Nostalgia has an air of total irreconcilability. There is the feeling the word describes, of course: a fundamentally impossible yearning, a longing to go back even as we are driven ceaselessly forward, pushed further away from our desire even as we sit contemplating it. But it’s the actual feeling, too, that ceaselessly resists any attempt to give it shape or sense. If we say we feel nostalgic, in general or about something in particular, it rarely needs an explanation, and there likely isn’t a good one anyway: Why should it be the smell of our grandmother’s cookies or the feel of a particular sweater or the sight of a certain tree in a certain playground, and not something else, that sends us searching backwards? Why is it welling up now, on an otherwise unremarkable Tuesday? Why haven’t I felt this way for a long time? Why does it matter? And that assumes it even occurs to us to interrogate this sudden rush: one of nostalgia’s more persistent qualities is its ability to elide reason, to be felt deeply without prompting any further inquiry.

        It’s this strange aura of elusive profundity that makes nostalgia seem less like some sort of modern condition than a universal feeling that took us some time to put our finger on. If feelings in general are internal experiences that demand expression whether or not we have the means for it, our inability to actually do anything with nostalgia might be what kept it ineffable for so long. Most kinds of longing can be settled in one way or another, if not necessarily to the satisfaction of the yearner. Nostalgia can only be lived in or abandoned: it is yearning distilled to its essence, yearning not really for its own sake but because there is nothing else to be done. Maybe it resisted definition so long because naming it doesn’t help resolve anything anyway.

        Appropriately for the elusiveness of the concept, the word nostalgia did not originally mean what we now consider it to — also appropriately, it was coined with a longing for a time when there was no word for what it described. Specifically: in 1688, a Swiss medical student named Johannes Hofer gave the name nostalgia to a malady he had noticed in young Swiss people who had been sent abroad — chiefly mercenaries, one of Switzerland’s prime exports at the time, though also household servants and others who found themselves in “foreign regions.” As was the style at the time in the nascent field of “medicine more complicated than bleeding humours,” Hofer used a portmanteau from an indistinctly highfalutin form of Ancient Greek: nostos roughly means “home” — although it more often means “homecoming,” which incidentally was also the name for an entire subcategory of Greek literature, most notably the Odyssey — while algos means, more simply, “pain,” derived from Algea, the personifications of sorrow and grief, and a common classification at the time, attached to a variety of maladies that have since gotten either more precise or more vernacular names. (If you ever want to stoke excessive sympathy from, say, your boss, tell them you have cephalgia or myalgia — a headache or sore muscles, respectively).

        So nostalgia literally means “pain associated with home” — or in slightly more familiar terms, “homesickness.” This is not a coincidence, but more relevantly, it’s also not a case of fancy medical-speak being dumbed down for popular consumption. At least not generally: the English word homesickness is a more or less direct translation of nostalgia. But the original term is French, maladie du pays, and not only does it specifically refer to the tendency of the Swiss to powerfully miss their home country, it precedes Hofer by at least thirty years. Hofer’s coinage brought a specifically medical dimension, insomuch as medicine as we know it existed in his time: Hofer’s observations were quite detailed, but still entirely anecdotal, and subject to a lot of conjecture. What he lacked in scientific rigour he made up for with linguistics, attempting to legitimize medicine’s dominion over the concept with multiple coinages, including nostomania (obsession with home, which, as you’ll see in a second, is probably more accurate to the “disease” as he conceived it), philopatridomania (obsessive love of one’s homeland), and years later, in the second edition of his thesis, pothopatridalgia (pain from the longing for the home of one’s fathers, which certainly has the advantage of precision, if not rhythm).

        Though the difference between mere homesickness and medical nostalgia was mostly a case of ancient language, Hofer nevertheless describes a serious disease, one that could progress from simple physical ailments like ringing in the ears or indigestion to near-catatonia and even death. Its root cause, according to Hofer, was “the quite continuous vibration of animal spirits through those fibres of the middle brain in which impressed traces of ideas of the fatherland still cling.” As Helmut Illbruck explains in his book Nostalgia: Origins and Ends of an Unenlightened Disease, essentially what that means is that the nostalgic suffers from a powerful obsession with their home that eventually makes them entirely insensate to any other experience or stimulation. Illbruck points out that the action Hofer describes does loosely capture how the brain seems to store, process, and recall memories, which may explain some of why his concept caught on, at least in the medical circles in which it persisted for the next few hundred years.

