval jokes. I think part of it is about the devaluation of intelligence, 'if you've got a degree', and 'heaven help those who know what makes the world go slow'. Isn't it commonly said that unintelligent people are what makes the world go slow?

But I could be wrong about all this.

that makes sense. I agree that it's about different personalities around different groups of people. Everyone's experienced that; that's what's so great about all of her songs.