Like movie studios, publishing houses have long built their businesses on top of blockbusters. But never in the history of publishing has the blockbuster been so big. Thirty years ago, the industry defined a “hit” novel as a book that sold a couple of hundred thousand copies in hardcover. Today a book isn’t considered a blockbuster unless it sells at least one million copies.

The story of the blockbuster’s explosion is, paradoxically, bound up with that of publishing’s recent troubles. They each began with the wave of consolidation that swept through the industry in the 1980s. Unsatisfied with publishing’s small margins, the new conglomerates that now owned the various publishing houses pressed for bigger best sellers and larger profits. Mass-market fiction had historically been a paperback business, but publishers now put more energy and resources into selling these same books as hardcovers, with their vastly more favorable profit margins. At the same time, large stores like Barnes & Noble and Borders were elbowing out independent booksellers. Their growing dominance of the market gave them the leverage to demand wholesale discounts and charge hefty sums for favorable store placement, forcing publishers to sell still more books. Big-box stores like Costco accelerated the trend by stocking large quantities of books by a small group of authors and offering steep discounts on them. Under pressure from both their parent companies and booksellers, publishers became less and less willing to gamble on undiscovered talent and more inclined to hoard their resources for their most bankable authors. The effect was self-fulfilling. The few books that publishers invested heavily in sold; most of the rest didn’t. And the blockbuster became even bigger.

Patterson has been a beneficiary of the industry’s shifting economics, but he was also a catalyst for change at Little, Brown and in the world of publishing in general. When Patterson published his breakout book, “Along Came a Spider,” in 1993, Little, Brown was still a largely literary house, whose more commercial authors included the historian William Manchester, biographer of Winston Churchill. Patterson’s success in the subsequent years encouraged Little, Brown to fully embrace mass-market fiction. But more than that, Patterson almost single-handedly created a template for the modern blockbuster author.

There were, of course, blockbuster authors before Patterson, among them Mario Puzo, James Michener and Danielle Steel. But never had authors been marketed essentially as consumer goods, paving the way for a small group of writers, from Charlaine Harris to Malcolm Gladwell, to dominate best-seller lists — often with several titles at a time — in the same way that brands like Skippy and Grey Poupon dominate supermarket shelves. “Until the last 15 years or so, the thought that you could mass-merchandise authors had always been resisted,” says Larry Kirshbaum, former C.E.O. of the Time Warner Book Group, which owned Little, Brown until 2006. “Jim was at the forefront of changing that.”

The lesson was not easily learned. Publishing is an inherently conservative business. Patterson repeatedly challenged industry convention, sometimes over the objections of his own publisher. When Little, Brown was preparing to release “Along Came a Spider,” Patterson tried to persuade his publisher that the best way to get the book onto best-seller lists was to advertise aggressively on television. Little, Brown initially balked. Bookstores typically base their stocking decisions on the sales of an author’s previous books, and Patterson’s had not done particularly well. This was going to be the first of several novels about an African-American homicide detective in Washington, D.C., named Alex Cross; the prevailing wisdom was that the audience for a series built around a recurring character needed to be nurtured gradually. What’s more, large-scale TV advertising was rare in publishing, not only because of the prohibitive cost but also for cultural reasons. The thinking was that selling a book as if it were a lawn-care product could very well backfire by turning off potential readers.

Patterson wrote, produced and paid for a commercial himself. It opened with a spider dropping down the screen and closed with a voice-over: “You can stop waiting for the next ‘Silence of the Lambs.’ ” Once Little, Brown saw the ad, it agreed to share the cost of rolling it out over the course of several weeks in three particularly strong thriller markets — New York, Chicago and Washington. “Along Came a Spider” made its debut at No. 9 on the New York Times hardcover best-seller list, ensuring it favorable placement near the entrance of bookstores, probably the single biggest driver of book sales. It rose to No. 2 in paperback and remains Patterson’s most successful book, with more than five million copies in print.

It’s not hard to understand the popularity of “Along Came a Spider.” It’s a police procedural with an uncomplicated yet ever-twisting plot, some sex, betrayal and plenty of violence. The book’s hero, Cross, is smart and tough, yet sensitive and vulnerable. He has a Ph.D. in forensic psychology from Johns Hopkins, lost his wife in a drive-by shooting — leaving him to raise his two children alone — plays Gershwin on a beat-up baby-grand piano and volunteers at the soup kitchen of his local parish. Still, hundreds of suspenseful, fast-paced novels are published each year; few become successful, let alone blockbusters. It’s entirely possible, even quite likely, that without those ads, “Along Came a Spider ” never would have made the best-seller list, and that James Patterson would now be just another thriller writer.