A few years ago he was reduced to returning bottles and cans for grocery money. Now his Amazon earnings pay for lengthy stays in Italy and Paris, as well as expeditions to the real Amazon. “I go wherever I want, do whatever I want and live however I want,” he said recently at a bar in Mill Valley, Calif., a San Francisco suburb where he was relaxing after a jaunt to Nepal.

While Mr. Zandri celebrates Amazon as the best thing to happen to storytellers since the invention of movable type, many other writers are denouncing what they see as its bullying tendencies and an inclination toward monopoly.

From household names to deeply obscure scribblers, authors are inflamed this summer, perhaps more deeply divided than at any point in nearly a half-century. Back then, it was the question of being a hawk or dove on Vietnam. Now it is not a war but an Internet retailer and its unparalleled grip on the cultural machinery that is provoking fierce controversy.

At first, those in the publishing business considered Amazon a cute toy (you could see a book’s exact sales ranking!) and a useful counterweight to Barnes & Noble and Borders, chains willing to throw their weight around. Now Borders is dead, Barnes & Noble is weak and Amazon owns the publishing platform of the digital era. The company founded and still run by Jeff Bezos dragged the publishers into modern times, forced them to digitize and urged on the Justice Department in its 2012 antitrust suit against the publishers and Apple. The conflict is unrelenting.

The latest struggle between publishers and Amazon burst into public view two months ago, after the company began seeking concessions on book sales from Hachette, the fourth-largest publisher, which Hachette was unwilling to give. Amazon sought to get its way by delaying delivery of Hachette books, which roused Hachette’s authors. At this point, Hachette is losing sales and Amazon is reaping a considerable amount of bad publicity.