In which I pretend to be some sort of writer

Nostalgia. A familiar word. But defining precisely can be difficult.
This particular word is Greek in origin.

Nost-, comes from Nostos, the theme of the return home, often in literature after a hero's formative journey.
-Algia, refers to pain, whether physical, or psychological.

In medical parlance, arthr-algia is join pain. Neur-algia is nerve pain.
Nost-algia is the pain of a yearning for the return home.
Home to the familiar, to the place where we belong and from which we came, to our point of origin.

In modern use, it is a where, and it is a when, simultaneously.
A previous life, a longing for the times gone by, when things were different: the people in our lives, the challenges we faced, were different. It's a longing, and it's a feeling, something inside of us which reaches the surface when reminded about ourselves in a different place and time.

We have fond memories for the way things used to be.
Were they better? Usually not. Simpler? Perhaps. Maybe we are driven by the longing for a time that we better understand, now that we have the benefit of hindsight to better understand it.
Of course at time things felt no simpler to us than the present day feels today.
We were uncertain about many things. Today these are barely remembered. Our worries never panned out. Or they did, for better or worse, but always into something certain.

There is no uncertainty thinking about our pasts. Not when we remember through the lens of nostalgia.
This lens is tinted rose, and long in focal length. We remember small details, objects and environments. Specific afternoons, time spent with people who were a huge part of our lives then, specific object, environments, the colour of the light, the smell of the filing cabinet, of the cooking… The bigger picture, jobs, society, are less tangible. We survived. So we think wistfully upon this selectively imagined past, free of all the uncertainties which are a constant in life.

Some people choose to live their lives in the here and now, and not excessively worry about what could be. Nostalgia might be the longing to attain the ultimate form of this, applied retrospectively.

We long for the times gone by. For the relationships with people no longer in our life. Or for the situations in which we found ourselves. A mourning over the things we have had, relationships for example, which necessarily fall by the wayside as our lifestyles and priorities change. We wonder how these people, who once held such esteem in our heart, are doing now, and secretly, how they could have fallen so far from our focus.

And sometimes, we think things really were better back then. Some things probably were. Thing probably were simpler. Today, each of us has experienced a lifetime of learning, of exposure to new experiences, to the realities of society and of life. Things about life, about society, felt complicated back then too, to different people in different time in their life. Maybe things were simpler. Maybe you're just better equipped now to understand it.

Technology, healthcare, convenience, these were definitely much worse. Slow, big, expensive, annoying. Yet we remember out first mobile phone, our colour TV, with wistful yearning to go back and feel the static of the screen against our tongue. We connect with our past through remembrance of these objects.

Some things were a lot more difficult than today in many ways. More work to achieve the same goal. Fewer conveniences. More difficulty in getting what we needed to feel fulfilled. Even, sometimes, to survive. And yet, the nostalgia, even when we know times are better, can still persist. We've weathered the storm of living through those times, tumultuous, long, or even just uneventful, and now we have a good understanding of how it was. Or if not, we have at least taken away what we needed to move on.
And yet we long for this? Yes, I feel this in my chest and behind my eyes. Recognition. Perhaps our struggles, the challenges we faced, became a part of our identity, our raison d'être. Something to be appreciated, not to long for, but to understand how it shaped us into the people we have become.

Nostalgia is memory. It isn't isn't wanting to actually go back. It never should be. Sometime people mistake it for this.
It's the recognition of how things have changed, and the warm feeling of recounting familiarity (for better or worse).
It's the reflection on the times and places and experiences in our lives which give us a sense of belonging, and of identity. What gives you this feeling cannot be rationalised or faked or reasoned away. When you feel it, you know. It is a reflection of our authentic selves, of our path through this life.

It's the longing for something that has been, and which can never be again. Nor should it.