In the Warsaw Ghetto in 1940, an historian named Emanuel Ringelblum organised and carried out an act of resistance without parallel, a feat of historical heroism that has only come fully to light recently: he set about preserving the present, for the benefit of the future.

Ringelblum was one of 450,000 Jews herded into the ghetto by the Nazis. Over the next three years many died of disease or starvation. Most of the remainder were rounded up and murdered in Treblinka. Those who survived until April 1943 were almost all killed in the Warsaw Ghetto Uprising. The ghetto was razed.

Yet, Ringelblum's great idea survived the war. Hidden beneath the ghetto buildings were a number of sealed tin boxes and milk churns, containing some 35,000 documents: essays, letters, poems, bus tickets, posters, milk coupons, photographs, personal testimonies, official papers, menus, souvenirs, sketches, sweet papers and songs. Here was the detailed story of daily life in a man-made hell. This was Ringelblum's legacy - a triumph of preservation.

The vast collection lay deep beneath the rubble of the ghetto for years, but was finally exhumed after the war when a survivor led the way to the secret cellar. It has taken another half-century for the story to be told in full by Samuel Kassow, in an extraordinary book, Who Will Write Our History?.

Ringelblum appointed himself to that task. This was not some desperate ad hoc hoarding of symbolic artefacts, but a systematic, scholarly project by a brave and brilliant historian. Ringelblum recruited about 60 collaborators (of whom only three survived the war), to study and document every aspect of ghetto life: an executive committee provided funding, and a governing board met on Saturday afternoons (giving the project the codename Oyneg Shabes, meaning Sabbath Joy.) Three young men were appointed to hide the archive when Ringelblum gave the signal.

The compilers of this archive knew they were doomed, and framed their project as an act of intellectual resistance to totalitarianism. “History is usually written by the victor,” wrote one of the team. “Should our murderers be victorious, should they write the history of this war, our destruction will be presented as one of the most beautiful pages of world history. Or they may wipe out our memory altogether.”

The effort was collective, but the emphasis was individualistic. The written material ranges from dense academic treatises to the most heartbreaking personal appeals to posterity. As he hurried to bury the first cache of documents in 1942, Israel Lichtenstein scribbled a note, and added it to the container: “I wish my little daughter to be remembered. Margalit is 20 months old today. She too deserves to be remembered.”

The historians' faith in the survival of their story is deeply moving, their intellectual courage in the face of death and tyranny is inspirational. But when set against our own attitudes to contemporary history, it also offers a warning.

History is more popular today than it has ever been. We scour the past for our antecedents and delve into family history as never before. Yet we treat our own contemporary everyday history as a disposable commodity.

Far from preserving history, technology is helping to erode it. Few bother to archive or preserve e-mails. Officials delete swaths of electronic information routinely. Methods of storing information that seemed cutting-edge ten years ago are already obsolete. The BBC's Doomsday Project collected information about society in 1986 on a series of 12-inch videodiscs; by 2000 it was already unreadable without specialist equipment.

Reading Who Will Write Our History? made me wonder: Who will write ours? What will the historians of the future base their history on? “Collect as much as possible,” wrote Ringelblum. Today we are collecting little or nothing, in a paperless, digital world, where few still write letters, blogs have taken the place of diaries, telephone texts vanish into the air, and the life expectancy of a web-posting is roughly one month.

Digital experts at the National Archives have begun working with government to preserve contemporary records for later generations, while combing the internet for vulnerable digital information that will tell future researchers what we were like. Less easy to preserve in a throwaway, digitised culture are the everyday items and words of our lives, the small exchanges, pastimes, preoccupations, and ephemera.

Such preservation seems to be a universal human urge. The Mass Observation Archive was set up in the 1930s to enable ordinary people to record their daily lives. On October 17, 2006, about 8,000 people contributed individual diaries of that single day to create a countrywide snapshot of society, now held at the British Library.

The Oyneg Shabes project is more than simply an archive: by preserving the warp and weft of ordinary daily lives, it defied mass murder.

Emanuel Ringelblum collected to the end, feverishly writing as the Nazis closed in on him. He was arrested after the uprising, sent to a concentration camp, escaped and went into hiding in Warsaw. In March 1944 his refuge was discovered: Ringelblum was executed, along with his family, and the Poles who had protected him. But the hiding place of his masterwork was never found by the Nazis.

We are familiar with stories, rare enough, of Jews who escaped the Holocaust by being hidden or smuggled to safety. Ringelblum, the unsung Oskar Schindler of historians, achieved something still more exceptional: he hid history itself, to ensure the survival of truth.

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