India, Aug. 6 -- Five floors and shelves stacked with more than 300,000 books is the definition of a problem of plenty. As I look around and walk the aisles, I see a telling sign: "You may not find a book, but a book will find you."

I traipse around Baldwin's Book Barn, a five-storey barn located in the leafy quiet outside Philadelphia, in the charming borough of West Chester, Pennsylvania. Housed in a historic 1822 structure with thick stone walls, creaky wooden floors, and ancient corners, it's one of the most unusual second-hand bookstores in the United States.

Baldwin's story goes back to 1934, when William and Lilla Baldwin launched a humble bookstore in their Wilmington home. The couple initially sold rare and used books from thei...