Joe Sobran wrote a nice column about the historical value of movies. Link. Opening paragraphs:
One of the ways I like to study American history is by watching old Hollywood movies, especially those made (usually in black and white) around and before 1946, the year I was born. I don't mean historical movies as such; Hollywood has always courted absurdity when it has consciously tried to show historical persons and events as they actually were, as in its sentimental portrayals of “great” presidents. I like them best when they show us history by accident.
Old movies show us old manners, the standards of behavior that used to hold American society together. The rules were mostly implicit, enforced less by law than by civil affections. We became conscious of those rules mostly when they'd lost their authority. Before that we took them so much for granted that we hardly knew they were there.
Oddly enough, it's when the movies aren't trying to tell us anything that they often tell us most. They give us accurate reflections of the way people really thought they should behave when they weren't even thinking about their manners. They show us what Americans of another time could safely assume – a country enviably at peace with itself, even in wartime.
