When a cultural institution of long standing goes away, it’s a little bit like a death. This is what we’ve learned since we announced last Monday that we are closing our bookstore, the Penn Book Center, in May.

We were lucky enough to buy the store in 2005 from Olga and Achilles Nickles, who founded it with Peter Nickles in 1962. We believed then, and still believe, that the Penn Book Center is a truly unusual place, a product of its location in the intellectual hub of University City.

We, of course, have been heartbroken over our decision. But the last few days have made it clear that we are not alone. The response in emails, on social media, and from customers in person has been overwhelming — some Penn faculty even started a petition for the university to save the store. So many people share our sense of loss and are grieving with us.

We’ve heard from people who’ve been buying books in the store since it opened, who shopped here as students and now shop here with their children, who fondly remember working for Peter or Achilles, who met lifetime friends here, who recall their first book launch at our store. There’s a richness to this layered history that will be hard to replace.

This shared grief reminds us of the extent to which an independent bookstore is rooted in its community. Like a plant, it’s shaped by its environment. Those daily interchanges between booksellers and customers — conversations about books, the weather, politics — help us choose which books to buy and how to display them. The Penn Book Center is truly a collaboration between us and our customers.

But recently, a larger change in the climate for book selling has overwhelmed the local support that sustains the Penn Book Center. The explosive growth of online book sales at cut-rate prices has made selling books in brick-and-mortar stores a difficult proposition.

In response to these challenges, two years ago we shifted our focus away from the textbook sales that for many years were the bulk of our revenue, dramatically increasing our in-store events, running book clubs, changing the store layout to focus on trade sales, and extending our hours. It was a labor of love, and we are proud of the results, especially of our events calendar, which reflects the strength and diversity of literary culture in Philadelphia.

As happy as we are with these changes, however, they have not generated the sales we need to stay open.

We understand the appeal of the low prices and convenience offered by online shopping. But let us not overlook what we lose when a store like the Penn Book Center closes.

For one thing, stores like ours keep the streetscape interesting. Over the years, our huge windows facing Sansom Street have featured themed displays on: women’s history, philosophy, French history, film, jazz, Pope Francis, cats vs. dogs, just to name a few. Our 34th Street window always features books by Philly authors.

Independent stores form great partnerships with the local community. Our windows have promoted shows at the Institute of Contemporary Art and Wolf Humanities Center lectures. Penn writing classes hold readings at our store. Students from Drexel and Penn have designed our store windows. We’ve collaborated on events with nonprofits like Philadelphia Stories, Blue Stoop, and Mighty Writers, along with the All But True Reading Series, among many others.

An independent bookstore is an intellectual hub, a place to talk books and ideas. But it is also a place for more casual conversations. Our lead bookseller, James Gleeson, who has vast knowledge of poetry and philosophy, is likely to ask, “How was your weekend?” on a Monday morning — and be genuinely interested in your response. These casual exchanges are essential to urban life.

A lot of heart has gone into building the Penn Book Center, and it’s very sad to see that come to an end.

Happily, Philadelphia has other independent stores that are, like ours, wonderful in their own particular ways, shaped by and transforming the communities that surround them. We will support them, and we urge you to support them too.

Ashley Montague and Michael Row have owned the Penn Book Center since 2005 and are graduates of the University of Pennsylvania.