When did Cymburgis of Masovia die? Whom did the Elector of Hanover elect? Was anyone's nose harmed in the naming of Brasenose College, Oxford? Most of us, it would be fair to say, wouldn't know the answers to such rarefied questions. But we would know where to look for them. Whether lining our walls, acting as our internet home page, or propping up the cock-eyed hall table, we've all at some point turned to an encyclopedia.

There has always been too much to know. A Google search for the term "information overload" yields 5.3 million results. Even God grumbled about it in Ecclesiastes: "Of making books, there is no end," he said (though admittedly in the 14th chapter of his own 1,180-chapter tome). And yet, since time immemorial, we have lusted after knowledge. Encyclopedias have helped us to sate that hankering.

"The ancients sorted information as readily as we do today," says Ann Blair, professor of history at Harvard University and author of Too Much to Know, a history of scholarly information. "Note-takers abounded; the naturalist Pliny left 166 double-sided papyrus sheets covered in notes on all sorts of topics. This urge led to the construction of the first encyclopedia in the Western world."

"There is no book," Pliny wrote, "that was so bad that something good cannot be got from it." So he set about copying them, filleting the best ones, discarding the uninteresting. The product of this lifetime of exertion was the Naturalis Historia, a 37-volume encyclopedia which covered everything from the anatomy of a hippo to how best to extract copper from a rock. And all helpfully split into easy-to-find categories with a handy system of cross-referencing.

"Pliny was almost the father of the genre, the model on which subsequent authors plotted their own works," Blair says, "and the inspiration for subsequent scholars who ceaselessly chivvied out knowledge and recorded it on paper."

Some needed more encouragement than others. Vincent of Beauvais, an industrious Dominican friar of the 13th century, took it upon himself to record all the knowledge in the world up to the reign of his king, Louis IX. His book, Speculum Maius, surpassed even Pliny's work in scope and weightiness. Hand-written in his 3m x 4m cell, the work ran to 4.5 million words, which theological students flocked to his monastery to copy. Although a scholarly hit, it was something of a miss with his monastic brethren. Vincent was accused of "idle curiosity", a grievous charge to level at a friar. Although, like later encyclopedists, he was quick to defend his work: "The book," he shot back, "contains only things that are good and godly."

Godly and good early encyclopedias may have been, but they were sometimes put to dubious use. Nani Mirabelli's Polyanthea of 1503, which started life as a dictionary and grew to become a one million-word mini-library, has a walk-on part in the history of England. Henry VIII was an early subscriber, and his copy survives. The book remains largely unmolested, apart from on those pages concerned with three particular topics. The sections concerned with "matrimony", "law" and "vows" are surrounded by royal scribbles, underlinings and pointing figures.

Theodor Zwinger, professor of ethics at Basel University in the late 1500s, put together a brief compendium of knowledge (a mere 2,500 pages), which he hoped would be circulated to "scholars, teachers and secretaries". Alongside entries on zoology and the wonders of the cabbage, he included an exhaustive guide on "how to behave in every conceivable situation". Jeremy Drexel, a contemporary, wrote: "The Theatrum sells at over 70 florins! [A skilled workman earned around 300 florins a year.] And that is to say nothing of binding." The instructive work did not fly from medieval shelves.

Encyclopedists became outlandish figures in the 18th century. The philosopher Denis Diderot claimed the Encyclopédie he edited with Jean d'Alembert was so compendious, so broad in scope and learning, that if a catastrophe were to befall the earth and all the books but his were destroyed, there would be sufficient information in his manuscript for civilisation to survive – even prosper. As well as being exhaustive and innovatively organised, it stood out for another reason. The book was the first to acknowledge explicitly that it was the product of a collective of writers, rather than a single, well-honed mind. In part a nod to intellectual fraternity, it was mainly because the thing was so seditious. The entry for "The Eucharist", for example, said: "See cannibalism". Believing the work to be the output of an organised "band of conspirators" acting to undermine French society, the government suppressed the 17-volume work in 1759. Diderot ploughed on for another five years, sometimes printing the work himself.

Compilers of encyclopedias took a battering not only from the state, but also from fellow intellectuals. The father of modern philosophy, René Descartes, thundered at "[books] confusingly heaped in such large volumes that it would take longer to read them than we have life to live". So ponderous and discordant had some of the works become, Descartes claimed, that they were no longer useful as receptacles of knowledge. Only a return to first principles and the laborious testing of all material for a base of truth would do.

Cartesian hard logic, however, was no match for a canny Scot out to make a bob or two. The Encyclopaedia Britannica, the world's pre-eminent reference book, was the product of a hard-headed publisher's desire to make money from the emergent merchant classes and their clamour for knowledge. Colin Macfarquhar hit upon the idea while reading of the encyclopedias of classical Rome in Edinburgh's library. He recruited William Smellie, a brilliant 28-year-old classical scholar, to ensure the book was accurate and up to date. And Andrew Bell, an engraver of dog collars, was engaged as an illustrator. Between 1768 and 1771, the trio released their encyclopedia one pamphlet at a time. Scientific method, the arts and practical tips were the main focuses. Curing disease in horses had a 39-page entry, while the entry for "Woman" was just three words in length: "Female of man". The first pamphlet even calculated the precise number of species on board Noah's Ark (177 in total).

To Macfarquhar's joy and Smellie's credit, the book proved a commercial success. Appendices were added, expert articles sought and the entry for "Woman" expanded to two-and-a-half pages. "Britannica was not as rarefied as its ancient ancestors, nor as political as Diderot's work, but what it did have was practical appeal," Blair says. "It had a single alphabetic index and the long articles were supplemented by brief notices on modish topics – its appeal was broad."

Now in its 15th edition, it is the oldest English encyclopedia still in print, and has 100 full-time editors and 4,000 expert contributors working to ensure it remains error-free. Though the price, which in the 1960s did much to ensure a copy was seen as a symbol of upward mobility and intellectual aspiration, now seems steep at £1,195 – especially since online encyclopedias appear to do the same job for free.

Wikipedia has surpassed Smellie's work. With 400 million users per month and 17.5 million unique articles, it is the seventh-most popular website on the net. But size isn't everything. From Pliny, through Diderot and right up to the current editors of Britannica, the aim of encyclopedists has been the accurate selecting, sorting and précising of information. Can a reference work that relies on the "wisdom of the crowd" ever be reliable? Especially when the crowd sometimes looks like a mob. Rival editorial factions fight endless "edit wars" on the site, disgruntled authors cast doubt on the parentage of their competitors and, in 2005, someone suggested that Tony Blair grew up with a picture of Hitler on his dormitory wall (a suggestion strenuously denied at the time).

And yet, should you feel the need to find out when Cymburgis died (1429), whom the Elector elected (the Holy Roman Emperor), or how Brasenose got its name (from a nose-shaped door knocker, apparently), Wikipedia is probably the first place you'd check. Still, you may still want to keep those old copies of Britannica, with their triple-checked facts and 240-year-old cross-referencing system – even if it is just to prop up the hall table.