"My life is an open bookstore,” Keith Peterson likes to say, with a chuckle.

Peterson is the owner of Selected Works Used Books and Sheet Music at 410 S. Michigan Ave., which has been in business for more than a quarter-century. He works six days a week — “that’s a lot,” he adds — but he has good company. You might say he has a co-owner.

“He just strutted out and he was in charge from the minute he set foot in this place,” Peterson said, describing his then-three-month-old kitten’s first day at the bookstore. The cat, Hodge, whose previous home was the city pound, has since become a favorite with customers. “Just a fearless, really smart, beautiful cat,” Peterson said.

Simply put, Hodge and the bookstore represent two of Peterson’s loves in life: cats and books.

But not long ago he could have lost it all. With the new millennium came declining sales and rising expenses for necessities such as rent and heating. Even downsizing from a larger store to the current 1,200-square-foot location was not enough to compete with an increasingly powerful rival.

“I realized finally that the Internet was eroding into my sales and that people didn’t have to go to bookstores anymore to buy books,” Peterson said.

Peterson estimates overall sales have declined by at least 25 percent since the mid- to late-1990s when annual sales were $80,000 to $90,000 and business was at its height. Annual sales have since dropped to about $50,000 to $60,000. Peterson, who does not take a salary, has one employee who works Wednesdays, the day he has off.

Fellow bookstore owners began selling books online to make up for sinking sales, but Peterson said he was reluctant to do the same.

“One of the ways I reasoned it was, why would I want to dumb down my store and sell the best things I had to people who didn’t even come here, and the people who did come here would not get a chance to get those?” he said.

Even so, in 2003, Peterson had to face and embrace the very thing that was destroying his business. In his words, he made a “survival proposition.” He began selling works on Alibris.com, an online marketplace for independent sellers of new and used books. “If I didn’t start selling online, I wasn’t going to be there to sell anything to anybody,” he said.

Ironically, the Internet became his lifeline.

“It takes away, but it gives,” he said. “I probably get more people coming here from Yelp or other online stuff than from old-fashioned, printed Yellow Pages, which I stopped advertising in.”

Online sales do not make up a large portion of overall sales, but Peterson said if he wasn’t doing it, he wouldn’t be getting by.

Business didn’t always used to be this way.

“The first 15 years or so, I did well,” he said. “I had an eye for what I liked and people, enough of them agreed with me and bought my stuff. It never occurred to me that things would ever take a turn in another direction.”

Peterson has been working in the book business for most of his life. After college graduation, he worked for several bookstores before opening his own on Broadway and Addison streets, then moving to a larger location on Broadway before settling in the current location in the Fine Arts Building. He sells used books and sheet music, everything from $2 novels to collectible books worth several hundred dollars. But most of his books can be bought for less than $20.

“I think the important thing to note is that independent bookstores are not all going away,” said Meg Z. Smith, spokeswoman for the American Booksellers Association in Tarrytown, N.Y. Last year, the organization had a 7 percent increase in membership. Since 2005, more than 400 new bookstores opened and joined the organization.

Along with this growth in the bookselling industry, Smith said, a wider mix of inventory in the past few years has allowed “the bookstore to become a new kind of bookstore.” The inventory includes used books, and increasingly, electronic works. There is reason to be “cautiously optimistic about the future of independent booksellers,” she said.

Kitti Drake, a visitor to Selected Works, hopes to open a used bookstore in her hometown of Indianapolis where a Borders store recently closed as part of a companywide bankruptcy liquidation.

“I love used bookstores, and I don’t want the Nooks [e-book readers] to take over and put us out of business,” she said.

“E-books are here and they are here to stay,” said Carrie Obry, executive director of the Midwest Booksellers Association. “Booksellers need to see that it’s just another format and embrace it as another product they can sell to their customers.”

One way for independent bookstores to do that is to sell Google eBooks on their websites using IndieCommerce, an online business product developed by the American Booksellers Association. For a monthly fee, member bookstores can sell e-books at prices comparable to those on Amazon.com, Obry said.

Investing in the e-book market may be a good idea, based on results of a July Harris Poll, which surveyed more than 2,000 adults. Survey results show one in six Americans use an e-book reader, up from less than one in 10 a year ago. Among those who do not own an e-book reader, one in six say they are likely to get one in the next six months.

Even with the popularity of e-books, Peterson says print books offer something e-books can’t. “If you … can’t get your hands on what you’re suddenly interested in, the impulse will pass. But if you have the book on the shelf,” he said, “suddenly I am really interested in that book I picked up 10 years ago, and I’m so glad I had it.”

Peterson calls himself “one of the last evangelists of Gutenberg technology,” but he knows the book industry is changing. He said more and more books may eventually become available online for free. But he can adapt as he did in 2003 when he began selling books online.

“I think I might have to, as time goes on, try to concentrate as best I could on better books,” he said. “It will be more of a collectors’ kind of retail where people will be looking at specialized interest like really nice art books or first editions — not average books.”

Based on Yelp customer reviews, Selected Works is more than an average bookstore. It has 14 reviews, all five-star ratings.

“I may not be doing everything I should or as well as I should,” Peterson said. “But I’m happy the way it’s turned out and I’m going to try to survive doing what I know how to do and what I like doing, and hopefully people will let me do it.”

And Hodge, the blue-gray cat, will be there to keep him company.