The image of the e-book as a juggernaut has certainly taken a beating.

It wasn't so long ago that book publishers and bookstore owners were quailing about the coming of e-books, like movie theatre owners at the dawn of the television age.

Now they're taking things more calmly. Recent statistics confirm a trend first noticed by the book trade in late 2015: At least among major publishers, e-book sales have plateaued or even begun to decline.

It turns out that not all readers are quite ready to give up the tactile pleasures of holding a hardcover or paperback in their hands in order to partake of the convenience and digital features of e-reading.

Here are the signposts: E-book sales for the first nine months of 2016 were down 18.7 per cent compared to the same period a year earlier. It was the only category of four - including hardcovers, paperbacks, and audiobooks, to suffer a decline.

E-books' share of the total market fell to 17.6 percent from 21.7 percent in that time frame.

Finally, sales of dedicated e-readers such as Amazon Kindles appear to be on the decline; ownership of those devices fell to about 19 per cent of all US adults in 2015 from more than 30 per cent in 2013.

Yet e-book specialists say the overall market for digital reading is continuing to expand.

"I won't dispute that the Big 5 publishers' share of the e-book market is declining," says Jeffrey Bruner, who distributes a newsletter of e-book recommendations via his website, thefussylibrarian.com. "But small presses and independent authors are taking a larger share."

The Big 5 - Hachette, HarperCollins, Macmillan, Simon & Schuster, and Penguin Random House - account for 37 per cent of the overall book market, but only 26 per cent of all e-book sales.

The image of the e-book as a juggernaut has certainly taken a beating.

"Five or six years ago, there was widespread panic that digital reading would take over our business," says Oren Teicher, chief executive of the American Booksellers Association.

Physical books and e-books may have reached a sort of equilibrium, he says. "The projection that it would be an either-or proposition has turned out not to be true. Customers who buy books are also reading digitally."

What slowed the march of e-books to world domination? Economics, technology, and habit.

Several analysts point to e-book price increases imposed by major publishers in 2015, which brought the average price from US$6 (NZ$8.75) to nearly US$10.

As the price gap narrowed, the relative allure of e-books declined.

The fragmenting of the e-reader market has blunted innovation in e-books. The latest industry specification for e-book formats, EPUB 3.1, accommodates interactivity and other digital features familiar from web browsers. But they're incompatible with dedicated e-readers and even some smartphones and tablets. So publishers have little incentive to exploit those features.

Nor do device manufacturers have much incentive to meet the challenge.

Amazon crushes the competition in e-books and e-readers with more than 80 per cent of the English-language market, so there may not be much it can gain by making its offerings more feature-rich.

Then there's the cost of the reading device. Kindles range in price from US$80 for a no-frills version to US$290 for its glitzy though underperforming Oasis, and its best device, the Voyage, costs a hefty US$200.

As it happens, an increasing share of e-books are read on tablets (50 per cent of e-reading) and smartphones (about 18 per cent), with dedicated e-readers accounting for about 20 per cent.

Finally, there's no getting away from the tangible delights of reading in a format that has remained essentially unchanged since the printer Aldus Manutius pioneered the portable, hand-held book - small enough to fit in a saddlebag - in 15th century Venice.

What the publishing market has told us so far is that there's room for the physical and the digital.