A personal microcosm

In the historically brief period from 1990 to 2025, I witnessed removable storage change from 3.5-inch disks, to CDs, DVDs, Memory Stick cards, MMC cards, CF cards, and SD cards. I have files in old versions of Word and FrameMaker that I have no hope of reading, and software that can't run on current operating systems.

I've also willingly deleted countless text messages, emails, software I've written, and documents that have no lasting value to me.

This is a tiny microcosm of experiences over a tiny blip of time. I've lived through the same pattern that has repeated throughout history: deliberate choices about what to keep, accidental losses from format changes, and the quiet erosion of things that seemed permanent.

The difference is scale. We're generating orders of magnitude more data than any previous civilization, stored on media that degrades faster than clay tablets, in formats that may be unreadable in decades. The filtering is happening all around us, constantly, and we barely notice.

This is not a new problem

The Sumerian advantage

We know more about daily life in Sumer (c. 3500–1900 BCE) than we do about daily life from many periods over the past 2,000 years.

The reason is almost embarrassingly simple: the Sumerians wrote on clay tablets, and clay is durable. Their mundane records survived because they persisted even when discarded: clay doesn't burn easily or rot. We have their school texts, bills of sale, court cases, casual letters, and administrative receipts. The everyday detritus of a civilization, preserved by accident of medium.

Once paper emerged, ephemeral material was easy to dispose of. People preserved what they thought was important: works worth copying. Medieval scribes wouldn't waste time, or paper, preserving records on how many bags of barley would buy a sheep, how many sheep would buy a wife, or popular drinking songs. But these things would be invaluable to historians today.

We may be repeating that pattern. The difference is that today, the filtering is not only a human choice. It is also the quiet pressure of format decay, device turnover, and corporate product decisions.

What got saved

The texts that survived from antiquity were those considered valuable at the time: religious scriptures, works by canonical authors, and official histories. The Bible, the Quran, and the Torah were copied and recopied across centuries because communities considered them sacred. Homer, Virgil, and Cicero were preserved because they were considered to be important and were taught in schools.

The loss of ancient literature was not primarily caused by dramatic library burnings. It was the consequence of the basic fragility of texts before the advent of printing.

Papyrus, the pre-paper writing material first developed in ancient Egypt, couldn't stand the test of time. In relatively humid western Europe, most papyri had to be recopied every century or so. When the Roman Empire collapsed, the elites who had traditionally commissioned new copies all but vanished.

We have only about one-third of Aristotle's works. His famous treatise on laughter and comedy, desperately sought in Umberto Eco's The Name of the Rose, has never been found. Sappho composed perhaps 10,000 lines of poetry; fewer than 70 complete lines exist. The Roman Sibylline Books, consulted by leaders during political crises for approximately 900 years, were destroyed, first burned in 83 BCE, and their replacements allegedly destroyed by a 5th-century Roman general who feared that invading Visigoths would use them.

We lost an estimated 99% of ancient Greek and Roman literature, not primarily through dramatic conflagrations, but through the quiet attrition of copying decisions.

What got destroyed

Some losses were deliberate.

Works that contradicted canonical thought were actively suppressed. Biblical apocrypha, texts that didn't make it into the official canon, were discouraged or destroyed. Pagan texts were neglected or purged as Christianity spread. Heretical writings were burned.

Political upheaval erased knowledge systematically. Emperor Qin Shi Huang's "Burning of Books and Burying of Scholars" in 213 BCE resulted in the destruction of numerous Chinese texts. The Yongle Encyclopedia, an 11,000-volume Ming dynasty compendium on subjects ranging from agriculture to theology, was decimated: half of the remaining 800 volumes burned in the Boxer Rebellion of 1900, and only 3% of the original text survives.

The Library of Alexandria is the most famous example (at least to those of us who took countless rides on Spaceship Earth in Disney's EPCOT), though historians debate exactly how and when it was destroyed. However, even that loss, dramatic as it was, was not the primary cause of ancient knowledge's disappearance. The real killer was quieter: the fragility of papyrus, the cost of copying, the seeming unimportance of the content, and the slow collapse of the institutions that had funded preservation.

Secrets kept too well

Some knowledge is lost not through neglect or destruction, but through excessive protection.

Greek fire: Compartmentalized into oblivion

Greek fire was the Byzantine Empire's decisive naval weapon from the 7th to 14th centuries. Contemporary accounts describe a liquid that could be projected from tubes, burned fiercely on water, clung to enemy ships, and could not be extinguished by ordinary means. It terrorized Arab fleets, repelled sieges, and helped Constantinople survive for centuries.

