Libraries have many uses. Some are public spaces, where even the homeless are welcome. Some are centers for literacy and technology education. Some have public lecture programs and concerts.
Great research libraries have a unique use: supporting what might be called exploratory research. Let us say that one is interested in the Marshall Plan, the post-WWII or early Cold War economic initiative of the United States. One might begin by browsing the catalogue of the New York Public Library on-line from home or at the Library itself, locating books of obvious interest. But as these cannot (yet) all be read on-line, one goes to the Library and orders up a few and after a short time--in my experience, not more than 20 minutes--one sits down at one of the tables in the wonderful Rose Reading Room and begins to read. Sooner or later one finds a reference to a book (or newspaper article, say) that one had not noted in the catalogue. That ordered, one returns to the first book and finds another new reference. By the time that is ordered, the other has appeared. Leafing through that book, one might find other references and order them. Within a few hours there are stacks of books on the table, some one has found to be absolutely essential, others not so pertinent to the research.
Now think about doing this when 2 million books have been removed from the Library and are somewhere in New Jersey. The first part of the task goes smoothly, except that a few books are not available at the Library and will, one is told, appear the next day. So it is with the references one comes across as one reads: some are there, some are not. Crucially, the references that one might have found in those books that are in New Jersey, one does not find that day. Of course if one lives in or near Manhattan, one can return the next day and order up those books that have arrived from New Jersey. If not, one will have to wait for one's next opportunity for a research expedition. But in either place the chain of research is broken. Clues lie hidden in New Jersey. New thoughts and theories they might have suggested do not appear.
It should be easy to see from this story that exploratory research, finding something one had not known about from a book that might have lain untouched in the stacks for fifty years, will be very difficult for people living near the Library and nearly impossible for the not inconsiderable number of people who live far away and journey to New York specifically to use the Library.
Does that matter? Perhaps not. But using this method I have found that much of what I had "known" about the Marshall Plan was not true at all and much about it, for example its influence on Greek politics, is much more relevant today than one might think. That matters to me. Similar results matter to many others. Thus scholarship advances.
That's an interesting thought: Does scholarship advance? Perhaps there are some books on that subject at the NYPL. Some new, some old, some useful, some leading to others about which one has not heard.