One of the pleasures of libraries is that, unlike bookstores, their holdings are not confined only to current titles. In fact, most of the books on a library's shelves have been out of print for years! The purpose of a library, at its most fundamental level, is to provide shelf-space for just such no-longer marketable books. Many of them sit there for years without being checked-out. A bookstore, on the other hand, operates according to a different imperative. The point is to "move" books, not to provide a home for them. That's why a library's books are called its "collection" or its "holdings," but the books in a bookstore are merely "stock." There's just no point in holding onto a title that will not sell. If we think of a bookstore as a lens through which we peer into the world of books, well, even the largest bookstores provide a very narrowly-defined perspective. But the lens of the library gives a broader view that includes within its range centuries of writing and publishing.
These days I'm reading a library book by John Stott, called The Cross of Christ. It's not particularly old (1986), and it's not out of print, but it's also not likely to be on the shelf of your local Borders. I discovered this book by hunting through an online library catalog that combines most of the academic libraries in my state, including that of a local seminary. I instructed the catalog to find me all its books that included the words "Christian" and "atonement" as its subject.
I had to sort through quite a few books, most of them of an overly-academic nature (for my tastes) or from a theological perspective that I wanted nothing to do with. But then I landed on Stott's book and knew it was just what I'd been looking for.
The CBD description of this book is:
A major study of the cross in Christian theology, life and mission, this book enters into a dialogue with Scripture, tradition and the world today. Beginning with the centrality of the cross, Stott goes on to examine the apparent and underlying reasons for Christ's death. He then defends the substitutionary view of the atonement and explores the achievement of Christ on the cross. Finally, he discusses the implications of the cross for Christian worship, self-understanding, life and hope.And, by the way, it's a marvelous book. I will be reporting back on it here at Mr. Standfast, I hope. In the meantime, why don't you take a trip to your local library. Explore its shelves. Learn to use its online catalog. There are riches waiting there that no "Barnes & Noble" can ever match.