We know what was written in the first telegram, sent by Samuel F. B. Morse in 1844: “What hath God wrought?” We know the words spoken by Alexander Graham Bell when he made the first telephone call in 1876, to his assistant, Thomas Watson: “Mr Watson — come here — I want to see you.” (The “polite telephone manner” had not yet been invented.) But we have absolutely no idea what was said in the first e-mail, just 35 years ago.

The digital age brought with it the false promise that everything written, filmed, photographed or recorded might now be preserved, for ever. The “save” key would eliminate the need for filing and storage. Since 1945 we have gathered 100 times more information than in the whole of human history up until that point. Entire libraries could be preserved on disks that fitted into a pocket. Paper was dead.

It has not quite worked out that way. Digital information may be impossibly voluminous and convenient, but it is also vulnerable and dangerously disposable. Already a vast amount of information has been lost. CDs disintegrate in just 20 years, whereas the Domesday Book, written on sheepskin in 1086, will still be with us in another millennium. Few people still write regular letters, but their replacement, the ubiquitous e-mail, is so easily deleted and forgotten, to say nothing of the fleeting text message.

Technology has already left behind the forms of electronic storage once expected to be eternal: the laser disk, the 5¼in, the 3.5in floppy, the Amstrad all-in-one word processor have all been flung into obsolescence, often taking their information with them. Only a small fraction of government bodies and companies even bother to archive their digital material. Who, save the most fastidious self-chronicler, takes the trouble to embalm their own e-mails electronically? Historians of the future may look back on the 1980s and 1990s as a black hole in the collective memory, a time when the historical record thinned alarmingly owing to the pace of technological change. Future biographers may be reduced to trying to extract personality from whatever electronic fragments survive, cheque stubs and those few ritual moments (birth, death and overdraft) when a subject still puts pen to paper.

I have recently spent many hours in the National Archives, ferreting through the wartime records of MI5.

The sheer richness of written material is overwhelming: letters, memos, telephone transcripts, diaries, scribbled notes in the margins. You can smell the pipe smoke and personalities wafting off the pages.

When MI5’s current files are released decades hence, historians will have a far drier time of it. Electronic messages not deemed to be of “archival” value are routinely deleted by civil servants, simply as an insurance policy — significant or potentially damaging information is strictly verbal, particularly since Jo Moore’s attempt to “bury bad news” by e-mail.

Arguably, the most important and reliable real-time histories of places such as Iraq and Iran are currently being written on weblogs, the online journals and discussion forums that are, by definition, mutable and impermanent. A historian 50 years hence would probably get the most accurate picture of life in Baghdad today by collecting and studying the blogs of the moment, but it may already be too late. The average life expectancy of a website is about 44 days, roughly the same as the common house fly.

Just as importantly, by committing to erasable electronic memory the things we once committed to paper, we may be denying future generations the chance to witness the warp and weft of our lives. Our ancestors were writers and hoarders. I have a collection of my grandfather’s letters in the attic, describing the life of a sheep farmer in New South Wales in the 1930s. They are of interest, I suspect, to no one but me, but to me they are invaluable, a chronicle of where I come from. What will we bequeath to our grandchildren? At best a bunch of antiquated disks that they may well be unable to open and read.

Anyone (with a magnifying glass and patience) can read letters, but there is a real danger that technology will leave much of the electronically written record marooned and illegible. The BBC’s Doomsday Project of 1986, intended to record the economic, social and cultural state of Britain for all time, was recorded on two 12in videodisks. By 2000 it was obsolete, and rescued only thanks to a specialist team working with a single surviving laser disk player.

When Nasa sent two Viking Lander spacecraft to Mars in 1975, the data was carefully recorded on magnetic tape. Two decades later, no one could decode it. The original printouts had be tracked down, and typed out again on paper.

And that, ironic as it seems, may be the answer. The Digital Preservation Coalition, a group encouraging governments, businesses and individuals to curate and preserve electronic information, recently published a report stating that “storage of printed copies of important documents is generally accepted as a reasonably failsafe method of preservation”.

This, then, is a plea for paper. So long as it is stored properly and acid-free, paper endures. Leave the ephemera to the electronic ether, but if you value certain words and images, preserve them on paper. The “print” button is a more faithful saviour than the “save” button.

Before the Battle of Trafalgar, Nelson sent his message to the fleet by raising flags using Sir Home Popham’s telegraphic code (a rather newfangled form of communication, which not everyone approved of) — whereupon the words were written down for posterity, on paper.

Today the same message would probably be sent by text — instant, easy, and instantly perishable: “UK xpx dat evry man wll do his duT.”

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