There can be no clearer evidence of the swift and steep decline of the printed reference book than these figures taken from a recent New York Times: In 1990, the Encyclopedia Britannica sold 120,000 sets (each set comprising 32 volumes) in the USA. That turned out to be its peak year. Since its last revision in 2010, it has sold only 8,000 sets in the same market. Another 4,000 sets lie in a warehouse. When the last of those goes, the paper-and-ink Britannica will be no more. This week its publisher announced that future editions will appear exclusively online, bringing to a close a printing history that began in Edinburgh in 1768.

The news prompted some retrospection and analysis about what the Britannica had stood for – not so much the meaning of what was inside it as what owning it signified. Aspiration was particularly remembered. Many people who bought Britannica imagined that books containing "the sum of human knowledge" opened the way to a prosperous enlightenment. That at least was the message of the salesman who called, to be treated more reverently than the other men who bent down on the doorstep to open a suitcase and speak warmly of Brasso or Mansion furniture polish. Perhaps he arrived by appointment. Certainly he was honoured as a gentler type and given a seat in the living room, where he sat for what seemed like hours, smiling at any child present and speaking of him or her as an extra special reason for the potential purchaser to part with a couple of months' wages, to be paid in weekly instalments that stretched to the crack of doom. The sacrifice would be worth it. On the tilting deck of the SS Ignorance, so the salesman implied, it was a father's duty to stand back and make sure his children had seats in the lifeboats marked Knowledge and Opportunity.

We were never a Britannica family. The salesman went away with no forms signed, leaving us to get by with what we already had: a mid-Victorian edition of Chambers Encyclopedia, Arthur Mee's Children's Encyclopedia, Pears Cyclopedia, the Vimto Book of Knowledge. All had their drawbacks. The dozen volumes of Chambers had been acquired secondhand before the war and looked splendid in their gilt-lettered spines and marbled endpapers, but the source of the Nile was only one of many discoveries that came too late to be found in their pages. And while the Children's Encyclopedia undeniably belonged to the 20th century, and had pictures of biplanes to prove it, its sentimentality and capricious arrangement – not so much A to Z as M to C via Y – made it a poor source of information. Pears had a nice frontispiece, Bubbles by Millais, and was good as far as it went (one volume, so not very far). All I can remember about the Vimto book was that it was really just a pamphlet of odd facts and figures, and had a detailed engraving of the Vimto factory, smoking away busily somewhere in Lancashire.

The Britannica would have been a vast improvement, but expense ruled it out. And so we contrived to look down on it – for behaving treasonably and becoming "too American" in ways my father never specified, or for its role as an ornament in houses where, we were sure, nobody ever bothered to disturb its military uprightness on bookshelves that contained no other books. Then one day my father's closest friend came to visit and announced he was about to buy the Britannica, just like that, and not because he wanted his family to do better than he had – he and his wife had no children – or because he imagined the books would enhance his social status. He would buy the Britannica to read it from beginning to end, for no other reason than to be better informed. This mission impressed my father, who himself was no slouch as an autodidact, and from then on we saw the Britannica in a kinder light.

My father's friend, Sandy Paterson, needs a little description, because almost nobody like him is still alive. Like my father, he left school at 14, served a factory apprenticeship and found work as a fitter. They had a mutual enthusiasm for cycling, which was how they met in a small Scottish border town in the 1920s when they were both far from home on a long ride; my father parked his bike against another outside a grocer's shop and went inside to find a young man standing on a biscuit box and declaiming a Burns poem to the shopkeeper. In my father's words, "That was Sandy all over", meaning it was typical of somebody who talked with lively good humour to anyone he came across, who in his 50s could still jump on to the kitchen table from a standing start, who shot rabbits, who made violins as well as played them (purely for the fun of both activities), and who dashed off high-spirited letters that made their recipients laugh.

He and his wife, who'd been crippled with arthritis as a young woman, lived in a small West Lothian village. This was shale-oil country: pink waste heaps rose above fields and woodland, while narrow-gauge railways ran through cuttings to the mines. We would visit as a family by taking a ferry and then the bus, and then climbing the stairs to their flat above the village shop. There was no electricity; not even gas. When it got dark, Sandy would pump up the Tilley lamp, which then hissed in the background all evening as the adults' conversation moved from the personal and present to the general and historic, from (say) the alleged misrule of the local landlord, the Marquess of Linlithgow, via Kant to the reign of the pharaohs. Sandy did most of the talking, but nobody minded – he was so amusing and vivid. He sucked at cigarettes and threw their ends impatiently into the fire.

I realise I'm in danger here of creating a kitsch version of a painting by Joseph Wright of Derby, but it really was as I describe. When Sandy consulted the Encyclopedia Britannica and read aloud a passage from one of its entries, the decoration on the binding would glisten in the light of the Tilley lamp. How much of it he managed to read eventually I have no idea, but he wasn't a man to give up lightly on a self-improving ambition.

Information – "the sum of human knowledge" – had a different shape then, and for 40 years after. Rather than an invisible omnipresence that can be tapped into wherever a laptop or a phone can find a signal, it lived like miser's gold in hard, little piles that were distributed unevenly throughout the country. The Britannica gave Sandy one such pile. To find another in his vicinity might have been difficult. You might have needed to take the bus all the way into Edinburgh, where the piles turned into towers in libraries, bookshops and museums. To the city, in fact, where 244 years ago a baker's son and a wigmaker's son got together to publish the first instalment of the work they called an encyclopedia, printing summaries of knowledge alphabetically in the belief that people liked to find out.