Few buildings in America resonate in the collective imagination as powerfully as the New York Public Library at Fifth Avenue and 42nd Street. The marble palace behind the stone lions is seen by many as the soul of the city. For a century it provided limitless possibilities of gaining knowledge and satisfying curiosity for immigrants just off the boat, and it still opens access to worlds of culture for anyone who walks in from the street. Tamper with that building and you risk offending some powerful sensitivities.

Yet the trustees of the New York Public Library—I write as one of them but only in my capacity as a private individual—have decided to rearrange a great deal of that sacred space. According to a plan given preliminary approval by them last February, they will sell the run-down Mid-Manhattan branch library—just opposite the main public library on Fifth Avenue—and the Science, Industry, and Business Library (SIBL) at Madison Avenue and 34th Street, and they will use the proceeds to expand the interior of the 42nd Street building. They will not touch the famous façade on Fifth Avenue, but they will install a new circulating library on the lower floors to replace the Mid-Manhattan branch, whose collections will be incorporated into the holdings of the main library.

All this shifting about of books will require rebuilding parts of the infrastructure at 42nd Street. The steel stacks now hidden under the great Rose Main Reading Room on the third floor will be replaced by the new branch and business library on the lower floors. Several grand rooms on the second floor will be refurbished for the use of readers and writers, who will be provided with carrels, computer stations, a lounge, and possibly a café. Most of the three million volumes from the old stacks will remain in the building, either in redesigned storage space or in shelving located under Bryant Park. But many—for the most part books that are rarely consulted and journals that are also available online—will be shipped to the library’s storage facility in Princeton, New Jersey, along with some of the holdings from the SIBL.

Most of the renovated library will look the same as it does today. Its special collections and manuscripts will remain in place, and readers will be able to consult them in the same quiet setting of oak panels and baronial tables. The great entrance hall, grand staircases, and marble corridors will continue to convey the atmosphere of a Beaux-Arts palace of the people. But the new branch library on the lower floors…