I feel like in The Devil Wears Prada there are two moments that really capture the essence of fashion.
On the influence of fashion on all clothing people are often so unaware of:
Miranda: This ... "stuff"? Oh. Ok, I see you think this has nothing to do with you. You go to your closet and you select, I don't know, that lumpy blue sweater for instance because you're trying to tell the world that you take yourself to seriously to care about what you put on your back, but what you don't know is that sweater is not just blue, it's not turquoise, it's not lapus, it's actually cerulean. And your also blithely unaware of the fact that in 2002 Oscar de la Renta did a collection of cerulean gowns and than I think it was Yves Saint Laurent wasn't it who showed cerulean military jackets, and then cerulean quickly showed up in the collections of eight different designers. And then it filtered down through the department stores and than trickled on down into some tragic casual corner where you no doubt fished it out of some clearence bin. However, that blue represents millions of dollars and countless jobs, and it sort of comical how you think that you've made a choice that exempts you from to fashion industry when in fact you're wearing a sweater that was chosen for you by the people in this room ... from a pile of stuff.
On fashion is greater than art:
Nigel: Don't you know you're working at the place that published some of the greatest artists of the century? Halston, Lagerfeld, de la Renta? What they did, what they created, was greater than art, because you live your life in it. (Well not you of course, some people.) You think this is just a magazine, hm? This is not just a magazine, this is a shining beaken of hope! For, oh I don't know, let's say a young boy growing up in Rhode Island with six brothers pretending to go to soccer practice when he was really going to sowing class, and reading Runway under the covers at night with a flashlight. You have no idea how many legends have walked this halls and what's worse: you don't care.