Filmic Measures is a glossery of critical terms and rules in which help us define the movies we watch.
I don't really follow so I'm not so sure if it's the case anymore but once upon a time one of the big arguments against the legalization of marijuana is that it is a gateway drug. Once you have become accustomed to the high that smoking pot comes with it opens the mind up to trying other, more stronger highs. Once you've driven 110 on the expressway, why not try 120 as well? And so forth.
In that sense, based on that argument, marijuana is an introduction to drug use: the first step on a path to other things (ed: I am not, of course, making any kind of comment on how much I agree or reject this argument).
There are certain movies that act in the same way: They are the first step into exploring greater, more sophisticated, deeper filmic experiences. Some of them are good in their own right, many of them have achieved a cult status, a couple are unjustly praised by those who are using them as their gateway because they don't know any better and so on. Quality hardly matters in such a case as long as they serve their specific purpose.
Now that I've laid out the foundations let me lead with some examples: The Usual Suspects is a gateway to the classic noir of Double Indemnity or Out of the Past; Pulp Fiction is the gateway to the highly stylised and homage friendly cultural hipness of early Godard like Breathless and Band of Outsiders; Fight Club is the gateway to experimental film-as-state-of-mind works like After Hours, Goodfellas is the gateway to more under appreciated Scorsese classics; Donnie Darko is the gateway to more obscure movies that actually know what they are about; Inception is the gateway to great science fiction like 2001: A Space Odyssey and even the films of David Lynch are a cross between the surrealism of Luis Bunuel mixed with the Hollywood cynicism of Billy Wilder. And so on down the line.
Is it ironic that they are all American movies? Maybe it is. Whenever, after all, we see a bland European movie it feels too "Americanized." But that's not the point I don't think. The vast majority of film goers learn the trade off of American movies. They strike a nice balance between trying to be (sometimes at least) hip and original while also trying to be popular and profitable (Scorcese, Tarantino, Forester, Soderberg and so on all fall into this category).
Some people, of course, will never get beyond this stage. Some are content not pushing the horizons, not being introduced to new forms of expression, culture, history or society. Fair enough. But if they ever choose, there's a whole new arena of things to experience after the baby steps.
Other Filmic Measures:
Chocolate Bar Movies
Where's the Airship Movies
The Documentary Rule