The composition was a state secret of the highest order. The Byzantines ascribed its discovery to divine intervention and bound themselves never to reveal the formula. Emperor Constantine Porphyrogennetos declared that three things must never reach foreign hands: the imperial regalia, any royal princess, and Greek fire.

Knowledge of the weapon was compartmentalized so thoroughly that no single person understood the complete system. Chemists who prepared the liquid didn't know how to deploy it. Engineers who built the projection devices didn't know the formula. Commanders couldn't make or use Greek fire without imperial authorization. Even when enemies captured equipment or samples, they couldn't replicate the weapon.

This paranoid secrecy was effective against foreign powers. It was fatal for the knowledge itself. When the Byzantine Empire declined due to civil wars, invasions, and shifting military priorities, the chain of transmission was broken. Sometime between the 8th and 13th centuries, the secret was lost.

Modern researchers have attempted recreations using petroleum, resins, quicklime, and other period-appropriate materials. Some mixtures produce impressive flames. None definitively replicates the historical accounts of Greek fire's ferocity, adhesion, and resistance to water. The secret that was too important to share became too fragmented to survive.

Roman concrete: Lost with the empire

Roman concrete structures have stood for 2,000 years. The Pantheon's unreinforced concrete dome remains the world's largest. Roman harbor structures have actually strengthened over time through interaction with seawater.

Modern concrete typically lasts 50–100 years before requiring significant repair.

The precise formulation of Roman concrete was not recorded in detail, or if it was, those records did not survive the collapse of the empire. For centuries, the recipe was simply lost. Scientists are only now beginning to understand the chemistry: volcanic ash, seawater, and a self-healing mechanism that involves mineral growth.

When Rome fell, the institutions that maintained engineering knowledge fell with it. There was no one left to copy the technical manuals, no one to train new engineers, no one to fund the preservation of specialized knowledge. Europe entered centuries in which Roman engineering techniques, roads, aqueducts, concrete,were mysteries rather than capabilities.

Cryptography and military secrets

Military encryption methods throughout history were deliberately kept secret and often deliberately destroyed. When practitioners died or regimes fell, techniques vanished.

This was sometimes intentional. Cryptographic knowledge in wartime is dangerous to share and dangerous to preserve. Codebooks were designed to be burned. Encryption machines were built to be destroyed rather than captured. The knowledge existed in a small number of heads, and when those heads were gone, so was the knowledge.

Industrial knowledge: The quiet extinctions

Trade secrets occupy an uncomfortable middle ground. They're too valuable to share widely, too specialized to attract broad interest, and too dependent on institutional continuity. When the institutions fail, the knowledge often goes with them.

Polaroid: The formula that vanished

Polaroid announced the end of instant film production in 2008. Edwin Land had introduced the first instant camera in 1947, and Polaroid refined the technology for over 50 years. By the end, the chemistry was extraordinarily sophisticated: a precisely timed sequence of dyes, developers, and chemical reactions that occurred automatically within a paper-thin packet of materials.

When a group of entrepreneurs purchased the last remaining Polaroid factory in the Netherlands, they discovered that they had acquired the machinery but not the knowledge. The formulas were gone. The supply chains had been destroyed. The chemical suppliers who had existed solely to provide Polaroid with specialized materials had gone out of business.

"Doc might have saved the factory, retrieved the machines from the scrap yard and persuaded the workers to return," one account noted, "but he had overlooked that the chemicals and formula to make Polaroid's vintage instant film had been lost."

The Impossible Project, later rebranded as Polaroid Originals, spent years reverse-engineering instant film from scratch. They've made remarkable progress. Their current products work. But after more than 15 years of effort, the film still doesn't match the original's quality, speed, or stability.

Fifty years of refinement by Polaroid. Fifteen years of reinvention by its successors. The gap remains.

Kodachrome: Too complex to survive

Kodachrome was introduced in 1935 and remained in production for 74 years. It was renowned for its color accuracy, fine grain, and archival stability. National Geographic's iconic "Afghan Girl" photograph was shot on Kodachrome.

The K-14 development process was extraordinarily complex: three separate color developers, three filtered light re-exposures between each color step, and specialized chemistry at each stage. Unlike most color films, which have dye layers built in, Kodachrome was essentially a three-layer black-and-white film; the colors were added during development through a precise chemical dance.

When Kodak discontinued Kodachrome in 2009, it also stopped producing the K-14 chemistry. No one else made it. The last lab in the world capable of processing Kodachrome, Dwayne's Photo in Parsons, Kansas, processed its final roll in January 2011.

One hobbyist attempting to revive the process described the challenge: "It turned out that it was true that many of the original chemicals were totally impossible to source, so I was forced to fabricate many of them myself. I dove into a crash course in organic chemistry via Professor Google."

