FINGERS stroke vellum; the calfskin pages are smooth, like paper, but richer, almost oily. Theblack print is crisp, and every Latin sentence starts with a lush red letter. One of the book'searly owners has drawn a hand and index finger which points, like an arrow, to passages worthremembering.

In 44BC Cicero, the Roman Republic's great orator, wrote a book for his son Marcus called deOfficiis ("On Duties"). It told him how to live a moral life, how to balance virtue withself-interest, how to have an impact. Not all his words were new. De Officiis draws on the views ofvarious Greek philosophers whose works Cicero could consult in his library, most of which havesince been lost. Cicero's, though, remain. De Officiis was read and studied throughout the rise ofthe Roman Empire and survived the subsequent fall. It shaped the thought of Renaissance thinkerslike Erasmus; centuries later still it inspired Voltaire. "No one will ever write anything morewise," he said.

The book's words have not changed; their vessel, though, has gone through relentlessreincarnation and metamorphosis. Cicero probably dictated de Officiis to his freed slave,Tiro, who copied it down on a papyrus scroll from which other copies were made in turn. Within afew centuries some versions were transferred from scrolls into bound books, or codices. A thousandyears later monks meticulously made copies by hand, averaging only a few pages a day. Then, in the15th century, de Officiis was copied by a machine. The lush edition in your correspondent'shands-delightfully, and surprisingly, no gloves are needed to handle it-is one of the very firstsuch copies. It was printed in Mainz, Germany, on a printing press owned by Johann Fust, an earlypartner of Johannes Gutenberg, the pioneer of European printing. It is dated 1466.

Some 500 years after it was printed, this beautiful volume sits in the Huntington Library in SanMarino, California, its home since 1916. Few physical volumes survive five centuries. This oneshould last several more. The vault that holds it and tens of thousands of other volumes, built in1951, was originally meant to double as a nuclear-bomb shelter.

Although this copy of de Officiis may be sequestered, the book itself is freer than ever.In its printed forms it has been a hardback and, more recently, a paperback, published in all sortsof editions-as a one off, a component of uniform library editions, a classic pitched at anaffordable price, a scholarly, annotated text that only universities buy. And now it is availablein all sorts of non-printed forms, too. You can read it free online or download it as an e-book inEnglish, Latin and any number of other tongues.

Many are worried about what such technology means for books, with big bookshops closing, newdevices spreading, novice authors flooding the market and an online behemoth known as Amazongrowing ever more powerful. Their anxieties cannot simply be written off as predictabletechnophobia. The digital transition may well change the way books are written, sold and read morethan any development in their history, and that will not be to everyone's advantage. Veterans andrevolutionaries alike may go bust; Gutenberg died almost penniless, having lost control of hispress to Fust and other creditors.

But to see technology purely as a threat to books risks missing a key point. Books are not just"tree flakes encased in dead cow", as a scholar once wryly put it. They are a technology in theirown right, one developed and used for the refinement and advancement of thought. And thistechnology is a powerful, long-lived and adaptable one.

Books like de Officiis have not merely weathered history; they have helped shape it. Theability they offer to preserve, transmit and develop ideas was taken to another level by Gutenbergand his colleagues. Being able to study printed material at the same time as others studied it andto exchange ideas about it sparked the Reformation; it was central to the Enlightenment and therise of science. No army has accomplished more than printed textbooks have; no prince or priest hasmattered as much as "On the Origin of Species"; no coercion has changed the hearts and minds of menand women as much as the first folio of Shakespeare's plays.

Books read in electronic form will boast the same power and some new ones to boot. The printedbook is an excellent means of channelling information from writer to reader; the e-book can sendinformation back as well. Teachers will be able to learn of a pupil's progress and questions;publishers will be able to see which books are gulped down, which sipped slowly. Already readerscan see what other readers have thought worthy of note, and seek out like-minded people for furtherdiscussion of what they have read. The private joys of the book will remain; new public pleasuresare there to be added. What is the future of the book? It is much brighter than people think.

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ESSAY• THE FUTURE OF THE BOOK(www.economist.com/news/essays/21623373-which-something-old-and-powerful-encountered-vault)