This year the eighty-two-branch New York Public Library celebrates its centenary. In the spring of 1895 a plan was signed to drain the Croton Reservoir on Fifth Avenue between Fortieth and Forty-second streets to make way for the system’s flagship research library—the graceful Beaux Arts building guarded by the now-famous twin lions. Completed in 1911, it has provided much of the raw stuff out of which this and other magazines have been spun over the years. Beneath the smokey golden ceilings of its reading rooms sit people enjoying the day’s New York Post or scrolling through the long-gone New York World . But the library’s tremendous catacomb under the Bryant Park lawn remains the heart of the place. Turn in a slip for an obscure political pamphlet by William Jennings Bryan from September 1915 and up out of the tunnels come the Commoner’s yellowed remarks from eighty years ago, like a prehistoric fish from the ocean floor. These days the library is impressively computerized, too, but what it can still drag up from its holdings (despite thefts, budget cuts, and a winnowed staff) seems almost as wondrous as it must have generations ago. It handled four million requests last year.

Last spring the library put on a tremendous birthday light show out front (the switch was flipped by Mayor Giuliani), and currently it offers two shows celebrating freedom of thought: on the third floor a display of the library’s one hundred and fifty most important books of our century, from Freud’s Interpretation of Dreams to Ed Krol’s The Whole Internet , and on the main floor a seventyeight-foot glass-ark exhibit honoring people who through the centuries have risked everything for freedom.