Although he has made progress, he has not matched the original results. And his effort is essentially a one-person archaeological expedition into industrial chemistry.

The broader risk to photographic knowledge

The intricacies of producing high-quality photographic emulsions, both film and paper, are at risk of disappearing. Much of this knowledge was proprietary, passed down within companies, never fully documented for outsiders.

I purchased a book some 15 years ago that attempts to document the proprietary processes Kodak used to make its film during the period 2007–2010, when that technology reached its apex. It's a thin volume: enough information to make one appreciate the complexity, but not nearly enough to rebuild the machinery and chemistry should the technology fully disappear.

If film manufacturing were to cease entirely, rebuilding it would require something like archaeological recovery of industrial processes.

Stradivari: Craftsmanship as a lost art

Antonio Stradivari crafted violins in the 1700s that remain unmatched in tonal quality. The instruments are so valued that modern performers compete for the chance to play them.

The precise methods, wood treatment, varnish composition, and construction techniques died with the craftsmen. Stradivari trained apprentices, but whatever combination of knowledge, skill, and materials produced those instruments did not survive intact.

Modern scientific analysis has revealed some secrets: unusual wood density, possible chemical treatments, and specific varnish ingredients. No one has successfully replicated the sound. The knowledge was embodied in practice, not documentation, and when the practitioners died, it died with them.

The filtering problem

We cannot save everything

Humanity now takes more photos in a few minutes than were created in the entire 19th century. A 2015 analysis suggested more photographs would be taken that year than in the entire history of film photography. Ten years later, that number is clearly much higher.

Do future generations need to see a few thousand pictures of my dogs? (I'm guessing yes.)

We generate data at a scale that makes universal preservation impossible and arguably undesirable. Every email, every text message, every social media post, every blurry smartphone photo, the sheer volume exceeds any realistic capacity for curation, migration, and long-term storage.

Some triage is inevitable.

We cannot predict what matters

Future historians do not only want official records or works of great literature. They want the mundane: how people talked, what they cared about, what they argued about, what they ate, what they wore, what they fixed, and what they ignored.

The details that feel disposable now can become an invaluable signal later. A medieval shopping list would be a treasure today. Contemporary scholars would love to have the bar tabs, the graffiti, the casual letters of ordinary Romans. But those were exactly the things that weren't worth preserving at the time.

We face the same problem. It makes no sense to preserve everything, but preserving only what we believe is important will be a disservice to future civilizations. We don't know what questions they'll want to ask.

The quiet filters

The filtering today is not only a human choice.

It's also format decay: files that become unreadable as software evolves.

It's device turnover: media that can't be read because the drives no longer exist.

It's corporate product decisions: platforms that shut down, taking user content with them.

It's the economics of storage: services that charge more than users are willing to pay, leading to quiet deletion.

MySpace lost millions of songs in a server migration. Google+ shut down. Vine disappeared. Countless personal websites have vanished as hosting providers closed or users stopped paying. The Internet Archive works heroically to preserve what it can, but it operates on limited funding and cannot capture everything.

We may be creating a future in which certain eras are nearly invisible, not through deliberate destruction, but through quiet obsolescence.

What we leave behind

The technical problems are real, but the harder issue is human.

We cannot save everything. The world produces an avalanche of photos, documents, messages, and recordings, and even large institutions struggle to curate, migrate, and validate digital collections indefinitely. Most of us do not even try. We keep what fits, what syncs, and what we remember.

At the same time, we cannot predict what will matter later.

That creates a quiet tension.

Preservation is partly about engineering: durable media, open formats, regular migration, and tested backups. But it is also about choosing what to carry forward. Every choice is a guess made in the present, under constraints we rarely notice, shaped by the formats we use, the services that survive, and the devices we discard.

I've willingly deleted countless text messages, emails, software I've written, and documents that have no lasting value to me. Future historians might disagree about the "lasting value" part, but I'll never know, and neither will they.

The Sumerians didn't set out to preserve their shopping lists for 5,000 years. They just wrote on clay, and clay endures. We write on media that decays, in formats that obsolesce, on platforms that disappear. The filtering is constant, invisible, and largely outside our control.

If we want future generations, or even future civilizations, to understand us, we have to think beyond storage. We need durable media, durable formats, and a context that endures, along with a little humility about what we cannot foresee.

We also need to accept that much will be lost anyway. The question is whether we lose it by accident, by neglect, or by choice ... and whether we've thought carefully about which things deserve the effort of preservation.

That's the human problem of preservation. The technology is the easy part.

For a companion discussion of the technical barriers to preservation: hardware, formats, and media decay, see the precursor article, The Fragility of Digital Memory"