        As it happens, though, a primordial understanding of the structure of the mind isn’t the only key insight that would stick to nostalgia even as its conception developed. There are two other big ones. First, Hofer recognized that nostalgia was less about whatever the nostalgic claimed to be missing than about “the strength of the imagination alone”: it seemed to have less to do with any material differences in the patient’s circumstances than with the collective weight of their memories, even though those were centred on a very real and specific place. Hofer’s final, curiously potent observation is his suggested cure, which he meant quite sincerely, but which elegantly captures the futility of trying to tame nostalgia, disease or otherwise: “Nostalgia admits no remedy other than a return to the Homeland.” In all his observations and diagnoses, Hofer does not seem to fully appreciate that home is often more time than place. The proof of this will reveal itself as nostalgia evolves into something so incurable that it stops being a disease entirely, and its longing begins to be associated specifically with times past — but we are getting slightly ahead of ourselves.

        Doctors proceeded to speculate about the causes and potential cures of nostalgia until roughly the twentieth century, often ignoring Hofer’s observation about the imagination’s effects, causing some curious mutations in the idea. Nostalgia did remain almost the exclusive province of the Swiss for the first few hundred years after its naming — one of the original German words for homesickness, in fact, was Schweizerkrankheit, or “the Swiss illness.” Hofer’s near-contemporary Johann Jakob Scheuchzer — a Swiss naturalist who was chiefly interested in rescuing his countrymen’s reputation from accusations of weakness — suggested that it was the change in air pressure (and maybe even quality) that made them so prone to debilitating longing. He suggested that a brief stay at the top of a tower or on a hill might restore some of their strength. There isn’t much proof Scheuchzer’s conception of the disease or cure ever really worked, but there is some indication that this sort of thinking is where Switzerland got its reputation as a healthful place to recover in a sanatorium or spa. Well after Scheuchzer, eighteenth-century physicians spent some time looking for a physical locus for nostalgia — a specific brain structure or bone — which was just as futile, with even less of an impact on Swiss tourism.

        Gradually, the notion of nostalgia attached itself almost exclusively to soldiers — Swiss mercenaries being very popular hires in armies across the continent, and doctors being a regular part of army life. It would take a little more than two centuries for doctors to figure out that there might be something more than a mysterious nerve disorder causing young men whose sole job was dismembering other humans and dying gruesomely to yearn for the comforts of home; in the meantime, cures and coping methods grew a little more creative. There are stories, including one from Jean-Jacques Rousseau’s Dictionnaire de musique, of foreign officers banning the playing of Swiss Ranz-des-Vaches — cow-based folk songs, historically played by herdsmen on horns as they drove their cattle down from the mountain pastures — and even the sound of cowbells, lest it paralyze their troops in nostalgic reverie. (It became a tenet of folk wisdom about the Swiss that the Ranz-des-Vaches had this power over them; it featured as metaphor or plot point in eighteenth- and nineteenth-century philosophical dialogues, dramas, poems and operas, particularly by German Romantics, who were constitutionally interested in a disease that spoke so acutely to our conceptions of self.)

        By the 1800s, the terrors of nostalgia finally spread to other countries’ soldiers. Russian physicians recommended burying alive anyone who started showing symptoms, to stop the spread of the disease — which apparently did prove quite effective. On the other side of the Atlantic, the American Civil War saw several outbreaks among the young fighting men, even though they technically had never left their homeland, per se. Their physicians were a bit kinder, suggesting occasional removal from frontline fighting would bolster their spirits (not that the doctors didn’t also suspect that the nostalgia betrayed a deep flaw in their character). The American army did apparently continue furtive explorations of the concept all the way up to the Second World War, chiefly as a way to reduce desertion, and nostalgia did maintain some interest for psychologists and psychiatrists in the first half of the twentieth century, albeit in a downgraded form: it became less disease than symptom or even disposition, usually of people who had far bigger and more immediate problems (a 1987 survey of its common historical-psychological invocations cited “acute yearning for a union with the preoedipal mother, a saddening farewell to childhood, a defence against mourning, or a longing for a past forever lost”). Despite these last tendrils, the Civil War was really the last time anybody was diagnosed as a nostalgic, as such: nostalgia was largely abandoned by the medical community by the last decades of the nineteenth century. This seems to have had less to do with any particular breakthroughs regarding brain structure or mental health than with the general inability of anyone to make meaningful headway on understanding, let alone curing, nostalgia.

