The term “nostalgia” was coined in 1688 by Johannes Hofer in a dissertation in which he described it as a disease he saw in Swiss mercenaries. He saw it as an acute form of homesickness, and ascribed to it several physical ailments, including fainting, fever, indigestion, and even death. The notion of nostalgia as an actual illness didn’t begin to decline until the middle of the 19th century, and over the next hundred years or so was replaced with the more romantic version we’re familiar with today.

Nostalgia today can be seen more as a memory of being happy. Recalling a time and place where a person enjoyed life a great deal more. Though such recollections are frequently seen through rose-colored glasses, the memories help to distract  one from any difficulties being faced currently and can lead to an improved mood or attitude. Harvard professor Svetlana Boym went on to point out that “nostalgia inevitably reappears as a defense mechanism in a time of accelerated rhythms of life and historical upheavals.” That is, we see more interest in nostalgia as a society on the whole during times of signifcant change.

This past weekend’s box office toppers included: Fantastic Four and Ant-Man, two movies about superheroes created in the 1960s; the seventh installment in National Lampoon’s Vacation series; a fifth Terminator movie; yet another reimagining of the Sherlock Holmes character; a fourth Jurassic Park picture; Minions, a movie spun off from the successful Despicable Me films; and the fifth installment of the Mission: Impossible movie franchise, itself a revival of the 1960s’ television show. It’s been an increasing “complaint” about Hollywood in recent years: that audiences are largely just being given remakes and sequels without much in the way of original content. This is that societial-level nostalgia at work.

In the late 1960s, futurist Alvin Toffler coined the term “future shock.” He noted that, by almost every objective measure, the pace of change was speeding up. Technology, certainly, but also social norms and mores. Some people who found themselves unable to keep up would experience a form of culture shock when they suddenly realized—once the changes are so substaintial that they can no longer be ignored or dismissed—that the culture they were used to doesn’t surround them any more.

One of the things people subconsciously do to combat the effects of future shock, as suggested by Boym, is to engage in nostalgia. To revisit times when things were more familiar and, therefore, comfortable. For those who don’t like to acknowledge that things do change, they find safety and security in what (they believe) doesn’t: their memories. So even if writers have to find ways to justify why a Terminator robot is aging, or even if we’re on the sixth actor to portray Rusty Griswold, there’s enough familiarity to spark the memories of years gone by, regardless of whether the new material is as good as the original.