Mad Men's image of the '60s is compelling not only because of its beauty, but because of its completeness: the lamps go with the dresses, which go with the way the people talk. It's immersive; it's an illusion that's so complete that when Megan Draper (Jessica Pare) sings "Zou Bisou Bisou," it is somehow both different from everything the show has ever done and instantly part of its DNA. It transports us effectively. It doesn't really matter where we're going; it matters that we get to go.

That's why it can just as easily be, as Wickman points out, the dirty, violent world of Boardwalk Empire decades earlier, or the grandeur of Downton Abbey. In fact, it can just as easily be the future, or an entire world that has never existed at all. For an individual, nostalgia is a function of memory. But for a culture, nostalgia is a kind of travel. It is about somewhere else, somewhere different but vaguely recognizable, another place to look at the sunset. If we were really looking for a time when things felt easier, after all, we wouldn't love times of war and social upheaval; we'd be making shows about the dot-com boom. But we don't, because it isn't different enough yet. It has to be elsewhere; it cannot be here, because we cannot be here, not always, not every day.