        As it moved out of the medical realm and into the cultural, though, nostalgia did not fully shed its strange stigma. It first took hold in the worlds of philosophy and theory, albeit used interchangeably with the idea of homesickness, where it tended to be classed as a symptom of disorder — if not of the individual, then of the society they had built. Friedrich Nietzsche, in The Birth of Tragedy, is indicative of this line of thought: “One is no longer home anywhere, so in the end one longs to be back where one can somehow be at home because it is the only place where one would wish to be at home.” From almost its earliest non-medical considerations, nostalgia was regarded as a kind of reaction to the modern condition, a port in the discombobulating and alien storm that was modern life. Philosophers, critics, and theorists are still exploring variations on this theme, though as an object of critical theory nostalgia has gradually lost any meaningful sense of place (or even, arguably, a time) and gotten more tightly entwined with the notion of authenticity and our search for the same (as such, its usefulness and meaning spiked slightly with the waxing and waning of postmodernist thought). This is what underlies something like Baudrillard’s observation in Simulacra and Simulation that “when the real is no longer what it used to be, nostalgia assumes its full meaning”: the underlying implication is that if we were awash in some sense of the authentic, we would not have much occasion to look backwards to find it — let alone yearn for a return.

        It took some time for the popular conception to catch up to the cultural theorists. Homesickness as an idea percolated through the first half of the twentieth century, but it wasn’t until the fifties and sixties that nostalgia, as both concept and preferred term for that concept, really started to insinuate itself into the popular consciousness. Like much about nostalgia, the precise reasons for its sudden surge in popularity are fuzzy and elusive: Fred Davis, in his 1979 study of contemporary nostalgia, noted that even in the fifties nostalgia had been considered a “fancy word,” limited to professionals and “cultivated lay speakers,” but by the sixties it was in common enough parlance to be the subject of consideration in popular books and magazines. One theory Davis alludes to is that, as the notion of “home” became less potent — as people moved around more frequently, gained easier access to wider-spread sources of information, and became less creatures of a specific place — homesick lost some of its power, and nostalgia slipped in as a way to capture the same feeling without being tied down: essentially, nostalgia became a better metaphor for the feeling it was trying to describe. The concept of home became a time, not a place, so we needed a new word for it.

        One of the bitterer truths that nostalgia helps us to deal with is the fact that we so rarely know when things are ending. Nearly all of the widely accepted momentous occasions of a life are those rare times when we are definitively, incontrovertibly aware that something is over: graduations and moving-away parties and retirements and funerals — admittedly it can be hard for a person to fully appreciate the importance of their own funeral — but even birthdays and anniversaries and weddings and births, too. Some of these events, of course, tend to be dominated more by the optimism of potential, but I don’t think it’s excessively cynical to suggest that we’re able to really indulge the future precisely because we’ve had a chance to process and accept the fact that things are changing, that our school days or our pure independence or even just our twenties are definitively over. (And, of course, it’s not at all rare for even the look-forward events to provoke nostalgia for the past that’s about to be left behind.)

        For all the big moments of finality and (ideally) transition, though, there are thousands of less obvious and often profoundly more meaningful endings that we realize only in retrospect, whether their finality creeps up on us across the ages or announces itself with thunderous realization. When was the last time your daughter fell asleep on your chest? The last time you had a drink with your best friend? The last time you ate the pasta at your favourite restaurant? The last time you petted your cat? The last time you felt like a kid? The last time a song made you cry? The last time you kissed your ex? The last time you hugged your old man? It’s not just that we don’t know while it’s happening but that we literally can’t until the experience is well and truly out of reach. We don’t know what we’ve got until it’s gone, and we don’t even know when it will go.

        The idea that things will go on forever is simple delusion on our part — all things pass, etc. — but as delusions go, it is surely among the most understandable, if not the most fundamentally necessary. The knowledge that life is fleeting is barely digestible in retrospect; in real time, it’s debilitating.