Anything that’s any good seems to be about pretty much everything. “Inside Llewyn Davis” isn’t a documentary about the folk-music scene; it’s about the existential tricks of time—the terrible, subtle blow that knocks a person from the vanguard to the sidelines, from the promise of youth to the nostalgia of age in a single moment. I found myself thinking about my colleague in the magazine about Duke Ellington—about how it must have felt for Ellington and the other luminaries of swing, around 1941, when they found out about the young modernists up at Minton’s, whose music, soon known as bebop, made the big-band sound an instant relic. “The Wolf of Wall Street” is even more capacious. Let’s start with that last shot, which I cited but remained coy about when.