The book is changing. Electronic books, or ebooks, are more portable than their paper counterparts, capable of being carried in their hundreds on a single reader or tablet. Thousands more are just a click away. It can be argued that ebooks are more robust than paper ones: an ebook reader can be stolen or dropped in the bath, but the books on it are stored safely in the cloud, waiting to be downloaded onto a new device. It is not too much to say that books and reading are in the throes of a revolution.  Books and reading are in the throes of a revolution  Not everyone is happy about this. Book lovers, publishers and booksellers alike are watching the book-v-ebook sales battle with great interest, and when Tom Tivnan of The Bookseller reported recently that ebook sales had dipped for the first time, he sounded almost relieved: “For those who predicted the death of the physical book and digital dominating the market by the end of this decade, the print and digital sales figures […] for 2015 might force a reassessment.” Physical books may have the upper hand for now, but the debate is a long way from being settled.  The odd thing is that the current angst over the book’s changing face mirrors a strikingly similar episode in history. Two thousand years ago, a new and unorthodox kind of book threatened to overturn the established order, much to the chagrin of the readers of the time.  Rome in the 1st Century CE was awash with the written word. Statues, monuments and gravestones were inscribed with stately capital letters; citizens took notes and sent messages on wax-covered wooden writing tablets; and the libraries of the wealthy were stocked with books on history, philosophy and the arts. But these were not books as we know them – they were scrolls, made from sheets of Egyptian papyrus pasted into rolls anywhere from 4.5 to 16 metres (14.76ft to 52.49ft) in length. For all their ubiquity, however, they were not without their flaws.  For one thing, it took both hands to read a scroll properly. Unless the reader was seated at a desk (in which case paperweights or wooden pegs could be used to pin down the springy papyrus), the only way to read a scroll was to unwind it carefully from the right hand and, passing it to the left, to roll it up again. Writers and copyists usually wrote in columns a few inches wide, so that the bulk of the fragile papyrus in the scroll could be kept safely rolled up. Even so, archaeologists have found scrolls whose bottom edges have been worn away where they rubbed against the reader’s clothing.  This, then, was the second major problem with scrolls: papyrus was not an inherently long-lived material, especially if removed from its hot, dry Mediterranean comfort zone. Having taken a liking to a historian who shared his name, Tacitus, emperor from 275 to 276, had to send out new copies of the historian’s works each year to replace those that had rotted away in Gaul and Germania. Papyrus will also crack and tear if it is folded too often, leading naturally to the gently curved shape of the scroll itself – and so to the fact that most scrolls carried writing only on one side. Only if the text on the front of a scroll was no longer needed would its owner flip it over and use the other side; a double-sided scroll was just too difficult to read otherwise.  Sometime in or before the First Century CE a new kind of book appeared that promised to address the scroll’s shortcomings. The evidence is sparse but telling: archaeologists have discovered a few key scraps of papyrus whose text unexpectedly continues from the front to the back, and whose neat margins one might expect to find in a paged book. And that is exactly what these fragments are: they are leaves from the first paged books the world had ever seen. We know that the Romans called this new kind of book the codex (from caudex or tree trunk, because of its similarity to their wooden writing tablets), but how the codex came to be in the first place is shrouded in mystery. The first written mention of the codex appears in the words of a Roman poet named Martial, who encouraged his readers to buy his books in this new, paged format:  “You who long for my little books to be with you everywhere and want to have companions for a long journey, buy these ones which parchment confines within small pages: give your scroll-cases to the great authors – one hand can hold me.”  Written between 84 and 86 CE, Martial’s sales pitch tells us not only that paged books were known of in the First Century CE but also that some of them, at least, were made from a new material called parchment. This alternative to papyrus, invented in a Greek city-state some centuries earlier, was made from cleaned, stretched animal skins by means of a bloody and labour-intensive process, but its smoothness and strength made it an ideal writing material. Archaeologists have since confirmed Martial’s claims via fragments of parchment codices dated to the First Century – and yet, these few tantalising finds aside, we still know very little about where or why the codex was invented, or who might have done so. Even the question of whether the first codices were made of papyrus or parchment has never been satisfactorily answered.  Robust, efficient and accessible, the codex was literally the shape of things to come  Whatever the truth of the matter, the paged book was a considerable step forward from the scroll. Codices leant themselves to being bound between covers of wood or ‘pasteboard’ (pasted-together sheets of waste papyrus or parchment), which protected them from careless readers. Their pages were easy to riffle through and, with the addition of page numbers, paved the way for indices and tables of contents. They were space-efficient too, holding more information than papyrus scrolls of a comparable size: referring to the works of the prolific writer Titus Livius, Martial raved that “narrowed into scanty skins [parchment] is bulky Livy, the whole of whom my library does not contain”. Robust, efficient and accessible, the codex was literally the shape of things to come.  Yet the people of Rome, and of the lands surrounding it, were split over the merits of the codex. Rome’s pagan majority, along with the Jewish population of the ancient world, preferred the familiar form of the scroll; the empire’s fast-growing Christian congregation, on the other hand, enthusiastically churned out paged books containing Gospels, commentaries and esoteric wisdom. Of course, we know how this story ends: by the Sixth Century, both paganism and the scroll were on the verge of extinction and Judaism had been firmly eclipsed by its younger sibling. Pulled along in the wake of the Christian church, the paged book found its place in history and society.  The ebook of the 21st Century may not have as devout a following as the codex of the Ancient World, but it inspires strong opinions nonetheless. Will it displace the paper book in its turn, or will it be the one to go the way of the scroll? Time, and booksellers’ profit margins, will tell.  The Book: A Cover-to-Cover Exploration of the Most Powerful Object of Our Time by Keith Houston is published this month by W.W. Norton & Co. Ltd.  If you would like to comment on this story or anything else you have seen on BBC Culture, head over to our Facebook page or message us on Twitter.  And if you liked this story, sign up for the weekly bbc.com features newsletter, called “If You Only Read 6 Things This Week”. A handpicked selection of stories from BBC Future, Earth, Culture, Capital, Travel and Autos, delivered to your inbox every Friday.
The debate about ebooks v paper books is nothing new. Keith Houston explains how a very similar debate raged as the first books came to be in ancient Rome.