However, what if a book contains so much information you can hardly pick it up, let alone afford to buy it? The 34-volume, 26 million-word Grove Dictionary of Art is a case in point. Published by Macmillan, the world's most comprehensive art reference book weighs 85kg, takes up 176cm of shelf space, and costs pounds 4,900 - meaning only well-funded libraries and extremely wealthy private collectors can afford it.
Enter the Internet. Last November, Macmillan started offering subscriptions to an online version of the dictionary. Institutions pay pounds 900 and individuals pay pounds 275 for a one-year subscription (carnets for 10 24-hour sessions cost pounds 50). The online version has all the text of the print version, plus updates and links to images of artworks. With the Grove Dictionary of Art Online, Macmillan is betting that ease, affordability and the promise of constant updates will bring customers around to the idea of buying access to - rather than owning - a digital book.
To date, about 300 subscriptions to the online version have sold - compared with 5,000 copies of the print version, published in 1996. But Macmillan expects sales to pick up. Already, the online version has attracted prestigious institutions: subscribers include the Bodleian Library at Oxford, the Barber Fine Art Library at Birmingham University, the Art Institute of Chicago and the Frick Collection in the US. As people realise how accessible the dictionary is, Macmillan believes individuals interested in the art world, as well as corporations and institutions, will subscribe.
Certainly, the online version beats the print version in terms of utility. Instead of travelling to a library, subscribers can use the dictionary from any computer with Internet access and a version 4.0 browser, simply by going to the dictionary's website (www.groveart.com) and entering a user ID and password. Search engines scour 41,000 articles to bring up a list of places where a specified topic is mentioned. Cross-references embedded in the text mean users can move from article to related article with one click - far easier than the cumbersome process of reshelving one volume and picking up another.
The online version has also extended the print version's content. While the original contained 15,000 illustrations, the online version contains links to 12,000 images held by art galleries around the world (for example, a link from the article on Leonardo da Vinci goes to the Mona Lisa at the Louvre's website), and gives subscribers access to the Bridgeman Art Library's collection of 100,000 images (at the moment, 30,000 images are available; 70,000 will be added by the end of the year).
"We had to limit the print version's content - the number of illustrations of Picasso, for instance - because of the size," explains Richard Charkin, the chief executive of Macmillan and driving force behind the company's move into electronic publishing. In the online version, however, there is no limit to the number of illustrations and entries that can be included.
Another advantage is that entries can be updated to include new academic research and biographical changes. "Like any printed book, the print version was out of date as soon as it was published," Charkin says.
A team of editors at Macmillan keeps the online dictionary up to date. They have made more than 5,000 changes in 1999, including reports on the deaths of Roy Lichtenstein and Willem de Kooning, and new entries on Britpack artists Damien Hirst and Rachel Whiteread. The editorial staff also create original content covering art world events such as the Turner prize and are developing links to pricing and auction sites.
The move from print to Internet publishing hasn't been trouble-free, however. Macmillan has had to take measures to avoid pirating: access to the site automatically cuts off, for example, if too many pages are downloaded in one sitting. Also, Internet publishing demands high levels of maintenance and customer service. In the past, a book publisher's customer service department dealt with filling orders during business hours. Now, customer service representatives might also handle late-night technical queries.
The online dictionary has created new editorial tasks, such as maintaining the quality of the links. When the Louvre changed its URLs earlier this year, Macmillan had to work quickly to recode the links in the space of an hour. "We have to change our whole way of doing business," Charkin explains. "We're inventing systems."
Some museums are contesting the legality of the links. Macmillan, is currently in talks with the museums, maintaining that the links are perfectly legal. "We are not taking their content into the dictionary," says Charkin. "We are taking customers to them."
Charkin, who is chairman of the Whitechapel Art Gallery, believes that museums will have to find new ways of generating income by getting people who come to their sites via the Grove Dictionary to become a friend of the museum or make a purchase in an online store.
Still, the online version makes a lot of business sense. The original version took 14 years and over pounds 20m to complete. Publishing the online version cost a fraction of that, says Charkin - though he expects it to cost twice as much in the long term, as the expense of maintaining the dictionary adds up. Moreover, publishing on the Net doesn't incur printing, shipping, retail and other distribution costs, which account for 75 per cent of most cover prices. Internet publishers can pass this saving on to customers - or spend it enhancing editorial quality.
Ultimately, the online dictionary's success will depend on how many people buy it. Those who have seem satisfied, so far. Gregory Walker, head of collection development at the Bodleian, says it generated "strong academic interest", and Karen Jackson, arts liaison Librarian at the Barber, says she feels "very positive about how it's going to work". Both the Bodleian and the Barber own the print version, too, and at the moment Jackson says she can't imagine the online version entirely replacing the print version, though "if it is heavily used and we are struggling to find funds then that is something we would consider".
Charkin remains confident that the online dictionary will be as popular as the print version. "I really think this is going to be the single art source of the 21st century for all layers of users - academics, collectors, schools." More online projects are in the pipeline: The New Grove Dictionary of Opera Online is due out this month; The New Grove Dictionary of Music and Musicians Online are expected next year.
Charkin has said he aims to make Macmillan Reference 50 per cent electronic within three years. There are plans to take online publishing beyond reference books. A Web community for economists is in development, and Charkin is keen to publish English language teaching books online, where they can be inexpensively accessed by teachers in the Third World.
Is Charkin overly enthusiastic? It's too early to tell. Certainly at Macmillan his claims are taken seriously: in the downstairs lobby at the company's Eccleston Place headquarters, the 34-volumes of the print dictionary sit enclosed in a glass display case, like an outdated curiosity in a museum. A few minutes away in Victoria station, a bookshop stands empty at midday. But people are crowding to a bank of PCs, where an ISP is hawking free Web demonstrations. If there were ever a right time for publishers to introduce the digital book, this may be it.