Study the past, if you would divine the future. - Confucius

Consider nostalgia. That feeling that’s as sudden as it is strange in its ability to comfort. It’s a bullet train on memory lane, hurtling us towards another time from another place at 200 miles per hour. Nostalgia is the whiplash of happiness we get when we instantaneously arrive in a simple, happier, idealized part of our memory.

Naturally, people love nostalgia. Just take a look around at pop culture’s current topography. People are watching the Teenage Mutant Ninja Turtles and Transformers on the big screen. They’re purposefully paying for photo-editing apps that will add dust, light leaks, and all those little imperfections of film. They’re downloading AIM, T9, and Tomagatchi apps. They’re are even buying vinyl again.

The weird thing is -- if you think about -- most nostalgic items became passé for a reason. Nostalgic items aren’t very practical. The digital camera became easier, cheaper, and more convenient than film. Texting and social media supplanted AIM. Smartphones and built-in keyboards replaced T9. The MP3 replaced the CD, which replaced the cassette, which replaced vinyl.

Innovation slew all of these technologies, just as it’ll slay every gadget we think will never die. Yet, here they are: zombie technologies we are deliberately resurrecting.

Why is it that we defy cultural Darwinism?

Simple. According to science, it’s because nostalgia makes us feel good. Really good. In fact, you could even say that nostalgia is one of the purest forms of happiness.

Technically speaking, nostalgia is “a longing for a sanitized impression of the past, what in psychoanalysis is referred to as a screen memory -- not a true recreation of the past, but rather a combination of many different memories, all integrated together, and in the process all negative emotions filtered out,” according to “Nostalgia: A Neuropsychiatric Understanding.”

Basically, time erodes and polishes our memories. It buffs out the imperfections and unhappiness, leaving a pristine, false memory consisting only of happy moments and excited, little feelings. The anger, sadness, and fear are gone, and in their stead is joy, wonder, and excitement.

Nostalgia itself, however, is not about those memories or those specific moments. It’s about an emotional state composed, amalgamated, and collaged with scraps and hints and pieces of memory. We felt good at a time, in a place, with a thing, and so that era, area, and object becomes idealized. We put a piece of ourselves -- a piece of our emotional memory -- into these times, places, or things.

People don’t get nostalgic because they made their Instagram photos look like the type of pictures they used to take. They get nostalgic because of how they felt back when they used to use film. Adding the “Lo-Fi” filter when you Instagram that picture of your chicken caesar salad makes you remember those times you’d bring the old polaroid camera to the park with all your college friends.

So when brands repurpose old content, take advantage of nostalgia, and resell it, they’re not necessarily selling that product all over again. They’re selling a simpler, happier time to those who were around for the first generation. They’re selling the high of bygone days without the lows. The pros without the cons.

According to a study published this year in the Journal of Consumer Science, nostalgia makes consumers more willing to spend. Researchers say that designing products and promotions that elicit feelings of nostalgia in targeted consumers should encourage them to buy and spend more.

Of course, it’s easy for brands with long legacies to take advantage of nostalgic marketing tactics, but what about the newcomers?

According to an article on Inc. by Michael Schein, founder and principal of Michael Schein Communications, “Nostalgia is, at its core, a deep longing for and connection with something bigger than ourselves. People who are able to see themselves in the context of their past, their roots, and their culture have a positive bank of memories to draw from, which allows them to feel linked in to others and to avoid the existential despair that comes from viewing oneself as an isolated and doomed individual. … Businesses that stand the test of time are those that exist for a purpose that extends simply beyond making money. They create and foster meaning.”

Nostalgia as a marketing tool, according to Schein, is all about saying to consumers, “Hey, this is where we’re from; this what we’re about,” to which they’ll hopefully reply, “Hey, me too.”

Basically, new brands can appeal to consumers’ nostalgic feelings by talking about their roots, where they came from, what led them to do the work they do, and simply talk about their story and values.

Appealing to consumer’s nostalgia can be as simple as sharing old photos, celebrating milestones, and reposting old social media content from yesteryear, or it can be as complicated as packaging user’s activity over the past 12 months into a trendy little presentation.

Whether it’s a product packaged the same way it was in the 70s, or a hearkening back to simpler times, people are more willing to buy when they’re feeling nostalgic, because they’re freely associating that product with a pure sense of joy.

Even if a consumer had a tumultuous childhood, a gripping sense of nostalgia will make them feel as though it was a sweet and innocent time. As the French writer Marcel Proust once said, “Remembrance of things past is not necessarily the remembrance of things as they were.”