No one said revolutionizing textbook publishing would be easy.

It’s hard to argue against free and open information. Limiting access to knowledge and education only to those who can afford it just sounds evil, and we’ve got plenty of evidence that the textbook industry — once compared to predatory pharmaceutical reps by the New York Times — is no stranger to evil.

Every so often a bright-eyed startup will try to be a hero, setting out to revolutionize the industry by making books free. And then, reality sets in.

That’s the case with Flat World Knowledge, an open source textbook startup that raised $26.2 million for its crazy idea — giving away high-quality textbooks for free online. The company would act as a publisher, commissioning books, peer-reviewing them, and giving digital copies away for free. The company would make money selling cheap black-and-white prints along with ancillary tools and study guides.

In five years, the company’s 115 titles were adopted by 2,000 colleges. And after five years, Flat World is dropping the “free” aspect of its radical plan. Starting January 1, Flat World will charge for digital textbooks.

The company’s co-founder told the Chronicle that Flat World was simply losing too much money to keep offering books for free. “We’ve got to be smart with the limited capital we have if the company is to survive 10 years from now,” he said. The cost of $19.99 for a “Study Pass” is still lower than a standard new textbook, but the revolutionary promise of free information is gone.

Flat World’s business model is likely to blame. The company relied on print books to make its money, a dying field that positioned the company as a competitor, not a disruptor, to traditional players. Further, the company had to convince professors and institutions to use its books, and those relationships are built the old-fashioned way, by wining and dining faculty. It’s not cheap, and it showed that Flat World, despite its cries of revolution, still had to work within the confines of the existing infrastructure, selling the same way its traditional competitors were.

Consider it a loss for team revolution. Publishers will likely gloat that free can never be better.

The publishers have already attacked another startup with the same goal of making information free: Boundless, a Boston-based startup, offers free replicas of college textbooks. Boundless creates the books with information it gathers from already-free sources like Wikipedia and open source projects, and instead of working with institutions, has gone straight to the consumer. The company was sued for copyright infringement by three of the four big publishers. That hasn’t stopped the company, which fired back with a feisty defense.

Kno is another digital textbook startup fighting for consumer adoption first (though it charges for access to each book). The company has secured deals with the book publishers, because it doesn’t replace the books but offers a better way to interact with them digitally. The company has raised $68.7 million in venture backing.

Bookboon is a Denmark-based provider of more than 1,000 free ebooks focused on education, business, and travel guides. The books have been downloaded 11 million times in 2011, and the company expects to hit 50 million this year, monetizing them all with ads.

Even more revolutionary is the rise of high quality online learning led by the likes of 2u, Coursera, Minerva Project, and Udemy. This phenomena is apparently (and unfortunately) called MOOC, which stands for Massive Open Online Courses. The MOOCs tend to leave textbooks out of the equation entirely, opting (rationally) to use digital tools and affordable ebooks, but Flat World has partnered with one run by Harvard and MIT called edX.

So while Flat World drops the free books banner, other startups will be there to pick it up.

Update: Flat World’s former CTO and “Chief Openness Officer” David Wiley has posted a note of self-described confusion and bitterness on his personal blog about the company’s decision. He’s not happy to have learned about it secondhand, and not happy that the company chose to move to a closed product when the State of California is now pushing to make even more books available for free online in a couple of years. “Instead of choosing to become more open and gain access to these markets years ahead of the next closest competitor, it appears that the FWK board of directors didn’t have the patience to stay the course,” he wrote. “Do they realize the good will and free marketing they’re throwing away? Do they realize how wide the gaping void is between “inexpensive” and “free and open”?”